Tropical Storm Sally

Tropical Depression Sally Track 2200 Hours September 16 2020
Tropical Depression Sally Track 2200 Hours September 16 2020

Tropical Storm Sally Flash Flood WarningTropical Storm SallyNWS National Hurricane Center Miami FL 1000 PM  CDT Wed Sep 16, 2020 (see 11 pm video below)

Although it remains a prodigious rain producer, surface observations indicate that Sally has weakened to a 30-kt depression over southeastern Alabama. The cyclone will continue to gradually spin down over the southeastern United States, and is likely to become a remnant low-pressure system before merging with a frontal zone near North Carolina on Friday.

The cyclone is moving northeastward near 8 kt. A northeastward to east-northeastward motion is expected over the next 36 hours or so as the system moves to the south of a broad trough over the northeastern United States. The official track forecast is about in the middle of the model guidance.

KEY MESSAGES:

  • 1. Significant and widespread flooding is expected across inland portions of Alabama, central Georgia and upstate South Carolina, and widespread flooding is possible across western/central North Carolina, and far southeast Virginia. Most widespread moderate to major river flooding will crest by the weekend, but rivers will remain elevated across southern Alabama and the Florida Panhandle.
FORECAST POSITIONS AND MAX WINDS

INIT  17/0300Z 31.9N  86.1W   30 KT  35 MPH - Depression (ENE  Ansley, AL)
 12H  17/1200Z 32.7N  85.0W   30 KT  35 MPH - Depression (WSW Whiesville, GA)
 24H  18/0000Z 34.0N  82.5W   25 KT  30 MPH - Depression (ESE Mt Carmel, SC)
 36H  18/1200Z 35.0N  79.0W   25 KT  30 MPH - Low (WSWS Fayetteville, NC)
 48H  19/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Wed Sep 16, 2020 

The center of Sally continued its slow trek inland across the far western Florida Panhandle early this afternoon, and it is now located over southeastern Alabama. The satellite and radar presentation of the storm has continued to degrade, and surface observations and Doppler radar data show that winds have continued to gradually decrease. The initial intensity has been reduced to 50 kt, and rapidly weakening should continue as the circulation moves farther inland. Sally is forecast to become a tropical depression tonight or early Thursday, and degenerate into a remnant low in 36-48 hours. The system is expected to be absorbed by a frontal boundary near the southeast U.S. coast on Friday.

Sally is moving north-northeastward at a slightly faster forward speed of 6 kt. The cyclone should turn northeastward and move at a slightly faster forward speed as it become embedded within the southern extent of the mid-latitude westerlies, and this general motion should continue until dissipation occurs. The dynamical models are tightly clustered and the NHC track is near the center of envelope.

Although the winds and storm surge from Sally are expected to continue to subside this evening, heavy rainfall and flooding will continue to spread inland over southeastern Alabama, central Georgia, and western South Carolina over the next day or so.

KEY MESSAGES:

  • 1. Historic and catastrophic flooding, including widespread moderate to major river flooding, is unfolding along and just inland from west of Tallahassee, Florida to Mobile Bay, Alabama. Significant and widespread flooding is expected across inland portions of Alabama, central Georgia and upstate South Carolina, and widespread flooding is possible across western/central North Carolina, and far southeast Virginia.
  • 2. Life-threatening storm surge is occurring along portions of the coastline of the western Florida Panhandle, including Pensacola Bay.
  • 3. Tropical storm conditions are expected to continue this evening within portions of the Tropical Storm warning area in southern Alabama, and the western Florida panhandle.
FORECAST POSITIONS AND MAX WINDS

INIT  16/2100Z 31.2N  86.8W   50 KT  60 MPH - Tropical Storm (WSW Brooklyn, AL)
 12H  17/0600Z 31.9N  86.0W   30 KT  35 MPH - Depression (WSW Needmore, AL)
 24H  17/1800Z 33.2N  84.0W   25 KT  30 MPH - Depression (WSW Indian Springs, GA)
 36H  18/0600Z 34.2N  81.4W   25 KT  30 MPH - Low (ENE Little Mountain, SC)
 48H  18/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Wed Sep 16, 2020 

NWS Doppler Radar and fixes from an Air Force Reserve Hurricane Hunter aircraft indicate that Sally made landfall near Gulf Shores, Alabama, around 0945 UTC with an intensity of 90 kt and a minimum central pressure of 965 mb. Since that time, the center has been inching its way inland over southeastern Alabama and the extreme western portion of the Florida panhandle. The eye has degraded in radar imagery, and Doppler velocities are gradually decreasing. The intensity has therefore been reduced to 70 kt for this advisory. Sally should continue to rapidly weaken today, and once the majority of the circulation is onshore by Thursday morning, it should weaken to a tropical depression. The remnant low is forecast to be

Hurricane Sally Greatest Flood Risk
Hurricane Sally Greatest Flood Risk

absorbed by a frontal boundary near the southeastern United States coastline in a couple of days.

Radar and the earlier aircraft fixes show that the longer-term motion is 030/4 kt. Sally should continue to move north- northeastward to northeastward with a gradual increase in forward speed as it enters the southern extent of the mid-latitude westerlies over the next 24-36 hours. A faster east-northeastward motion is expected by 36-48 hours before Sally or its remnants merge with the aforementioned frontal zone. The updated NHC track forecast is close to the HFIP corrected consensus, which is slightly north of the previous advisory.

As Sally moves inland, ongoing heavy rainfall and flooding will spread northeastward across southeastern Alabama and portions of Georgia and western South Carolina during the next day or two.

KEY MESSAGES:

  • 1. Historic and catastrophic flooding, including widespread moderate to major river flooding, is unfolding along and just inland from west of Tallahassee, Florida, to Mobile Bay, Alabama. Significant and widespread flooding is likely across inland portions of Alabama into central Georgia, and possible across western South Carolina, western and central North Carolina, and far southeast Virginia.
  • 2. Life-threatening storm surge is occurring along portions of the coastline from Alabama to the western Florida Panhandle, including Pensacola Bay.
  • 3. Hurricane conditions are expected to continue this afternoon within portions of the Hurricane Warning area in southern Alabama and the western Florida panhandle.
FORECAST POSITIONS AND MAX WINDS

INIT  16/1500Z 30.6N  87.4W   70 KT  80 MPH - Category 1 (WSW  Cantonment, FL)
 12H  17/0000Z 31.3N  86.7W   45 KT  50 MPH - Tropical Storm (WNW Brooklyn, AL)
 24H  17/1200Z 32.4N  85.4W   30 KT  35 MPH - Depression (WSW Marvyn, AL)
 36H  18/0000Z 33.6N  83.1W   25 KT  30 MPH - Depression (WSW  Union Point, GA)
 48H  18/1200Z 34.6N  80.2W   25 KT  30 MPH - Low (WSW Chesterfield County, SC)
 60H  19/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 PM CDT Tue Sep 15, 2020 

Observations from an Air Force Hurricane Hunter aircraft and WSR-88D Doppler radar data indicate some strengthening. The eye has become a little better defined on the radar, and the central pressure has fallen to 972 mb. The eye has also become evident on recent IR imagery.

Using a blend of flight-level and SFMR-observed surface winds, along with the Doppler velocities, gives a current intensity estimate of 75 kt. Given the recent trends, the official forecast allows for some more intensification before landfall, which is likely to occur in less than 12 hours. Rapid weakening will occur after the center moves inland, and the system should become a remnant low in a couple of days. This is consistent with the model guidance.

Hurricane Sally Rainfall Estimates
Hurricane Sally Rainfall Estimates

Radar and aircraft center fixes indicate that the motion is now north-northeastward, or 020/2 kt. Sally should move north-northeastward, and then northeastward, with a gradual increase in forward speed, along the northwestern side of a weak mid-level high pressure area for the next couple of days. Then, as the system approaches the westerly flow at higher latitudes, the cyclone should turn toward the east-northeast with a slight further increase in forward speed until becoming a dissipating remnant low near the southeast U.S. coast in 2-3 days. The official forecast is close to the latest corrected dynamical model consensus, HCCA, prediction.

KEY MESSAGES:

  • 1. Historic, life-threatening flash flooding due to rainfall is likely through Wednesday along and just inland of the coast from the Florida Panhandle west of the Apalachicola River to the Alabama/Mississippi border. Widespread moderate to major river flooding is forecast across the Florida Panhandle and southern Alabama. Significant flash and urban flooding, as well as widespread minor to moderate river flooding, is likely across inland portions of Mississippi and Alabama, and into Georgia and the western Carolinas this week.
  • 2. Life-threatening storm surge is expected along portions of the coastline from Alabama to the western Florida Panhandle, including Mobile Bay. 3. Hurricane conditions are expected this evening and overnight within portions of the Hurricane Warning area along the Mississippi and Alabama coastlines and the western Florida Panhandle.
FORECAST POSITIONS AND MAX WINDS

INIT  16/0300Z 29.8N  87.8W   75 KT  85 MPH - Category 1 (WSW Gulf Shores, AL)
 12H  16/1200Z 30.3N  87.5W   80 KT  90 MPH - Category 1 (WNW Goat Point, AL)
 24H  17/0000Z 31.2N  86.8W   40 KT  45 MPH - Tropical Storm (WSW  Brooklyn, AL)
 36H  17/1200Z 32.0N  85.7W   30 KT  35 MPH - Depression (ESE Scottland, AL)
 48H  18/0000Z 32.9N  83.9W   25 KT  30 MPH - Depression (WSW  Bolingbroke, GA)
 60H  18/1200Z 33.6N  81.5W   20 KT  25 MPH - Depression (WSW Camp Rawls, SC)
 72H  19/0000Z 34.0N  79.0W   20 KT  25 MPH - Low (WSW Allsbrook, SC)
 96H  20/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Tue Sep 15, 2020 

Sally has been inching its way toward the north-central Gulf Coast today. The overall structure of the storm has remained about the same during the day with a large ragged eye in apparent in radar imagery. A NOAA P-3 aircraft that has been sampling the storm since late this morning has reported peak flight-level winds of 76 kt, and NWS Doppler radar has shown velocities of 75-80 kt at around 7000 ft.

