Tropical Storm Teddy

Post Tropical Teddy Track 1400 Hours September 23 2020
Post Tropical Teddy Track 1400 Hours September 23 2020

Post Tropical Teddy Wind Speed FieldPost-Tropical TeddyNWS National Hurricane Center Miami FL 500 PM AST Wed Sep 23, 2020 (see Wed video below)

Teddy is moving quickly north-northeastward just west of Newfoundland this afternoon as a decaying extratropical low. Maximum winds from an earlier scatterometer pass were about 50 kt, and the winds have probably come down based on pressure data from Meat Cove as the storm left Nova Scotia, so the initial wind speed is set to 45 kt. Little change in intensity is expected overnight as Teddy races near northwestern Newfoundland and southeastern Labrador overnight. The storm is then forecast to move across the Labrador Sea on Thursday and become absorbed into a powerful extratropical low, where hurricane-force winds are forecast southwest of Greenland. No changes were made to the previous track or intensity forecasts.

Even after Teddy passes Nova Scotia and Newfoundland, large swells creating dangerous rip currents will linger over much of the southwestern Atlantic basin for the next few days.

Key Messages:

  • 1. The most significant hazards expected from Teddy now are dangerous waves and high winds for Newfoundland, and Tropical Storm Warnings are in effect for parts of southwestern Newfoundland.
  • 2. Very large swells produced by Teddy are expected to affect portions of Bermuda, the Leeward Islands, the Greater Antilles, the Bahamas, the east coast of the United States, and Atlantic Canada during the next couple of days. These swells are expected to cause life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS

INIT  23/2100Z 48.6N  59.6W   45 KT  50 MPH - Post Tropical (WNW Mainland, NF Canada)
 12H  24/0600Z 52.0N  56.0W   45 KT  50 MPH - Post Tropical (WNW Henley Harbour NF Canada)
 24H  24/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM AST Wed Sep 23, 2020

Surface observations indicate that Teddy made landfall this morning near Ecum Secum, Nova Scotia, near 1200 UTC with estimated maximum sustained winds of 65 mph and a minimum pressure of 964 mb. Since then, the storm has continued to race across Nova Scotia and is slowly weakening. The initial wind speed is set to 50 kt. Teddy should move north-northeastward across the Gulf of St. Lawrence this afternoon then move near Newfoundland by tonight. After passing east of Labrador on Thursday, the global models show Teddy merging with another large extratropical low over the north Atlantic. No significant changes were made to the previous track or intensity forecasts, which are similar to a blend of the GFS and ECMWF models.

Even after Teddy passes Nova Scotia and Newfoundland, large swells creating dangerous rip currents will linger over much of the southwestern Atlantic basin for the next few days.

Key Messages:

  • 1. The most significant hazard expected from Teddy today is large destructive waves along the southeastern coast of Nova Scotia. Tropical Storm Watches and Warnings are in effect for portions of Nova Scotia, Newfoundland, Prince Edward Island and the Magdalen Islands, and heavy rainfall across Atlantic Canada is expected through Thursday.
  • 2. Very large swells produced by Teddy are expected to affect portions of Bermuda, the Leeward Islands, the Greater Antilles, the Bahamas, the east coast of the United States, and Atlantic Canada during the next few days. These swells are expected to cause life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS

INIT  23/1500Z 46.0N  61.3W   50 KT  60 MPH - Post Tropical (ESE Port Hood, NS Canada)
 12H  24/0000Z 49.5N  58.7W   45 KT  50 MPH - Post Tropical (WNW Trout River, NF Canada)
 24H  24/1200Z 54.5N  54.5W   45 KT  50 MPH - Post Tropical (ENE Indian Harbour, NF Canada)
 36H  25/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM AST Tue Sep 22, 2020 

Extratropical transition has been ongoing since last night, with the cyclone’s associated rain shield expanding over a great distance in the northern semicircle. In addition, multiple dropsonde observations from the Air Force Reserve hurricane hunters and buoy data show a sharp temperature gradient of nearly 20 degrees F from northwest quadrant to the southeast, indicative of the cyclone’s involvement with the strong baroclinic frontal zone.

Accordingly, Teddy has become a strong post-tropical extratropical cyclone. Highest flight-level winds recorded this evening were 83 kt about 85 miles northeast of the center and the highest SFMR surface winds were 63 kt. A recent METOP-C scatterometer pass showed sustained winds no higher than 59 kt in the east quadrant. A blend of these data yields an initial intensity of 70 kt for this advisory. Further gradual weakening is forecast through the period as a result of the rapidly decreasing sea surface temperatures (less than 20C) north of the North Wall of the gulf stream. The NHC forecast indicates Teddy approaching the coast of Nova Scotia below hurricane strength, but still as a strong post-tropical extratropical low. Teddy should continue to gradually spin down as the cyclone moves north-northeastward toward Newfoundland.

The initial motion is estimated to be northward, or 010/16 kt. A north-northeastward turn is forecast later tonight or early Wednesday in response to an approaching mid-latitude shortwave trough moving out of the northeast U.S. Teddy should move over Nova Scotia tomorrow and near the island of Newfoundland, and the adjacent waters of the Gulf of St. Lawrence Wednesday night. Afterward, the post-tropical cyclone will likely be absorbed by an even larger high latitude extratropical cyclone near Greenland. There has been no significant changes made to the NHC forecast track this evening, and it’s in best agreement with the HFIP Corrected Consensus Approach model.

Key Messages:

  • 1. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada late today through Thursday. The most significant hazard expected from Teddy is large destructive waves forecast along the southern coast of Nova Scotia through Wednesday.
  • 2. Very large swells produced by Teddy are expected to affect portions of Bermuda, the Leeward Islands, the Greater Antilles, the Bahamas, the east coast of the United States, and Atlantic Canada during the next few days. These swells are expected to cause life-threatening surf and rip current conditions.
  • 3. Tropical Storm Watches and Warnings are in effect for portions of Nova Scotia, Newfoundland, Prince Edward Island and the Magdalen Islands, and heavy rainfall across Atlantic Canada is expected through Thursday.
FORECAST POSITIONS AND MAX WINDS

INIT  23/0300Z 42.8N  63.9W   70 KT  80 MPH - Post Tropical (ESE Shelburne, NS Canada)
 12H  23/1200Z 45.3N  62.3W   60 KT  70 MPH - Post Tropical (ESE Garden of Eden, NS Canada)
 24H  24/0000Z 49.8N  58.7W   50 KT  60 MPH - Post Tropical (ESE Sally's Cove, NF Canada)
 36H  24/1200Z 54.7N  54.9W   45 KT  50 MPH - Post Tropical (ENE Emily Harbour, LAB Canada)
 48H  25/0000Z...ABSORBED BY A LARGER LOW

NWS National Hurricane Center Miami FL 500 PM AST Tue Sep 22, 2020

Teddy is a very impressive cyclone on satellite images this afternoon, even from full-disk images. The hurricane’s circulation is over 1000 miles wide, with an enormous distinct comma shape and frontal features especially in the eastern semicircle. As far as what to call the system convection has actually deepened near the center during the past several hours, and an AMSR pass around 1700 UTC showed that the system still had a low-level eye feature. For that reason and for simplicity’s sake, the system will remain a hurricane on this advisory, although it is obviously a hybrid low with many characteristics of a non-tropical cyclone. The initial wind speed is lowered to 80 kt, assuming the filling trend reported by the last NOAA Hurricane Hunter mission continued. The wind radii are expanded based on ASCAT data, with tropical-storm-force winds over eastern Nova Scotia already.

The hurricane is forecast to transition into a post-tropical cyclone later tonight or early tomorrow due to the cooler waters north of the Gulf Stream likely weakening any central convection. Teddy should decay below hurricane-strength before reaching Nova Scotia and steadily weaken as it moves over the even colder waters in the Gulf of St. Lawrence. The new intensity forecast is a little lower than the previous one and is closest to the GFS model.

Teddy is moving northward now and should turn north-northeastward tomorrow ahead of the next trough in the mid-latitudes. This will take Post-Tropical Teddy over Nova Scotia and near Newfoundland during the next couple of days, with the cyclone likely being absorbed into a larger extratropical cyclone west of Greenland in 2-3 days. There are no significant changes to report, though there has been a slight westward shift of the track near Newfoundland.

The hazards from Teddy are extending at quite a distance from the center of this hurricane. In addition to the 500-mile wind radii in the northeastern quadrant, Canadian buoy 44150 has recently reported 42 ft (13 m) significant wave heights, with the buoy still about 90 n mi from the center.

Key Messages:

  • 1. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada late today through Thursday. The most significant hazard expected from Teddy is large destructive waves forecast along the southern coast of Nova Scotia through Wednesday.
  • 2. Very large swells produced by Teddy are expected to affect portions of Bermuda, the Leeward Islands, the Greater Antilles, the Bahamas, the east coast of the United States, and Atlantic Canada during the next few days. These swells are expected to cause life-threatening surf and rip current conditions.
  • 3. Tropical Storm Watches and Warnings are in effect for portions of Nova Scotia, Newfoundland, Prince Edward Island and the Magdalen Islands, and heavy rainfall across Atlantic Canada is expected through Thursday.
FORECAST POSITIONS AND MAX WINDS

INIT  22/2100Z 41.1N  64.2W   80 KT  90 MPH - Category 1 (WNW New York City, NY)
 12H  23/0600Z 43.1N  63.5W   65 KT  75 MPH - Post Tropical (ESE Shelburne, NS Canada)
 24H  23/1800Z 47.0N  60.7W   55 KT  65 MPH - Post Tropical (ESE Meat Cove, NS Canada)
 36H  24/0600Z 51.5N  56.5W   45 KT  50 MPH - Post Tropical (WNW Eddies Cove, NF Canada)
 48H  24/1800Z 56.5N  53.5W   45 KT  50 MPH - Post Tropical (ENE Hopedale, LAB Canada)
 60H  25/0600Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM AST Tue Sep 22, 2020 

Teddy is in the late stages of extratropical transition. The hurricane has taken on a large comma shape in satellite images, with a huge dry-air intrusion aloft near the center and a cold front on the western side of the cyclone. While it is tempting to call it an extratropical now, temperature data from a NOAA Hurricane Hunter aircraft indicate that Teddy has maintained a significant warm core, and the strongest winds on the southwestern side appear to be more related to the cyclone and not the front. Lastly, deep convection is trying to re-develop near the center, another indication that the transition is not yet done. Thus Teddy will remain a hurricane on this advisory. The initial wind speed is set to 90 kt, a blend of the 122-kt flight-level winds, 75-kt SFMR values, and global model analyses since much of this large hurricane is not being sampled.

Teddy should transition into a post-tropical cyclone by the time it reaches Nova Scotia and steadily weaken as it moves over the cooler waters north of the Gulf Stream. The cyclone should turn northward today and north-northeastward tomorrow ahead of the next trough in the mid-latitudes. This will take Post-Tropical Teddy over Nova Scotia and near Newfoundland during the next couple of days, with the cyclone likely being absorbed into a larger extratropical cyclone west of Greenland in 2-3 days. There are no significant changes to report, except to show a sooner dissipation, which is consistent with the latest global models solutions.

The hurricane-force and tropical-storm-force winds fields, plus 12-ft seas area, from Teddy have just about doubled overnight, so it is important to note that hazards will extend much farther than normal from the center of this hurricane. The NOAA Hurricane Hunter reported hurricane-force surface winds 120 n mi northwest of the center, and Canadian buoy 44150 has recently reported 34-ft significant wave heights, with the buoy still about 180 n mi from the center.

Key Messages:

  • 1. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada late today through Thursday. The most significant hazard expected from Teddy is large destructive waves forecast along the southern coast of Nova Scotia through Wednesday.
  • 2. Very large swells produced by Teddy are expected to affect portions of Bermuda, the Leeward Islands, the Greater Antilles, the Bahamas, the east coast of the United States, and Atlantic Canada during the next few days. These swells are expected to cause life-threatening surf and rip current conditions.
  • 3. Tropical Storm Watches and Warnings are in effect for portions of Nova Scotia, Prince Edward Island and Newfoundland, and heavy rainfall across Atlantic Canada is expected with Teddy through Thursday.
FORECAST POSITIONS AND MAX WINDS

INIT  22/1500Z 39.6N  63.7W   90 KT 105 MPH - Category 2 (WNW New York City, NY)
 12H  23/0000Z 41.8N  64.1W   75 KT  85 MPH - Category 1 (ESE Shelburne, NS Canada)
 24H  23/1200Z 44.8N  62.4W   60 KT  70 MPH - Post Tropical (ESE Sober Island, NS Canada)
 36H  24/0000Z 48.8N  59.3W   50 KT  60 MPH - Post Tropical (WNW Lourdes, NF Canada)
 48H  24/1200Z 54.0N  54.0W   45 KT  50 MPH - Post Tropical (WSW Indian Tickle, LAB Canada)
 60H  25/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM AST Mon Sep 21, 2020

Air Force Reserve hurricane hunter found Teddy a little stronger this evening. Flight level peak wind was 111 kt in the east quadrant and the highest observed SFMR wind was 69 kt. A blend of these data yields an initial intensity of 85 kt for this advisory.

