Tropical Storm Delta

Tropical Depression Delta Track 1000 Hours October 10 2020
Tropical Depression Delta Track 1000 Hours October 10 2020

Hurricane Delta Wind Speed FieldTropical Storm DeltaNWS National Hurricane Center Miami FL 1000 AM CDT Sat Oct 10, 2020 (see FINAL  video below)

Surface observations, Doppler radar data, and satellite imagery indicate that Delta has continued to weaken as it moves from northeastern Louisiana into western Mississippi. There are no recent surface observations of sustained tropical-storm-force winds in the areas where the radar data show the strongest winds are occurring, so based on this the initial intensity is reduced to 30 kt. It should be noted that wind gusts to tropical-storm force are still occurring over portions of northern Mississippi and southeastern Arkansas, and these should continue through this afternoon.

The initial motion is now northeastward or 035/14. The flow between a mid-to upper-level ridge over the Gulf of Mexico and the mid-latitude westerlies over the United States should steer Delta or its remnants generally northeastward until the system dissipates. The new forecast track has only minor adjustments from the previous forecast, and it lies near the consensus models.

Continued weakening is expected, and Delta is forecast to degenerate to a remnant low pressure area in about 24 h. The global models are in good agreement that the cyclone should weaken to a trough between 48-60 h, and the intensity forecast follows this scenario.

This is the last advisory on Delta issued by the National Hurricane Center.

Key Messages:

  • 1. Water levels will continue to subside today along the Louisiana coast. Consult products issued by your local National Weather Service forecast office for additional information.
  • 2. Tropical-storm-force wind gusts will persist for a few more hours over portions of northern Mississippi and southeastern Arkansas.
  • 3. Heavy rainfall will lead to flash flooding and minor river flooding across portions of the Lower Mississippi and Tennessee Valleys today, and into the Southern Appalachians through Sunday. Minor to major river flooding will continue across portions of Louisiana and Mississippi though much of next week.
FORECAST POSITIONS AND MAX WINDS

INIT  10/1500Z 33.1N  90.8W   30 KT  35 MPH - Depression (WNW Delta City, Mississippi)
 12H  11/0000Z 34.1N  89.3W   25 KT  30 MPH - Depression (ENE Banner,  Mississippi)
 24H  11/1200Z 35.5N  87.4W   20 KT  25 MPH - Low (WNW Summertown, Tennessee)
 36H  12/0000Z 37.5N  84.8W   20 KT  25 MPH - Low (ENE Hustonville, Kentucky)
 48H  12/1200Z 39.7N  82.0W   20 KT  25 MPH - Low (ENE Yellowtown, Ohio)
 60H  13/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 PM CDT Fri Oct 09, 2020 

Delta made landfall around 23Z on the southwest Louisiana coast, and has been weakening over land. Assuming a fairly rapid weakening since landfall, the estimated current intensity is around 65 kt. Delta will continue weakening, and should become a tropical storm overnight. The system is likely to be reduced to a tropical depression on Saturday. This is in reasonable agreement with the NOAA corrected consensus prediction, HCCA.

Center position estimates from surface observations and satellite imagery indicate that the motion is north-northeastward, or 025/13 kt. Over the next couple of days, Delta should turn northeastward on the east side of a mid-level trough and move into the Tennessee Valley region.

The official forecast shows dissipation in 72 hours, but the global models suggest that this could occur a little sooner. Nonetheless, the vorticity and moisture remnants of Delta are likely to move over the northeastern United States early next week.

Key Messages:

  • 1. Life-threatening storm surge is still occurring along portions of the Louisiana coast, and a Storm Surge Warning is in effect from Cameron, Louisiana, eastward to the Mouth of the Pearl River. Water levels will slowly subside on Saturday as Delta moves farther inland.
  • 2. Tropical-storm-force winds and gusts to hurricane force will continue to spread inland overnight across portions of Louisiana near the path of Deltas center.
  • 3. Heavy rainfall will lead to significant flash flooding and minor to major river flooding in parts of Louisiana through Saturday. Additional flooding is expected across portions of the central Gulf Coast into the Lower Mississippi Valley.
FORECAST POSITIONS AND MAX WINDS

INIT  10/0300Z 30.6N  92.6W   65 KT  75 MPH - Category 1 (WNW Basile, Louisiana)
 12H  10/1200Z 32.2N  91.6W   35 KT  40 MPH - Tropical Storm (WNW Swampers, Louisiana)
 24H  11/0000Z 33.7N  89.9W   25 KT  30 MPH - Depression (WSW Grenada, Mississippi)
 36H  11/1200Z 35.1N  87.7W   25 KT  30 MPH - Depression (ESE Collinwood, Tennessee)
 48H  12/0000Z 37.0N  85.0W   20 KT  25 MPH - Low (ENE Jamestown, Kentucky)
 60H  12/1200Z 39.5N  81.5W   20 KT  25 MPH - Low (WNW Devola, Ohio)
 72H  13/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Fri Oct 09, 2020 

Reports from an Air Force Reserve Hurricane Hunter aircraft and WSR-88D Doppler radar data indicate that Delta has weakened some more since the last advisory. The eye structure on the radar has become less organized, with about 50 percent of the eyewall remaining in the northern semicircle. The aircraft reported maximum 700-mb flight-level winds have decreased to the 100-105 kt range, along with maximum SFMR surface wind estimates in the 80-85 kt range. In addition, the central pressure has risen to near 966 mb. Based on these data, the initial intensity is lowered to 90 kt.

The initial motion is now north-northeastward or 015/12 kt, with the hurricane moving between a deep-layer ridge over the eastern Gulf of Mexico and a mid- to upper-level trough over the U.S. Southern Plains. This motion should continue through the next 24 h or so, followed by a turn toward the northeast as Delta or its remnants move along the southern edge of the mid-latitude westerlies. While the track guidance remains tightly clustered, the guidance is a little faster than the previous run. So, the new track forecast is similar in direction, but slightly faster than the previous one. The forecast track has the center of Delta making landfall in southwestern Louisiana in the next few hours and then moving across central and northeastern Louisiana tonight and Saturday morning. After that, the system should move across northern Mississippi into the Tennessee Valley before it dissipates.

Increasing vertical shear and decreasing oceanic heat content along the forecast track could cause a little more weakening in the last few hours before landfall. However, there will still be significant impacts from winds and storm surge (see Key Messages below). After landfall, rapid weakening is anticipated, with Delta expected to weaken to a tropical storm tonight and to a tropical depression by Saturday afternoon. As in the last advisory, the cyclone is forecast to dissipate between 60-72 h based on the consensus of the global models.

Key Messages:

  • 1. Life-threatening storm surge is occurring and will continue near and east of where Delta makes landfall this evening, and a Storm Surge Warning is in effect from High Island, Texas, to the Mouth of the Pearl River, Louisiana. The highest inundation of 7 to 11 feet is expected somewhere between Rockefeller Wildlife Refuge and Morgan City, Louisiana.
  • 2. Hurricane-force winds are expected this afternoon and evening within portions of the Hurricane Warning area, especially along the coast of southwest Louisiana. Hurricane-force winds will also spread inland across portions of southern Louisiana near the path of Deltas center this evening and tonight.
  • 3. Heavy rainfall will lead to significant flash flooding and minor to major river flooding in parts of Louisiana today and Saturday. Additional flooding is expected across portions of the central Gulf Coast into the Lower Mississippi Valley.
FORECAST POSITIONS AND MAX WINDS

INIT  09/2100Z 29.3N  93.2W   90 KT 105 MPH - Category 2 (ESE Port Arthur, Texas )
 12H  10/0600Z 31.1N  92.5W   60 KT  70 MPH - Tropical Storm (ESE Woodworth, Louisiana)
 24H  10/1800Z 33.1N  91.0W   35 KT  40 MPH - Tropical Storm (ENE Chatham, Mississippi)
 36H  11/0600Z 34.4N  89.2W   30 KT  35 MPH - Depression (WNW Hurricane, Mississippi)
 48H  11/1800Z 35.9N  87.1W   25 KT  30 MPH - Depression (ESE Fairview, Tennessee)
 60H  12/0600Z 37.6N  84.8W   20 KT  25 MPH - Low (WNW Junction City, Kentucky)

NWS National Hurricane Center Miami FL 1000 AM CDT Fri Oct 09, 2020 

Reports from NOAA and Air Force Reserve Hurricane Hunter aircraft indicate that Delta has weakened a little since the last advisory. The central pressure has risen to 962 mb, and the strongest 700-mb flight-level winds reported by the NOAA plane were 107 kt. In addition, SFMR wind estimates have been in the 85-95 kt range. Based on these data, the initial intensity is lowered to 100 kt.

Delta is moving northward or 360/11 kt between a deep-layer ridge over the eastern Gulf of Mexico and a mid- to upper-level trough over the U.S. Southern Plains. A turn toward the north-northeast is expected during the next few hours, and the center is forecast to cross the southwestern coast of Louisiana late this afternoon or this evening. After landfall, a continued north-northeastward motion should bring the center across central and northeastern Louisiana by the 24 h point. Thereafter, Delta is expected to move generally northeastward through the lower Mississippi and Tennessee Valleys until it dissipates. The track forecast guidance remains tightly clustered, and the new forecast track is little changed from the previous forecast.

Increasing vertical shear and decreasing oceanic heat content along the forecast track should cause Delta to continue to weaken before landfall. However, there will still be significant impacts from winds and storm surge (see Key Messages below). After landfall, rapid weakening is anticipated, with Delta expected to weaken to a tropical storm tonight and to a tropical depression by Saturday afternoon or evening. The cyclone is forecast to dissipate between 60-72 h based on the consensus of the global models.