The intensity was reduced to 70 kt on the 1800 UTC intermediate advisory and remains at that value for this advisory. Radar and aircraft fixes show that Sally has been moving very slowly toward the north or 350/2 kt. The track forecast philosophy remains unchanged from the previous advisory. Sally is currently located within an area of weak steering flow between a couple of mid-level ridges to its east and west. A weak mid-level trough over the south-central United States is forecast to slide eastward over the next few days, which should cause Sally to turn north-northeastward and then northeastward over the next 24-36 hours.

Sally’s forward speed is expected to remain quite slow over the next 24-48 hours, but the guidance has trended slightly faster after that time. The slow forward speed is likely to result in a historical rainfall event for the north-central Gulf Coast. It may sound like a broken record, but the track guidance has again shifted eastward during the first 24-36 hours, and the NHC forecast has been adjusted accordingly. Since Sally has a large wind field, and storm surge and rainfall hazards extend far from the eye, users should not focus on the exact forecast track or specific location and timing of landfall as strong winds and bands of heavy rainfall are already affecting the Gulf Coast and will continue to do so for quite some time.

The combination of upwelling and moderate westerly shear is likely to result in little change in strength prior to Sally moving onshore. Once the center of the hurricane moves onshore, rapid weakening is expected and the global models indicate that the circulation will becoming elongated along a frontal boundary in 3 to 4 days.

KEY MESSAGES:

  • 1. Historic life-threatening flash flooding due to rainfall is likely through Wednesday along and just inland of the coast from the Florida Panhandle west of the Apalachicola River to far southeastern Mississippi. Widespread moderate to major river flooding is forecast along and just inland of the central Gulf Coast. Significant flash and urban flooding, as well as widespread minor to moderate river flooding, is likely across inland portions of Mississippi and Alabama, and into Georgia and the western Carolinas this week.
  • 2. Life-threatening storm surge is expected along portions of the coastline from Alabama to the western Florida Panhandle, including Mobile Bay.
  • 3. Hurricane conditions are expected this evening and overnight within portions of the Hurricane Warning area along the Mississippi and Alabama coastlines and the western Florida Panhandle.
FORECAST POSITIONS AND MAX WINDS

INIT  15/2100Z 29.5N  88.1W   70 KT  80 MPH - Category 1 (WSW Gulf Shores, AL)
 12H  16/0600Z 29.9N  88.1W   70 KT  80 MPH - Category 1 (WSW Dauphin Isand, AL)
 24H  16/1800Z 30.6N  87.7W   60 KT  70 MPH - Tropical Storm (ESE Loxley, AL)
 36H  17/0600Z 31.5N  86.9W   40 KT  45 MPH - Tropical Storm (WSW Garland, AL)
 48H  17/1800Z 32.5N  85.3W   30 KT  35 MPH - Depression (WNW Hugley, AL)
 60H  18/0600Z 33.1N  83.3W   25 KT  30 MPH - Depression (WNW Milledgeville, GA)
 72H  18/1800Z 33.5N  81.0W   20 KT  25 MPH - Low (ENE Bolen Town, SC)
 96H  19/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Tue Sep 15, 2020 

The satellite presentation of Sally has not changed much since overnight. A ragged eye is seen in WSR-88D radar imagery, with a band occasionally trying to wrap around the southwestern side. A NOAA reconnaissance aircraft has just recently provided a new center fix, and data from the center drop indicated the minimum pressure is 983 mb. The first pass through the northeastern quadrant suggests that the 50-kt wind field may have expanded, but there has been little change in peak winds reported by the aircraft. The intensity has been held at 75 kt pending additional data from the NOAA P-3 mission that has just begun. A highly elevated oil rig just northeast of the center reported peak has reported sustained winds of 69 kt with a gust to 86 kt around 1200 UTC this morning.

Sally has been meandering this morning, but the longer-term motion is northwestward or 315/2 kt. Sally remains within an area of weak steering flow, but a weak mid-level trough over the south-central United States is forecast to slide eastward over the next over the next couple of days. This pattern should cause Sally to move very slowly north-northwestward to northward over the next 24 hours, with the center of the hurricane nearing the northern Gulf Coast late tonight or Wednesday.

By late Wednesday, Sally should turn northeastward as the aforementioned trough approaches Missouri and Arkansas. The new forecast has been nudged slightly eastward in the early portion of the track forecast, but the latter portion is very close to the previous advisory. The new track lies a little to the west of the various consensus aids in deference to the typically reliable GFS and ECMWF models that are near the left edge of the guidance envelope. Sally’s forward motion is forecast to be around 5 kt or less throughout the forecast period, which will result in a long period of heavy rainfall and historic flooding along the north-central Gulf Coast.

Moderate westerly shear and upwelling beneath the slow moving hurricane are likely to prevent strengthening today. The shear is forecast to increase tonight and although some slight weakening could occur before the center reaches the coast, Sally is predicted to remain a dangerous hurricane through landfall. Once Sally moves inland, rapid weakening is expected and circulation is forecast to lose definition and dissipate by day 4.

Users are reminded to not focus on the specific timing and location of landfall. Life-threatening storm surge, historic flash flooding from heavy rainfall, and dangerous winds will affect a large portion of the north-central Gulf Coast during the next few days.

KEY MESSAGES:

  • 1. Life-threatening storm surge is expected from the Mouth of the Mississippi River to the Okaloosa/Walton County Line in the Florida Panhandle. The highest inundation is expected along the Alabama coast, including Mobile Bay.
  • 2. Historic life-threatening flash flooding is likely through Wednesday along and just inland of the coast from the western Florida Panhandle to far southeastern Mississippi. Widespread moderate to major river flooding is forecast along and just inland of the central Gulf Coast. Significant flash and urban flooding, as well as widespread minor to moderate river flooding, are likely across inland portions of Mississippi, Alabama, northern Georgia, and the western Carolinas through the week.
  • 3. Hurricane conditions are expected today within portions of the Hurricane Warning area along the Mississippi and Alabama coastlines and the western Florida Panhandle.
FORECAST POSITIONS AND MAX WINDS

INIT  15/1500Z 29.1N  88.2W   75 KT  85 MPH - Category 1 (ESE Pascagoula , MS)
 12H  16/0000Z 29.6N  88.2W   75 KT  85 MPH - Category 1 (ESE Pascagoula , MS)
 24H  16/1200Z 30.2N  88.1W   70 KT  80 MPH - Category 1 (ESE Dauphin Island, AL)
 36H  17/0000Z 31.0N  87.6W   55 KT  65 MPH - Tropical Storm (ESE Perdido, AL)
 48H  17/1200Z 31.9N  86.6W   35 KT  40 MPH - Tropical Storm (ESE Fort Deposit, AL)
 60H  18/0000Z 32.6N  85.2W   25 KT  30 MPH - Depression (ENE  Salem, AL)
 72H  18/1200Z 33.0N  83.6W   20 KT  25 MPH - Low (WNW  Gray, GA)
 96H  19/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 PM CDT Mon Sep 14, 2020 

After rapidly strengthening earlier today, Sally’s intensity has plateaued for now. Both the NOAA and Air Force Hurricane Hunters have been investigating Sally this evening and they have found that the minimum pressure and winds have leveled off, and support perhaps a generous initial intensity of 85 kt. Doppler radar images and reports from both aircraft indicate the inner core of the hurricane is quite small and that the eyewall is open on the south side, likely due to some dry air that has wrapped into that portion of the circulation.

Aircraft and Doppler radar fixes indicate that Sally is moving very slowly to the west-northwest, with the latest initial motion estimated to be 300/3 kt. Weak high pressure ridging to the north and east of Sally is expected to cause the hurricane to continue to move slowly west-northwestward to northwestward for another 12 hours, bringing the center of the storm very near the northern Gulf coast. By Tuesday afternoon, when the hurricane will likely be just offshore, the models show the steering currents collapsing and Sally is likely to drift northward before finally turning northeastward ahead of a developing mid-level trough over the central U.S. by late Wednesday.

There continues to be a significant amount of uncertainty on exactly where and when Sally turns northward and makes landfall, with model solutions ranging from a landfall on the Florida panhandle to a landfall in extreme southeastern Louisiana. It should be emphasized that it is always challenging to forecast the track of hurricanes in weak steering currents, and in Sally’s case the weak steering is occurring very near land. The new NHC track forecast is a little to the east of the previous one, trending toward the latest consensus aids.

Sally is still in generally favorable environmental conditions consisting of very warm SSTs and low wind shear. Since the hurricane will likely remain in those conditions through Tuesday morning, some strengthening seems likely in the short term. In 12 to 24 hours, when Sally is forecast to be very near the coast, a combination of an increase in westerly shear and cooler upwelled shelf waters should limit additional intensification. After the hurricane makes landfall, rapid weakening is forecast and Sally should become post-tropical in 3 to 4 days over the southeast U.S. The NHC intensity forecast lies at the high end of the model guidance and is quite similar to the previous one.

Users are reminded to not focus on the exact forecast track or the specific timing and location of landfall. Hurricane-force winds, dangerous storm surge, and flooding rainfall will affect a large portion of the north-central Gulf Coast during the next few days.