Teddy is accelerating toward the north in response to a mid- to upper tropospheric mid-latitude trough approaching from the northwest. Dynamic forcing produced by the aforementioned baroclinic system and warm (27-28C) waters associated with the Gulf Stream could induce a short period of strengthening during the next few hours, or so. Through the remaining portion of the forecast period, Teddy will traverse cooler oceanic temperatures north of the Gulf Stream and lose its baroclinic support inducing a gradual weakening trend as the post-tropical cyclone quickly moves over eastern Nova Scotia, the Gulf of St. Lawrence and Newfoundland. After that time, Teddy should become absorbed by a larger non-tropical, high latitude low pressure system.

There still remains much uncertainty as to whether or not Teddy will complete its extratropical transition prior to reaching Nova Scotia. The global models show the cyclone merged or embedded in the baroclinic zone, but the associated simulated infrared presentation shows Teddy maintaining a rather small warm, inner core. Regardless of it classification during that time, high winds, heavy rain, storm surge and destructive waves are still predicted for the south coast of Nova Scotia.

Teddy’s horizontal wind profile is forecast to nearly double during the next couple of days as it moves northward and interacts with the aforementioned baroclinic system. Gale-force winds are likely along portions of the near shore waters of the northeast United States. The forecast wind radii at the 24 hour period and beyond are based on the RVCN Wind Radii Consensus model that consists of a bias-corrected average of the global and regional models.

Please see products from your local office for more information about marine hazards, including extremely dangerous rip currents expected over much of the western Atlantic beaches.

Key Messages:

  • 1. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada late Tuesday through Thursday, where direct impacts from wind, rain, and storm surge are expected. Tropical Storm Watches and Warnings are in effect for portions of Nova Scotia, Prince Edward Island and Newfoundland.
  • 2. Very large swells produced by Teddy are expected to affect portions of Bermuda, the Leeward Islands, the Greater Antilles, the Bahamas, the east coast of the United States, and Atlantic Canada during the next few days. These swells are expected to cause life-threatening surf and rip current conditions.
  • 3. Heavy rainfall across Atlantic Canada is expected with Teddy between Tuesday and Thursday after it becomes a strong post-tropical cyclone.
FORECAST POSITIONS AND MAX WINDS

INIT  22/0300Z 35.6N  61.5W   85 KT 100 MPH - Category 2 (ENE St. Georges, Bermuda)
 12H  22/1200Z 38.4N  62.6W   85 KT 100 MPH - Category 2 (ESE Atlantic City, NJ)
 24H  23/0000Z 41.1N  63.1W   70 KT  80 MPH - Category 1 (ENE New York City, NY)
 36H  23/1200Z 44.6N  61.5W   60 KT  70 MPH - Category 1 (ESE Port Dusserin NS Canada)
 48H  24/0000Z 49.0N  58.7W   50 KT  60 MPH - Post Tropical (WSW York Harbour, NF Canada)
 60H  24/1200Z 52.8N  54.8W   45 KT  50 MPH - Post Tropical (ENE Charlottetown, NF Canada)
 72H  25/0000Z 58.1N  51.4W   40 KT  45 MPH - Post Tropical (WSW Nanortalik, Greenland)
 96H  26/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 PM AST Mon Sep 21, 2020

Teddy is gradually losing tropical characteristics with weaker deep convection near the center and more convective asymmetry. The initial wind speed is kept at 80 kt, assuming any decrease in organization has been offset by the doubling of the forward speed since the last advisory. Note that Dvorak estimates are likely to underestimate the true maximum winds in this extratropical transition situation.

The hurricane is now moving quickly northward as a mid-latitude trough picks up the cyclone. All of the guidance show Teddy strengthening overnight due to a baroclinic energy infusion from this trough and increased instability from the warmer waters of the Gulf Stream/North Atlantic. Afterward, Teddy should lose its baroclinic forcing and move over cooler water late Tuesday, causing weakening while it accelerates to the north-northeast across eastern Nova Scotia, the Gulf of St. Lawrence and Newfoundland before dissipating in 3-4 days. No significant changes were made to the track forecast except for a westward shift beyond 48 hours. While there is some uncertainty about the exact status of Teddy near Nova Scotia, since much of the model guidance keeps the cyclone with a warm core and some convection, it doesn’t change the hazards much with significant chances of high winds, heavy rain, storm surge and destructive waves for the south coast of Nova Scotia.

Teddy’s size will likely double during the next couple of days as it moves northward and interacts with the aforementioned trough. Gale-force winds are likely along portions of the near shore waters of the northeast United States. Please see products from your local office for more information about marine hazards, including extremely dangerous rip currents expected over much of the western Atlantic beaches.

Key Messages:

  • 1. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada late Tuesday through Thursday, where direct impacts from wind, rain, and storm surge are expected. Tropical Storm Watches and Warnings are in effect for portions of Nova Scotia, Prince Edward Island and Newfoundland.
  • 2. Very large swells produced by Teddy are expected to affect portions of Bermuda, the Leeward Islands, the Greater Antilles, the Bahamas, the east coast of the United States, and Atlantic Canada during the next few days. These swells are expected to cause life-threatening surf and rip current conditions.
  • 3. Heavy rainfall across Atlantic Canada is expected with Teddy between Tuesday and Thursday after it becomes a strong post-tropical cyclone.
FORECAST POSITIONS AND MAX WINDS

INIT  21/2100Z 33.2N  62.0W   80 KT  90 MPH - Category 1 (ENE St. Georges, Bermuda)
 12H  22/0600Z 36.5N  62.5W   90 KT 105 MPH - Category 2 (ENE St. Georges, Bermuda)
 24H  22/1800Z 39.5N  63.7W   80 KT  90 MPH - Category 1 (ENE New York City, NY)
 36H  23/0600Z 42.2N  63.2W   70 KT  80 MPH - Category 1 (ESE Shelburne, NS Canada)
 48H  23/1800Z 46.5N  61.5W   60 KT  70 MPH - Post Tropical (WNW Margaree Harbour, NS Canada)
 60H  24/0600Z 50.5N  58.0W   50 KT  60 MPH - Post Tropical (WNW Bellburns, NF Canada)
 72H  24/1800Z 54.5N  53.5W   45 KT  50 MPH - Post Tropical (ENE Catwright, LAB Canada)
 96H  25/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM AST Mon Sep 21, 2020 

Teddy has weakened some since yesterday. While the maximum 700-mb winds from the latest Air Force Reserve Hurricane Hunter aircraft mission were 93 kt, the peak SFMR values were only 68 kt. A blend of these data with some undersampling due to the large size of Teddy gives an initial wind speed of 80 kt.

The hurricane is beginning to accelerate to the north-northeast as the long-awaited mid-latitude trough begins to pick up the cyclone. All of the guidance is in very good agreement that Teddy will benefit from this interaction, growing in both size and maximum winds due to this trough and warmer waters in the Gulf Stream. Thus, the hurricane should intensify overnight, and the new intensity forecast is close to the latest GFS model. Afterward, the baroclinic energy source is exhausted, and Teddy should move north of the Gulf Stream by Wednesday, helping to complete its post-tropical transition. The cyclone should weaken while it accelerates to the north-northeast across eastern Nova Scotia, the Gulf of St. Lawrence, and Newfoundland before dissipating in 3-4 days. No significant changes were made to the track forecast.

Teddy’s size will likely increase substantially during the next couple of days as it moves northward and interacts with the aforementioned frontal system. Gale force winds are likely along portions of the near shore waters of the northeast U.S. Please see products from your local office for more information about marine hazards.

Key Messages:

  • 1. The center of Teddy is forecast to move east of Bermuda today. Wind gusts of tropical-storm-force have been reported on the island, and tropical storm conditions could continue today.
  • 2. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada late Tuesday through Thursday, where there is an increasing risk of direct impacts from wind, rain, and storm surge. A Tropical Storm Watch is in effect for portions of Nova Scotia, and heavy rainfall across Atlantic Canada is expected with Teddy between Tuesday and Thursday after it becomes a strong post-tropical cyclone.
  • 3. Large swells produced by Teddy are expected to affect portions of Bermuda, the Leeward Islands, the Greater Antilles, the Bahamas, the east coast of the United States, and Atlantic Canada during the next few days. These swells will likely cause life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS

INIT  21/1500Z 31.1N  62.7W   80 KT  90 MPH - Category 1 (ESE St. Georges, Bermuda)
 12H  22/0000Z 34.4N  62.4W   85 KT 100 MPH - Category 2 (ENE St. Georges, Bermuda)
 24H  22/1200Z 38.2N  63.7W   90 KT 105 MPH - Category 2 (ENE St. Georges, Bermuda)
 36H  23/0000Z 40.7N  64.3W   80 KT  90 MPH - Category 1 (ESE New York City, NY)
 48H  23/1200Z 43.7N  63.0W   65 KT  75 MPH - Post Tropical (WSW Darmouth NS Canada)
 60H  24/0000Z 47.5N  60.5W   55 KT  65 MPH - Post Tropical (WSW Searston, NF Canada)
 72H  24/1200Z 51.5N  55.5W   45 KT  50 MPH - Post Tropical (WSW Nymph Island NF Canada)
 96H  25/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM AST Sun Sep 20, 2020 

Teddy’s satellite presentation has changed little during the past several hours albeit some warming of the eye. The 53rd Air Force Reserve hurricane hunters recorded a central pressure this evening of 963 mb, unchanged from the previous mission, and the Dvorak subjective intensity estimates haven’t changed either. Therefore, the initial intensity is held at 90 kt for this advisory.

There is a chance, within the next 24 hours, that Teddy could strengthen a bit due to dynamic forcing as a result of the approaching baroclinic zone moving off of the northeast coast of the United States. In Fact, the HCCA intensity model shows a peak of 95 kt at the 24 hour period. By Tuesday afternoon, however, increasing southwesterly shear associated with the rapidly approaching mid-latitude major shortwave trough, from the northwest, should induce weakening. Because Teddy is a very large and strong tropical cyclone, only gradual weakening is predicted. By mid period, the large-scale models agree that Teddy will merge with the aforementioned trough and associated frontal zone and complete its extratropical cyclone transition south of Nova Scotia Tuesday evening. Teddy is still forecast to be a very large and powerful extratropical cyclone as it approaches, Nova Scotia at that time. Wind, rain, surf and storm surge hazards are expected to spread over an extensive portion of Atlantic Canada mid-week.

The forecast wind radii at the 36 hour period and beyond, are based on the RVCN Wind Radii Consensus model that consists of a bias-corrected average of the global and regional models.

The initial motion is estimated to be north-northwestward, or 5 kt. The hurricane is likely to turn northward Monday morning and continue in this general motion through Wednesday morning. Around the 60 hour period, a turn north-northeastward is forecast ahead of yet another mid-latitude pulse moving into eastern Canada. No significant adjustments were made to the NHC track forecast and it lies in between the surprisingly tightly clustered model guidance.

Extremely dangerous surf conditions with 20-ft waves have been reported on the south shore of Bermuda, and officials are encouraging residents to avoid going into or near the water.

Key Messages:

  • 1. The center of Teddy is forecast to move east of Bermuda on Monday. Tropical storm conditions are likely on the island beginning overnight and could continue into Monday evening.
  • 2. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada late Tuesday through Thursday, where there is an increasing risk of direct impacts from wind, rain, and storm surge. A Tropical Storm Watch is in effect for portions of Nova Scotia, and heavy rainfall across Atlantic Canada is expected with Teddy between Tuesday and Thursday after it becomes a strong post-tropical cyclone.
  • 3. Large swells produced by Teddy are expected to affect portions of Bermuda, the Leeward Islands, the Greater Antilles, the Bahamas, the east coast of the United States, and Atlantic Canada during the next few days. These swells could cause life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS

INIT  21/0300Z 29.4N  63.6W   90 KT 105 MPH - Categoey 2 (ESE St. Georges, Bermuda)
 12H  21/1200Z 30.9N  63.5W   90 KT 105 MPH - Categoey 2 (ESE St. Georges, Bermuda)
 24H  22/0000Z 34.8N  62.9W   95 KT 110 MPH - Categoey 2 (ESE St. Georges, Bermuda)
 36H  22/1200Z 38.5N  63.8W   90 KT 105 MPH - Categoey 2 (ESE St. Georges, Bermuda)
 48H  23/0000Z 41.3N  64.2W   80 KT  90 MPH - Post Tropical (ESE New York City, NY)
 60H  23/1200Z 44.5N  62.8W   65 KT  75 MPH - Post Tropical (ESE Clam Harbour, NS Canada)
 72H  24/0000Z 48.6N  59.9W   50 KT  60 MPH - Post Tropical (WNW Mainland, NF Canada)
 96H  25/0000Z 57.4N  47.0W   45 KT  50 MPH - Post Tropical (ESE PC, Greenland)
120H  26/0000Z...ABSORBED BY A LARGER LOW

NWS National Hurricane Center Miami FL 500 PM AST Sun Sep 20, 2020

Satellite images show that Teddy is continuing to maintain a central core, albeit eroded on the western side due to shear and dry air. However, the latest microwave data show a more distinct eye than conventional data would indicate, along with an open eyewall. The initial intensity is held at 90 kt, pending Air Force Reserve Hurricane Hunter aircraft data this evening.