Key Messages:

  • 1. Life-threatening storm surge is expected near and east of where Delta makes landfall this evening, and a Storm Surge Warning is in effect from High Island, Texas, to the Mouth of the Pearl River. The highest inundation of 7 to 11 feet is expected somewhere between Rockefeller Wildlife Refuge and Morgan City, Louisiana. Water levels in this area will rise quickly this afternoon and evening as Delta approaches and efforts to protect life and property should be rushed to completion.
  • 2. Hurricane-force winds are expected this afternoon and evening within portions of the Hurricane Warning area, especially along the coast of southwest Louisiana. Hurricane force winds will also spread inland across portions of southern Louisiana near the path of Deltas center this evening and tonight.
  • 3. Heavy rainfall will lead to significant flash flooding and minor to major river flooding in parts of Louisiana today and Saturday. Additional flooding is expected across portions of the central Gulf Coast into the Lower Mississippi Valley.
FORECAST POSITIONS AND MAX WINDS

INIT  09/1500Z 28.0N  93.8W  100 KT 115 MPH - Category 3 (ESE Galvesyon, Texas)
 12H  10/0000Z 30.0N  93.0W   90 KT 105 MPH - Category 2 (WSW Bell City, Louisiana)
 24H  10/1200Z 32.2N  91.8W   50 KT  60 MPH - Tropical Storm (WNW Winnsboro, Louisiana)
 36H  11/0000Z 33.7N  90.2W   30 KT  35 MPH - Depression (ENE Money, Mississippi)
 48H  11/1200Z 35.0N  88.4W   25 KT  30 MPH - Depression (ESE Michie, Tennessee)
 60H  12/0000Z 36.7N  86.2W   20 KT  25 MPH - Low (WSW Scottsville, Kentucky)
 72H  12/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 PM CDT Thu Oct 08, 2020 

Reports from Air Force and NOAA Hurricane Hunter aircraft investigating Delta indicate that the hurricane strengthened a little more this evening. Peak flight-level winds were 120 kt, and the highest SFMR-observed surface winds were 98 kt. Using a blend of adjusted flight-level and surface wind observations, the current intensity estimate is set at 105 kt. The eye became obscured on satellite images a couple of hours ago, but recently it has become apparent again. Delta could intensify a little more within the next 6 hours or so. Thereafter, sharply decreasing oceanic heat content, significantly increasing west-southwesterly shear, and drier mid-level air should cause weakening. The official intensity forecast through landfall is above most of the model guidance. However, even 24-hour tropical cyclone intensity forecasts are still subject to an uncertainty of 1 Saffir-Simpson category, so one should not focus on the exact official landfall intensity forecast. Moreover, even if Delta weakens some, it will still have serious storm surge impacts due to its large size.

Aircraft and satellite center fixes show that the hurricane is gradually turning toward the right. The motion is now north-northwestward, or 340/10 kt. Delta should turn northward on Friday as it moves on the western side of a mid-tropospheric high pressure area. Later on Friday, a 500-mb shortwave trough over the southern United States is likely to cause the tropical cyclone to turn north-northeastward and cross the northern Gulf of Mexico coast. Delta should then move northeastward on the eastern side of the trough over the southeastern United States for the next day or two before dissipating near Kentucky. The official track forecast is very close to the previous NHC track, and in very good agreement with the various consensus track predictions.

Key Messages:

  • 1. Life-threatening storm surge is expected near and east of where Delta makes landfall Friday, and a Storm Surge Warning is in effect from High Island, Texas, to Ocean Springs, Mississippi. The highest inundation of 7 to 11 feet is expected somewhere between Rockefeller Wildlife Refuge and Morgan City, Louisiana. Residents in the warning area should promptly follow advice given by local officials. The storm surge risk remains high despite the forecast decrease in intensity before landfall since Delta is a relatively large hurricane.
  • 2. Hurricane-force winds are expected Friday afternoon and evening somewhere within the Hurricane Warning area between High Island, Texas, and Morgan City, Louisiana. Hurricane force winds will also spread inland across portions of southern Louisiana near the path of Deltas center Friday evening and Friday night.
  • 3. Heavy rainfall will lead to significant flash flooding and minor to major river flooding in parts of Louisiana Friday and Saturday. Additional flooding is expected across portions of the central Gulf Coast into the Lower Mississippi Valley.
FORECAST POSITIONS AND MAX WINDS

INIT  09/0300Z 25.7N  93.6W  105 KT 120 MPH - Category 3 (ESE Brownsville, Texas)
 12H  09/1200Z 27.4N  93.7W  105 KT 120 MPH - Category 3 (ESE Galveston, Texas)
 24H  10/0000Z 29.8N  93.0W   85 KT 100 MPH - Category 2 (WNW Grand Chenier, Louisiana)
 36H  10/1200Z 32.0N  91.9W   45 KT  50 MPH - Tropical Storm (WNW Enterprise, Louisiana)
 48H  11/0000Z 33.5N  90.2W   25 KT  30 MPH - Depression (WSW Greenwood, Mississippi)
 60H  11/1200Z 34.9N  88.4W   20 KT  25 MPH - Low (ESE Farmington, Mississippi)
 72H  12/0000Z 36.5N  87.0W   20 KT  25 MPH - Low (WNW Coopertown, Tennessee)
 96H  13/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Thu Oct 08, 2020 

Delta is strengthening. In satellite imagery, an eye is now seen in the cold cloud tops of the central dense overcast. On the aircraft side, just received reports from an Air Force Reserve Hurricane Hunter aircraft included 700-mb flight-level winds of 119 kt, SFMR winds estimates near 90 kt, and a central pressure of 959 mb inside a 30 n mi wide eye. A blend of the flight-level and SFMR wind estimates give an initial intensity of 100 kt, and Delta is again a major hurricane.

The initial motion is now northwestward or 320/10 kt. There is no change to the track forecast philosophy and little change to the track forecast from the previous advisory. During the next 12-24 h, Delta should turn to the north between a mid- to upper-level ridge over the Florida Peninsula and eastern Gulf of Mexico and a mid- to upper-level level trough over the U.S. Southern Plains. This should be followed by a north-northeastward motion that is expected to bring the center near or over the northern Gulf coast, most likely in southwestern Louisiana, in about 30 h. After landfall, the cyclone should move northeastward through the Lower Mississippi and Tennessee Valleys along the southern edge of the mid-latitude westerlies until it dissipates. The track guidance remains very tightly clustered in terms of direction, and the new forecast track is near the various consensus models.

Shear, sea surface temperature, and moisture conditions appear favorable for strengthening during the next 12 h or so, and based on this additional intensification is expected tonight. A short period of rapid intensification remains possible given current trends, although the various rapid intensification indices are not enthusiastic about the possibilities of this, After 12 h, the global models again forecast strong southwesterly shear developing over the hurricane before landfall, and based on this some weakening is forecast. Rapid weakening is expected after landfall. The system is expected to weaken to a depression no later than 60 h and degenerate to a remnant low by 72 h, with dissipation following shortly thereafter. The intensity forecast lies at or above the upper edge of the intensity guidance.

Recent scatterometer data indicates that Delta is growing in size as it approaches the Louisiana coast. The NHC wind radii forecast again follows a combination of the data and the forecasts from global and hurricane regional models.

Key Messages:

  • 1. Life-threatening storm surge is expected near and east of where Delta makes landfall Friday, and a Storm Surge Warning is in effect from High Island, Texas, to Ocean Springs, Mississippi. The highest inundation of 7 to 11 feet is expected somewhere between Rockefeller Wildlife Refuge and Morgan City, Louisiana. Residents in the warning area should promptly follow advice given by local officials. The storm surge risk remains high despite the forecast decrease in intensity before landfall since Delta is expected to grow in size.
  • 2. Hurricane-force winds are expected Friday afternoon and evening somewhere within the Hurricane Warning area between High Island, Texas, and Morgan City, Louisiana. Hurricane force winds will also spread inland across portions of southern Louisiana near the path of Deltas center Friday evening and Friday night.
  • 3. Heavy rainfall will lead to significant flash flooding and minor to major river flooding in parts of Louisiana Friday and Saturday. Additional flooding is expected across portions of the central Gulf Coast into the Lower Mississippi Valley.
FORECAST POSITIONS AND MAX WINDS

INIT  08/2100Z 24.8N  93.4W  100 KT 115 MPH - Category 3 (ESE Brownsville, Texas)
 12H  09/0600Z 26.3N  93.9W  110 KT 125 MPH - Category 3 (ENE Brownsville, Texas)
 24H  09/1800Z 28.6N  93.5W  105 KT 120 MPH - Category 3 (ESE Galveston, Texas)
 36H  10/0600Z 31.0N  92.5W   65 KT  75 MPH - Category 1 (ESE Forest Hill, Louisiana)
 48H  10/1800Z 32.9N  91.1W   40 KT  45 MPH - Tropical Storm (WNW Mayersville, Mississippi)
 60H  11/0600Z 34.3N  89.2W   30 KT  35 MPH - Depression (WSW Thaxton, Mississippi)
 72H  11/1800Z 35.8N  87.2W   20 KT  25 MPH - Low (WNW Fly, Tennessee)
 96H  12/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Thu Oct 08, 2020

Satellite imagery shows that Delta is better organized this morning, with the center well embedded in a cold central dense overcast and a hint of a eye developing in the overcast. Reports from Air Force Reserve and NOAA Hurricane hunter aircraft indicate that the central pressure has fallen to 968 mb inside a 35 n mi wide eye, along with flight-level and SFMR winds that support an initial intensity of 90 kt.

The initial motion remains northwestward or 305/12 kt. The track forecast is reasonably straightforward. During the next 12-24 h, Delta should turn to the north between a mid- to upper-level ridge over the Florida Peninsula and eastern Gulf of Mexico and a mid- to upper-level level trough over the U.S. Southern Plains. This should be followed by a north-northeastward motion that is expected to bring the center near or over the northern Gulf coast, most likely in southwestern Louisiana, in about 36 h. After landfall, the cyclone should move northeastward through the Lower Mississippi and Tennessee Valleys along the southern edge of the mid-latitude westerlies until it dissipates. The track guidance is very tightly clustered in terms of direction, and the new forecast track has only minor tweaks from the previous one.