KEY MESSAGES:

  • 1. It is still too early to determine where Sally’s center will move onshore given the uncertainty in the timing and location of Sally’s northward turn near the central Gulf Coast. Users should not focus on the details of the official forecast track, since NHC’s average forecast error at 36 hours is around 60 miles, and dangerous storm surge, rainfall, and wind hazards will extend well away from the center.
  • 2. An extremely dangerous and life-threatening storm surge is expected for areas outside the southeastern Louisiana Hurricane and Storm Damage Risk Reduction System from Port Fourchon, Louisiana, to the Okaloosa/Walton County Line in the Florida Panhandle, where a Storm Surge Warning is in effect. Residents in these areas should follow any advice given by local officials.
  • 3. Hurricane conditions are expected early Tuesday within the Hurricane Warning area in southeastern Louisiana and are expected by late Tuesday and Tuesday night within the Hurricane Warning area along the Mississippi and Alabama coastlines and the western Florida Panhandle. Tropical storm conditions are already occurring in some of these areas.
  • 4. Life-threatening flash flooding is likely with Sally, as well as widespread minor to isolated major flooding on area rivers, along and just inland of the Central Gulf Coast. Significant flash and urban flooding, as well as widespread minor to moderate river flooding is likely across inland portions of Mississippi and Alabama and into northern Georgia, southeastern Tennessee and the western Carolinas through the week. Sally may continue to produce flash flooding across the Florida peninsula and prolong existing minor river flooding across west-central Florida through tonight.
FORECAST POSITIONS AND MAX WINDS

INIT  15/0300Z 28.9N  87.6W   85 KT 100 MPH - Category 2 (ESE Gulf Shores, AL)
 12H  15/1200Z 29.1N  88.1W   95 KT 110 MPH - Category 2 (WNW Pascagoula, MS)
 24H  16/0000Z 29.6N  88.4W   90 KT 105 MPH - Category 2 (WNW Pascagoula, MS)
 36H  16/1200Z 30.4N  88.3W   85 KT 100 MPH - Category 2 (WSW Bayou La Batre, AL)
 48H  17/0000Z 31.3N  87.4W   50 KT  60 MPH - Tropical Storm (WSW Goodway, AL)
 60H  17/1200Z 32.0N  86.3W   30 KT  35 MPH - Depression (WSW Ramer, AL)
 72H  18/0000Z 32.7N  84.9W   25 KT  30 MPH - Depression (WSW Kingsboro, GA)
 96H  19/0000Z 33.1N  82.3W   25 KT  30 MPH - Low (WNW Gough, GA)
120H  20/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Mon Sep 14, 2020

After the rapid spin up of the inner core late this morning, the most recent aircraft passes through the center have not found any higher flight-level winds, however there have been a few SFMR winds of 85-90 kt reported. Using a blend of the flight-level and SFMR winds the initial intensity has been increased to 85 kt for this advisory. The next Air Force and NOAA aircraft have begun to sample the storm. Now that Sally has developed an inner core, the favorable atmospheric and ocean conditions of low vertical wind shear and warm water should allow for additional strengthening tonight while the system moves over the north-central Gulf of Mexico, and Sally could approach major hurricane strength. On Tuesday, the global models are predicting an increasing in southwesterly flow aloft, and this increase in shear, the potential for land interaction, and some upwelling over the shallower shelf waters over the northern Gulf should slow the intensification process. The NHC intensity forecast is again near the upper-end of the guidance envelope in best agreement with the HWRF and HFIP corrected consensus models.

Sally did not move much earlier today as the center re-formation took place, but it appears that a slow west-northwestward to northwestward motion has resumed. Weak ridging over the southeastern United States is expected to steer Sally generally west-northwestward through early Tuesday. After that time, steering currents weaken and a slow northward motion is forecast as a weak mid-level trough develops over the the central United States. This trough is forecast to slide eastward, allowing Sally to begin a slow north-northeastward or northeastward motion.

The specific timing and location of the turn will be critical as to the eventual location and timing of landfall along the north-central Gulf Coast. The UKMET and ECMWF models show a more northeastward motion after the turn and have trended eastward, with the ECMWF much slower than the remainder of the guidance. The NHC track has been adjusted eastward, and this requires and eastward extension of the hurricane warning. The new track most closely follows the GFS and it ensemble mean, but lies to the west of the various consensus aids, so some additional eastward adjustments could be needed in subsequent advisories.

Given the uncertainty in the timing and location of the northward turn and the lack of well-defined steering currents, users are reminded to not focus on the exact forecast track or the specific timing and location of landfall. Hurricane-force winds, dangerous storm surge, and flooding rainfall will affect a large portion of the north-central Gulf Coast during the next few days.

KEY MESSAGES:

  • 1. It is too early to determine where Sally’s center will move onshore given the uncertainty in the timing and location of Sally’s northward turn near the central Gulf Coast. Users should not focus on the details of the official forecast track, since NHC’s average forecast error at 36 to 48 hours is around 60 to 80 miles, and dangerous storm surge, rainfall, and wind hazards will extend well away from the center.
  • 2. An extremely dangerous and life-threatening storm surge is expected for areas outside the southeastern Louisiana Hurricane and Storm Damage Risk Reduction System from Port Fourchon, Louisiana, to the Okaloosa/Walton County Line in the Florida Panhandle, where a Storm Surge Warning is in effect. Residents in these areas should follow any advice given by local officials.
  • 3. Hurricane conditions are expected late tonight or early Tuesday within the Hurricane Warning area in southeastern Louisiana and are expected by late Tuesday and Tuesday night within the Hurricane Warning area along the Mississippi and Alabama coastlines and the western Florida Panhandle. Tropical storm conditions are likely to begin this evening in these areas and preparations should be rushed to completion.
  • 4. Life-threatening flash flooding is likely, as well as widespread minor to isolated major flooding, on area rivers along and just inland of the Central Gulf Coast. Significant flash and urban flooding, as well as widespread minor to moderate river flooding is likely across Mississippi and Alabama through the middle of the week. Flooding impacts are expected to spread farther across the Southeast through the week. Sally could continue to produce flash flooding across the Florida peninsula and prolong existing minor river flooding across west-central Florida through today.
FORECAST POSITIONS AND MAX WINDS

INIT  14/2100Z 28.8N  87.4W   85 KT 100 MPH - Category 2 (ESE Gulf Shore, AL)
 12H  15/0600Z 29.2N  88.2W   95 KT 110 MPH - Category 2 (ENE Port Eads, LA)
 24H  15/1800Z 29.7N  88.7W   95 KT 110 MPH - Category 2 (ESE Biloxi, MS)
 36H  16/0600Z 30.4N  88.6W   90 KT 105 MPH - Category 2 (ENE Gautier, MS)
 48H  16/1800Z 31.3N  88.0W   55 KT  65 MPH - Tropical Storm (ESE Sunflower, AL)
 60H  17/0600Z 32.2N  86.8W   30 KT  35 MPH - Depression (WNW  Mosses, AL)
 72H  17/1800Z 32.9N  85.5W   25 KT  30 MPH - Depression (WNW  La Fayette, AL)
 96H  18/1800Z 33.5N  83.0W   20 KT  25 MPH - Low (ENE White Plains, GA)
120H  19/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1130 AM CDT Mon Sep 14, 2020

A NOAA Hurricane Hunter aircraft investigating Sally recently measured peak flight-level winds of 88 kt at 700 mb and SFMR winds of 78 kt north of the center, and an Air Force reconnaissance aircraft just measured 79 kt flight-level winds at 700 mb. These data indicate that Sally has rapidly strengthened into a hurricane with an intensity of around 80 kt. In addition, data from the KEVX WSR-88D show an eye forming at around 16,000 ft altitude.

This special advisory has been issued to increase the initial and forecast intensity. Additional adjustments to the intensity forecast could be required this afternoon. Only a slight adjustment was made to the 12-h track forecast position based on the more northward and eastward initial position.

KEY MESSAGES:

  • 1. It is too early to determine where Sally’s center will move onshore given the uncertainty in the timing and location of Sally’s northward turn near the central Gulf Coast. Users should not focus on the details of the official forecast track, since NHC’s average forecast error at 48 hours is around 80 miles, and dangerous storm surge, rainfall, and wind hazards will extend well away from the center.
  • 2. An extremely dangerous and life-threatening storm surge is expected for areas outside the southeastern Louisiana Hurricane and Storm Damage Risk Reduction System from Port Fourchon, Louisiana, to the Alabama/Florida border, where a Storm Surge Warning is in effect. Residents in these areas should follow any advice given by local officials.
  • 3. Hurricane conditions are expected tonight within the Hurricane Warning area in southeastern Louisiana and are expected by late Tuesday within the Hurricane Warning area along the Mississippi and Alabama coastline. Tropical storm conditions are likely to begin later today and this evening in these areas and preparations should be rushed to completion.
  • 4. Life-threatening flash flooding is likely, as well as widespread minor to isolated major flooding, on area rivers along and just inland of the Central Gulf Coast. Significant flash and urban flooding, as well as widespread minor to moderate river flooding is likely across Mississippi and Alabama through the middle of the week. Flooding impacts are expected to spread farther across the Southeast through the week. Sally could continue to produce flash flooding across the Florida peninsula and prolong existing minor river flooding across west-central Florida through today.
FORECAST POSITIONS AND MAX WINDS

INIT  14/1630Z 28.7N  87.0W   80 KT  90 MPH - Category 1 (WSW Destin, FL)
 12H  15/0000Z 28.8N  87.8W   85 KT 100 MPH - Category 2 (WSW Gulf Shores, AL)
 24H  15/1200Z 29.2N  88.8W   90 KT 105 MPH - Category 2 (ENE Port Eads, LA)
 36H  16/0000Z 29.8N  89.1W   90 KT 105 MPH - Category 2 (ESE Crossroads, MS)
 48H  16/1200Z 30.8N  88.7W   65 KT  75 MPH - Category 1 (ESE Crossroads, MS)
 60H  17/0000Z 31.8N  87.7W   30 KT  35 MPH - Depression (ENE Fulton, AL)
 72H  17/1200Z 32.6N  86.5W   25 KT  30 MPH - Depression (WNW Pine Level, AL)
 96H  18/1200Z 33.1N  84.0W   20 KT  25 MPH - Low (WNW Forsyth, GA)
120H  19/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Mon Sep 14, 2020 

An intense burst of deep convection with cloud tops colder than -80 degrees Celsius has developed over and the to east of the center this morning. A recent fix from an Air Force Reserve Hurricane Hunter aircraft indicates that the center has reformed to the east of the previous estimated location, beneath the burst of deep convection. NWS WSR-88D radar imagery shows an increase in banding around the eastern and southeastern portion of new center found by the aircraft and it appears that an eye is in its formative stage. The aircraft has reported believable SFMR winds of 55 kt, and that is the basis for the initial intensity. The most recent minimum pressure estimated from the aircraft data is 991 mb, down several millibars from the first fix on this flight.