The hurricane has turned north-northwestward and is likely to turn northward tonight and north-northeastward tomorrow due to an approaching large mid-latitude trough. By early Tuesday, the cyclone should turn back to the north-northwest as it rotates around the same trough, then turn northeastward early Wednesday ahead of yet another trough moving into from eastern Canada. Track model guidance remains in very good agreement, and only a slight westward adjustment was made to the forecast.

The global models are in excellent agreement on Teddy transitioning into a large non-tropical low between Bermuda and Nova Scotia in about 2 days. In many respects, the upcoming trough interaction reminds me of an extratropical transition like Sandy 2012, thankfully happening at a good distance from land, with the GFS/ECMWF models showing pressures into the 940s tomorrow, a slight increase in maximum winds, and a large increase in the size of the tropical-storm-force winds. Beyond Tuesday, the hurricane should become post-tropical near or south of Nova Scotia and be absorbed by a larger extratropical low after day 4 to the northeast of Newfoundland. Little change was made to the official forecast, other than show a small increase tomorrow as the peak extratropical forcing deepens the cyclone. It is still worth noting every model has a rather large and strong post-tropical cyclone near Nova Scotia in 2-3 days, with hazards that will extend a very long way from the center.

Extremely dangerous surf conditions with 20-ft waves have been reported on the south shore of Bermuda, and officials are encouraging residents to avoid going into or near the water.

Key Messages:

  • 1. The center of Teddy is forecast to move east of Bermuda on Monday. Tropical storm conditions are likely on the island beginning this evening and could continue into Monday evening.
  • 2. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada late Tuesday through Thursday, where there is an increasing risk of direct impacts from wind, rain, and storm surge. A Tropical Storm Watch has been issued for portions of Nova Scotia, and heavy rain is also expected across sections of Atlantic Canada.
  • 3. Large swells produced by Teddy are expected to affect portions of Bermuda, the Leeward Islands, the Greater Antilles, the Bahamas, the east coast of the United States, and Atlantic Canada during the next few days. These swells could cause life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS

INIT  20/2100Z 29.0N  63.4W   90 KT 105 MPH - Category 2 (ESE St. Georges, Bermuda)
 12H  21/0600Z 30.1N  63.5W   85 KT 100 MPH - Category 2 (ESE St. Georges, Bermuda)
 24H  21/1800Z 32.8N  62.6W   90 KT 105 MPH - Category 2 (ENE St. Georges, Bermuda)
 36H  22/0600Z 36.9N  63.0W   90 KT 105 MPH - Category 2 (ENE St. Georges, Bermuda)
 48H  22/1800Z 40.0N  64.0W   85 KT 100 MPH - Category 2 (ESE New York City, NY)
 60H  23/0600Z 42.7N  63.5W   75 KT  85 MPH - Post Tropical (ESE Shelburne, NS Canada)
 72H  23/1800Z 46.0N  61.3W   60 KT  70 MPH - Post Tropical (ESE Mull River, NS Canada)
 96H  24/1800Z 54.5N  50.5W   40 KT  45 MPH - Post Tropical (ESE PC, Greenland)
120H  25/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM AST Sun Sep 20, 2020 

The satellite signature of Teddy has degraded from an eye pattern overnight into a central dense overcast this morning. Air Force Reserve Hurricane Hunter aircraft data indicate that the hurricane has weakened, and the initial wind speed is set to 90 kt, perhaps generously. The aircraft data does still show that Teddy remains a large hurricane, with hurricane-force winds extending outward in the northeastward quadrant to about 70 n mi.

While the forecast intensity does not change much over the next couple of days, the hurricane should undergo significant changes during that time. Teddy should not lose any more strength by late today due to favorable positioning with an approaching trough, and the gale-force winds should greatly expand due to this trough interaction. In 2 or 3 days, after the system occludes and becomes post-tropical, the cyclone should weaken because of a loss of extratropical forcing while over the cooler water south of Nova Scotia. Eventually Teddy will probably get absorbed by a larger extratropical low around day 5. Model guidance is fairly tightly packed around the official wind forecast, which leans on the global models given the substantial extratropical contributions, plus or minus 5 kt throughout the forecast period.

The hurricane has resumed a northwestward motion or 320/8 kt. Teddy is likely to turn northward today and north-northeastward tomorrow due to the aforementioned trough. By early Tuesday, the cyclone should turn back to the north-northwest as it rotates around the same trough, then turn northeastward early Wednesday ahead of yet another trough moving into from eastern Canada. Although the forecast evolution is complex, model guidance is in remarkably good agreement, and no substantial changes were made to the previous forecast. Regardless of the details, every model has a rather large and strong post-tropical cyclone south of Nova Scotia in about 3 days.

Key Messages:

  • 1. The center of Teddy is forecast to move east of Bermuda on Monday. Tropical storm conditions are likely on the island beginning this evening and could continue into Monday evening.
  • 2. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada early next week, where there is an increasing risk of direct impacts from wind, rain, and storm surge. Residents there should closely monitor the progress of Teddy and updates to the forecast.
  • 3. Large swells produced by Teddy are expected to affect portions of the Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, the east coast of the United States, and Atlantic Canada during the next few days. These swells could cause life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS

INIT  20/1500Z 28.3N  62.8W   90 KT 105 MPH - Category 2 (ESE St. Georges, Bermuda)
 12H  21/0000Z 29.2N  63.4W   85 KT 100 MPH - Category 2 (ESE St. Georges, Bermuda)
 24H  21/1200Z 31.0N  62.9W   85 KT 100 MPH - Category 2 (ESE St. Georges, Bermuda)
 36H  22/0000Z 34.8N  62.1W   85 KT 100 MPH - Category 2 (ENE St. Georges, Bermuda)
 48H  22/1200Z 38.8N  63.0W   85 KT 100 MPH - Category 2 (ENE St. Georges, Bermuda)
 60H  23/0000Z 41.7N  63.4W   75 KT  85 MPH - Extra Tropical (ESE Boston MA)
 72H  23/1200Z 44.5N  62.0W   60 KT  70 MPH - Extra Tropical (ESE Port Dufferin NS Canada)
 96H  24/1200Z 53.0N  53.0W   40 KT  45 MPH - Extra Tropical (ESE Cartwright, Canada))
120H  25/1200Z 60.5N  39.5W   35 KT  40 MPH - Extra Tropical (ESE PC, Greenland)

NWS National Hurricane Center Miami FL 1100 PM AST Sat Sep 19, 2020

Some convective cells have been developing within Teddy’s large outer eye, and it is possible that this convection is forming an inner eyewall. In any event, observations from an Air Force Hurricane Hunter aircraft indicate that the maximum winds have decreased slightly, to near 100 kt. The hurricane is expected to remain in a low shear environment until tomorrow evening, and to more or less maintain its intensity for 12-24 hours. Thereafter, increasing shear associated with an upper-level trough to the west should cause weakening. Although the shear is predicted by the global models to become fairly strong after 48 hours, the system has a a very large and intense circulation so only slow weakening is expected. By 72 hours, Teddy should merge with a frontal zone to the east of New England and become a strong extratropical cyclone. The official intensity forecast is close to the model consensus.

The system’s wind field will likely become even larger as the wind field of Teddy interacts within a high pressure system behind a cold front during the next few days. This could prolong the period of strong winds over Bermuda into Monday night.

Teddy continues on a general northwestward track or about 315/11 kt. The hurricane should move on the western side of a subtropical high pressure area for the next day or so, and then begin to accelerate northward ahead of a strong mid-tropospheric trough that develops into a cutoff low off the northeast U.S. coast in a couple of days. The interaction of Teddy with this low will likely result in a slight leftward bend of the track around days 2-3. In 4-5 days, post-tropical Teddy is likely to turn north-northeastward to northeastward in the flow on the east side of a broad 500 mb trough. The official track forecast is a blend of the simple and corrected dynamical model consensus predictions.

The extent of 12-foot or higher seas associated with Teddy continues to increase. See the Key Message below regarding swells caused by the hurricane.

Key Messages:

  • 1. While the center of Teddy is forecast to move east of Bermuda late Sunday or Monday, tropical storm conditions are likely on the island beginning Sunday evening.
  • 2. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada early next week, where there is an increasing risk of direct impacts from wind, rain, and storm surge. Residents there should closely monitor the progress of Teddy and updates to the forecast.
  • 3. Large swells produced by Teddy are expected to affect portions of the Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, the east coast of the United States, and Atlantic Canada during the next few days. These swells could cause life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS

INIT  20/0300Z 27.3N  61.2W  100 KT 115 MPH - Category 3 (ESE St. Georges, Bermuda)
 12H  20/1200Z 28.3N  62.3W  100 KT 115 MPH - Category 3 (ESE St. Georges, Bermuda)
 24H  21/0000Z 29.6N  63.0W   95 KT 110 MPH - Category 2 (ESE St. Georges, Bermuda)
 36H  21/1200Z 31.6N  62.4W   90 KT 105 MPH - Category 2 (ESE St. Georges, Bermuda)
 48H  22/0000Z 35.7N  61.8W   90 KT 105 MPH - Category 2 (ENE St. Georges, Bermuda)
 60H  22/1200Z 39.7N  62.5W   80 KT  90 MPH - Category 1 (ENE Atlantic, NJ)
 72H  23/0000Z 42.5N  62.8W   70 KT  80 MPH - Post Tropical (ESE Shelburne, NS Canada)
 96H  24/0000Z 49.5N  56.0W   50 KT  60 MPH - Post Tropical (ESE Springdale, NF Canada)
120H  25/0000Z 57.0N  42.5W   40 KT  45 MPH - Post Tropical (WSW PC, Greenland)

NWS National Hurricane Center Miami FL 500 PM AST Sat Sep 19, 2020

The earlier eyewall replacement cycle occuring in Teddy since last night appears to have completed. There is now a more pronounced outer ring of convection noted in satellite and microwave imagery, and a large ragged eye is beginning to appear in the satellite images. The latest satellite intensity estimates from TAFB and UW-CIMSS ADT support keeping the initial intensity at 105 kt. A U.S. Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate the hurricane later this evening.

There is no change to the forecast intensity and structure for Teddy. The hurricane will be moving over slightly cooler waters caused by upwelling from Paulette over the next 24h and this should cause the hurricane to slowly weaken. However, in about 36 h as the system passes east of Bermuda, the cyclone’s wind field is forecast to begin rapidly expanding as it interacts with an approaching frontal system. By 48 h, vertical wind shear is expected to dramatically increase as Teddy becomes embedded in the flow around a sharp mid-latitude upper-level trough. The interaction of the cyclone with both the front and trough should cause Teddy to begin an extratropical transition, with this transition expected to be completed by 72 h. This transition timing is in agreement with the global models. Once this transition occurs, the post-tropical cyclone is forecast to rapidly weaken, but is still expected to be a powerful extratropical cyclone as it approaches Atlantic Canada early next week. The latest NHC intensity forecast is little changed from the previous one and is near the SHIPS and HFIP corrected consensus HCCA.

Teddy jogged a little west of track today, but the longer term motion is still northwestward at about 11 kt. This motion is expected to continue through most of the day Sunday. Teddy should then turn northward to north-northeastward late Sunday as it approaches a frontal system over the western Atlantic. This pattern should steer the hurricane east of Bermuda, though the hurricane’s large wind field means that the island will still likely experience tropical storm conditions beginning by Sunday evening and continuing into Monday evening. A slight turn to the north then perhaps the north- northwest with a faster forward motion should occur Monday night into Tuesday as Teddy pivots around the upper trough. By Tuesday night, the cyclone is forecast to turn northeastward as the upper trough to its southwest begins to lift into the higher latitudes.

Teddy is producing an extensive area of large waves and swells which are impacting much of the western Atlantic basin. See the Key Messages below.

Key Messages:

  • 1. While the center of Teddy is forecast to move east of Bermuda late Sunday or Monday, tropical storm conditions are likely on the island beginning Sunday evening.
  • 2. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada early next week, where there is an increasing risk of direct impacts from wind, rain, and storm surge. Residents there should closely monitor the progress of Teddy and updates to the forecast.
  • 3. Large swells produced by Teddy are expected to affect portions of the Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, the east coast of the United States, and Atlantic Canada during the next few days. These swells could cause life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS

INIT  19/2100Z 26.7N  60.2W  105 KT 120 MPH - Category 3 (ESE St. Georges, Bermuda) 
 12H  20/0600Z 27.9N  61.6W  100 KT 115 MPH - Category 3 (ESE St. Georges, Bermuda) 
 24H  20/1800Z 29.1N  62.7W   95 KT 110 MPH - Category 2 (ESE St. Georges, Bermuda)
 36H  21/0600Z 30.7N  62.7W   90 KT 105 MPH - Category 2 (ESE St. Georges, Bermuda)
 48H  21/1800Z 33.6N  61.8W   90 KT 105 MPH - Category 2 (ENE St. Georges, Bermuda)
 60H  22/0600Z 38.3N  61.9W   85 KT 100 MPH - Category 2 (ENE St. Georges, Bermuda)
 72H  22/1800Z 41.9N  62.7W   80 KT  90 MPH - Extra Tropical (ESE Provincetown, MA)
 96H  23/1800Z 47.7N  58.5W   50 KT  60 MPH - Extra Tropical (ESE La Poile, NF Canada)
120H  24/1800Z 55.5N  45.5W   45 KT  50 MPH - Extra Tropical (WSW PC, Greenland)

NWS National Hurricane Center Miami FL 1100 AM AST Sat Sep 19, 2020 

The overall appearance of Teddy has degraded slightly since early this morning, with the eye no longer readily apparent in satellite imagery. However, microwave data a few hours ago showed that a well- defined outer eyewall exists with a decaying partial inner eyewall. This indicates that an eyewall replacement cycle is just about complete. The objective and subjective satellite intensity estimates generally agree on an intensity of 98-102 kt, but out of respect for the completing eyewall replacement cycle the initial intensity is set to a slightly more generous 105 kt.