Shear, sea surface temperature, and moisture conditions appear favorable for strengthening during the next 12-24 h or so, and based on this Delta is expected to regain major hurricane strength. Rapid intensification cannot be ruled out, although the various rapid intensification indices do not suggest a high chance, and the first 24 h of the forecast is already above the intensity guidance. The global models forecast strong southwesterly shear developing over the hurricane during the last 12 h before landfall, and based on this some weakening is forecast. Rapid weakening is expected after landfall, with Delta forecast to degenerate to a remnant low by 72 h and dissipate shortly after that. It should be noted that the NHC 1-2 day intensity forecasts are subject to errors of around 1 Saffir-Simpson category.

Delta is expected to grow in size as it approaches the Louisiana coast. The NHC wind radii forecast again follows a consensus of the global and hurricane regional models.

Key Messages:

  • 1. Life-threatening storm surge is expected near and east of where Delta makes landfall on Friday, and a Storm Surge Warning is in effect from High Island, Texas, to Ocean Springs, Mississippi. The highest inundation of 7 to 11 feet is expected somewhere between Rockefeller Wildlife Refuge and Port Fourchon, Louisiana. Residents in the warning area should promptly follow advice given by local officials. The storm surge risk remains high despite the forecast decrease in intensity before landfall since Delta is expected to grow in size.
  • 2. Hurricane-force winds are expected Friday afternoon and evening somewhere within the Hurricane Warning area between High Island, Texas, and Morgan City, Louisiana. Hurricane-force winds will also spread inland across portions of southern Louisiana near the path of Deltas center Friday evening and Friday night.
  • 3. Significant flash flooding and minor to moderate river flooding are likely in parts of Louisiana Friday and Saturday, with additional flooding in portions of the central Gulf Coast into the Lower Mississippi Valley.
FORECAST POSITIONS AND MAX WINDS

INIT  08/1500Z 24.0N  92.7W   90 KT 105 MPH - Category 2 (ENE Tampico, Mexico)
 12H  09/0000Z 25.4N  93.6W   95 KT 110 MPH - Category 2 (ESE Brownsville, Texas)
 24H  09/1200Z 27.5N  93.8W  100 KT 115 MPH - Category 3 (ESE Corpus Christi, Texas)
 36H  10/0000Z 29.8N  93.1W   90 KT 105 MPH - Category 2 (ENE Creole, Louisiana)
 48H  10/1200Z 32.4N  91.7W   45 KT  50 MPH - Tropical Storm (ESE Rayville, Louisiana)
 60H  11/0000Z 34.0N  90.0W   30 KT  35 MPH - Depression(ESE Charleston, Mississippi)
 72H  11/1200Z 35.6N  87.9W   20 KT  25 MPH - Low (WSW  Linden, Tennessee)
 96H  12/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 PM CDT Wed Oct 07, 2020

Observations from an Air Force Reserve Unit Hurricane Hunter aircraft indicate that Delta is gradually strengthening while it moves over the open waters of the south-central Gulf of Mexico. Based on a blend of adjusted flight-level and SFMR wind measurements from the plane, the current intensity is set at 80 kt. The cloud pattern of the hurricane continues to become better organized on satellite images, with a growing Central Dense Overcast, and convective banding features becoming better defined, particularly over the northern semicircle of the circulation. Additional intensification is likely while Delta moves through a favorable environment during the next day or so, and the official forecast is fairly close to the corrected consensus guidance, HCCA. When the system moves into the northern Gulf, a decrease in oceanic heat content, drier mid-tropospheric air, and increased vertical shear should cause at least slow weakening. The NHC intensity forecast is above the numerical guidance in 36-48 hours. It should be noted that 1-2 day tropical cyclone intensity forecasts are subject to errors of around 1 Saffir-Simpson category.

The global models show a further increase in the size of the hurricane while it moves into the northern Gulf. The official wind radii forecasts are based on a consensus of these model predictions.

The latest center fixes from the Hurricane Hunters show a west-northwestward motion, at about 300/15 kt. Delta should turn toward the north-northwest and north over the next 36 hours or so while moving around the western periphery of a subtropical high pressure system centered over Florida. When the hurricane moves into the northern Gulf of Mexico on Friday, Delta should turn toward the north-northeast on the southeastern side of a mid-tropospheric shortwave over the southern United States. The official track forecast is close to both the simple and corrected dynamical model consensus predictions, TVCA and HCCA, respectively. These objective aids are in close agreement with one another.

Based on the official forecast, it is time to issue storm surge and hurricane warnings for a portion of the northern Gulf of Mexico coast.

Key Messages:

  • 1. Delta is expected to grow in size as it approaches the northern Gulf Coast, where life-threatening storm surge and dangerous hurricane-force winds are likely beginning Friday, particularly for portions of the Louisiana coast. Storm Surge and Hurricane Warnings are in effect, and residents in these areas should follow advice given by local officials and rush preparedness actions to completion.
  • 2. Flash, urban, small stream and minor to isolated moderate river flooding is likely Friday and Saturday from portions of the central Gulf Coast into portions of the Lower to Middle Mississippi Valley. As Delta moves farther inland, additional heavy rainfall is expected in the Ohio Valley and Mid Atlantic this weekend.
FORECAST POSITIONS AND MAX WINDS

INIT  08/0300Z 22.5N  90.9W   80 KT  90 MPH - Category 1 (WNW Progreso, Mexico)
 12H  08/1200Z 23.7N  92.2W   95 KT 110 MPH - Category 2 (ENE Tampico, Mexico)
 24H  09/0000Z 25.4N  93.4W  105 KT 120 MPH - Category 3 (ESE Brownsville, Texas)
 36H  09/1200Z 27.5N  93.5W  100 KT 115 MPH - Category 3 (ESE Galveston, Texas)
 48H  10/0000Z 30.0N  92.7W   85 KT 100 MPH - Category 2 (WSW Lake Arthur, Louisiana)
 60H  10/1200Z 32.4N  91.5W   35 KT  40 MPH - Tropical Storm (WSW Delhi, Louisiana) 
 72H  11/0000Z 34.2N  89.6W   20 KT  25 MPH - Low (ESE Springdale, Mississippi)
 96H  12/0000Z 37.5N  85.0W   20 KT  25 MPH - Low (WSW Forkland, Kentucky)
120H  13/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Wed Oct 07, 2020

The center of Delta has moved off the northern coast of the Yucatan peninsula and is now located over the southern Gulf of Mexico. The hurricane remains well organized in satellite imagery with a large curved band wrapping around the center and a fairly symmetric CDO. An Air Force Reserve reconnaissance aircraft has provided a few center fixes this afternoon, and found that Delta’s passage over land has resulted in weakening, and the initial wind speed is set at 75 kt, which is based on a peak flight-level wind of 81 kt. The aircraft also reported a minimum pressure of 977 mb on its final center penetration, and data from the plane indicate that there has been some increase in the radius of maximum winds.

Re-strengthening is anticipated over the next 24-36 hours while Delta moves within a favorable upper-level environment and over the relatively deep warm waters of the southern and central Gulf of Mexico. Most of the intensity guidance brings Delta back up to major hurricane status, and so does the official forecast. The global models also significantly deepen Delta during the next 36 hours, lending confidence to re-intensification. After 36 hours, increasing shear and cooler waters over the northern Gulf of Mexico are likely to cause some decrease in intensity before Delta makes landfall, however the hurricane’s wind field is forecast to expand, which will increase the storm surge and wind threats. Regardless of Delta’s landfall intensity, life-threatening storm surge and strong winds are likely over a large portion of the northwestern and northern Gulf coast.

Delta has been moving on a consistent northwestward heading of 305 degrees at about 15 kt. Delta should continue on this general heading with some reduction in forward speed tonight and early Thursday as it approaches the western extent of the subtropical ridge. A mid- to upper-level trough over Texas is forecast to slide eastward over the next couple of days, which is expected to cause Delta to turn north-northwestward on Thursday, and northward toward the northern Gulf coast by Friday. A faster northward to north-northeastward motion in 48-60 hours will bring the center onshore along the northern Gulf coast late Friday. The cross track spread in the dynamical models has decreased this cycle, with the model predictions converging on the previous NHC track forecast. Therefore, little change has been made to the previous official forecast, and it lies near the center of the now tightly clustered guidance envelope.