Sally is located within a conducive environment of low wind shear, warm waters, and a moist atmosphere. These conditions are likely to lead to steady strengthening over the next 24 hours or so. With the recent increase in organization of the inner core, there is more confidence that Sally will strengthen to a hurricane later today or tonight. Additional strengthening is possible on Tuesday while the storm moves slowly northwestward near the coast of southeast Louisiana. Increasing westerly wind shear and land interaction will probably slow the intensification rate by late tomorrow. The new NHC intensity forecast is similar to the previous advisory and is near the upper-end of the guidance envelope. Since Sally is forecast to be moving very slowly around the time of landfall a slower rate of weakening is indicated since a large portion of the circulation will remain over water for some time.

Given the recent re-formation of the center, the initial motion is a somewhat uncertain west-northwestward at 5 kt. Weak ridging over the southeastern United State should steer Sally slowly west- northwestward through tonight. After that time, a northwestward to northward turn is anticipated but the exact timing and location of the turn remains uncertain. The general trend in the guidance has been eastward for the past few cycles, and the NHC forecast has been nudged in that direction and lies between the GFS and ECMWF models but a little west of the various consensus aids.

Regardless of the exact forecast track and intensity of Sally, the slow-moving storm is expected to cause a life-threatening storm surge and freshwater flooding event.

KEY MESSAGES:

  • 1. It is too early to determine where Sally’s center will move onshore given the uncertainty in the timing and location of Sally’s northward turn near the central Gulf Coast. Users should not focus on the details of the official forecast track, since NHC’s average forecast error at 48 hours is around 80 miles, and dangerous storm surge, rainfall, and wind hazards will extend well away from the center.
  • 2. An extremely dangerous and life-threatening storm surge is expected for areas outside the southeastern Louisiana Hurricane and Storm Damage Risk Reduction System from Port Fourchon, Louisiana, to the Alabama/Florida border, where a Storm Surge Warning is in effect. Residents in these areas should follow any advice given by local officials.
  • 3. Hurricane conditions are expected tonight within the Hurricane Warning area in southeastern Louisiana and are expected by late Tuesday within the Hurricane Warning area along the Mississippi and Alabama coastline. Tropical storm conditions are likely to begin later today and this evening in these areas and preparations should be rushed to completion.
  • 4. Life-threatening flash flooding is likely, as well as widespread minor to isolated major flooding, on area rivers along and just inland of the Central Gulf Coast. Significant flash and urban flooding, as well as widespread minor to moderate river flooding is likely across Mississippi and Alabama through the middle of the week. Flooding impacts are expected to spread farther across the Southeast through the week. Sally could continue to produce flash flooding across the Florida peninsula and prolong existing minor river flooding across west-central Florida through today.
FORECAST POSITIONS AND MAX WINDS

INIT  14/1500Z 28.4N  86.9W   55 KT  65 MPH - Tropical Storm (ESE Gulf Shores, AL)
 12H  15/0000Z 28.7N  88.0W   65 KT  75 MPH - Category 1 (ESE Gulfport, MS)
 24H  15/1200Z 29.2N  88.8W   75 KT  85 MPH - Category 1 (ENE Port Eads, LA)
 36H  16/0000Z 29.8N  89.1W   80 KT  90 MPH - Category 1 (ESE Crossroads, MS)
 48H  16/1200Z 30.8N  88.7W   60 KT  70 MPH - Tropical Storm (ESE Crossroads, MS)
 60H  17/0000Z 31.8N  87.7W   30 KT  35 MPH - Depression (ENE  Fulton, AL)
 72H  17/1200Z 32.6N  86.5W   25 KT  30 MPH - Depression (WSW  Marbury, AL)
 96H  18/1200Z 33.1N  84.0W   20 KT  25 MPH - Low (WNW Forsyth, GA)
120H  19/1200Z...DISSIPATED

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

Sally is gradually getting better organized. Satellite images show that deep convection has increased near the center, and the cyclone is now a little more symmetric and vertically aligned compared to earlier today. The Air Force Hurricane Hunters are currently investigating Sally, and so far they have found maximum 850-mb flight-level winds of 54 kt and maximum believable SFMR winds of 49 kt, which support the 50-kt initial intensity.

Reports from the aircraft indicate that the center of Sally has jogged to the northeast, with the latest 12-hour motion estimated to be 305/7 kt. The global models show a trough exiting the northeast U.S. tomorrow and a ridge building to the north of Sally, which should cause the storm to resume a west-northwest motion at a relatively slow pace on Monday. By Monday night and Tuesday, the ridge is forecast to slide southeastward as another trough develops over the south-central U.S. This change in the pattern should cause Sally to slow down even more and gradually turn to the north and then the northeast. The new NHC tack forecast is slower and east of the previous one based on the initial position/motion and the latest models. However, the official forecast still lies west of the latest consensus aids, so further adjustments may be necessary overnight. While the current forecast shows landfall along the northern Gulf coast in 36 to 48 hours, the bottom line is that Sally is expected to be a slow- moving tropical cyclone near and over the northern Gulf Coast during the next few days.

The upper-level low that was producing northwesterly shear over Sally is moving away, resulting in a more favorable upper-level wind pattern for strengthening. These more conducive winds aloft combined with the very warm Gulf of Mexico waters and a moist air mass should allow the cyclone to steadily strengthening until Sally crosses the coast in 36 to 48 hours. The NHC intensity forecast is largely an update of the previous one and lies near the high end of the model guidance. After landfall, rapid weakening is forecast, and Sally is expected to become a tropical depression by 72 hours and dissipate in about 5 days.

The eastward shift in the track forecast necessitates the extension of the hurricane warning eastward to the Mississippi/Alabama border.

KEY MESSAGES:

  • 1. It is too early to determine where Sally’s center will move onshore given the uncertainty in the timing and location of Sally’s northward turn near the central Gulf Coast. Users should not focus on the details of the official forecast track, since NHC’s average forecast error at 48 hours is around 80 miles, and dangerous storm surge, rainfall, and wind hazards will extend well away from the center.
  • 2. An extremely dangerous and life-threatening storm surge is expected for areas outside the southeastern Louisiana Hurricane and Storm Damage Risk Reduction System from Port Fourchon, Louisiana, to the Alabama/Florida border, where a Storm Surge Warning is in effect. Residents in these areas should follow any advice given by local officials.
  • 3. Hurricane conditions are expected by late Monday within portions of the Hurricane Warning area from Morgan City, Louisiana, to the Mississippi/Alabama border, including Metropolitan New Orleans, with tropical storm conditions likely to begin Monday. Preparations should be rushed to completion in those areas.
  • 4. Sally could continue to produce flash flooding across central and northern Florida and prolong existing minor river flooding across west-central Florida through Monday. Widespread significant flash flooding and minor to isolated major river flooding is likely across southeastern Louisiana, Mississippi, and Alabama through the middle of the week. Flooding impacts are expected to spread farther across the Southeast U.S. through the week.
FORECAST POSITIONS AND MAX WINDS

INIT  14/0300Z 28.2N  86.2W   50 KT  60 MPH - Tropical Storm (WNW Clearwater, FL)
 12H  14/1200Z 28.6N  87.3W   60 KT  70 MPH - Tropical Storm (ESE Gulf Shores, AL)
 24H  15/0000Z 29.0N  88.3W   70 KT  80 MPH - Category 1 (ESE Port Eads, LA)
 36H  15/1200Z 29.4N  89.0W   80 KT  90 MPH - Category 1 (ESE Empire, LA)
 48H  16/0000Z 30.3N  89.4W   70 KT  80 MPH - Category 1 (WNW Waveland, MS)
 60H  16/1200Z 31.2N  89.1W   45 KT  50 MPH - Tropical Storm (WSW Mahned, MS)
 72H  17/0000Z 32.1N  88.3W   30 KT  35 MPH - Depression (WNW  Butler, AL)
 96H  18/0000Z 33.6N  85.8W   25 KT  30 MPH - Low (ESE Oxford, AL)
120H  19/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Sun Sep 13, 2020

The overall structure of Sally has not changed much since this morning, but there has been a recent increase in convection near and to the east of the center this afternoon. It appears that the northwesterly shear is beginning to relax, and the increase in convection near the center may be a harbinger of the expected strengthening phase. Air Force and NOAA Hurricane Hunter aircraft that have been in the storm since the previous advisory have reported a fairly stable central pressure of 996-998 mb, and recent data from the NOAA aircraft still supports an initial intensity of 50 kt. Earlier ASCAT data have been helpful in analyzing the radius of 34-kt winds, which has expand over the eastern semicircle.

Sally is forecast to move beneath a narrow upper-level ridge axis through Monday and the expected decrease in shear should allow the storm to strengthen. Since Sally is forecast to decelerate on its approach to the northern Gulf coast, the system still has at least another 36 h to take advantage of the expected conducive environmental conditions. As a result, the NHC intensity forecast continues to call for Sally to become a hurricane on Monday, with additional strengthening likely until landfall. The intensity guidance has trended slightly lower this cycle, with the HMON model now at the upper end of the guidance envelope. The reduction in the statistical guidance is likely due to the fact that Sally has not strengthened today and there is a persistence component to the forecast from those models. The latest NHC intensity forecast is similar to the previous advisory and lies a little above the latest HFIP corrected consensus aid.