Teddy will be moving over slightly cooler waters caused by upwelling from Paulette over the next day or so and this should cause the hurricane to slowly weaken. However, in about 36 h the cyclone’s wind field is forecast to begin expanding as it interacts with an approaching frontal system. Around 48-60 h, vertical wind shear is expected to dramatically increase as Teddy becomes embedded in the flow around a sharp mid-latitude upper-level trough. The interaction of the cyclone with both the front and trough should cause Teddy to begin an extratropical transition, with the post-tropical cyclone quickly weakening once the transition is complete. The SHIPS guidance and global model simulated satellite imagery tend to agree that the extratropical transition should be completed just after 72 h. The latest NHC intensity forecast was nudged downward slightly mainly due to the change in the initial intensity, and is close to the HFIP corrected consensus HCCA.

The hurricane continues its northwestward movement, now at 12 kt. The track forecast for Teddy remains essentially unchanged and is in the middle of tightly clustered guidance. Teddy is expected to turn northward to north-northeastward Sunday morning as it approaches a frontal system over the western Atlantic. This pattern should steer the hurricane east of Bermuda, though the hurricane’s large wind field means that the island will still likely experience tropical storm conditions beginning by Sunday evening and continuing through much of Monday. A slight turn to the north then perhaps the north- northwest should occur Monday night into Tuesday as Teddy pivots around the upper trough. By Tuesday night, the cyclone is forecast to turn northeastward as the upper trough to its southwest begins to lift into the higher latitudes.

Teddy is producing an extensive area of large waves and swells which are impacting much of the western Atlantic basin. See the Key Messages below.

Key Messages:

  • 1. While the center of Teddy is forecast to move east of Bermuda late Sunday or Monday, tropical storm conditions are likely on the island beginning Sunday afternoon or evening.
  • 2. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada early next week, where there is an increasing risk of direct impacts from wind, rain, and storm surge. Residents there should closely monitor the progress of Teddy and updates to the forecast.
  • 3. Large swells produced by Teddy are expected to affect portions of the Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, the east coast of the United States, and Atlantic Canada during the next few days. These swells could cause life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS

INIT  19/1500Z 26.0N  59.0W  105 KT 120 MPH - Category 3 (ENE St. John's A&B)
 12H  20/0000Z 27.3N  60.4W  100 KT 115 MPH - Category 3 (ENE St. John's A&B)
 24H  20/1200Z 28.8N  61.7W   95 KT 110 MPH - Category 2 (ESE St. Georges, Bermuda)
 36H  21/0000Z 30.4N  62.2W   90 KT 105 MPH - Category 2 (ESE St. Georges, Bermuda)
 48H  21/1200Z 33.1N  61.6W   90 KT 105 MPH - Category 2 (ENE St. Georges, Bermuda)
 60H  22/0000Z 37.1N  61.2W   90 KT 105 MPH - Category 2 (ENE St. Georges, Bermuda)
 72H  22/1200Z 40.8N  61.8W   80 KT  90 MPH - Category 1 (ESE Ocean City, MD)
 96H  23/1200Z 47.0N  59.8W   55 KT  65 MPH - Post Tropical (ESE Meat Cove NS Canada)
120H  24/1200Z 52.9N  51.1W   40 KT  45 MPH - Post Tropical (ESE Cartwright, NF Canada)

NWS National Hurricane Center Miami FL 1100 PM AST Fri Sep 18, 2020 

Teddy continues to have an impressive appearance on satellite images with a fairly symmetrical Central Dense Overcast, although recent images show some warming of the cloud tops over the southeastern part of the circulation. Upper-level outflow is well-defined over the northern semicircle of the hurricane and not as strong to the south. Earlier microwave images showed a concentric eyewall structure and it appears that the hurricane has re-intensified slightly over the past several hours.

The current intensity estimate is set at 115 kt which is a blend of subjective and objective Dvorak estimates. Some additional fluctuations in strength as a result of eyewall replacements could occur through Saturday. On Sunday and beyond, a less conducive oceanic and atmospheric environment should lead to slow weakening. However, Teddy should remain a powerful hurricane for the next several days. The numerical guidance shows that the circulation will become even larger during the forecast period due to Teddy combined with a high pressure area coming behind a cold front over the eastern United States. Teddy is expected to make the transition to an extratropical cyclone when it moves into Atlantic Canada.

The hurricane continues its northwestward trek and is moving around 325/11 kt. Teddy should move around the western side of a subtropical high pressure system for the next day or so. Then, the cyclone should turn northward with an increase in forward speed as it approaches a strong mid-latitude trough cutting off into a low as it moves off the northeast U.S. coast in 2-3 days. The track of the system could bend a bit the left as it interacts with the trough/low while approaching Nova Scotia. Around the end of the forecast period, the post-tropical cyclone should turn northeastward as it moves along the eastern side of a mid-level trough. The official track forecast is close to the corrected model consensus. Teddy is producing seas to 48 feet and an extensive area of large waves and swells which are impacting much of the western Atlantic basin. See the Key Messages below.

Key Messages:

  • 1. While the center of Teddy is forecast to move east of Bermuda late Sunday or Monday, there is still a risk of strong winds, storm surge, and heavy rainfall on the island, and a Tropical Storm Watch is in effect.
  • 2. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada early next week, where there is an increasing risk of direct impacts from wind, rain, and storm surge. Residents there should closely monitor the progress of Teddy and updates to the forecast through the weekend.
  • 3. Large swells produced by Teddy are expected to affect portions of the Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, the east coast of the United States, and Atlantic Canada during the next few days. These swells could cause life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS

INIT  19/0300Z 24.0N  57.4W  115 KT 130 MPH - Category 4 (ENE St. John's A&B)
 12H  19/1200Z 25.5N  58.6W  115 KT 130 MPH - Category 4 (ENE St. John's A&B)
 24H  20/0000Z 27.3N  60.4W  110 KT 125 MPH - Category 3 (ENE St. John's A&B)
 36H  20/1200Z 29.0N  61.8W  105 KT 120 MPH - Category 3 (ESE St. Georges, Bermuda)
 48H  21/0000Z 30.8N  62.3W  100 KT 115 MPH - Category 3 (ESE St. Georges, Bermuda)
 60H  21/1200Z 33.5N  61.4W   95 KT 110 MPH - Category 2 (ENE St. Georges, Bermuda)
 72H  22/0000Z 37.7N  61.1W   85 KT 100 MPH - Category 2 (ENE St. Georges, Bermuda)
 96H  23/0000Z 45.5N  62.5W   70 KT  80 MPH - Post Tropical (ESE Ocean City, MD)
120H  24/0000Z 50.5N  56.0W   45 KT  50 MPH - Post Tropical (ESE Canada Harbour, Canada)

NWS National Hurricane Center Miami FL 500 PM AST Fri Sep 18, 2020 

Both NOAA and U.S. Air Force Hurricane Hunter aircraft have been investigating Teddy since this morning. The highest flight level wind measured by the aircraft was 119 kt at 750 mb, which reduces to around 101 kt at the surface. The latest central measured by the aircraft is up 4 mb from the previous advisory, indicating only some slight weakening. Earlier microwave images indicated that an eyewall replacement cycle had been taking place and some drier air had intruded into the southern portion of the circulation, leaving a partial break in the eyewall. This may explain the reason why the aircraft have not been finding winds as strong as they did previously, and in fact found a double wind maxima in the northern portion of the circulation. These eyewall replacement cycles are common in intense tropical cyclones, and oftentimes the systems recover within 12-24 h as long as the environmental conditions support it.

Over the past hour or so, the ring of deep convection has appeared less broken and is beginning to expand in size, which could be an indication that the hurricane is recovering from the eyewall replacement. Based on the possibility of some undersampling by the aircraft, the increase of only 4 mb in central pressure, and the latest convective trends, the initial intensity is being lowered only slightly to 110 kt. Teddy continues its long trek northwestward, now at 12 kt. The hurricane is expected to remain on that general course during the next couple of days as it moves on the southwestern periphery of a mid-level ridge. By the end of the weekend, when Teddy will likely be approaching Bermuda, a turn to the north or north-northeast is forecast to occur as a mid- to upper-level trough moves off the northeastern U.S. coast. Early next week, the trough is expected to cut off, causing Teddy to turn slightly to the left and approach Nova Scotia in about 4 days. The models continue to be in good agreement on this scenario, and only small adjustments were made to the previous forecast track.

The environment around Teddy will be conducive for maintaining an intense hurricane for the next 24 h or so, as the ocean temperatures will remain warm with low vertical wind shear and a fairly moist atmosphere. After 24 h, the hurricane is forecast to cross cooler waters churned up by Paulette last week. This should cause a slow weakening trend to begin. By Monday night, vertical wind shear is expected to drastically increase ahead of an approaching mid-latitude trough. This should not only weaken Teddy, but begin its transition to a large extratropical cyclone, and that transition should be completed around day 4 of the forecast period. The latest NHC intensity forecast is near or a little above HCCA and IVCN through 24 h, and then trends toward the SHIPS intensity guidance thereafter.

Teddy is producing a large area of high seas. The latest maximum seas estimated by TAFB near the core of the hurricane are near 45 feet. Swells from Teddy are spreading far from the center, see Key Messages below.

Key Messages:

  • 1. While the center of Teddy is forecast to move east of Bermuda late Sunday or Monday, there is still a risk of strong winds, storm surge, and heavy rainfall on the island, and a Tropical Storm Watch is in effect.
  • 2. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada early next week, where there is an increasing risk of direct impacts from wind, rain, and storm surge. Residents there should closely monitor the progress of Teddy and updates to the forecast through the weekend.
  • 3. Large swells produced by Teddy are expected to affect portions of the Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, the east coast of the United States, and Atlantic Canada during the next few days. These swells could cause life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS

INIT  18/2100Z 23.1N  57.0W  110 KT 125 MPH - Category 3 (ENE St. John's A&B)
 12H  19/0600Z 24.5N  58.1W  110 KT 125 MPH - Category 3 (ENE St. John's A&B)
 24H  19/1800Z 26.5N  59.9W  110 KT 125 MPH - Category 3 (ENE St. John's A&B)
 36H  20/0600Z 28.1N  61.6W  105 KT 120 MPH - Category 3 (ESE St. Georges, Bermuda)
 48H  20/1800Z 29.7N  62.6W  100 KT 115 MPH - Category 3 (ESE St. Georges, Bermuda)
 60H  21/0600Z 31.8N  62.5W   95 KT 110 MPH - Category 2 (ENE St. Georges, Bermuda)
 72H  21/1800Z 35.6N  61.7W   85 KT 100 MPH - Category 2 (ENE St. Georges, Bermuda)
 96H  22/1800Z 43.2N  62.7W   75 KT  85 MPH - Post Tropical (ESE Shelburne, Canada)
120H  23/1800Z 48.5N  59.3W   50 KT  60 MPH - Post Tropical (WSW Cape St George, Canada)

NWS National Hurricane Center Miami FL 1100 PM AST Thu Sep 17, 2020

After a significant strengthening episode this afternoon, Teddy is maintaining Category Four intensity. Observations from a NOAA Hurricane Hunter aircraft conducting a research mission into the hurricane this evening indicate that the maximum winds remain near 120 kt. Since Teddy should remain in a low-shear environment for the next day or so, additional strengthening could occur on Friday. An upper-level cyclone seen in water vapor images to the southeast of Bermuda and the cool wake of previous Hurricane Paulette could impede strengthening in a couple of days. However, Teddy is likely to remain a dangerous major hurricane for the next 72 hours, including the time it passes closest to Bermuda. Some fluctuations in strength due to eyewall replacements are possible during that period.

The hurricane has continued to move northwestward, or around 315/10 kt. Teddy should move along the southwestern periphery of a mid-level high during the next 2-3 days, and then turn northward around days 3-4 while moving through a weakness in the subtropical ridge. Around the end of the forecast period, Teddy will probably interact with a deep mid-tropospheric cyclone in the vicinity of Nova Scotia. This interaction will probably cause Teddy to bend somewhat toward the left around day 5, but there is significant uncertainty in the details of the track at that forecast time range. It is also possible that the system will be losing tropical characteristics by the end of the period, but this remains to be seen.