Key Messages:

  • 1. Winds and water levels along the northern coast of the Yucatan Peninsula will gradually subside this evening. Heavy rainfall, which could lead to significant flash flooding, will affect the northern Yucatan Peninsula through early Thursday.
  • 2. Delta is expected to grow in size as it approaches the northern Gulf Coast, where life-threatening storm surge and dangerous hurricane-force winds are likely beginning Friday, particularly for portions of the Louisiana coast. Storm Surge and Hurricane Watches are in effect, and residents in these areas should follow advice given by local officials.
  • 3. Flash, urban, small stream and minor to isolated moderate river flooding is likely Friday and Saturday from portions of the central Gulf Coast into portions of the Lower to Middle Mississippi Valley. As Delta moves farther inland, additional heavy rainfall is expected in the Ohio Valley and Mid Atlantic this weekend.
FORECAST POSITIONS AND MAX WINDS

INIT  07/2100Z 22.1N  89.5W   75 KT  85 MPH - Category 1 (ENE Progreso, Mexico)
 12H  08/0600Z 23.2N  91.2W   85 KT 100 MPH - Category 2 (WNW Progreso, Mexico)
 24H  08/1800Z 24.8N  92.9W   95 KT 110 MPH - Category 2 (ESE Brownsville, Texas)
 36H  09/0600Z 26.7N  93.4W  100 KT 115 MPH - Category 3 (ESE Corpus Christi, Texas)
 48H  09/1800Z 29.1N  92.9W   90 KT 105 MPH - Category 2 (ESE Cameron, Louisiana)
 60H  10/0600Z 31.6N  91.9W   45 KT  50 MPH - Tropical Storm (WSW Jonesville, Louisiana)
 72H  10/1800Z 33.7N  90.5W   30 KT  35 MPH - Depression (ESE Ruleville, Mississippi)
 96H  11/1800Z 37.0N  85.5W   20 KT  25 MPH - Low (WSW Weed, Kentucky)

NWS National Hurricane Center Miami FL AL262020 1000 AM CDT Wed Oct 07, 2020

Satellite and surface observations show that Delta made landfall along the northeastern coast of the Yucatan peninsula around 1030 UTC near Puerto Morelos. A WeatherFlow observing site at Puerto Morelos reported near calm winds and a minimum pressure of around 972 mb when the center passed that location. Another WeatherFlow site near Cancun reported peak sustained winds of 73 kt with a gust to 92 kt. Hurricane-force winds gusts were also reported at an observing site on Cozumel. Since landfall, Delta has moved across the northeastern portion of the Yucatan peninsula and is now about the emerge off the northern coast of the peninsula into the southern Gulf of Mexico. Assuming some weakening has occurred, the initial intensity has been set at 90 kt, but this could be a little generous. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate Delta early this afternoon. A NOAA P-3 aircraft has been preforming a Tail Doppler Radar mission this morning.

Once Delta moves over the southern Gulf of Mexico, warm waters and expected low vertical wind shear conditions are expected to allow for re-strengthening during the next 24 to 36 hours. After 48 hours, increasing southwesterly shear and cooler waters over the northern Gulf are likely to induce some weakening. The intensity guidance has trended downward this cycle, and the NHC forecast has been adjusted accordingly. Delta, however is still expected to regain major hurricane status and the wind field is likely to grow in size during its approach to the northern Gulf coast, which will increase the storm surge and wind threats. Regardless of Delta’s landfall intensity, life-threatening storm surge and strong winds are likely over a large portion of the northwestern and northern Gulf coast, which has necessitated the issuance of Storm Surge, Hurricane, and Tropical Storm watches for portions of that area. Delta is moving northwestward or 305/15 kt. The hurricane should continue moving northwestward around the southwestern portion of a subtropical ridge that extends over Florida and the northeastern Gulf of Mexico through early Thursday. After that time, a developing mid-level trough over the south-central United States should cause Delta to slow down and turn north-northwestward on Thursday.

Delta is forecast to begin accelerating northward or north-northeastward toward the northern Gulf coast ahead of the trough Thursday night and Friday. There has been little change to the early portion of the track forecast, but there has been a little westward shift in the guidance envelope after 24 hours, and the NHC forecast has been moved in that direction. The new forecast track lies near or just left of the TVCA multi-model consensus and a little right of the HFIP corrected consensus aid, again close to the GFS, GFS ensemble mean, and UKMet models.

Key Messages:

  • 1. Life-threatening storm surge and dangerous winds will continue within portions of the northern Yucatan Peninsula of Mexico into early afternoon. Heavy rainfall, which could lead to significant flash flooding, will affect the northern Yucatan Peninsula through early Thursday.
  • 2. Delta is expected to grow in size as it approaches the northern Gulf Coast, where there is an increasing likelihood of life- threatening storm surge and dangerous hurricane-force winds beginning Friday, particularly for portions of the Louisiana coast. Storm Surge and Hurricane Watches are in effect, and residents in these areas should follow advice given by local officials.
  • 3. Flash, urban, small stream, and minor river flooding is likely Friday through Saturday from portions of the central Gulf Coast northward into portions of the Lower to Middle Mississippi Valley. As Delta moves farther inland, additional heavy rainfall is expected in the Ohio Valley and Mid Atlantic this weekend.
FORECAST POSITIONS AND MAX WINDS

INIT  07/1500Z 21.4N  88.0W   90 KT 105 MPH - Category 2 (WSW Emal, Mexico)
 12H  08/0000Z 22.8N  90.2W   95 KT 110 MPH - Category 2 (WNW Progresdo, Mexico)
 24H  08/1200Z 24.3N  92.4W  100 KT 115 MPH - Category 3 (WSW Brownsville, Texas)
 36H  09/0000Z 26.0N  93.3W  105 KT 120 MPH - Category 3 (WNW Brownsville, Texas)
 48H  09/1200Z 28.1N  93.3W  105 KT 120 MPH - Category 3 (WSW Galveston, Texas)
 60H  10/0000Z 30.8N  92.4W   70 KT  80 MPH - Category 1 (ENE Pine Prairie, Louisiana)
 72H  10/1200Z 33.2N  90.9W   40 KT  45 MPH - Tropical Storm (WNW Hollandale, Mississippi)
 96H  11/1200Z 36.5N  86.2W   25 KT  30 MPH - Low (ENE Bransford, Tennessee)
120H  12/1200Z 39.5N  81.0W   20 KT  25 MPH - Low (WSW Adonis, West Virginia)

NWS National Hurricane Center Miami FL 1000 PM CDT Tue Oct 06, 2020 

Observations from a NOAA Hurricane Hunter aircraft and conventional and microwave satellite imagery indicate that Delta has not intensified since earlier today. The central pressure has risen somewhat and the current intensity estimate, 115 kt, is probably generous based on flight-level and SFMR-observed surface winds from the NOAA plane. Although the hurricane continues to have very deep convection near and over the center, the cloud pattern lacks well-defined banding features, and an eye is not evident on either geostationary or polar-orbiting satellite images. Surveillance data from the NOAA G-IV aircraft suggest that Delta’s circulation does not extend as markedly into the upper troposphere as one would expect for a major hurricane. Given the current state of the system, not much strengthening seems likely before the center reaches northeastern Yucatan tomorrow morning. Some weakening is likely due to the interaction with land during the next 12-18 hours. Re-intensification over the southern Gulf of Mexico is still expected, but when Delta reaches the northern Gulf, lower oceanic heat content is likely to cause at least slight weakening. The official intensity forecast is somewhat above most of the model guidance, but not much different from the regional hurricane models, HWRF and HMON, over the northern Gulf.

Fixes from the aircraft indicate a continued west-northwestward motion at just a slightly slower forward speed, 300/14 kt. The track forecast reasoning is basically unchanged from earlier today. Delta should move along and around the southwestern and western periphery of a mid-tropospheric anticyclone centered just east of Florida for the next couple of days. Around 72 hours, the flow ahead of a shortwave trough over the south-central United States should cause the tropical cyclone to turn north-northeastward and move across the central Gulf coast late Friday or early Saturday. The official track forecast remains close to the dynamical model consensus, TVCA.

Key Messages:

  • 1. Life-threatening storm surge and potentially catastrophic wind damage are expected within portions of the northern Yucatan Peninsula of Mexico beginning tonight. All preparations to protect life and property should be rushed to completion.
  • 2. Heavy rainfall will affect portions of the Cayman Islands, western Cuba and the northern Yucatan Peninsula through midweek. This rainfall could lead to significant flash flooding and mudslides. The potential for heavy rain, flash and possible minor river flooding will increase across portions of the central Gulf Coast, Tennessee Valley, and southeastern United States as Delta moves inland later this week.
  • 3. There is an increasing likelihood of life-threatening storm surge and dangerous hurricane-force winds, especially along the coasts of Louisiana and Mississippi, beginning on Friday. Residents in these areas should ensure they have their hurricane plan in place and follow advice given by local officials. Storm surge and hurricane watches will likely be issued for portions of the northern Gulf Coast on Wednesday.
FORECAST POSITIONS AND MAX WINDS

INIT  07/0300Z 19.5N  85.1W  115 KT 130 MPH - Category 4 (ESE Tulum, Mexico)
 12H  07/1200Z 20.9N  87.1W  115 KT 130 MPH - Category 4 (WNW Puerto Morelos, Mexico)
 24H  08/0000Z 22.3N  89.8W  105 KT 120 MPH - Category 3 (ENE Progreso, Mexico)
 36H  08/1200Z 23.6N  91.7W  110 KT 125 MPH - Category 3 (ENE Tampico, Mexico)
 48H  09/0000Z 25.0N  92.7W  115 KT 130 MPH - Category 4 (ESE Brownsville, Texas)
 60H  09/1200Z 26.8N  92.8W  115 KT 130 MPH - Category 4 (ESE Corpus Christi, Texas)
 72H  10/0000Z 29.0N  92.2W  110 KT 125 MPH - Category 3 (ESE Pecan Island, Louisiana)
 96H  11/0000Z 33.0N  89.8W   50 KT  60 MPH - Tropical Storm (WSW Sallis, Mississippi)
120H  12/0000Z 36.0N  86.0W   20 KT  25 MPH - Low (WSW Liberty, Tennessee)

NWS National Hurricane Center Miami FL 500 PM EDT Tue Oct 06, 2020 

Shortly after the release of the 1500 UTC advisory package, the NOAA Hurricane Hunter aircraft measured a peak flight-level wind of 132 kt, and during its final passage through the northeast eyewall around 1700 UTC it reported a peak SFMR wind of 121 kt. The aircraft continued to report an extremely small 4-to-5-nmi-wide eye. The central pressure did level off somewhat on the final couple of penetrations, with the latest reported central pressure at 956 mb. The initial wind speed was raised to 120 kt on the earlier intermediate advisory, and has been set at 125 kt for this advisory. The next reconnaissance aircraft mission into the hurricane is scheduled for this evening.