Recent satellite and aircraft fixes show that Sally continues to move west-northwestward at about 10 kt. The tropical storm is currently being steered around the southern portion of a mid-level ridge to its northeast. Sally is forecast to reach the western extent of the ridge on Monday, and a slower northwestward motion is expected when the storm is near the north-central Gulf coast. The steering currents are forecast to weaken further in a couple of days as Sally rounds the western extent of the ridge and a slow northward motion is expected during that time. By 72 hours, the cyclone should begin to move somewhat faster toward the northeast as a trough deepens to its west. As often occurs, there has been some run-to-run variability among the various track models, and the latest iterations of them have shifted eastward with a slower forward speed.

Despite the shifts of the individual models, the latest consensus aids are only slightly north and east of the previous NHC track through 60 hours, so only a small adjustment has been made to the earlier official forecast through that time. It is important not to focus too much on these small track changes and to the exact forecast track itself, as impacts are expected to extend far from the center. Also, since there is still quite a bit of model spread in both the location and timing of when the center of Sally reaches the northern Gulf Coast, additional adjustments to the track forecast are possible.

Regardless of Sally’s exact landfall location and intensity, the cyclone is expected to bring wind, storm surge, and rainfall hazards to a large part of the north-central Gulf Coast. In particular, Sally’s slow forward speed near the coast will exacerbate the storm surge and heavy rainfall threats.

KEY MESSAGES:

  • 1. An extremely dangerous and life-threatening storm surge is expected for areas outside the southeastern Louisiana Hurricane and Storm Damage Risk Reduction System from Port Fourchon, Louisiana, to the Mississippi/Alabama border, where a Storm Surge Warning is in effect. Residents in these areas should follow any advice given by local officials.
  • 2. Hurricane conditions are expected by late Monday within portions of the Hurricane Warning area from Morgan City, Louisiana, to Ocean Springs, Mississippi, including Metropolitan New Orleans, with tropical storm conditions likely to begin Monday. Preparations should be rushed to completion in those areas.
  • 3. Sally could continue to produce flash flooding across central and northern Florida and prolong existing minor river flooding across west-central Florida through Monday. Widespread significant flash flooding and minor to isolated major river flooding is likely across southeastern Louisiana, Mississippi, and Alabama through the middle of the week. Flooding impacts are expected to spread farther across the Southeast U.S. through the week.
FORECAST POSITIONS AND MAX WINDS

INIT  13/2100Z 27.8N  85.9W   50 KT  60 MPH - Tropical Storm (WSW Clearwater, FL)
 12H  14/0600Z 28.3N  87.3W   60 KT  70 MPH - Tropical Storm (WSW Pensacola, FL)
 24H  14/1800Z 28.7N  88.7W   70 KT  80 MPH - Category 1 (ESE Port Eads, LA)
 36H  15/0600Z 29.2N  89.6W   80 KT  90 MPH - Category 1 (WNW Pilottown, LA)
 48H  15/1800Z 29.8N  90.1W   60 KT  70 MPH - Tropical Storm (ESE Estelle, LA)
 60H  16/0600Z 30.7N  90.1W   45 KT  50 MPH - Tropical Storm (WSW Zona, LA)
 72H  16/1800Z 31.8N  89.6W   30 KT  35 MPH - Depression (WSW Mize, MS)
 96H  17/1800Z 33.5N  87.5W   25 KT  30 MPH - Depression (WNW Windham Springs, AL)
120H  18/1800Z 34.5N  83.0W   20 KT  25 MPH - Low (WSW Fair Play, SC)

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

Although the center of Sally remains near the northwestern edge of the deep convection, there is a large area of convection and some banding evident over the southeastern portion of the circulation. An Air Force Reserve Hurricane Hunter aircraft investigating the storm this morning reported a peak 850-mb flight-level wind of 62 kt, and believable SFMR winds of around 50 kt, and these data are the basis for the 50-kt initial wind speed. The plane reported minimum pressures in the 996-998 mb range, with the higher value being the most recent information available.

Northwesterly shear continues over the cyclone, but this shear is expected to decrease later today and tonight as Sally moves beneath a narrow upper-level ridge axis. This more conducive upper-level pattern is expected to allow the tropical storm to strengthen while it moves over the north-central Gulf of Mexico tonight and Monday. Most of the intensity guidance calls for Sally to become a hurricane in about 24 hours and so does the official forecast. Additional strengthening is expected after that time and Sally could be slightly stronger at landfall than indicated below since it is forecast to reach the coast between the 36 h forecast point and 48 h when it is inland over southeast Louisiana. The NHC intensity forecast is close to the consensus aids through 24 hours and at or just above the SHIPS, LGEM and HFIP corrected consensus aids at 36 and 48 hours.

Sally is moving west-northwestward at about 10 kt. The tropical storm should continue on that general heading and speed over the next 12 to 24 hours as it steered around the southern flank of a mid-level ridge. After 24 hours, Sally is expected to be near the western portion of the ridge which should cause the storm to slow down and turn northwestward. The global models have trended toward slightly more ridging over the northern Gulf during the next 24 hours, and the track guidance has edged westward. The NHC track has been adjusted slightly westward and lies near the lastest run of the GFS, but is not as far west as the ECMWF and the various consensus aids. As Sally rounds the ridge in 48 to 72 h, the steering flow is expected to be quite weak, and a slow northward motion is forecast at that time. Afterward, a north-northeastward to northeastward motion should commence as the cyclone moves in that direction ahead of a short-wave trough.

Users are reminded to not focus on the exact details of the track or intensity forecasts, as the average NHC track error at 36-48 h is 60-80 miles and the average intensity error is 10-15 mph. In addition, wind, storm surge, and rainfall hazards will extend far from the center. Unfortunately, confidence is increasing that Sally’s expected slow forward speed near the Gulf Coast will exacerbate the storm surge and heavy rainfall threats.

KEY MESSAGES:

  • 1. An extremely dangerous and life-threatening storm surge is now expected, and a Storm Surge Warning is in effect for areas outside the southeastern Louisiana Hurricane and Storm Damage Risk Reduction System from Port Fourchon, Louisiana to the Mississippi/Alabama border. Residents in these areas should follow any advice given by local officials.
  • 2. Hurricane conditions are expected by late Monday from Grand Isle, Louisiana to Ocean Springs, Mississippi, including Metropolitan New Orleans, with tropical storm conditions likely by Monday. Preparations should be rushed to completion in those areas.
  • 3. Sally is expected to produce flash flooding across southwest and central Florida and prolong existing minor river flooding across west-central Florida through Monday. Widespread significant flash flooding and minor to isolated major river flooding is likely across portions of the central Gulf Coast Monday through the middle of the week, with flooding impacts spreading farther into the Southeast in the middle to late parts of the week.
FORECAST POSITIONS AND MAX WINDS

INIT  13/1500Z 27.5N  84.9W   50 KT  60 MPH - Tropical Storm (WSW St Peterburg, FL)
 12H  14/0000Z 28.0N  86.6W   55 KT  65 MPH - Tropical Storm (WSW Clarwater, FL)
 24H  14/1200Z 28.5N  88.2W   65 KT  75 MPH - Category 1 (WSW New Orleans, LA)
 36H  15/0000Z 28.9N  89.4W   80 KT  90 MPH - Category 1 (WSW Port Eads, LA)
 48H  15/1200Z 29.7N  90.2W   65 KT  75 MPH - Category 1 (WSW  Barataria, LA)
 60H  16/0000Z 30.3N  90.5W   50 KT  60 MPH - Tropical Storm (WSW Killian, LA)
 72H  16/1200Z 31.5N  90.3W   35 KT  40 MPH - Tropical Storm (WNW  East Lincoln, MS)
 96H  17/1200Z 33.6N  88.3W   25 KT  30 MPH - Depression (WSW Woodlawn, MS)
120H  18/1200Z 34.8N  83.8W   20 KT  25 MPH - Low (WNW  Helen, GA)

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

Sally’s structure remains somewhat disorganized this evening. While there has been a recent increase in deep convection near the low- level center, there is a large CDO feature with -70 to -80C tops displaced 50 to 60 miles to the south and southeast. This structure could be due to the 10 to 15 kt of northwesterly shear analyzed by the SHIPS model and UW-CIMSS. The initial intensity remains 35 kt based on the latest Dvorak estimates from TAFB and SAB, and the central pressure of 1003 mb is based on surface observations in the Naples area as the center passed offshore before 00Z.

An Air Force Reserve Hurricane Hunter aircraft will be investigating Sally overnight to provide more information on the storm’s intensity and structure. Given the current structure, only gradual strengthening is expected in the short term. However, once the cyclone develops more of an inner core, it should be able to take advantage of warm SSTs and low shear over the Gulf of Mexico during the next couple of days. Steady intensification to hurricane strength is forecast through 48 hours, with a leveling off of the intensity in 60-72 hours as the shear is expected to increase. Overall, the intensity guidance is a little less bullish this cycle, with the HWRF more aggressive while the remainder of the guidance shows a slower rate of intensification. The NHC intensity forecast through landfall remains unchanged from the previous advisory, but now lies a little above HCCA and the intensity consensus.

The initial motion estimate is a somewhat uncertain 285/07. Sally is currently being steered by a mid-level ridge centered over the Carolinas that will shift eastward and weaken as a longwave trough moves into the eastern United States over the next 24 to 36 hours. During this time, Sally should move generally west-northwestward or northwestward with a decrease in forward speed on Monday. By 48 hours, the trough lifts out and a narrow ridge builds in north and east of Sally, which should result in the tropical cyclone turning north-northwestward and then northward at less than 5 kt as it approaches the north-central Gulf Coast and moves inland over the Mississippi Valley. After that time, the next trough should induce a faster northeastward motion by day 5. There is a fair bit of spread in the track guidance after 24 hours, with the COAMPS-TC well to the right and the GEFS ensemble mean and UKMET to the left. However, the GFS and ECMWF are in good agreement through 60 hours near the middle of the guidance envelope. The NHC track is similar to the previous one and lies in the middle of the guidance and is near the TVCA multi-model consensus and HCCA.

