Tropical Storm Isaias Forecast Discussion Number 4

What happened Source facts

Issued at 1000 AM CDT Wed Oct 07 2026 000 WTNT44 KNHC 071454 TCDAT4 Tropical Storm Isaias Discussion Number 4 NWS National Hurricane Center Miami FL AL092026 1000 AM CDT Wed Oct 07 2026 Isaias has gotten better organized during the past several hours with a large area of deep convection near and northeast of the center. Recent Air Force Hurricane Hunter data indicate that the center is re-forming a bit to the north of the previous advisory nearer to the mid-level center, with an estimated pressure of 1000 mb derived from dropsonde data. The initial wind speed is set to 40 kt in consideration of increase in satellite organization and the 4-mb dropsonde pressure fall, close to the UW-CIMSS SATCON values and many of the other objective estimates. The storm is moving east-northeast at 7 kt. The motion should gradually bend northward and increase during the next few days as a trough along the northwestern Gulf coast amplifies and the subtropical ridge east of Florida builds westward. This pattern should cause a fast-moving Isaias to approach the northern Gulf coast by Friday afternoon. Model guidance continues to be somewhat split, with the AI-based models generally on the right side of the model envelope, and the physics based models on the left side. The new NHC forecast is nudged a bit eastward, but isn't as far east as the latest HFIP Corrected Consensus Approach (HCCA) or Google DeepMind ensemble mean (GDMI). It is worth noting that many of the stronger solutions tend to be on the eastern half of the guidance and faster, which necessitates a variety of watches at this time. With the center re-formation, the low- and mid-level centers appear to be coming into better alignment. This structural change could facilitate rapid intensification during the next day or two given light-to-moderate shear along the forecast track, near-record SSTs for this time of the year and a very moist environment. Near landfall, increasing shear could cause some weakening, but it isn't certain how fast the winds will diminish. Regardless, Isaias should be growing in size as it approaches the northern Gulf coast due to a trough interaction. The latest guidance is very close to the last NHC intensity forecast, so little changes were made, and the NHC prediction is just below the corrected-consensus HCCA. Key Messages: 1. Isaias is expected to strengthen into a strong hurricane before approaching the northern Gulf Coast on Friday. There is an increasing risk of life-threatening storm surge along portions of the northern Gulf coast, and a Storm Surge Watch has been issued from The Mouth of the Mississippi River to Yankeetown Florida. Residents in the watch area should follow advice given by local officials and evacuate if told to do so. 2. The risk of damaging hurricane force-winds is increasing over portions of the Florida Panhandle, southern Alabama, and Mississippi. A Hurricane Watch has been issued from Bay St. Louis, Mississippi, to Indian Pass, Florida. Residents in these areas should prepare for the possibility of long-duration power outages. 3. Isaias will bring areas of heavy rainfall to the central U.S. Gulf coast and much of the Southeast Friday into the weekend. Flash and urban flooding, along with isolated river flooding, will be possible. 4. Isaias could bring gusty winds and areas of heavy rain to the western portion of the Yucatan Peninsula over the next day or so. FORECAST POSITIONS AND MAX WINDS INIT 07/1500Z 22.4N 93.6W 40 KT 45 MPH 12H 08/0000Z 22.7N 92.4W 50 KT 60 MPH 24H 08/1200Z 23.4N 90.8W 65 KT 75 MPH 36H 09/0000Z 24.6N 89.2W 80 KT 90 MPH 48H 09/1200Z 26.6N 88.1W 95 KT 110 MPH 60H 10/0000Z 29.2N 87.5W 90 KT 105 MPH 72H 10/1200Z 32.2N 87.6W 45 KT 50 MPH...INLAND 96H 11/1200Z 38.0N 87.5W 20 KT 25 MPH...POST-TROP/INLAND 120H 12/1200Z...DISSIPATED $$ Forecaster Blake

Recorded source facts

Issued at 1000 AM CDT Wed Oct 07 2026 000 WTNT44 KNHC 071454 TCDAT4 Tropical Storm Isaias Discussion Number 4 NWS National Hurricane Center Miami FL AL092026 1000 AM CDT Wed Oct 07 2026 Isaias has gotten better organized during the past several hours with a large area of deep convection near and northeast of the center. Recent Air Force Hurricane Hunter data indicate that the center is re-forming a bit to the north of the previous advisory nearer to the mid-level center, with an estimated pressure of 1000 mb derived from dropsonde data. The initial wind speed is set to 40 kt in consideration of increase in satellite organization and the 4-mb dropsonde pressure fall, close to the UW-CIMSS SATCON values and many of the other objective estimates. The storm is moving east-northeast at 7 kt. The motion should gradually bend northward and increase during the next few days as a trough along the northwestern Gulf coast amplifies and the subtropical ridge east of Florida builds westward. This pattern should cause a fast-moving Isaias to approach the northern Gulf coast by Friday afternoon. Model guidance continues to be somewhat split, with the AI-based models generally on the right side of the model envelope, and the physics based models on the left side. The new NHC forecast is nudged a bit eastward, but isn't as far east as the latest HFIP Corrected Consensus Approach (HCCA) or Google DeepMind ensemble mean (GDMI). It is worth noting that many of the stronger solutions tend to be on the eastern half of the guidance and faster, which necessitates a variety of watches at this time. With the center re-formation, the low- and mid-level centers appear to be coming into better alignment. This structural change could facilitate rapid intensification during the next day or two given light-to-moderate shear along the forecast track, near-record SSTs for this time of the year and a very moist environment. Near landfall, increasing shear could cause some weakening, but it isn't certain how fast the winds will diminish. Regardless, Isaias should be growing in size as it approaches the northern Gulf coast due to a trough interaction. The latest guidance is very close to the last NHC intensity forecast, so little changes were made, and the NHC prediction is just below the corrected-consensus HCCA. Key Messages: 1. Isaias is expected to strengthen into a strong hurricane before approaching the northern Gulf Coast on Friday. There is an increasing risk of life-threatening storm surge along portions of the northern Gulf coast, and a Storm Surge Watch has been issued from The Mouth of the Mississippi River to Yankeetown Florida. Residents in the watch area should follow advice given by local officials and evacuate if told to do so. 2. The risk of damaging hurricane force-winds is increasing over portions of the Florida Panhandle, southern Alabama, and Mississippi. A Hurricane Watch has been issued from Bay St. Louis, Mississippi, to Indian Pass, Florida. Residents in these areas should prepare for the possibility of long-duration power outages. 3. Isaias will bring areas of heavy rainfall to the central U.S. Gulf coast and much of the Southeast Friday into the weekend. Flash and urban flooding, along with isolated river flooding, will be possible. 4. Isaias could bring gusty winds and areas of heavy rain to the western portion of the Yucatan Peninsula over the next day or so. FORECAST POSITIONS AND MAX WINDS INIT 07/1500Z 22.4N 93.6W 40 KT 45 MPH 12H 08/0000Z 22.7N 92.4W 50 KT 60 MPH 24H 08/1200Z 23.4N 90.8W 65 KT 75 MPH 36H 09/0000Z 24.6N 89.2W 80 KT 90 MPH 48H 09/1200Z 26.6N 88.1W 95 KT 110 MPH 60H 10/0000Z 29.2N 87.5W 90 KT 105 MPH 72H 10/1200Z 32.2N 87.6W 45 KT 50 MPH...INLAND 96H 11/1200Z 38.0N 87.5W 20 KT 25 MPH...POST-TROP/INLAND 120H 12/1200Z...DISSIPATED $$ Forecaster Blake