There has been no evidence of an outer eyewall from the aircraft reports or earlier radar imagery from Grand Cayman. As a result, some additional strengthening is likely to occur before Delta reaches the northeastern coast of the Yucatan peninsula late tonight or early Wednesday. The NHC intensity forecast is once again a little above the various intensity aids until landfall in Mexico. When the small inner core of Delta moves over land, weakening is expected, but warm waters and low vertical wind shear over the southern Gulf of Mexico should support re-strengthening, and a second peak in intensity is likely when Delta is over the central Gulf of Mexico in 48-60 hours. After that time, increasing southwesterly shear and the cooler shelf waters over the northern Gulf are expected to cause some reduction in wind speed. The global models, however, depict a significant increase in the size of Delta’s wind field while it is over the Gulf of Mexico, which increases the spatial extent of the storm surge and wind threats for the northern Gulf coast. So regardless of Delta’s final landfall intensity, the projected large size of the hurricane is likely to result in a significant storm surge and wind event for portions of the northern Gulf coast later this week.

Delta has been moving steadily west-northwestward today at 300/15 kt. The track forecast reasoning remains unchanged from the previous advisory. A mid-level ridge over Florida and the northeastern Gulf of Mexico is expected to continue steering Delta west-northwestward during the next 36-48 hours. After that time, a developing trough over the south-central United States should cause Delta to turn northward, and by Friday the hurricane is forecast to begin accelerating northward or north-northeastward ahead of the trough. This motion will bring Delta onshore along the northern Gulf coast between 72 and 96 hours. The dynamical models continue to be tightly clustered through 48-72 hours with some increase in spread thereafter. The overall trend in the guidance has been slightly westward, and the new forecast has been adjusted accordingly and lies near the middle of the envelope. Supplemental upper-air balloon launches at 0600 and 1800 UTC have begun at upper-air sites across portions of the southeastern United States. In addition, a NOAA G-IV synoptic surveillance mission is in progress and should provide additional data for the 0000 UTC cycle of the dynamical models.

FORECAST POSITIONS AND MAX WINDS

INIT  06/2100Z 18.9N  84.1W  125 KT 145 MPH - Category 4 (ENE Mahahual, Mexico)
 12H  07/0600Z 20.2N  86.1W  135 KT 155 MPH - Category 4 (ESE Cozumel, Mexico)
 24H  07/1800Z 21.8N  88.8W  105 KT 120 MPH - Category 3 (WNW Rio Lagartos, Mexico)
 36H  08/0600Z 23.0N  91.1W  110 KT 125 MPH - Category 3 (WNW Progreso, Mexico)
 48H  08/1800Z 24.4N  92.6W  115 KT 130 MPH - Category 4 (ESE Brownsville, Texas)
 60H  09/0600Z 25.9N  93.2W  115 KT 130 MPH - Category 4 (ESE Brownsville, Texas)
 72H  09/1800Z 28.0N  92.9W  110 KT 125 MPH - Category 3 (ESE Galveston, Texas)
 96H  10/1800Z 32.4N  90.9W   55 KT  65 MPH - Tropical Storm (WNW Vicksburg, Mississippi)
120H  11/1800Z 35.5N  87.3W   20 KT  25 MPH - Low (WSW Mt Pleasant, Tennessee)

Key Messages:

1. Life-threatening storm surge and potentially catastrophic wind damage are expected within portions of the northern Yucatan Peninsula of Mexico beginning tonight. All preparations to protect life and property should be rushed to completion.

2. Heavy rainfall will affect portions of the Cayman Islands, western Cuba and the northern Yucatan Peninsula through midweek. This rainfall could lead to significant flash flooding and mudslides. The potential for heavy rain, flash and possible minor river flooding will increase across portions of the central Gulf Coast, Tennessee Valley, and southeastern United States as Delta moves inland later this week.

3. There is an increasing likelihood of life-threatening storm surge and dangerous hurricane-force winds, especially along the coasts of Louisiana and Mississippi, beginning on Friday. Residents in these areas should ensure they have their hurricane plan in place and follow advice given by local officials. Storm surge and hurricane watches will likely be issued for portions of the northern Gulf Coast on Wednesday.

NWS National Hurricane Center Miami FL 1100 AM EDT Tue Oct 06, 2020

Satellite imagery and recent NOAA Hurricane Hunter aircraft data show that Delta is a very symmetric and compact hurricane. The aircraft reported a tiny 5-nmi-wide eye, which has also been seen in radar imagery from the Cayman Islands, and there is a hint of a pinhole eye in infrared satellite data. The central pressure has continued to fall, with the lastest center dropwindsonde data supporting a pressure of 955 mb. The plane has reported a peak flight-level winds of 109 kt, and believable SFMR winds of 102 kt. Therefore, the initial intensity is set at 100 kt, making Delta the third major hurricane of the 2020 Atlantic hurricane season.

Delta has continued to rapidly strengthen over the past 24 hours, with an estimated 55-kt increase in wind speed between 1200 UTC Monday and 1200 UTC today. Environmental conditions of low vertical wind shear, deep warm waters, and sufficient mid-level moisture are expected to support additional rapid intensification through today, and the only reason that the strengthening could slow is if a difficult-to-predict eyewall replace cycle begins. The SHIPS Rapid intensification index continues to indicate a high likelihood of at least an additional 25-30 kt of intensity increase before the system reaches the northeastern portion of the Yucatan Peninsula. Given that, the NHC intensity forecast is above the various intensity aids and call for Delta to be an extremely dangerous category 4 hurricane when it nears the Yucatan. It could be stronger than indicated below since landfall is predicted to occur between the 12 and 24 h forecast points. Some reduction in intensity is likely when Delta moves over land, but the environmental conditions over the southern Gulf of Mexico are expected to support re-strengthening, and the NHC intensity forecast shows a second peak in 48-72 hours. As mentioned before, increasing southwesterly shear and cooler shelf waters near the northern Gulf coast are expected to cause some reduction in wind speed, but Delta is still expected to be a dangerous hurricane when it nears the northern Gulf coast.

Delta is moving west-northwestward at about 14 kt. A mid-level ridge that extends westward across Florida and the northeastern Gulf of Mexico should continue to steer Delta west-northwestward to northwestward during the next couple of days. As the hurricane nears the western portion of the ridge it should slow down. By day three a developing trough over the south-central United States is expected to cause Delta to turn northward toward the northern Gulf coast. The track guidance is tightly clustered through 48 hours, but there is still a fair amount of spread thereafter regarding the timing and details of the northward turn. The ECMWF and its ensemble mean are well west of the bulk of the remainder of the guidance. The NHC track lies near the TVCA multi-model consensus which is close to a blend of the GFS, HWRF, UKMET ensemble mean.

Key Messages:

  • 1. Extremely dangerous storm surge and hurricane conditions are expected within portions of the northern Yucatan Peninsula of Mexico beginning tonight, and a Hurricane Warning is in effect.
  • 2. Heavy rainfall will affect portions of the Cayman Islands, western Cuba and the northern Yucatan Peninsula through midweek. This rainfall could lead to significant flash flooding and mudslides. The potential for heavy rain and flash flooding will increase across portions of the central Gulf Coast, Tennessee Valley, and southeastern United States as Delta moves inland later this week.
  • 3. There is an increasing likelihood of life-threatening storm surge and dangerous hurricane-force winds, especially along the coasts of Louisiana and Mississippi, beginning on Friday. Residents in these areas should ensure they have their hurricane plan in place and monitor updates to the forecast.
FORECAST POSITIONS AND MAX WINDS

INIT  06/1500Z 18.2N  82.6W  100 KT 115 MPH - Category 3 (WSW Georgetown, Grand Cayman)
 12H  07/0000Z 19.4N  84.5W  120 KT 140 MPH - Category 4 (WSW Cozumel, Mexico)
 24H  07/1200Z 21.0N  87.2W  120 KT 140 MPH - Category 4 (WSW Cancun, Mexico)
 36H  08/0000Z 22.3N  89.6W  105 KT 120 MPH - Category 3 (WNW Progreso, Mexico)
 48H  08/1200Z 23.4N  91.3W  110 KT 125 MPH - Category 3 (WNW Progreso, Mexico)
 60H  09/0000Z 24.6N  92.3W  115 KT 130 MPH - Category 4 (WSW Brownsville, Mexico)
 72H  09/1200Z 26.3N  92.5W  110 KT 125 MPH - Category 3 (WNW Brownsville, Mexico)
 96H  10/1200Z 30.5N  91.2W   70 KT  80 MPH - Tropical Storm (WNW Baton Rouge, LA)
120H  11/1200Z 34.5N  87.5W   25 KT  30 MPH - Low (WNW Russellville, AL)

NWS National Hurricane Center Miami FL 1100 PM EDT Mon Oct 05, 2020 

A few hours ago, data from the NOAA Hurricane Hunters supported upgrading Delta to a hurricane. Very recent reports from the Air Force Hurricane Hunters, who are currently in Delta, support increasing the intensity a little more to 70 kt. The minimum pressure has also decreased a few mb from the NOAA mission, and is now estimated to be 977 mb. Delta has strengthened at a rapid rate of 40 kt since genesis occurred just 24 hours ago. The hurricane is quite compact with a developing tight inner core, and even the tropical-storm-force winds extend only up to 60 n mi or so from the center.

After moving westward for much of the day, aircraft fixes from NOAA and the Air Force indicate that the hurricane has resumed a west-northwest motion, with the latest initial motion estimated to be 295/6 kt. Delta is expected to move to the northwest at a fairly quick pace on Tuesday and Wednesday as it moves in the flow between a subtropical high over the western Atlantic and Post-Tropical Cyclone Gamma over or near the Yucatan Peninsula. This motion should take Delta over or very near the northeastern portion of the Yucatan Peninsula by Tuesday night and over the southern Gulf of Mexico on Wednesday. After that time, the western part of the ridge is expected to slowly erode as a trough moves eastward across the south-central U.S. This change in the steering pattern should cause Delta to slow down and then turn northward toward the northern Gulf coast, and it will likely make landfall there in a little more than 4 days. The models are in fair agreement, and the NHC track forecast is only a touch to the west of the previous one.