Users are reminded to not focus on the exact details of the track or intensity forecasts, as the average NHC track error at 72 h is around 110 miles and the average intensity error is around 15 mph. In addition, wind, storm surge, and rainfall hazards will extend far from the center. Unfortunately, confidence is increasing that Sally’s expected slow forward speed near the Gulf Coast will exacerbate the storm surge and heavy rainfall threats.

KEY MESSAGES:

  • 1. Life-threatening storm surge is possible along the Gulf Coast beginning on Monday, and a Storm Surge Watch is in effect for areas outside the southeastern Louisiana Hurricane and Storm Damage Risk Reduction System from the Mouth of the Mississippi River to the Alabama/Florida border. Residents in these areas should follow any advice given by local officials.
  • 2. Hurricane conditions are possible by early Tuesday from Grand Isle, Louisiana to the Alabama/Florida border, including Metropolitan New Orleans, with tropical storm conditions possible by Monday.
  • 3. Sally is expected to produce flash flooding across portions of southern Florida and prolong existing minor river flooding across central Florida through Sunday. Flash and urban flooding and minor to moderate river flooding are likely across portions of the central Gulf Coast from Sunday through the middle of next week.
  • 4. Tropical storm conditions are possible early next week in portions of the Florida Panhandle, where a Tropical Storm Watch is in effect. Wind gusts to tropical storm force could occur over portions of the lower Florida Keys overnight.
FORECAST POSITIONS AND MAX WINDS

INIT  13/0300Z 26.3N  82.9W   35 KT  40 MPH - Tropical Storm (WSWS Sanibel, FL)
 12H  13/1200Z 27.0N  84.4W   40 KT  45 MPH - Tropical Storm (WSW Venice, FL)
 24H  14/0000Z 27.7N  86.0W   50 KT  60 MPH - Tropical Storm (WSW Clearwater, FL)
 36H  14/1200Z 28.3N  87.5W   60 KT  70 MPH - Tropical Storm (ESE Gulf Shores, AL)
 48H  15/0000Z 28.8N  88.6W   70 KT  80 MPH - Category 1 (ESE New Orleans, LA)
 60H  15/1200Z 29.4N  89.2W   75 KT  85 MPH - Category 1 (ESE Buras-Triumph, LA)
 72H  16/0000Z 30.1N  89.5W   75 KT  85 MPH - Category 1 (WSW Bay St Louis, MS)
 96H  17/0000Z 31.7N  89.1W   50 KT  60 MPH - Tropical Storm (ENE Laurel, MS)
120H  18/0000Z 33.5N  86.5W   25 KT  30 MPH - Low (ENE Vandiver, AL)

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

Sally continues to gradually become better organized, with developing convective banding features primarily over the southern portion of the circulation at this time. Upper-level outflow is still rather limited over the northern semicircle, possibly due to a weak upper low near the Georgia/Florida border. The latter feature is likely to soon move away from the area, however. Based on earlier scatterometer passes that showed tropical-storm-force winds over the Straits of Florida, the advisory intensity remains 35 kt. With very warm waters and a moist tropospheric environment ahead of Sally, strengthening seems likely. Some increase in westerly shear over the northern Gulf in 48-72 hours could at least slow down the intensification process around that time. The official intensity forecast is not far from the latest model consensus and a little above the previous forecast.

Fixes from an Air Force Hurricane Hurricane aircraft, radar, satellite, and surface observations indicate a slow, generally westward motion of about 280/6 kt. A weakening mid-level high pressure system to the northeast of Sally should cause a generally west-northwestward to northwestward motion for the next few days. Because of the weakening steering currents, the cyclone should move rather slowly while it approaches the northern Gulf Coast. However, there is expected to be enough of a narrow north-south oriented ridge to the east of Sally in 3-4 days to steer the cyclone northward across the coast. The official track forecast has been nudged just slightly west of the previous one and lies between the simple and corrected dynamical track model consensus predictions.

Users are reminded to not focus on the exact details of the track or intensity forecast as the average NHC track error at 96 h is around 150 miles and the average intensity error is around 15 mph. In addition, winds, storm surge, and rainfall hazards will extend far from the center.

KEY MESSAGES:

  • 1. Life threatening storm surge is possible along the Gulf Coast beginning on Monday, and a Storm Surge Watch is in effect for areas outside the southeast Louisiana Hurricane and Storm Damage Risk Reduction System from the Mouth of the Mississippi River to the Alabama/Florida border. Residents in these areas should follow any advice given by local officials.
  • 2. Hurricane conditions are possible by early Tuesday from Grand Isle, Louisiana to the Alabama/Florida border, including Metropolitan New Orleans, with tropical storm conditions possible by Monday.
  • 3. Sally is expected to produce flash flooding across portions of southern Florida and prolong existing minor river flooding across central Florida through Sunday. Flash, urban, and minor to moderate river flooding is likely across portions of the central Gulf Coast from Sunday through the middle of next week.
  • 4. Tropical storm conditions are possible early next week in portions of the Florida Panhandle, where a Tropical Storm Watch is in effect. Wind gusts to tropical-storm force could occur over portions of the southern Florida Peninsula and the Florida Keys this evening.
FORECAST POSITIONS AND MAX WINDS

INIT  12/2100Z 25.7N  81.9W   35 KT  40 MPH - Tropical Storm (ESE Ten Thousand Island, FL)
 12H  13/0600Z 26.4N  83.4W   40 KT  45 MPH - Tropical Storm (WSW Cape Coral, FL)
 24H  13/1800Z 27.3N  85.3W   50 KT  60 MPH - Tropical Storm (WSW St. Petersburg, FL)
 36H  14/0600Z 28.0N  86.9W   60 KT  70 MPH - Tropical Storm (WSW Dustin, FL)
 48H  14/1800Z 28.5N  88.1W   70 KT  80 MPH - Category 1 (ESE Port Eads, LA)
 60H  15/0600Z 29.0N  89.0W   75 KT  85 MPH - Category 1 (ESE Port Eads, LA)
 72H  15/1800Z 29.7N  89.3W   75 KT  85 MPH - Category 1 (ESE Saint Malo, LA)
 96H  16/1800Z 31.1N  89.2W   55 KT  65 MPH - Tropical Storm (WNW Brooklyn, MS)
120H  17/1800Z 33.1N  87.0W   30 KT  35 MPH - Low (ESE Maevel, AL)

NWS National Hurricane Center Miami FL 1100 AM EDT Sat Sep 12, 2020 

The tropical cyclone’s cloud pattern has exhibited little change on satellite imagery over the past several hours, although recently the Miami radar shows better-defined banding features over the southern portion of the circulation. The current intensity estimate remains at 30 kt for now, which is consistent with surface observations over the extreme southern Florida peninsula. An Air Force Hurricane Hunter aircraft is scheduled to investigate the system in a few hours, which should provide a better estimate of the cyclone’s intensity. Since the system will be traversing very warm waters and through a moist air mass with moderate vertical shear for the next few days, steady strengthening is anticipated. The cyclone will likely become a hurricane in 2-3 days, although an increase in vertical shear could slow the rate of intensification over the northern Gulf of Mexico. The official forecast intensity around 72 hours is very close to that shown by the simple and corrected model consensus predictions.

The depression has been moving a little north of west, or about 280/8 kt. A west-northwestward or northwestward motion is expected for the next day or two, along the southwestern periphery of a mid-level high pressure system centered just east of the mid-Atlantic coast. This high is forecast to weaken within 2-3 days which should lead to a slowing of the forward motion by Monday. The forward speed is likely to remain slow through 96 hours, although a high that is predicted to build over the Florida peninsula in 4-5 days should push the system across the coastline before the end of the forecast period. The official track forecast is close to the corrected consensus track prediction, HCCA, which has been a reliable performer so far.

Users are reminded to not to focus on the exact details of the track or intensity forecast as the average NHC track error at 96 h is around 150 miles and the average intensity error is around 15 mph. In addition, winds, storm surge, and rainfall hazards will extend far from the center.

KEY MESSAGES:

  • 1. The depression is forecast to strengthen to a hurricane early next week as it moves across the northeastern Gulf of Mexico, and there is an increasing risk of life-threatening storm surge and dangerous hurricane-force winds from southeastern Louisiana to the Alabama coast. Residents in these areas should closely monitor the progress of this system and updates to the forecast, as Storm Surge and Hurricane watches will likely be issued later today.
  • 2. The depression is expected to produce flash flooding across portions of southern Florida and prolong existing minor river flooding across central Florida through Sunday. Flash, urban, and minor to isolated moderate river flooding is likely across portions of the central Gulf Coast Sunday through Tuesday.
  • 3. Tropical storm conditions are possible by Sunday night in portions of the Florida Panhandle, where a Tropical Storm Watch is in effect. Wind gusts to tropical-storm force could occur over portions of the southern Florida Peninsula today.
FORECAST POSITIONS AND MAX WINDS

INIT  12/1500Z 25.6N  81.5W   30 KT  35 MPH - Depression (WSW Marco Island, FL)
 12H  13/0000Z 26.2N  83.0W   35 KT  40 MPH - Tropical Storm (WSW Naples, FL)
 24H  13/1200Z 27.1N  84.8W   40 KT  45 MPH - Tropical Storm (WSW Sarasota, FL)
 36H  14/0000Z 28.0N  86.4W   50 KT  60 MPH - Tropical Storm (ESE Panama City, FL)
 48H  14/1200Z 28.7N  87.6W   60 KT  70 MPH - Tropical Storm (ESE Gulf Shores, AL)
 60H  15/0000Z 29.3N  88.5W   65 KT  75 MPH - Category 1 (ESE Gulfort, MS)
 72H  15/1200Z 29.8N  89.1W   70 KT  80 MPH - Category 1 (ESE Shell Beach, LA)
 96H  16/1200Z 30.6N  89.9W   55 KT  65 MPH - Tropical Storm (ESE Bush, LA)
120H  17/1200Z 32.0N  89.5W   30 KT  35 MPH - Low (ESE Raleigh, MS)

NWS National Hurricane Center Miami FL 1100 PM EDT Fri Sep 11, 2020 

Doppler radar data from Miami and satellite images indicate that the depression is gradually becoming better organized. The low-level center is estimated to be near the northwestern edge of the main area of deep convection due to some northerly wind shear. Surface observations and satellite classifications support holding the initial intensity at 30 kt. The minimum pressure appears to be a little lower than before, now 1007 mb.