Key Messages:

  • 1. Teddy is expected to approach Bermuda as a hurricane this weekend and make its closest approach to the island late Sunday or Monday. While the exact details of Teddy’s track and intensity near the island are not yet known, the risk of strong winds, storm surge, and heavy rainfall on Bermuda is increasing.
  • 2. Large swells produced by Teddy are expected to affect portions of the Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, and the southeastern United States late this week and into the weekend. These swells could cause life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS

INIT  18/0300Z 20.9N  54.7W  120 KT 140 MPH - Category 4 (ESE St. John's A&B)
 12H  18/1200Z 22.1N  55.7W  125 KT 145 MPH - Category 4 (ESE St. John's A&B)
 24H  19/0000Z 23.8N  57.1W  120 KT 140 MPH - Category 4 (ESE St. John's A&B)
 36H  19/1200Z 25.6N  58.8W  115 KT 130 MPH - Category 4 (ESE St. John's A&B)
 48H  20/0000Z 27.4N  60.8W  110 KT 125 MPH - Category 3 (ESE St. Georges, Bermuda)
 60H  20/1200Z 29.0N  62.6W  110 KT 125 MPH - Category 3 (ESE St. Georges, Bermuda)
 72H  21/0000Z 30.7N  63.5W  105 KT 120 MPH - Category 3 (ESE St. Georges, Bermuda)
 96H  22/0000Z 36.9N  62.2W   90 KT 105 MPH - Category 2 (ENE Virginia Beach, VA)
120H  23/0000Z 44.0N  63.0W   65 KT  75 MPH - Category 1 (ESE Dartmouth, NS Canada)

NWS National Hurricane Center Miami FL 500 PM AST Thu Sep 17, 2020

Teddy has intensified quickly today, with the cyclone now having a more symmetrical appearance while the eye has become mostly clear. The deep convection with cloud tops ranging from -60 to -75 degrees have surrounded the eye for much of the day, and there are well-defined outflow channels to the south and east of the hurricane. Both NOAA and US Air Force Reserve Hurricane Hunter aircraft have spent time investigating Teddy today as it has been intensifying and have been able to provide very useful data in determining both the size and strength of the hurricane. The peak SFMR winds measured by the aircraft this afternoon were 113 kt, while the peak 700 mb flight-level winds were 130 kt. Based on a reduction to 117 kt from 700 mb, and assuming some slight undersampling may be occurring, the initial intensity has been raised to 120 kt.

The hurricane is expected to remain in an environment of low-moderate shear while over warm waters for the 48 h or so. And since the period of rapid strengthening of Teddy appears to be ongoing, the hurricane is expected to strengthen some more into tonight. Once this round of intensification completes, there will likely be some fluctuations in strength due to eyewall replacement cycles and other short term changes in structure. After 48 h, the path of Teddy should take it over some cooler waters caused by upwelling from Hurricane Paulette last week. This should cause the cyclone to slowly weaken.

By 96 h, vertical wind shear is forecast to increase ahead of an approaching mid-latitude trough and associated frontal boundary. This should hasten the weakening trend of Teddy. By 120 h, the hurricane is expected to have crossed the 26 degree SST isotherm, and will begin to interact with the aforementioned mid-latitude system causing it to begin an extratropical transition that may or may not be completed by the end of the forecast period. The latest NHC intensity forecast has been increased due to the higher initial intensity, and the forecast trends fit well with the various intensity consensus and SHIPS guidance.

Teddy continues its northwestward motion, now at 11 kt. The track guidance is in very good agreement on a continuation of this motion for the next 72 h as the cyclone is steered by a mid-level ridge over the central Atlantic. The model guidance has come into better agreement on the evolution of the large scale features later on in the forecast period as the hurricane is expected to recurve ahead of the approaching mid-latitude trough moving off the coast of the eastern United States in a few days. The new NHC track forecast is little changed from the previous one, and is in the middle of the track guidance. On the forecast track, Teddy will make its closest approach to Bermuda Sunday night into Monday.

Key Messages:

  • 1. Teddy is expected to approach Bermuda as a hurricane this weekend and make its closest approach to the island late Sunday or Monday. While the exact details of Teddy’s track and intensity near the island are not yet known, the risk of strong winds, storm surge, and heavy rainfall on Bermuda is increasing.
  • 2. Large swells produced by Teddy are expected to affect portions of the Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, and the southeastern United States late this week and into the weekend. These swells could cause life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS

INIT  17/2100Z 20.1N  54.1W  120 KT 140 MPH - Category 4 (ESE St. John's A&B)
 12H  18/0600Z 21.2N  55.2W  130 KT 150 MPH - Category 4 (ESE St. John's A&B)
 24H  18/1800Z 22.8N  56.6W  125 KT 145 MPH - Category 4 (ESE St. John's A&B)
 36H  19/0600Z 24.5N  58.1W  125 KT 145 MPH - Category 4 (ESE St. John's A&B)
 48H  19/1800Z 26.3N  59.9W  120 KT 140 MPH - Category 4 (ESE St. Georges, Bermuda)
 60H  20/0600Z 28.0N  62.1W  110 KT 125 MPH - Category 3 (ESE St. Georges, Bermuda)
 72H  20/1800Z 29.5N  63.3W  105 KT 120 MPH - Category 3 (ESE St. Georges, Bermuda)
 96H  21/1800Z 33.9N  63.0W   95 KT 110 MPH - Category 2 (ESE St. Georges, Bermuda)
120H  22/1800Z 41.3N  62.0W   80 KT  90 MPH - Category 1 (ESE Chatham, MA)

NWS National Hurricane Center Miami FL 1100 AM AST Thu Sep 17, 2020 

Corrected to add Key Messages Since the previous advisory, Teddy’s satellite appearance has steadily improved. There is now a ragged warming eye surrounded by a ring of convection with cloud tops colder than -60 degrees C. Very recently the objective satellite intensity estimates from UW-CIMSS have been rapidly increasing. And although a blend of the 1130 and 1200 UTC Dvorak intensity estimates from SAB and TAFB, respectively, averaged out to an intensity of about 95 kt, the improved satellite presentation since that time suggests that the hurricane should have winds of at least 105 kt, which is the initial intensity for this advisory, which could even be a little conservative based on the latest UW-CIMMS ADT and SATCON values of 120 and 111 kt, respectively. There will be NOAA and Air Force Reserve Hurricane Hunter aircraft inside Teddy later today, which should provide much more detail on the structure and intensity of Teddy.

The only negative factor for intensification during the next 24 h is about 10 to 15 kt of vertical wind shear. However, Teddy has been able to begin the latest burst of intensification despite that shear. Therefore additional strengthening is anticipated through this evening, and Teddy is forecast to become a category 4 hurricane by tonight. The overall environment does not change significantly for the next couple of days, so other than some fluctuations intensity such as due to potential eyewall replacement cycles, no change in strength is indicated during that time. As Teddy continues moving northwest over the weekend, it is likely to begin to encounter some of the cooler waters upwelled by Hurricane Paulette last week. This could cause the cyclone to slowly weaken. By late this weekend, increasing vertical wind shear should also contribute to weakening. Due to the fast increase in intensity this morning, the latest NHC intensity is a bit higher than all of the guidance for the first 48 h, but the overall intensity trends are closely mirrored by the various multi-model consensus. Beyond 48 h, the NHC forecast closely follows the LGEM guidance.

Teddy continues to move northwestward at 10 kt. The track forecast and reasoning both remain straightforward and unchanged for the next 72 h. The latest NHC model guidance is in excellent agreement that a deep-layer ridge situated over the central Atlantic will force Teddy on a northwestward track toward the western Atlantic. There is a little less divergence among the models on days 4 and 5 then on previous cycles, and these differences are due to timing differences in where and how fast the hurricane begins to recurve ahead of an approaching mid-latitude trough and frontal system moving off the coast of the eastern United States in about 3 days. The new NHC track forecast is little changed from the previous one, and is in the middle of the tightly clustered track guidance. On the forecast track, Teddy will make its closest approach to Bermuda on Monday.

Key Messages:

  • 1. Teddy is expected to approach Bermuda as a hurricane this weekend and make its closest approach to the island late Sunday or Monday. While the exact details of Teddy’s track and intensity near the island are not yet known, the risk of strong winds, storm surge, and heavy rainfall on Bermuda is increasing.
  • 2. Swells produced by Teddy are expected to affect portions of the Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, and the southeastern United States late this week and into the weekend. These swells could cause life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS

INIT  17/1500Z 19.3N  53.0W  105 KT 120 MPH - Category 3 (ESE St. John's A&B)
 12H  18/0000Z 20.4N  54.0W  115 KT 130 MPH - Category 3 (ESE St. John's A&B)
 24H  18/1200Z 21.8N  55.5W  115 KT 130 MPH - Category 3 (ESE St. John's A&B)
 36H  19/0000Z 23.5N  57.0W  115 KT 130 MPH - Category 3 (ESE St. John's A&B)
 48H  19/1200Z 25.5N  58.9W  110 KT 125 MPH - Category 3 (ESE St. John's A&B)
 60H  20/0000Z 27.3N  60.9W  105 KT 120 MPH - Category 3 (ESE St. Georges, Bermuda)
 72H  20/1200Z 28.7N  62.7W  100 KT 115 MPH - Category 3 (ESE St. Georges, Bermuda)
 96H  21/1200Z 32.4N  63.4W   95 KT 110 MPH - Category 2 (ESE St. Georges, Bermuda)
120H  22/1200Z 38.9N  62.3W   85 KT 100 MPH - Category 2 (ESE tlantic City, NJ)

NWS National Hurricane Center Miami FL 1100 PM AST Wed Sep 16, 2020

Teddy has been a perplexing hurricane thus far. The infrared satellite presentation appears rather impressive, with the center embedded beneath a Central Dense Overcast with cloud tops as cold as -85 degrees Celsius. Despite the presentation, however, Dvorak estimates from TAFB and SAB are a consensus T4.5/77 kt, and objective estimates range between 70-75 kt.

Teddy’s initial intensity is therefore set just above these estimates at 80 kt. A recent ASCAT pass indicated that Teddy’s center is a little farther to the southwest than previously estimated. However, the long-term motion remains toward the northwest (315/11 kt). The track forecast remains straightforward the the next 3 days, with the guidance in good agreement that a mid-tropospheric high over the central Atlantic will drive the hurricane northwestward toward the western Atlantic. There is a little more spread among the track models on days 4 and 5, related to timing differences on exactly where and how fast Teddy begins to recurve ahead of an approaching mid-latitude trough coming from the northeastern United States. The new NHC track forecast has been nudged westward during the first 3 days to account for the initial position adjustment, but otherwise it’s still close to the previous prediction even with the increasing model spread on days 4 and 5.

An upper-level trough situated to the northwest of Teddy is causing about 10-15 kt of deep-layer southwesterly shear over the hurricane, and some model analyses suggest that there could be stronger shear in a layer below the level of the upper-level outflow. The deep-layer shear is expected to increase a bit during the next day or so, but this should be offset by a favorable thermodynamic environment, allowing for some intensification during that time. The shear might relax by days 3 and 4, but then the thermodynamic environment becomes a little less conducive for strengthening. In particular, Teddy may move over the cold wake of Hurricane Paulette, and the SHIPS guidance indicates that relatively warm upper-level temperatures could be a negative factor. All that said, the NHC intensity forecast lies near the top end of the guidance envelope, showing Teddy peaking in intensity in a couple of days and then only gradually weakening through the end of the forecast period.

FORECAST POSITIONS AND MAX WINDS

INIT  17/0300Z 17.8N  51.5W   80 KT  90 MPH - Category 1 (ESE St. John's A&B)
 12H  17/1200Z 18.9N  52.6W   85 KT 100 MPH - Category 2 (ESE St. John's A&B)
 24H  18/0000Z 20.3N  54.1W   95 KT 110 MPH - Category 2 (ESE St. John's A&B)
 36H  18/1200Z 21.8N  55.6W  100 KT 115 MPH - Category 3 (ESE St. John's A&B)
 48H  19/0000Z 23.5N  57.1W  100 KT 115 MPH - Category 3 (ESE St. John's A&B)
 60H  19/1200Z 25.3N  59.1W   95 KT 110 MPH - Category 2 (ESE St. John's A&B)
 72H  20/0000Z 27.0N  61.1W   95 KT 110 MPH - Category 2 (ESE St. John's A&B)
 96H  21/0000Z 30.0N  64.0W   90 KT 105 MPH - Category 2 (ESE St. Georges, Bermuda)
120H  22/0000Z 35.0N  64.0W   90 KT 105 MPH - Category 2 (ENE St. Georges, Bermuda)

NWS National Hurricane Center Miami FL 500 PM AST Wed Sep 16, 2020

Recent satellite imagery is suggesting that Teddy is undergoing some westerly vertical wind shear, as indicated by outflow being more limited in the western portion of the circulation. The latest UW-CIMSS shear analysis suggests the magnitude of this shear could be about 10-15 kt, which could help to explain the lack of increase in organization of the cyclone today. The most recent Dvorak satellite intensity estimates provided CI values of 4.5-5.0, indicating that the initial intensity is still around 85 kt.