The hurricane has taken advantage of the near ideal conditions of low vertical wind shear, high amounts of moisture, and very warm 29-30 C SSTs. These favorable environmental conditions for the hurricane will persist for the next 2 or 3 days or so, and therefore, it seems reasonable to believe that rapid intensification will continue in the short term. Delta is expected to become a major hurricane in about 24 hours when it is near the Yuctan Peninsula. If Delta makes landfall on that landmass, it would likely temper the cyclone’s strength for a period of time. Beyond a few days, when Delta is forecast to approach the northern Gulf coast, there will likely be an increase in southwesterly wind shear. These less conducive upper-level winds and cooler shelf waters should end the strengthening trend prior to the U.S. landfall. The NHC intensity forecast is largely an update of the previous one and lies close to the HCCA and IVCN consensus models.

Users are reminded to not focus on the details of the track or intensity forecasts, as the average 4-day track error is around 150 miles and the average 4-day intensity error is close to 15 mph.

Key Messages:

  • 1. Dangerous storm surge and hurricane conditions are expected within portions of the northern Yucatan Peninsula of Mexico beginning Tuesday night, and a Hurricane Warning is in effect.
  • 2. Heavy rainfall will affect portions of Jamaica, the Cayman Islands, western Cuba and the northern Yucatan Peninsula during the next few days. This rainfall could lead to significant flash flooding and mudslides.
  • 3. Tropical storm conditions are expected in portions of the Cayman Islands beginning early Tuesday, and a Tropical Storm Warning is in effect.
  • 4. Delta is forecast to approach the northern Gulf Coast late this week as a hurricane. While there is large uncertainty in the track and intensity forecasts, there is an increasing risk of dangerous storm surge, wind, and rainfall hazards along the coast from Louisiana to the western Florida Panhandle beginning Thursday night or Friday. Residents in these areas should ensure they have their hurricane plan in place and monitor updates to the forecast of Delta.
FORECAST POSITIONS AND MAX WINDS

INIT  06/0300Z 16.8N  80.3W   70 KT  80 MPH - Category 1 (WSW Negril, Jamaica)
 12H  06/1200Z 18.1N  82.0W   85 KT 100 MPH - Category 2 (WSW Georgetown, Grand Cayman )
 24H  07/0000Z 19.8N  84.6W  100 KT 115 MPH - Category 3 (ESE Cozumel, Mexico)
 36H  07/1200Z 21.5N  87.1W  105 KT 120 MPH - Category 3 (WSW Isla Mujeres, Mexico)
 48H  08/0000Z 23.0N  89.5W  105 KT 120 MPH - Category 3 (ENE Progreso, Mexico)
 60H  08/1200Z 24.0N  90.8W  105 KT 120 MPH - Category 3 (ENE Tampico, Mexico)
 72H  09/0000Z 25.2N  91.7W  100 KT 115 MPH - Category 3 (ESE Brownsville, Texas)
 96H  10/0000Z 28.6N  91.2W   85 KT 100 MPH - Category 2 (WSW Cocodrie, Louisiana)
120H  11/0000Z 33.6N  88.4W   35 KT  40 MPH - Tropical Storm (ENE Columbus, Mississippi)

NWS National Hurricane Center Miami FL 500 PM EDT Mon Oct 05, 2020 

Visible satellite imagery shows that the convective banding of Delta has continued to quickly improve since this morning. The primary convective band now wraps entirely around the center, with what appears to be a banding-type eye feature occasionally noted. There are some dry slots between the convective bands but those appear to be gradually filling in. A NOAA Hurricane Hunter aircraft currently collecting data in the storm environment found peak SFMR winds of 55 kt during its first pass through the center from northwest to southeast. The plane also reported a minimum pressure of 983 mb, much lower than previously estimated. The aircraft also observed an 18 nmi-wide-eye that was open to the west-northwest. Assuming that there are stronger winds yet to be sampled in the northeastern quadrant, the initial intensity has been raised to 60 kt.

Delta is situated within a very conducive environment for strengthening. The storm will be moving over SSTs of 29-30 degrees Celsius and the vertical wind shear is forecast to remain 5 kt or less while Delta traverses the northwestern Caribbean. These conditions are expected to allow for rapid strengthening over the next 24 to 36 hours. The SHIPS Rapid Intensification Index gives a better than 50 percent chance of a 35-40 kt increase in wind speed over the next 24 hours.

The NHC intensity forecast follow suit by calling for rapid intensification over the next day or so, and Delta is forecast to be a major hurricane when is passes near or over the northeastern portion of the Yucatan peninsula. Once the storm reaches the central Gulf of Mexico in 60-72 hours, increasing southwestern vertical wind shear and cooler shelf waters over the northern Gulf are likely to result in some reduction in wind speed as the system nears the northern Gulf coast. Although there is still significant uncertainty regarding Delta’s intensity when it nears the northern Gulf coast, it is becoming increasing likely that the system will pose a significant wind and storm surge threat to a portion of that area. The center has jogged southward again this afternoon, which appears to be primarily due to the system organizing rather than a true storm motion.

The initial motion estimate remains an uncertain 275/7 kt. Delta should begin moving west-northwestward this evening, and a west-northwestward to northwestward motion around the southwestern portion of a deep-layer ridge to its northeast is expected over the next couple of days. The more southward initial position and more ridging over the eastern Gulf of Mexico has resulted in a significant westward shift in the track envelope through the first 60-72 hours. The NHC has been adjusted in that direction, and this has required the issuance of a Hurricane Warning for the northeastern portion of the Yucatan peninsula of Mexico. After 72 hours, a mid- to upper-level trough is forecast to develop over Texas which should cause Delta to turn northward and then north-northeastward toward the northern Gulf Coast. Although the track forecast has not changed much during the latter portion of the period, there is more cross-track spread in the model guidance than before, which has increased the uncertainty regarding potential landfall and the timing of Delta’s approach to the northern Gulf Coast.

Key Messages:

  • 1. Dangerous storm surge and hurricane conditions are expected within portions of the northern Yucatan Peninsula of Mexico and are possible in extreme western Cuba beginning Tuesday night, and a Hurricane Warning is in effect.
  • 2. Heavy rainfall will affect portions of Jamaica, the Cayman Islands, western Cuba and the northern Yucatan Peninsula during the next few days. This rainfall could lead to significant flash flooding and mudslides.
  • 3. Tropical storm conditions are expected in portions of the Cayman Islands beginning tonight or early Tuesday, and a Tropical Storm Warning is in effect.
  • 4. Delta is forecast to approach the northern Gulf Coast late this week as a hurricane. While there is large uncertainty in the track and intensity forecasts, there is an increasing risk of dangerous storm surge, wind, and rainfall hazards along the coast from Louisiana to the western Florida Panhandle beginning Thursday night or Friday. Residents in these areas should ensure they have their hurricane plan in place and monitor updates to the forecast of Delta.
FORECAST POSITIONS AND MAX WINDS

INIT  05/2100Z 16.2N  79.4W   60 KT  70 MPH - Tropical Storm (WSW Hayes, Jamaica )
 12H  06/0600Z 17.1N  80.9W   75 KT  85 MPH - Category 1 (WSW Tulum, Mexico)
 24H  06/1800Z 19.0N  83.5W   95 KT 110 MPH - Category 2 (WSW Tulum, Mexico)
 36H  07/0600Z 21.0N  86.2W  105 KT 120 MPH - Category 3 (WSW Cancún, Mexico)
 48H  07/1800Z 22.6N  88.7W  105 KT 120 MPH - Category 3 (WNW Rio Lagartos, Mexico)
 60H  08/0600Z 23.7N  90.6W  105 KT 120 MPH - Category 3 (WNW Tampico, Mexico)
 72H  08/1800Z 24.8N  91.5W   95 KT 110 MPH - Category 2 (ESE Brownsville, Texas)
 96H  09/1800Z 28.5N  91.5W   85 KT 100 MPH - Category 2 (WSW Cocodrie, LA)
120H  10/1800Z 33.0N  89.0W   40 KT  45 MPH - Tropical Storm (ESE Louisville, MS)

NWS National Hurricane Center Miami FL 1100 AM EDT Mon Oct 05, 2020 

The convective structure of Delta has continued to improve this morning. Earlier microwave data and early-light visible satellite imagery showed that the center of the tropical cyclone re-formed farther south within the area of deep convection. Since that time, banding has continued to increase around the southern and eastern portion of the circulation, and a small CDO-like feature has formed. The intensity has been set at 40 kt, which is a blend of the subjective Dvorak estimate from TAFB and objective satellite intensity estimates from UW/CIMSS.

A NOAA Hurricane Hunter aircraft is scheduled to investigate the tropical storm this afternoon, which should provide a better assessment of the cyclone’s intensity, structure, and wind field. With the earlier center re-formation, the initial motion estimate is a somewhat uncertain 280/6 kt. Delta is expected to resume a west-northwestward motion later today. A northwestward heading around the southwestern portion of a deep-layer ridge should begin tonight or Tuesday, and that general motion with some increase in forward speed is expected to continue through 60-72 hours. After that time, a broad mid- to upper-level trough is forecast to develop over the south-central United States, which should weaken the western portion of the ridge and cause Delta to turn northward toward the northern Gulf Coast. After day 4, Delta should begin to accelerate north-northeastward or northeastward ahead of the aforementioned trough. The new NHC track forecast has been adjusted to the south and west of the previous advisory during the first couple of days, primarily due to the recent center re-formation and more southward initial position. After that time, the NHC track is not much different than the previous forecast and lies near the center of the tightly clustered dynamical model envelope.