The tropical depression is moving west-northwestward at about 7 kt. A subtropical ridge extending from the southeast U.S. to the western Atlantic should steer the depression west-northwestward across south Florida tonight and Saturday morning and then over the eastern Gulf of Mexico late Saturday and Sunday. After that time, the ridge is forecast to weaken due to an approaching trough, but the trough is not expected to be strong enough to cause the cyclone to turn northward. Instead, the models suggest that a slow west-northwestward motion very near the northern Gulf coast is likely during the early and middle portions of next week. Although the models all show a relatively similar scenario, there is a fair amount of spread by the time the system nears the northern Gulf coast. The NHC track forecast lies roughly near the middle of the guidance envelope close to the consensus aids. Several of the local National Weather Service forecast offices across the southeast U.S. will be launching weather balloons four times per day, which should provide the models with excellent data in hopes to provide better track guidance during the next couple of days.

Since the depression is expected to move over very warm SSTs, once it reaches the eastern Gulf of Mexico tomorrow, and remain in an environment of low wind shear and high moisture, gradual strengthening seems likely. The models suggest that there could be an increase in westerly shear around the time the cyclone is forecast to move inland along the northern Gulf coast in about 4 days. Based on these expected environmental conditions, strengthening is forecast during the next few days, and the NHC intensity forecast follows the trend of the IVCN and HCCA models. The depression will likely be at or near hurricane strength when it reaches the northern Gulf coast.

Users are reminded to not to focus on the exact details of the track or intensity forecast as the average NHC track error at 96 h is around 150 miles and the average intensity error is around 15 mph. In addition, winds, storm surge, and rainfall hazards will extend far from the center.

KEY MESSAGES:

  • 1. Heavy rainfall is expected to produce isolated flash flooding over portions of central and southern Florida and prolong existing minor river flooding across central Florida.
  • 2. Tropical storm conditions are possible overnight and early Saturday along the southeast Florida coast where a Tropical Storm Watch is in effect. Tropical storm conditions are possible by Sunday night in portions of the Florida Panhandle, where a Tropical Storm Watch has been issued.
  • 3. The system is forecast to strengthen to near hurricane intensity by early next week as it moves across the northeastern Gulf of Mexico. Dangerous impacts from storm surge, wind, and heavy rainfall will be possible along the Gulf Coast from the Florida Panhandle to southeastern Louisiana late this weekend and early next week. Residents in these areas should monitor the progress of this system and updates to the forecast, as Storm Surge, Tropical Storm or Hurricane watches could be issued on Saturday.
FORECAST POSITIONS AND MAX WINDS

INIT  12/0300Z 25.7N  79.8W   30 KT  35 MPH - Depression (ESE  Cay Biscayne, FL)
 12H  12/1200Z 26.0N  81.0W   30 KT  35 MPH - Depression (Big Cypress, FL)
 24H  13/0000Z 26.8N  82.9W   35 KT  40 MPH - Tropical Storm (WSW Placida, FL)
 36H  13/1200Z 27.9N  84.6W   40 KT  45 MPH - Tropical Storm (WSW Clearwater, FL)
 48H  14/0000Z 28.8N  85.9W   45 KT  50 MPH - Tropical Storm (WSW Panama City, FL)
 60H  14/1200Z 29.3N  86.9W   55 KT  65 MPH - Tropical Storm (ESE Gulf Shores, AL)
 72H  15/0000Z 29.7N  87.7W   60 KT  70 MPH - Tropical Storm (ESE Gulf Shores, AL)
 96H  16/0000Z 30.2N  89.5W   60 KT  70 MPH - Tropical Storm (WSW Ansley, MS)
120H  17/0000Z 31.3N  90.9W   25 KT  30 MPH - Low (ENE Eunice, MS)

NWS National Hurricane Center Miami FL 500 PM EDT Fri Sep 11, 2020 

GOES-16 1-minute satellite data show that the system [TROPICAL DEPRESSION NINETEEN] near the Bahamas that we have been monitoring for the past couple of days has quickly organized into a tropical depression. Very deep convection has formed near the center, and the 1-min data now shows enough north and northwest flow to indicate that a well-defined center is present. The initial wind speed is 30 kt in agreement with recent ship data.

It is uncertain whether the large burst of convection over the center will continue and cause the depression to become a tropical storm before reaching Florida. However, since it is only a 5 kt increase from the current intensity, it is possible that tropical storm conditions could still occur along the southeast Florida coast late tonight, and a tropical storm watch has been issued. Otherwise, after the system reaches the eastern Gulf of Mexico, steady intensification is expected through the weekend due to expected light wind shear and very warm water. Some increase in shear could occur over the northern Gulf of Mexico but that is uncertain at this time. The first forecast will stay conservative and only show a peak intensity of 60 kt in 3 to 4 days, but do not be surprised if that is revised upward on later forecasts once other models better initialize the depression.

An uncertain estimate of the initial motion is 285/7. Strong ridging over the southeastern United States is expected to steer the cyclone to the west-northwest then northwest as a mid-latitude trough erodes the western side of the ridge over the weekend. The forecast gets tricky after that because the bulk of the guidance suggests the trough isn’t deep enough to recurve the system, and instead it gets left behind, moving slowly westward early next week due to weak ridging over the southern Plains. The NHC forecast is near the corrected-consensus guidance. The uncertainty in the track forecast is much larger than normal after 48 hours, as small changes in the forecast steering flow could result in this system moving over the northern Gulf Coast faster and to the northeast of what is shown here. As a result, the risk of seeing direct impacts from this system extends well outside the cone of uncertainty, even more so than usual in this case.

KEY MESSAGES:

  • 1. Heavy rainfall is expected to produce isolated flash flooding over portions of central and southern Florida and prolong existing minor river flooding in the Tampa Bay area.
  • 2. Tropical storm conditions are possible tonight along the southeast Florida coast where a Tropical Storm Watch is in effect.
  • 3. The system is forecast to strengthen to near hurricane intensity by early next week as it moves across the northeastern Gulf of Mexico. Dangerous impacts from storm surge, wind, and heavy rainfall will be possible along the Gulf Coast from the Florida Panhandle to southeastern Louisiana this weekend and early next week. Residents in these areas should monitor the progress of this system and updates to the forecast, as Storm Surge, Tropical Storm or Hurricane watches could be issued later tonight and Saturday.
FORECAST POSITIONS AND MAX WINDS

INIT  11/2100Z 25.4N  79.0W   30 KT  35 MPH - Depression (WSW Gun Cay, Bahamas)
 12H  12/0600Z 25.7N  80.1W   30 KT  35 MPH - Depression (ENE Cay Biscayne, FL)
 24H  12/1800Z 26.2N  81.9W   30 KT  35 MPH - Depression (WSW North Nales, FL)
 36H  13/0600Z 27.3N  83.8W   35 KT  40 MPH - Tropical Storm (WSW Sarasota, FL)
 48H  13/1800Z 28.4N  85.2W   45 KT  50 MPH - Tropical Storm (WSW Spring Hill, FL)
 60H  14/0600Z 29.1N  86.3W   55 KT  65 MPH - Tropical Storm (ESE Panama City, FL)
 72H  14/1800Z 29.5N  87.4W   60 KT  70 MPH - Tropical Storm (ESE Gulf Shores, AL)
 96H  15/1800Z 30.0N  89.0W   60 KT  70 MPH - Tropical Storm (ESE Bay Shores, AL)
120H  16/1800Z 31.0N  91.0W   25 KT  30 MPH - Low (ESE Centreville, MS)

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.
  • 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.

NWS National Hurricane Center Miami FL 1125 AM EDT Fri Sep 11, 2020 

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

Special Tropical Weather Outlook issued to update the discussion and development potential for the area of disturbed weather near the Bahamas.

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

  • 1. Updated: 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 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, crossing the Bahamas and Florida today and tonight and moving into the eastern Gulf of Mexico on Saturday. The disturbance could become a tropical depression while it is near South Florida tonight, but it is more likely to become a tropical depression while it moves slowly west-northwestward over the eastern 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…medium…60 percent. * Formation chance through 5 days…high…70 percent.
  • 2. Another trough of low pressure is located over the north-central Gulf of Mexico. Although the associated shower and thunderstorm activity is currently minimal, some slow development of this system is possible while it moves westward and then southwestward over the northern and western Gulf of Mexico through early next week. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low…30 percent.
  • 3. A tropical wave is located a few hundred miles south 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 large area of disturbed weather associated with a tropical wave is beginning to move off the west coast of Africa. Environmental conditions appear conducive for 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.