The environmental conditions are not forecast to change much for Teddy over the next couple of days. The cyclone is forecast to move over warm waters within a somewhat dry atmospheric environment, while moderate shear is expected to continue due to an upper trough to its northwest. Based on these only somewhat favorable conditions for strengthening, along with what we have witnessed with the lack of intensification today, the NHC intensity forecast over the next few days is being lowered. Beyond day 3, there is evidence to suggest that Teddy may move over some cooler waters due to upwelling caused by Paulette. And, by day 4 global models are forecasting a further increase in vertical wind shear. These two factors should cause the cyclone to weaken late in the forecast period. This updated intensity forecast is in good agreement with the HFIP corrected consensus, HCCA.

Teddy is moving northwestward at about 11 kt. This motion is forecast to continue for the next few days, as the cyclone is steered by a mid-level ridge to its north and northeast. Late in the forecast period, the portion of the ridge north of Teddy is expected to erode as a mid-latitude trough digs across the northeastern United States. This evolution should cause the cyclone to turn north-northwest and possibly north by day 5. The track guidance is tightly clustered through day 3, but increases quite a bit after that time, likely due to how the models are handling the approaching trough. The latest GFS delays a turn and shows a more westerly track, with the cyclone southwest of Bermuda by day 5, while the rest of the global models turn the system north sooner and take the system just east of Bermuda. The NHC track forecast is close to the previous one and is near the various multi-model track consensus aids. On the forecast track, Teddy could make a close to approach to Bermuda in about 5 days. However, based on the model spread at that time frame and average track error of about 200 n mi at 120 h, it is certainly too soon to know what impacts Teddy may have on the island.

FORECAST POSITIONS AND MAX WINDS

INIT  16/2100Z 17.5N  50.8W   85 KT 100 MPH - Category 2 (ESE St. John's A&B)
 12H  17/0600Z 18.6N  52.0W   90 KT 105 MPH - Category 2 (ESE St. John's A&B)
 24H  17/1800Z 20.0N  53.4W  100 KT 115 MPH - Category 3 (ESE St. John's A&B)
 36H  18/0600Z 21.5N  54.9W  105 KT 120 MPH - Category 3 (ESE St. John's A&B)
 48H  18/1800Z 23.0N  56.3W  105 KT 120 MPH - Category 3 (ESE St. John's A&B)
 60H  19/0600Z 24.8N  58.0W  100 KT 115 MPH - Category 3 (ESE St. John's A&B)
 72H  19/1800Z 26.5N  60.2W  100 KT 115 MPH - Category 3 (ESE St. John's A&B)
 96H  20/1800Z 29.5N  63.6W   90 KT 105 MPH - Category 2 (ESE St. Georges, Bermuda)
120H  21/1800Z 33.3N  64.6W   85 KT 100 MPH - Category 2 (ENE St. Georges, Bermuda)

NWS National Hurricane Center Miami FL 1100 AM AST Wed Sep 16, 2020 

Teddy’s overall appearance has changed little over the past several hours. Microwave and infrared satellite images depict a well-defined inner core with an eye evident in the microwave imagery. However, visible imagery reveals that the eye remains cloud filled. Over the past few hours, the coldest cloud tops and have become confined to the western portion of the circulation, which could be the early signs of the cyclone experiencing some westerly wind shear. The latest satellite intensity estimates remain unchanged from 6 h ago, and therefore the initial intensity will remain 85 kt.

Environmental conditions appear favorable for additional strengthening over the next 18-24 h, and with the inner-core well defined, rapid intensification could resume shortly. By 36 h, increasing westerly wind shear and drier air should limit any further intensification, and possibly induce some weakening. Later on in the forecast period, Teddy could encounter some cooler waters due to upwelling caused by Paulette. This could also attribute to additional weakening. The latest NHC forecast is largely unchanged from the previous one, and is on the high end of the guidance. It should be noted that if the rapid intensification that has paused recently doe not resume soon, adjustments to the intensity forecast will be necessary.

Teddy continues to move northwestward at about 10 kt. This motion is forecast to continue for the next few days, as the cyclone is steered by a mid-level ridge to its north and northeast. Late in the forecast period, the portion of the ridge north of Teddy is expected to erode as a mid-latitude trough digs across the northeastern United States. This evolution should cause the cyclone to turn north-northwest and possibly north by day 5. The track guidance is tightly clustered through day 3, then the spread increases after that time, likely due to how the models are handling the approaching trough. The NHC track forecast is close to the previous one and is near the various multi-model track consensus aids. On the forecast track, Teddy could make a close to approach to Bermuda in about 5 days. However, based on average 5-day track and intensity errors, it is too soon to know what type of impacts the cyclone could have on the island.

FORECAST POSITIONS AND MAX WINDS

INIT  16/1500Z 16.5N  49.7W   85 KT 100 MPH - Category 2 (ESE St. John's A&B)
 12H  17/0000Z 17.5N  50.8W   95 KT 110 MPH - Category 2 (ESE St. John's A&B)
 24H  17/1200Z 19.0N  52.3W  110 KT 125 MPH - Category 3 (ESE St. John's A&B)
 36H  18/0000Z 20.4N  53.8W  115 KT 130 MPH - Category 3 (ESE St. John's A&B)
 48H  18/1200Z 21.9N  55.3W  115 KT 130 MPH - Category 3 (ESE St. John's A&B)
 60H  19/0000Z 23.5N  56.9W  110 KT 125 MPH - Category 3 (ESE St. John's A&B)
 72H  19/1200Z 25.1N  58.7W  105 KT 120 MPH - Category 3 (ESE St. John's A&B)
 96H  20/1200Z 28.3N  62.7W   95 KT 110 MPH - Category 2 (WSW St. Georges, Bermuda)
120H  21/1200Z 31.7N  64.1W   90 KT 105 MPH - Category 2 (ESE St. Georges, Bermuda)

NWS National Hurricane Center Miami FL 1100 PM AST Tue Sep 15, 2020

At a glance, Teddy looks like a hurricane in conventional infrared satellite imagery. Two hooking convective bands are rotating around the center, and cold convective tops are becoming more symmetric within the circulation. Objective intensity estimates have still struggled to increase for some reason, but a blend of Dvorak estimates from TAFB and SAB support increasing Teddy’s intensity to 60 kt. Overall, the environment looks generally conducive for strengthening. The main limiting factors would be moderate southwesterly shear in 2-3 days, paired with a drier environment with mid-level relative humidity dropping from 55-60 percent to about 40 percent in 3 days. The updated NHC intensity forecast has not been changed significantly from the previous prediction mainly to ensure continuity. Nearly all of the intensity models are below this forecast, and downward intensity adjustments could be required in later forecasts if Teddy doesn’t show sure signs of significant intensification.

Teddy has turned toward the northwest and slowed down a bit with an initial motion of 305/8 kt. A mid-tropospheric high pressure area is expected to be nearly stationary over the central Atlantic for the entire forecast period, which is likely to keep Teddy on a constant northwestward heading with only small fluctuations in forward speed. If I was to look for any outlier among the tightly clustered track guidance, it would be the ECMWF, which is slightly off to the west of the main pack of models. The NHC track forecast is just a little to the west of the TVCA multi-model consensus aid in deference to the ECMWF, and it’s fairly close to the latest HCCA solution.

FORECAST POSITIONS AND MAX WINDS

INIT  16/0300Z 15.0N  48.3W   60 KT  70 MPH - Tropical Storm (ESE St. John's A&B)
 12H  16/1200Z 16.0N  49.2W   65 KT  75 MPH - Category 1 (ESE St. John's A&B)
 24H  17/0000Z 17.3N  50.5W   75 KT  85 MPH - Category 1 (ESE St. John's A&B)
 36H  17/1200Z 18.8N  52.0W   85 KT 100 MPH - Category 2 (ESE St. John's A&B)
 48H  18/0000Z 20.2N  53.4W   90 KT 105 MPH - Category 2 (ESE St. John's A&B)
 60H  18/1200Z 21.6N  54.8W   95 KT 110 MPH - Category 2 (ESE St. John's A&B)
 72H  19/0000Z 23.0N  56.2W  100 KT 115 MPH - Category 3 (ESE St. Georges, Bermuda)
 96H  20/0000Z 26.5N  60.0W  100 KT 115 MPH - Category 3 (ESE St. Georges, Bermuda)
120H  21/0000Z 29.5N  62.5W   95 KT 110 MPH - Category 2 (ESE St. Georges, Bermuda)

NWS National Hurricane Center Miami FL 500 PM AST Tue Sep 15, 2020

Overall, Teddy’s organization has continued to slowly improve during the past several hours. AMSR microwave imagery near 1630 UTC showed that a low- to mid-level eye feature is beginning to form. The overall convective pattern has also improved, though not enough to increase the intensity estimates at this time, which only range from 45-55 kt. The intensity is therefore held at 55 kt, but it does appear that some intensification is imminent.

The AMSR image showed indications of a microwave signature commonly associated with rapid intensification in favorable environments. Low shear and warm SSTs along the forecast track are certainly conducive, though dry air continues to be a possible limiting factor. The dry air is probably the reason that dry slots continue to occasionally appear in IR imagery near the center of Teddy. Rapid intensification probabilities are not particularly high; the SHIPS RI gives a 22 percent chance of a 30-kt increase during the next 24 h while DTOPS shows a mere 1 percent chance. The rest of the intensity models forecast only modest strengthening for the next couple of days. The NHC intensity forecast is at the top of the intensity guidance for the next 48 h and slightly above all of the models after that, but I am hesitant to lower it any further at this time given the recent microwave signature and overall improvement in Teddy’s structure.

In contrast, Teddy’s track outlook remains straightforward, and no changes of note were made to the official forecast. The tropical storm is turning gradually toward the northwest and should begin moving in that direction tonight. A ridge over the central Atlantic should then steer Teddy in that general direction for the rest of the week. The model spread is still much lower than normal, and confidence in the track forecast is fairly high.

FORECAST POSITIONS AND MAX WINDS

INIT  15/2100Z 14.6N  47.9W   55 KT  65 MPH - Tropical Storm (ESE St. John's A&B)
 12H  16/0600Z 15.5N  49.0W   65 KT  75 MPH - Category 1 (ESE St. John's A&B)
 24H  16/1800Z 16.8N  50.2W   75 KT  85 MPH - Category 1 (ESE St. John's A&B)
 36H  17/0600Z 18.2N  51.6W   85 KT 100 MPH - Category 2 (ESE St. John's A&B)
 48H  17/1800Z 19.7N  53.1W   95 KT 110 MPH - Category 2 (ESE St. John's A&B)
 60H  18/0600Z 21.0N  54.4W  100 KT 115 MPH - Category 3 (WSW St. John's A&B)
 72H  18/1800Z 22.5N  55.8W  100 KT 115 MPH - Category 3 (WSW St. John's A&B)
 96H  19/1800Z 25.4N  58.8W  105 KT 120 MPH - Category 3 (WSW St. John's A&B)
120H  20/1800Z 28.5N  61.5W   95 KT 110 MPH - Category 2 (ESE St. Georges, Bermuda)

NWS National Hurricane Center Miami FL 1100 AM AST Tue Sep 15, 2020 

Teddy’s structure is slowly improving. Visible and IR imagery indicate that inner-core convection has increased, despite the continued presence of dry slots. The latest Dvorak intensity estimates from TAFB and SAB support the initial intensity of 55 kt. Teddy is still heading west-northwestward for the moment with a forward speed estimate of 11 kt.

Teddy will likely turn northwestward today and continue steadily moving northwestward along the southwest periphery of a ridge over the central Atlantic for the next several days. In fact, all available guidance indicates that once it makes that northwestward turn, Teddy will barely deviate from its heading or forward speed for the rest of the week. The latest NHC track forecast is virtually identical to the previous one. The model spread is smaller than usual and confidence in the track forecast is high.

Teddy’s low shear and warm SST environment should be conducive for further strengthening, and the NHC intensity forecast is largely unchanged. Some dry air in the environment could restrict Teddy’s intensification rate, but is not expected to prevent Teddy from becoming a hurricane later today or tonight. Continued strengthening is expected thereafter and Teddy is forecast to become a major hurricane within the next few days. On the whole, the intensity guidance is a little lower at the longer-range times, so the NHC forecast at days 4 and 5 is at the very top end of the guidance. I’d rather see a more consistent signal from the models before making a larger change to the forecast, especially given the impressive depiction of Teddy in the global model forecasts at that time.

The 34 kt wind radii were expanded to the northwest of Teddy based on data from an 1136 UTC ASCAT-A overpass.