Delta is forecast to traverse very warm waters over the northwestern Caribbean Sea and be in a very low vertical wind shear environment during the next couple of days. These conditions should allow for significant strengthening during that time, and the NHC intensity forecast is at or above the various intensity aids. It is somewhat surprising that the intensity aids were generally a little lower this cycle, but the expected low shear and SHIPS rapid intensification index support the higher than climatological rate of intensification. After 72 hours, increasing southwesterly shear and the cooler shelf waters over the northern Gulf are likely to induce some weakening later in the period. The updated NHC intensity forecast calls for a faster rate of intensification over the next 48-60 hours, but is similar to the previous advisory thereafter.

Key Messages:

  • 1. Tropical storm conditions are expected in the Cayman Islands beginning late today or tonight, and a Tropical Storm Warning is in effect.
  • 2. Dangerous storm surge and hurricane conditions are expected in portions of western Cuba by Tuesday afternoon, and a Hurricane Warning is in effect.
  • 3. Heavy rainfall will affect portions of Jamaica, the Cayman Islands, and western Cuba during the next few days. This rainfall could lead to significant flash flooding and mudslides.
  • 4. Delta is forecast to approach the northern Gulf Coast late this week as a hurricane. While there is large uncertainty in the track and intensity forecasts at these time ranges, there is an increasing risk of dangerous storm surge, wind, and rainfall hazards along the coast from Louisiana to the western Florida Panhandle. Residents in these areas should monitor the progress of Delta and check for updates to the forecast during the week.
FORECAST POSITIONS AND MAX WINDS

INIT  05/1500Z 16.4N  78.6W   40 KT  45 MPH - Tropical Storm (WSW Kingston, Jamaica)
 12H  06/0000Z 17.1N  79.6W   50 KT  60 MPH - Tropical Storm (WSW Negril, Jamaica)
 24H  06/1200Z 18.7N  81.7W   60 KT  70 MPH - Tropical Storm (WSW West Bay, Grand Cayman)
 36H  07/0000Z 20.8N  84.3W   75 KT  85 MPH - Category 1 (WSW Maria la Gorda, Cuba)
 48H  07/1200Z 22.8N  86.8W   85 KT 100 MPH - Category 2 (ENE Cancun, Mexico)
 60H  08/0000Z 24.6N  89.1W   90 KT 105 MPH - Category 2 (WNW Key West, FL)
 72H  08/1200Z 26.0N  90.7W   90 KT 105 MPH - Category 2 (ESE Grand Isle, LA)
 96H  09/1200Z 28.8N  91.1W   85 KT 100 MPH - Category 2 (WSW Cocodrie, LA)
120H  10/1200Z 33.1N  88.2W   40 KT  45 MPH - Tropical Storm (WSW Aliceville, AL)

NWS National Hurricane Center Miami FL 1100 PM EDT Sun Oct 04, 2020

Satellite data indicate that the disturbance just south of Jamaica has become better organized this evening. Microwave and shortwave infrared images indicate that the center is now well defined, and deep convection has been persisting near and to the south of the center. Based on this data, the system now meets the criteria to be considered a tropical depression. The initial intensity remains 30 kt for this advisory.

The depression is currently moving west-northwestward at 8 kt on the southern side of an Atlantic subtropical ridge. A continued west-northwest to northwest motion at about the same forward speed is expected during the next 24 to 36 hours, taking the system across the Cayman Islands and toward western Cuba. Around the time the depression is expected to be near western Cuba, the models show it accelerating northwestward as it moves in the faster flow between the ridge and Tropical Storm Gamma. This motion should bring the tropical cyclone into the southern Gulf of Mexico Tuesday night or early Wednesday. Later on, a notable slow down and a turn to the north is forecast to occur late in the week when the depression will likely be approaching the northern Gulf coast. This change in the forecast motion is a result of the ridge weakening and a trough approaching the cyclone from the west. The models are in relatively good agreement, which is surprising since they often diverge for weak systems, and the NHC track forecast lies near the middle of the guidance envelope.

There is currently some northeasterly shear affecting the depression, but the models all show the shear lessening by tomorrow and remaining fairly light for the next few days. These improving upper-level wind conditions combined with a moist air mass and warm waters should allow for at least steady strengthening during the next few days. By late in the week, when the storm is forecast to approach the U.S. Gulf coast, there could be an increase in southerly or southwesterly shear, which could limit additional strengthening by that time. The NHC intensity forecast lies fairly close to the IVCN and HCCA consensus aids, and shows the depression becoming a hurricane near western Cuba with additional strengthening over the Gulf of Mexico.

Users are reminded that the average 4- and 5-day NHC track forecast errors are about 160 to 200 miles at those time periods, respectively.

Key Messages:

  • 1. Tropical storm conditions are expected in the Cayman Islands beginning late Monday, and a Tropical Storm Warning is in effect.
  • 2. Dangerous storm surge and hurricane conditions are possible in portions of western Cuba and the Isle of Youth by Tuesday afternoon, and a Hurricane Watch is in effect.
  • 3. Heavy rainfall will affect portions of Hispaniola, Jamaica, the Cayman Islands, and western Cuba during the next few days and could lead to life-threatening flash floods and mudslides.
  • 4. The system is forecast to approach the northern Gulf Coast late this week as a hurricane. While there is large uncertainty in the track and intensity forecasts at these time ranges, there is a risk of dangerous storm surge, wind, and rainfall hazards along the coast from Louisiana to the western Florida Panhandle. Residents in these areas should monitor the progress of the system and check for updates to the forecast during the week.
FORECAST POSITIONS AND MAX WINDS

INIT  05/0300Z 17.0N  77.3W   30 KT  35 MPH - Depression (ESE Kingston, Jamaica)
 12H  05/1200Z 17.4N  78.3W   35 KT  40 MPH - Tropical Storm (WSW Treasure Beach, Jamaica)
 24H  06/0000Z 18.3N  79.8W   40 KT  45 MPH - Tropical Storm (WNW Negril, Jamaica)
 36H  06/1200Z 20.0N  81.9W   50 KT  60 MPH - Tropical Storm (WNW West Bay, Grand Cayman)
 48H  07/0000Z 22.2N  84.4W   65 KT  75 MPH - Category 1 (WSWS Mantua, Cuba)
 60H  07/1200Z 24.1N  87.0W   80 KT  90 MPH - Category 1 (WSW Key West, FL)
 72H  08/0000Z 25.4N  88.8W   85 KT 100 MPH - Category 2 WSW Naples, FL)
 96H  09/0000Z 27.2N  90.4W   90 KT 105 MPH - Category 2 (WSW Grand Isle, LA)
120H  10/0000Z 30.0N  89.9W   75 KT  85 MPH - Category 1 (ENE New Orleans, LA)

NWS National Hurricane Center Miami FL 500 PM EDT Sun Oct 04, 2020 

Visible satellite imagery and earlier scatterometer data indicated that the circulation associated with the area of low pressure in the central Caribbean Sea has gradually become better defined. The associated deep convection does not yet have enough organization to classify the system as a tropical depression, but there has been some increase in convection just south of the estimated center. The earlier ASCAT data revealed peak winds of around 30 kt over the northeastern portion of the circulation, and that is the basis for the initial intensity. The disturbance is located over warm waters and in a moist environment, but there is some modest northeasterly shear over the system. The global models indicate that the shear will decrease overnight, and the oceanic and atmospheric environment is expected to quite favorable for both the development of a tropical cyclone and subsequent strengthening of the system over the northwestern Caribbean Sea during the next couple of days. The intensity guidance is quite aggressive, but also assumes that the system already has a tropical cyclone structure. Therefore, the NHC intensity forecast is a little below the intensity consensus during the first 24-48 hours, but does show the system at or near hurricane strength by the time is near western Cuba on Tuesday. Environmental conditions are expected to remain favorable for strengthening over the southeastern Gulf of Mexico, and additional strengthening is predicted during that time. Late in the period, conditions are forecast to become less conducive as the vertical wind shear increases and the system nears the cooler shelf waters of the northern Gulf of Mexico.

The disturbance is moving west-northwestward or 290/9 kt. A mid- to upper-level ridge over the western Atlantic is forecast to build westward over the next few days, which should continue to steer the system west-northwestward to northwestward over the northwestern Caribbean Sea and southeastern Gulf of Mexico. The forward speed of the system is likely to increase in 48 to 72 hours while it moves between the ridge and Tropical Storm Gamma to its southwest. After 72 hours, the cyclone is forecast to slow down and turn northward around the western portion of the ridge and a mid- to upper-level trough over the south-central United States. The track guidance is in relatively good agreement during the first 48 to 72 hours, but there is increasing spread thereafter. Users are reminded that the average 4- and 5-day NHC track forecast errors are about 160 to 200 miles at those time periods.

Key Messages:

  • 1. Tropical storm conditions are expected in the Cayman Islands beginning late Monday, and a Tropical Storm Warning is in effect.
  • 2. Dangerous storm surge and hurricane conditions are possible in portions of western Cuba and the Isle of Youth by Tuesday afternoon, and a Hurricane Watch is in effect.
  • 3. Heavy rainfall will affect portions of Hispaniola, Jamaica, the Cayman Islands, and western Cuba during the next few days and could lead to life-threatening flash floods and mudslides.
  • 4. The system is forecast to approach the northern Gulf Coast late this week as a hurricane. While there is large uncertainty in the track and intensity forecasts at these time ranges, there is a risk of dangerous storm surge, wind, and rainfall hazards along the coast from Louisiana to the western Florida Panhandle. Residents in these areas should monitor the progress of the system and check for updates to the forecast during the week.
FORECAST POSITIONS AND MAX WINDS

INIT  04/2100Z 16.7N  76.6W   30 KT  35 MPH - Depression (ESE Kingston, Jamaica)
 12H  05/0600Z 17.1N  77.7W   30 KT  35 MPH - Depression (ESE Treasure Beach, Jamaica)
 24H  05/1800Z 18.0N  79.1W   35 KT  40 MPH - Tropical Storm (ESE Negril, Jamaica)
 36H  06/0600Z 19.0N  80.5W   45 KT  50 MPH - Tropical Storm (ESE East End, Jamaica)
 48H  06/1800Z 21.0N  82.8W   60 KT  70 MPH - Tropical Storm (ESE Isla de la Juventud, Cuba)
 60H  07/0600Z 23.1N  85.4W   70 KT  80 MPH - Category 1 (WNW Las Tumbas,Cuba)
 72H  07/1800Z 24.7N  87.9W   80 KT  90 MPH - Category 1 (WNW Key West, FL)
 96H  08/1800Z 26.5N  90.3W   85 KT 100 MPH - Category 2 (WSW Grand Isle, LA) 
120H  09/1800Z 28.6N  90.3W   85 KT 100 MPH - Category 2 (WSW Port Fourchon, LA)

NWS National Hurricane Center Miami FL 200 PM EDT Sun Oct 4, 2020 

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

The National Hurricane Center is issuing advisories on Tropical Storm Gamma, located just north of the Yucatan Peninsula over the extreme southern Gulf of Mexico.