NWS National Hurricane Center Miami FL 800 PM EDT Thu Sep 10, 2020 

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

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

  • 1. A large area of disorganized showers and thunderstorms extending from near the Central and Northwest Bahamas eastward over the western Atlantic for a few hundred miles is associated with a surface trough of low pressure. This system is forecast to move westward, crossing the Bahamas and Florida on Friday and moving into the eastern Gulf of Mexico over the weekend. Upper-level winds are expected to become conducive for development, and a tropical depression could form while this system moves slowly west-northwestward over the eastern Gulf of Mexico early next week. Regardless of development, this system is expected to produce locally heavy rainfall over portions of South Florida and the Keys during the next couple of days. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…medium…50 percent.
  • 2. Another trough of low pressure is located over the north-central Gulf of Mexico. Although the associated shower and thunderstorm activity has diminished since earlier today, some slow development of this system is possible while it moves westward and then southwestward over the northern and western Gulf of Mexico through early next week. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low...20 percent.
  • 3. A tropical wave is located a few hundred miles southeast of the Cabo Verde Islands and is producing a large area of disorganized showers and thunderstorms. Gradual 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 across the eastern and central tropical Atlantic. * Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…high…90 percent. [Sally]
  • 4. Another tropical wave is forecast to emerge off the west coast of Africa this weekend. Environmental conditions are expected to be conducive for development, and a tropical depression could form over the far eastern tropical Atlantic early next week while the system moves slowly westward. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium…40 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Thu Sep 10, 2020 

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

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

  • 1. A trough of low pressure located just off the coast of North Carolina is producing minimal shower and thunderstorm activity. This system is expected to move inland over eastern North Carolina this afternoon, and therefore significant development is not expected. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…near 0 percent.
  • 2. A large area of disorganized showers and thunderstorms centered a couple of hundred miles northeast of the Central Bahamas is associated with a surface trough of low pressure. This system is forecast to move westward, crossing the Bahamas and Florida on Friday and moving into the eastern Gulf of Mexico over the weekend. Upper-level winds are expected to become conducive for some development of this system while it moves slowly west-northwestward over the eastern Gulf of Mexico early next week. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…30 percent.
  • 3. Another trough of low pressure has developed over the northeastern Gulf of Mexico and is producing a few disorganized showers and thunderstorms. Some slow development of this system is possible while this system moves westward and then southwestward over the northern and western Gulf of Mexico through early next week. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low...20 percent.
  • 4. A tropical wave is now moving off the west coast of Africa, producing a large area of showers and thunderstorms. Gradual development of this system is forecast, and a tropical depression is expected to form by this weekend or early next week while the system moves generally westward across the eastern and central tropical Atlantic. * Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…high…90 percent. [Sally]
  • 5. Another tropical wave is forecast to emerge off the west coast of Africa this weekend. Environmental conditions are expected to be conducive for development, and a tropical depression could form over the far eastern tropical Atlantic Ocean early next week while the system moves slowly westward. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium...40 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Wed Sep 9, 2020

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

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

  • 1. A small low-pressure area located about 240 miles southeast of Wilmington, North Carolina, has become less organized since yesterday. The low is forecast to move northwestward at 10 to 15 mph, and some development is still possible before it moves inland over eastern North Carolina Thursday afternoon. Interests along the coasts of North and South Carolina should continue to monitor the progress of this disturbance. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low…20 percent.
  • 2. A large area of disorganized showers and thunderstorm is centered a couple of hundred miles northeast of the Central Bahamas. This system is forecast to drift westward and will likely be in the vicinity of the Florida peninsula on Friday. Afterward, upper-level conditions could become conducive for some development this weekend while the system drifts west-northwestward over the eastern Gulf of Mexico. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…20 percent.
  • 3. A tropical wave is forecast to move off the west coast of Africa on Thursday. Gradual development is anticipated once the system moves over water, and a tropical depression is expected to form late this week or over the weekend while the system moves generally westward across the eastern tropical Atlantic. * Formation chance through 48 hours…medium…50 percent. * Formation chance through 5 days…high…90 percent. [Sally]
  • 4. Another tropical wave is forecast to emerge off the west coast of Africa this weekend. Environmental conditions could be conducive for slow development over the far eastern tropical Atlantic Ocean early next week while the wave moves slowly westward. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…20 percent.

NWS National Hurricane Center Miami FL 200 PM EDT Wed Sep 9, 2020

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

The National Hurricane Center is issuing advisories on Tropical Storm Paulette, located over the central tropical Atlantic, and on recently upgraded Tropical Storm Rene, located over the eastern tropical Atlantic.

  • 1. A small area of low pressure located about 300 miles southeast of Wilmington, North Carolina, continues to produce disorganized showers and thunderstorms near its center of circulation. The low is forecast to move northwestward at 10 to 15 mph, and some development is possible before it moves inland over eastern North Carolina Thursday afternoon. Interests along the coasts of North and South Carolina should continue to monitor the progress of this disturbance. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…low…30 percent.
  • 2. A tropical wave is forecast to emerge off the west coast of Africa on Thursday. Gradual development is expected once the system moves over water, and a tropical depression is likely to form late this week or over the weekend while the system moves generally westward across the eastern tropical Atlantic. * Formation chance through 48 hours…medium…50 percent. * Formation chance through 5 days…high…80 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Wed Sep 9, 2020

Corrected Friday to Thursday in the second paragraph For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

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

  • 1. A small area of low pressure located about 375 miles southeast of Wilmington, North Carolina, continues to produce minimal shower and thunderstorm activity near its center of circulation. The low is forecast to move northwestward at 10 to 15 mph, and some development is possible before it moves inland over eastern North Carolina Thursday afternoon. Interests along the coasts of North and South Carolina should continue to monitor the progress of this disturbance. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…low...30 percent.
  • 2. A tropical wave is forecast to emerge off the west coast of Africa on Thursday. Gradual development is expected once the system moves over water, and a tropical depression is likely to form late this week or over the weekend while the system moves generally westward across the eastern tropical Atlantic. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…high...80 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Tue Sep 8, 2020

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

The National Hurricane Center is issuing advisories on Tropical Storm Paulette, located over the central tropical Atlantic, and on Tropical Storm Rene, located just west of the Cabo Verde Islands.

  • 1. A small area of low pressure is located about 450 miles southeast of Cape Hatteras, North Carolina, with minimal shower and thunderstorm activity. Gradual development of the low is possible during the next two or three days, and it could become a tropical depression while it continues to move slowly west-northwestward toward the coasts of South and North Carolina. Interests in those areas should monitor the progress of this disturbance. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…medium…40 percent.
  • 2. A tropical wave is forecast to emerge off the west coast of Africa on Thursday. Gradual development is expected once the system moves over water, and a tropical depression is likely to form late this week or over the weekend while the system moves generally westward across the eastern tropical Atlantic. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…high...80 percent.

NWS National Hurricane Center Miami FL 200 PM EDT Tue Sep 8, 2020

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

The National Hurricane Center is issuing advisories on Tropical Storm Paulette, located over the central tropical Atlantic, and on Tropical Storm Rene, located just west of the Cabo Verde Islands.

  • 1. An area of low pressure is located about 350 miles west-southwest of Bermuda. Shower and thunderstorm activity associated with the low has decreased since this morning, but could increase again tonight. Gradual development of the low is possible during the next two or three days and it could become a tropical depression while it continues to move slowly westward to west-northwestward. Interests along the southeast coast of the U.S. should monitor the progress of this disturbance. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…medium…40 percent.
  • 2. A tropical wave is forecast to emerge off the west coast of Africa on Thursday. Gradual development is expected once the system moves over water, and a tropical depression is likely to form late this week or over the weekend while the system moves generally westward across the eastern tropical Atlantic. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…high…70 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Tue Sep 8, 2020

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

The National Hurricane Center is issuing advisories on Tropical Storm Paulette, located over the central tropical Atlantic, and on Tropical Storm Rene, located near the western Cabo Verde Islands.

  • 1. An area of low pressure is located about 300 miles west-southwest of Bermuda. Showers and thunderstorm activity associated with the low has increased since last night, but remains somewhat disorganized. Gradual additional development of this system is possible during the next two or three days and it could become a tropical depression while it moves slowly westward to west-northwestward. Interests along the southeast coast of the U.S. should monitor the progress of this disturbance. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…medium…40 percent.
  • 2. A tropical wave is forecast to emerge off the west coast of Africa by Thursday. Gradual development is expected once the system moves over water, and a tropical depression is likely to form late this week or over the weekend while the system moves generally westward across the eastern tropical Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…high…70 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Mon Sep 7, 2020

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

The National Hurricane Center is issuing advisories on Tropical Storm Paulette, located over the central tropical Atlantic, and on recently upgraded Tropical Storm Rene, located over the eastern Cabo Verde Islands.

  • 1. An area of low pressure located more than 200 miles southwest of Bermuda is producing disorganized showers and thunderstorms. Some gradual development of this system is possible during the next few days while the low moves slowly westward to west-northwestward. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…40 percent.
  • 2. A tropical wave is forecast to emerge off the west coast of Africa late Wednesday or Thursday. Gradual development is anticipated once the system moves over water, and a tropical depression could form late this week or over the weekend while the system moves generally westward across the eastern tropical Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium…60 percent.

NWS National Hurricane Center Miami FL 200 PM EDT Mon Sep 7, 2020

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

The National Hurricane Center is issuing advisories on recently upgraded Tropical Storm Paulette, located over the central tropical Atlantic, and on Tropical Depression Eighteen, located just east of the Cabo Verde Islands.

  • 1. An area of low pressure located just southwest of Bermuda is producing disorganized showers and a few thunderstorms. Some slow development of this system is possible during the next several days while it moves generally westward or west-northwestward. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low...30 percent.
  • 2. A tropical wave is forecast to emerge off the west coast of Africa late Wednesday or Thursday. Gradual development is anticipated once the system moves over water, and a tropical depression could form late this week or over the weekend while the system moves generally westward across the eastern Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium…50 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Mon Sep 7, 2020

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

The National Hurricane Center is issuing advisories on Tropical Depression Seventeen, located over the central tropical Atlantic, and on newly-developed Tropical Depression Eighteen, located a couple of hundred miles east of the Cabo Verde Islands.

  • 1. An area of low pressure located just southwest of Bermuda is producing disorganized showers and a few thunderstorms. Some slow development of this system is possible during the next several days while it moves generally westward or west-northwestward. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low…30 percent.
  • 2. A tropical wave is forecast to emerge off the west coast of Africa in a few days. Gradual development is anticipated once the system moves over water and a tropical depression could form late this week or over the weekend while the system moves generally westward across the eastern Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium…40 percent.

Video: Video shows damage in Orange Beach after Hurricane Sally