FORECAST POSITIONS AND MAX WINDS

INIT  15/1500Z 14.0N  47.0W   55 KT  65 MPH - Tropical Storm (ESE St. John's A&B)
 12H  16/0000Z 14.9N  48.2W   65 KT  75 MPH - Category 1 (ESE St. John's A&B)
 24H  16/1200Z 16.1N  49.5W   75 KT  85 MPH - Category 1 (ESE St. John's A&B)
 36H  17/0000Z 17.4N  50.8W   85 KT 100 MPH - Category 2 (ESE St. John's A&B)
 48H  17/1200Z 18.9N  52.3W   95 KT 110 MPH - Category 2 (ESE St. John's A&B)
 60H  18/0000Z 20.3N  53.6W  100 KT 115 MPH - Category 3 (WSW St. John's A&B)
 72H  18/1200Z 21.5N  55.0W  105 KT 120 MPH - Category 3 (WSW St. John's A&B)
 96H  19/1200Z 24.0N  57.4W  110 KT 125 MPH - Category 3 (WSW St. John's A&B)
120H  20/1200Z 27.1N  60.0W  100 KT 115 MPH - Category 3 (WSW St. John's A&B)

NWS National Hurricane Center Miami FL 1100 PM AST Mon Sep 14, 2020 

Teddy is displaying some mixed signals this evening. On one hand, satellite imagery shows an improving cloud pattern, with increasing central convection and a large curved band on the southern side of the circulation. The latest TAFB/SAB Dvorak estimates have increased to 55 kt on this basis. Scatterometer data, surprisingly, only shows 35-40 kt. The initial wind speed remains 45 kt as a blend of that data, assuming the typical undersampling from ASCAT, but there is a fair bit of uncertainty in the current wind speed. Teddy should have several days in a low or moderate shear environment over warm waters to intensify. All guidance responds to this forcing by showing Teddy near major hurricane strength in a few days, with the biggest disagreement being how fast it gets there. The new forecast is similar to the previous one, leaning toward the NOAA corrected-consensus guidance HCCA.

Teddy is moving about the same as before, or 280/11 kt. No substantial changes were made to the forecast track with the storm in a seemingly stable steering current provided by a deep-layer ridge over the central Atlantic. Teddy should turn west-northwestward overnight and then northwestward on Wednesday through the end of the forecast while it moves on the southwestern flank of the ridge. Model guidance is in excellent agreement, with only some minor speed differences.

The NHC track prediction is basically on top of the previous one and the consensus aids.

FORECAST POSITIONS AND MAX WINDS

INIT  15/0300Z 13.2N  45.0W   45 KT  50 MPH - Tropical Storm (ESE St. John's A&B)
 12H  15/1200Z 13.8N  46.5W   55 KT  65 MPH - Tropical Storm (ESE St. John's A&B)
 24H  16/0000Z 14.8N  48.3W   70 KT  80 MPH - Category 1 (ESE St. John's A&B)
 36H  16/1200Z 15.9N  49.8W   80 KT  90 MPH - Category 1 (ESE St. John's A&B)
 48H  17/0000Z 17.3N  51.3W   90 KT 105 MPH - Category 2 (ESE St. John's A&B)
 60H  17/1200Z 18.5N  52.6W   95 KT 110 MPH - Category 2 (ESE St. John's A&B)
 72H  18/0000Z 19.9N  54.2W  105 KT 120 MPH - Category 3 (WSW St. John's A&B)
 96H  19/0000Z 22.6N  56.9W  105 KT 120 MPH - Category 3 (WSW St. John's A&B)
120H  20/0000Z 25.5N  60.0W  105 KT 120 MPH - Category 3 (WSW St. John's A&B)

NWS National Hurricane Center Miami FL 500 PM AST Mon Sep 14, 2020 

Teddy is strengthening this afternoon. Recent satellite imagery shows a growing convective band south and west of the center and a CDO feature developing over the estimated low-level center position. The initial intensity is set to 45 kt based on the latest Dvorak estimates of T3.0/45 kt from TAFB and SAB.

The environment along Teddy’s forecast track features increasing SSTs and low shear for the next several days, and with the improved convective structure of the cyclone, steady strengthening is forecast. The NHC intensity prediction has been increased from the previous advisory, and shows a 25-kt increase in the next 24 hours, which is supported by the SHIPS model and some of the RII indices. Beyond that time, Teddy is forecast to reach major hurricane intensity in about 3 days. The new NHC forecast is near HCCA through the forecast period.

Microwave and geostationary satellite fixes suggest an initial motion of 275/12. The track forecast reasoning is similar to that of the previous advisory. Teddy will initially be steered westward and then west-northwestward by a deep-layer ridge located over the central Atlantic. As the ridge shifts eastward through the forecast period, Teddy is forecast to turn more northwestward as it moves around the western edge of the ridge. There is a fair amount of across track spread in the guidance, with the ECMWF on the right and the GFS and HWRF on the left. Overall the guidance envelope has shifted to the left since this morning. The new NHC track has been adjusted in that direction, and lies near or a little to the right of the latest consensus aids.

FORECAST POSITIONS AND MAX WINDS

INIT  14/2100Z 13.0N  44.0W   45 KT  50 MPH - Tropical Storm (ESE St. John's A&B)
 12H  15/0600Z 13.6N  45.8W   55 KT  65 MPH - Tropical Storm (ESE St. John's A&B)
 24H  15/1800Z 14.5N  47.7W   70 KT  80 MPH - Category 1 (ESE St. John's A&B)
 36H  16/0600Z 15.4N  49.3W   75 KT  85 MPH - Category 1 (ESE St. John's A&B)
 48H  16/1800Z 16.6N  50.8W   85 KT 100 MPH - Category 2 (ESE St. John's A&B)
 60H  17/0600Z 17.9N  52.2W   95 KT 110 MPH - Category 2 (ESE St. John's A&B)
 72H  17/1800Z 19.3N  53.6W  100 KT 115 MPH - Category 3 (WSW St. John's A&B)
 96H  18/1800Z 22.0N  56.0W  105 KT 120 MPH - Category 3 (WSW St. John's A&B)
120H  19/1800Z 24.5N  58.5W  100 KT 115 MPH - Category 3 (WSW St. John's A&B)

NWS National Hurricane Center Miami FL 1100 AM AST Mon Sep 14, 2020 

A timely 1156 UTC ASCAT-A pass was very helpful in locating the center of Teddy, which was farther south and west than previously estimated. Satellite imagery shows that the cloud pattern is gradually becoming better organized, with the center located near the northern edge of a curved convective band. Based on the ASCAT data and the latest Dvorak classification from TAFB and SAB, the intensity remains 35 kt for this advisory.

The initial motion estimate is a somewhat uncertain 270/12. Despite the adjustment to the center position, the overall track forecast reasoning has not changed. Teddy will be steered by a deep-layer ridge located over the central Atlantic, which should result in a west-northwestward motion resuming by tonight. The ridge is forecast to shift eastward with time, and Teddy is forecast to turn more northwestward in a couple of days around the western edge of the ridge. The new NHC track forecast has been adjusted about a degree to the left of the previous NHC prediction, largely due to the adjustment in the initial position, and lies near the consensus aids and the middle of the guidance envelope.

Teddy will be moving through a favorable environment for intensification for the next several days, with SSTs increasing along the forecast track and shear remaining relatively low. The new NHC intensity forecast is similar to the previous one, showing Teddy becoming a hurricane in 36 hours and reaching major hurricane strength in 4 to 5 days. This forecast is close to IVCN through the first 48 hours and then trends toward the higher HCCA guidance after that time.

FORECAST POSITIONS AND MAX WINDS

INIT  14/1500Z 12.8N  42.8W   35 KT  40 MPH - Tropical Storm (ESE St. John's A&B)
 12H  15/0000Z 13.2N  44.7W   45 KT  50 MPH - Tropical Storm (ESE St. John's A&B)
 24H  15/1200Z 13.9N  46.8W   55 KT  65 MPH - Tropical Storm (ESE St. John's A&B)
 36H  16/0000Z 14.7N  48.4W   65 KT  75 MPH - Category 1 (ESE St. John's A&B)
 48H  16/1200Z 15.7N  49.8W   75 KT  85 MPH - Category 1 (ESE St. John's A&B)
 60H  17/0000Z 16.9N  51.0W   85 KT 100 MPH - Category 2 (ESE St. John's A&B)
 72H  17/1200Z 18.3N  52.2W   95 KT 110 MPH - Category 2 (ESE St. John's A&B)
 96H  18/1200Z 21.0N  54.5W  100 KT 115 MPH - Category 3 (WSW St. John's A&B)
120H  19/1200Z 24.0N  57.0W  100 KT 115 MPH - Category 3 (WSW St. John's A&B)

NWS National Hurricane Center Miami FL 1100 PM AST Sun Sep 13, 2020 

The depression continues to march west-northwestward with little change in its structure so far. Scatterometer data near 00Z revealed that the system is still elongated southwest to northeast with maximum winds near 30 kt. Convection has become a little more concentrated to the southwest of the depression’s center during the past few hours, so perhaps this is a sign that it will start getting organized soon.

As long as the depression remains disorganized, only minimal strengthening is likely. However, once the system comes together, all indications are that it will strengthen, perhaps significantly so. The cyclone still has several days to strengthen within a low-shear/high-SST environment, and even the global models explicitly forecast the system to become a hurricane. The NHC intensity forecast is unchanged and still brings the depression to major hurricane strength by the middle of the week. Some of the dynamical hurricane models indicate it could strengthen faster than that, so this forecast could wind up being conservative.

The depression appears to be moving generally west-northwestward. A large mid-level ridge over the central Atlantic should keep the cyclone on this general heading for the next couple of days. After that, the ridge is forecast to move north and east, and the strengthening cyclone should turn toward the northwest in response. While the exact details vary from model to model, all of the dynamical track guidance supports this general scenario. The NHC forecast is based heavily on the model consensus and lies near the middle of the guidance envelope.

FORECAST POSITIONS AND MAX WINDS

INIT  14/0300Z 13.0N  39.0W   30 KT  35 MPH - Depression (WSW Cape Verde Islands)
 12H  14/1200Z 13.5N  41.2W   35 KT  40 MPH - Tropical Storm (ESE St. John's A&B)
 24H  15/0000Z 13.9N  43.7W   45 KT  50 MPH - Tropical Storm (ESE St. John's A&B)
 36H  15/1200Z 14.4N  45.9W   55 KT  65 MPH - Tropical Storm (ESE St. John's A&B)
 48H  16/0000Z 15.0N  47.3W   70 KT  80 MPH - Category 1 (ESE St. John's A&B)
 60H  16/1200Z 16.0N  48.7W   80 KT  90 MPH - Category 1 (ESE St. John's A&B)
 72H  17/0000Z 17.2N  50.0W   90 KT 105 MPH - Category 2 (ESE St. John's A&B)
 96H  18/0000Z 20.0N  52.4W  100 KT 115 MPH - Category 3 (ENE St. John's A&B) 
120H  19/0000Z 23.0N  55.0W  100 KT 115 MPH - Category 3 (ENE St. John's A&B) 

NWS National Hurricane Center Miami FL 500 PM AST Sun Sep 13, 2020 

The depression’s center is a little closer to the deep convection compared to this morning, but the overall structure has not changed significantly. Based on this morning’s ASCAT pass, and recent Dvorak estimates of T2.0 from TAFB and SAB, the initial intensity remains 30 kt. The northerly shear over the system has been analyzed to have decreased since this morning (now around 10 kt), which is probably why the center is closer to the convection.

The shear is forecast to decrease further, and once the depression becomes more detached from the ITCZ/monsoon trough, it is expected to go through a significant phase of strengthening as it heads west toward higher oceanic heat content and a more unstable atmosphere. As discussed this morning, the GFS-based SHIPS guidance indicates that there is a 50-50 chance that the depression will strengthen by at least 65 kt during the next 3 days, which is 10 times higher than the climatological mean. And, all three regional hurricane models (HWRF, HMON, and COAMPS-TC), as well as the HCCA aid, show the cyclone becoming a major hurricane by the end of the forecast period. As a result, the NHC intensity forecast has been adjusted upward and now explicitly shows major hurricane strength on days 4 and 5.

The motion remains west-northwestward (290/10 kt), with the depression located south of a large mid-level high centered over the central Atlantic. This feature should continue driving the system westward or west-northwestward for the next 2 days. After that time, the ridge is expected to shift northward, causing the potentially strengthening hurricane to move a little slower toward the northwest. Most of the track models are clustered close together, although the HWRF remains a southern outlier and the ECMWF model is a little slower and on the right side of the envelope. The new NHC track forecast has not moved much from the previous prediction and now lies closest to the HFIP Corrected Consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  13/2100Z 12.7N  37.6W   30 KT  35 MPH - Depression (WSW Cape Verde Islands)
 12H  14/0600Z 13.2N  39.5W   35 KT  40 MPH - Tropical Storm (ESE St. John's A&B)
 24H  14/1800Z 13.6N  42.1W   45 KT  50 MPH - Tropical Storm (ESE St. John's A&B)
 36H  15/0600Z 14.1N  44.4W   60 KT  70 MPH - Tropical Storm (ESE St. John's A&B)
 48H  15/1800Z 14.7N  46.3W   70 KT  80 MPH - Category 1 (ESE St. John's A&B)
 60H  16/0600Z 15.6N  47.7W   80 KT  90 MPH - Category 1 (ESE St. John's A&B)
 72H  16/1800Z 16.8N  49.0W   90 KT 105 MPH - Category 2 (ESE St. John's A&B)
 96H  17/1800Z 19.5N  51.5W  100 KT 115 MPH - Category 3 (ENE St. John's A&B)
120H  18/1800Z 22.5N  54.0W  100 KT 115 MPH - Category 3 (ENE St. John's A&B)

NWS National Hurricane Center Miami FL 1100 AM AST Sun Sep 13, 2020  

Convective banding features are generally limited to the southern semicircle of the circulation with the center exposed just to the north. A recent ASCAT pass indicated that the strongest winds–up to 30 kt–were primarily located in the southerly and southwesterly monsoonal flow trailing the depression, although some stronger winds are beginning to develop just west of the center. Light-to- moderate northerly shear is currently affecting the depression, but this shear is expected to decrease during the next 24-48 hours.