  • 1. A broad area of low pressure is located over the central Caribbean Sea, a little less than 100 miles south-southeast of eastern Jamaica. Recent satellite wind data and visible satellite imagery indicate that the circulation is gradually becoming better defined, however, the associated shower and thunderstorm activity has changed little in organization since this morning. Environmental conditions are expected to be conducive for additional development, and a tropical depression is likely to form within the next day or so, while the system moves over the central and northwestern Caribbean Sea. The disturbance is forecast to move near Jamaica through Monday, and then pass near the Cayman Islands early Tuesday and approach western Cuba by late Tuesday, and interests in those areas should closely monitor the progress of this system. The low is forecast to move into the southern or southeastern Gulf of Mexico Tuesday night or Wednesday. Regardless of development, locally heavy rainfall and gusty winds will be possible across portions of Hispaniola, Jamaica, the Cayman Islands, and Cuba during the next few days. This rainfall could lead to life-threatening flash floods and mudslides. * Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high…80 percent.
  • 2. Showers and thunderstorms associated with a tropical wave over the central tropical Atlantic have become limited today. The system is moving into an area of strong upper-level winds and development of this system is not anticipated. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…near 0 percent.
  • 3. An area of disorganized showers and thunderstorms over the central Atlantic about 1000 miles east-southeast of Bermuda is associated with a surface trough of low pressure. This system is expected to move toward the west-southwest at around 10 mph, and some slow development is possible during the next couple of days before it encounters strong upper-level winds. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low…10 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Sun Oct 4, 2020 

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

The National Hurricane Center is issuing advisories on Tropical Storm Gamma, located just north of the Yucatan Peninsula over the extreme southern Gulf of Mexico.

  • 1. A tropical wave accompanied by a low pressure system is located over the central Caribbean Sea a couple of hundred miles southeast of Jamaica. The associated shower and thunderstorm activity is beginning to show some signs of organization. Environmental conditions are expected to be conducive for additional development, and a tropical depression is likely to form within the next day or two. The system should move west-northwestward at 10 to 15 mph across the central and western Caribbean Sea today through Tuesday, and then move into the southern or southeastern Gulf of Mexico on Tuesday night and Wednesday. Locally heavy rainfall and gusty winds will be possible across portions of Hispaniola, Jamaica, Cuba, and the Cayman Islands during the next few days, and interests on those islands should monitor the progress of this disturbance. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…80 percent.
  • 2. Disorganized showers and thunderstorms continue in association with a tropical wave located over the central tropical Atlantic. This system has not become any better organized, and any development during the next day or so should be slow to occur while it moves west-northwestward or northwestward at 10 to 15 mph. Significant development is not expected beyond that time due to the system moving into a region of strong upper-level winds. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low…10 percent.
  • 3. An area of disorganized showers and thunderstorms over the central Atlantic about 1000 miles east-southeast of Bermuda is associated with a surface trough of low pressure. This system is expected to move toward the west-southwest at around 10 mph, and some slow development is possible during the next couple of days before it too encounters strong upper-level winds. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low…10 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Sat Oct 3, 2020

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

The National Hurricane Center is issuing advisories on Tropical Storm Gamma, located inland over the Yucatan Peninsula.

  • 1. A tropical wave located over the central Caribbean Sea is producing an area of disorganized showers and thunderstorms. Environmental conditions are expected to become more conducive for development, and a tropical depression is likely to form during the early or middle portions of next week while the system moves westward or west-northwestward at about 15 mph across the central and western Caribbean Sea and then into the southern Gulf of Mexico. Locally heavy rainfall and gusty winds will be possible across portions of Hispaniola, Jamaica, Cuba, and the Cayman Islands during the next few days, and interests on those islands should monitor the progress of this disturbance. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…high…70 percent. [Delta]
  • 2. Disorganized showers and thunderstorms continue in association with a tropical wave located over the central tropical Atlantic. Some slow development of this system is possible during the next couple of days while it moves west-northwestward or northwestward at 10 to 15 mph. Significant development is not expected beyond that time due to the system moving into a region of strong upper-level winds. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low…20 percent.
  • 3. An area of disorganized showers and thunderstorms over the central Atlantic more than 1000 miles east-southeast of Bermuda is associated with a surface trough of low pressure. This system is expected to move toward the west-southwest at around 10 mph, and some slow development is possible during the next couple of days before it too encounters strong upper-level winds. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low…10 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Sat Oct 3, 2020

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

The National Hurricane Center is issuing advisories on Tropical Storm Gamma, located over the northwestern Caribbean Sea.

  • 1. A tropical wave is producing widespread cloudiness, showers, and thunderstorms over the eastern and central Caribbean Sea, with locally heavy rainfall and gusty winds affecting portions of the ABC Islands, the Lesser Antilles, the Virgin Islands, Puerto Rico, and portions of the coasts of Colombia and Venezuela. Environmental conditions are expected to become a little more conducive for development, and a tropical depression could form next week while the system moves westward or west-northwestward at about 15 mph across the central and western Caribbean Sea and then into the southern Gulf of Mexico. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…50 percent.
  • 2. A tropical wave located over the central tropical Atlantic is producing disorganized showers and thunderstorms. This system is expected to move toward the west-northwest or northwest at 10 to 15 mph, and some development is possible during the next couple of days before it encounters strong upper-level winds. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low...20 percent.
  • 3. An area of disorganized showers and thunderstorms over the central Atlantic more than 1000 miles east-southeast of Bermuda is associated with a surface trough of low pressure. Some slow development of this system is possible during the next couple of days before it too encounters strong upper-level winds. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low...10 percent.

NWS National Hurricane Center Miami FL 200 PM EDT Fri Oct 2, 2020

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

The National Hurricane Center has initiated advisories on Tropical Depression Twenty-Five, located over the northwestern Caribbean Sea.

  • 1. A tropical wave is producing widespread cloudiness, showers, and thunderstorms over the eastern Caribbean Sea, with locally heavy rainfall and gusty winds affecting portions of the ABC Islands, the Lesser Antilles, the Virgin Islands, and Puerto Rico. Environmental conditions are expected to become a little more conducive for development, and a tropical depression could form next week while the system moves westward or west-northwestward at about 15 mph across the central and western Caribbean Sea. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…medium…40 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Fri Oct 2, 2020

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

  • 1. Satellite imagery indicates that shower activity associated with the broad low pressure area over the northwestern Caribbean Sea continues to become better organized. Environmental conditions are expected to be conducive for a tropical depression or a tropical storm to form later today or on Saturday if the system remains over the waters of the northwestern Caribbean Sea or the southern Gulf of Mexico. Interests in the Yucatan Peninsula and northern Central America should monitor the progress of this system while it moves generally northwestward, as tropical storm watches or warnings may be required for portions of these areas later today or tonight. Regardless of development, this system is expected to produce heavy rains, with possible flash flooding, over portions of southeastern Mexico, Central America, and western Cuba during the next several days. An Air Force Reserve reconnaissance aircraft is scheduled to investigate the system this afternoon, if necessary. * Formation chance through 48 hours…high…90 percent. * Formation chance through 5 days…high…90 percent. [Gamma}
  • 2. A tropical wave over the eastern Caribbean Sea is producing a large area of disorganized showers and thunderstorms, accompanied by locally heavy rainfall and gusty winds. This wave is forecast to move westward at 15 to 20 mph during the next several days, and environmental conditions could become a little more conducive for development when the system is over the central or western Caribbean Sea early next week. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…30 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Thu Oct 1, 2020

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

  •  2. Another tropical wave moving across the Lesser Antilles is producing a large area of disorganized showers and thunderstorms, accompanied by locally rainfall and gusty winds. This wave is forecast to move westward at 15 to 20 mph during the next several days, and environmental conditions could become a little more conducive for development when the system is over the central or western Caribbean Sea early next week. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…30 percent.

NWS National Hurricane Center Miami FL 200 PM EDT Thu Oct 1, 2020

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

  • 2. Another tropical wave located just east of the Lesser Antilles is also producing a large area of disorganized showers and thunderstorms. This wave is forecast to move westward at 15 to 20 mph during the next several days, and environmental conditions could become a little more conducive for development when the system is over the central or western Caribbean Sea early next week. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low...20 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Thu Oct 1, 2020

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

  • 2. Another tropical wave located just east of the Lesser Antilles is also producing a large area of disorganized showers and thunderstorms. This wave is forecast to move westward at 15 to 20 mph during the next several days, and environmental conditions could become a little more conducive for development when the system is over the central or western Caribbean Sea early next week. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…20 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Wed Sep 30, 2020

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

  • 2. Another tropical wave located a few hundred miles east of the Lesser Antilles is producing widespread cloudiness and disorganized shower activity. This disturbance is forecast to move westward during the next several days where environmental conditions could become a little more conducive for development over the central or western Caribbean Sea by early next week. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…20 percent.

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

Article Resources:

Recent Tropical Cruise Weather:

Video: Delta bringing rain, severe weather threat to central Alabama