In addition, global model fields indicate that the cyclone should become increasingly separated from the ITCZ/monsoon trough. Steady strengthening is anticipated for much of the forecast period, and the NHC intensity forecast closely follows the HCCA aid and the IVCN intensity consensus. This new forecast is a little higher than the previous prediction, especially on days 3 through 5. There are two main points that suggest this forecast could potentially go even higher in later forecast cycles: 1. the HWRF model shows more significant strengthening at the latter part of the period, bringing the system to major hurricane strength, and 2. the SHIPS Rapid Intensification guidance indicates that there is a 50-50 chance that the system will strengthen by at least 65 kt over the next 3 days, which is 9-10 times higher than the climatological mean.

The depression is moving west-northwestward (290/9 kt) to the south of a large mid-tropospheric high centered over the central subtropical Atlantic. This feature should continue to drive the cyclone westward or west-northwestward for the next 2-3 days. After that time, the mid-level high is expected to shift northward and elongate, and the potentially intensifying hurricane is likely to acquire more poleward motion, moving northwestward and a little slower on days 3-5. Most of the track models are clustered close together, except for the HWRF which has a trajectory farther to the south and west. The new NHC track forecast has been shifted a bit westward compared to the previous prediction, close to the GFS-ECMWF consensus but not as far to the left as the latest TVCA and HCCA solutions.

FORECAST POSITIONS AND MAX WINDS

INIT  13/1500Z 12.3N  36.4W   30 KT  35 MPH - Depression (WSW Cape Verde Isands)
 12H  14/0000Z 12.8N  38.0W   35 KT  40 MPH - Tropical Storm (WSW Cape Verde Isands)
 24H  14/1200Z 13.3N  40.6W   45 KT  50 MPH - Tropical Storm (WSW Cape Verde Isands)
 36H  15/0000Z 13.7N  43.0W   55 KT  65 MPH - Tropical Storm (WSW Cape Verde Isands)
 48H  15/1200Z 14.4N  45.1W   65 KT  75 MPH - Category 1 (WSW Cape Verde Isands)
 60H  16/0000Z 15.3N  46.7W   75 KT  85 MPH - Category 2 (WSW Cape Verde Isands)
 72H  16/1200Z 16.3N  48.2W   85 KT 100 MPH - Category 2 (ESE Les Abymes, Guadeloupe)
 96H  17/1200Z 19.0N  51.0W   95 KT 110 MPH - Category 2 (ESE St. Georges, Bermuda)
120H  18/1200Z 22.0N  53.5W   95 KT 110 MPH - Category 2 (ESE St. Georges, Bermuda)

NWS National Hurricane Center Miami FL 1100 PM AST Sat Sep 12, 2020

The depression is poorly organized at this time. A large convective band wraps around the northern and western portions of the cyclone, but its center of circulation is exposed and appears to have become somewhat elongated. Recent ASCAT data and the latest TAFB Dvorak analysis indicate that the maximum winds remain near 30 kt.

It will take some time for the depression to get better organized, and only slight strengthening is anticipated during the next 24 h. After that time, the cyclone’s environment is expected to support intensification, and the intensity guidance is quite aggressive. While the exact timing is somewhat uncertain, it is probable that the system will become a hurricane early next week. The new NHC intensity forecast has been adjusted higher than the previous advisory beyond 48 h, but it is below or near the model consensus at all times.

Little change was made to the NHC track forecast. The depression appears to be moving generally west-northwestward near 9 kt. In general, the system should continue west-northwestward for the next couple of days, with some slight fluctuations in its track possible tonight and tomorrow as the center consolidates. A weakness in the subtropical ridge is expected to develop by the middle of next week that could steer the cyclone more toward the northwest. The guidance is in very good agreement on this general scenario, though confidence in the forecast will be somewhat low until the system becomes a little better organized and strengthens. The official forecast is based primarily on the HCCA and TVCA consensus aids.

FORECAST POSITIONS AND MAX WINDS

INIT  13/0300Z 11.9N  34.6W   30 KT  35 MPH - Depression (WSW Cape Verde Isands)
 12H  13/1200Z 12.3N  35.9W   30 KT  35 MPH - Depression (WSW Cape Verde Isands)
 24H  14/0000Z 12.9N  37.7W   35 KT  40 MPH - Tropical Storm (WSW Cape Verde Isands)
 36H  14/1200Z 13.5N  40.1W   45 KT  50 MPH - Tropical Storm (WSW Cape Verde Isands)
 48H  15/0000Z 14.1N  42.5W   55 KT  65 MPH - Tropical Storm (WSW Cape Verde Isands)
 60H  15/1200Z 14.8N  44.5W   65 KT  75 MPH - Category 1 (WSW Roseau, Dominica)
 72H  16/0000Z 15.9N  46.2W   80 KT  90 MPH - Category 1 (ENE St.John's, A&B)
 96H  17/0000Z 18.5N  49.0W   90 KT 105 MPH - Category 2 (ESE St. Georges, Bermuda)
120H  18/0000Z 21.5N  51.0W   90 KT 105 MPH - Category 2 (ESE St. Georges, Bermuda)

NWS National Hurricane Center Miami FL 500 PM AST Sat Sep 12, 2020 

The tropical wave and associated area of low pressure that NHC has been tracking since it emerged off of Africa a couple of days ago has become sufficiently organized to be designated as a tropical depression. A curved band of deep convection developed early this morning and persisted just to the west of a well-defined low level circulation throughout the day. An earlier ASCAT overpass showed that 25-30 kt winds over the northwestern portion of the circulation, which is the basis for the initial intensity being set at 30 kt.

The depression has a rather large circulation, with the radius of maximum winds nearly 100 n mi from the center and the overall wind field appearing to extend outward over 300 n mi. The environment surrounding the cyclone over the next 36 h is characterized by moderate northeasterly vertical wind shear and plenty of warm water and atmospheric moisture. These factors are supportive of gradual strengthening, however, due to the large size of the system, it may take some time for it to consolidate. The NHC intensity forecast shows only slight strengthening through 36 h as the system consolidates, and that portion of the forecast is well below the intensity guidance. By early next week, the wind shear is expected to decrease to under 10 kt and a faster rate of intensification is indicated from 36-96 h in anticipation of the cyclone having a better structure to take advantage of the lower shear. After 96 h the intensity is held steady as northwesterly shear is forecast to increase while the system encounters some slightly drier air and moves over lower oceanic heat content. The NHC intensity forecast beyond 36 h starts well below most of the guidance, and trends close to the IVCN/ICON later on in the forecast period.

The depression is moving toward the west-northwest at 8 kt, steered by a mid-level ridge to its north. This ridge is forecast to build westward over the next few days, which should result in a continued general west-northwest motion, perhaps at a slightly faster forward speed early next week. By the middle of next week, a weakness is forecast to develop in the ridge, partially due to interaction of Paulette and a mid- to- upper level trough over the northern Atlantic at that time, and the cyclone should turn to the northwest into this weakness. Overall, track guidance from the global and regional models is in decent agreement on this scenario, and the NHC forecast is between the HFIP corrected consensus HCCA and the TVCN multimodel consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  12/2100Z 11.4N  33.5W   30 KT  35 MPH - Depression (WSW Cape Verde Isands)
 12H  13/0600Z 11.5N  34.5W   30 KT  35 MPH - Depression (WSW Cape Verde Isands)
 24H  13/1800Z 12.1N  36.1W   35 KT  40 MPH - Tropical Storm (WSW Cape Verde Isands)
 36H  14/0600Z 12.8N  38.3W   40 KT  45 MPH - Tropical Storm (WSW Cape Verde Isands)
 48H  14/1800Z 13.3N  40.7W   50 KT  60 MPH - Tropical Storm (WSW Cape Verde Isands)
 60H  15/0600Z 14.0N  42.8W   60 KT  70 MPH - Tropical Storm (WSW Cape Verde Isands)
 72H  15/1800Z 15.0N  44.5W   70 KT  80 MPH - Category 1 (WSW Roseau, Dominica)
 96H  16/1800Z 17.7N  47.3W   80 KT  90 MPH - Category 1 (ENE St.John's, A&B)
120H  17/1800Z 21.0N  49.7W   80 KT  90 MPH - Category 1 (ESE St. Georges, Bermuda)

NWS National Hurricane Center Miami FL 800 AM EDT Sat Sep 12, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Tropical Storm Paulette and Tropical Storm Rene, both located over the central Atlantic Ocean. The National Hurricane Center is also issuing advisories on Tropical Depression Nineteen, located near southern Florida.

  • 1. A surface trough over the north-central Gulf of Mexico is producing disorganized showers and a few thunderstorms. Some slow development of this system is possible while it moves westward and then southwestward over the northern and western Gulf of Mexico through the middle of next week. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low…30 percent.
  • 2. A broad area of low pressure located several hundred miles southwest of the Cabo Verde Islands is producing a large area of disorganized showers and thunderstorms. Development of this system is forecast, and a tropical depression is expected to form within the next couple of days while the system moves generally westward at 15 to 20 mph across the eastern and central tropical Atlantic. * Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high...90 percent.
  • 3. Another area of disturbed weather, associated with a tropical wave, is located near the Cabo Verde Islands. Environmental conditions support some development during the next few days, and a tropical depression could form over the far eastern tropical Atlantic early next week while the system moves slowly westward. By mid-week, upper-level winds could become less conducive for development. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…medium…60 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Fri Sep 11, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Tropical Storm Paulette and Tropical Storm Rene, both located over the central Atlantic Ocean. The National Hurricane Center is also issuing advisories on newly formed Tropical Depression Nineteen, located near southern Florida.

  • 1. A surface trough over the north-central Gulf of Mexico is producing disorganized showers and a few thunderstorms. Some slow development of this system is possible while it moves westward and then southwestward over the northern and western Gulf of Mexico through the middle of next week. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low...30 percent.
  • 2. A broad area of low pressure located a few hundred miles south-southwest of the Cabo Verde Islands is producing a large area of disorganized showers and thunderstorms. Development of this system is forecast, and a tropical depression is expected to form within the next couple of days while the system moves generally westward at 15 to 20 mph across the eastern and central tropical Atlantic. * Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high…90 percent.
  • 3. Another area of disturbed weather, associated with a tropical wave, is located just off of the west coast of Africa. Environmental conditions could support development during the next few days, and a tropical depression could form over the far eastern tropical Atlantic early next week while the system moves slowly westward. Upper-level winds could become less conducive for development by Tuesday. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…medium...40 percent.

NWS National Hurricane Center Miami FL 200 PM EDT Fri Sep 11, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Tropical Storm Paulette and Tropical Storm Rene, both located over the central Atlantic Ocean.

  • 1. Shower and thunderstorm activity located over the northwestern and central Bahamas and the adjacent waters continues to shows signs of organization. In addition, surface observations indicate that pressures have fallen over the area since yesterday and, along with wind and satellite data, suggest that a broad area of low pressure could be forming between the northwestern Bahamas and South Florida. This system is forecast to move westward at about 10 mph, and it could become a tropical depression while it is near South Florida tonight. But if not, the disturbance is expected to become a tropical depression while it moves slowly west-northwestward over the northeastern Gulf of Mexico this weekend and early next week. Regardless of development, this system is expected to produce locally heavy rainfall over portions of the Bahamas, South Florida, and the Florida Keys during the next couple of days, and interests there, as well as along the northern and eastern Gulf coast, should monitor its progress. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…80 percent. [Sally]
  • 2. Showers and thunderstorms have increased a little bit over the north-central Gulf of Mexico near a surface trough of low pressure. Some slow development of this system is possible while it moves westward and then southwestward over the northern and western Gulf of Mexico through the middle of next week. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low…30 percent.
  • 3. A broad area of low pressure, associated with a tropical wave, is located a few hundred miles south and southwest of the Cabo Verde Islands and is producing a large area of disorganized showers and thunderstorms. Development of this system is forecast, and a tropical depression is expected to form within the next few days while the system moves generally westward at 15 to 20 mph across the eastern and central tropical Atlantic. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…90 percent.
  • 4. Another area of disturbed weather is located just off of the west coast of Africa. Environmental conditions could support development during the next few days, and a tropical depression could form over the far eastern tropical Atlantic early next week while the system moves slowly westward. Upper-level winds could become less conducive for development by Monday or Tuesday. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…medium…40 percent.

If this system is named, it will become Tropical Storm Teddy.

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Video: Post-tropical storm Teddy moves into Atlantic Canada, warnings of storm surge