Hurricane Isaias Forecast Discussion Number 13

What happened Source facts

Issued at 400 PM CDT Fri Oct 09 2026 000 WTNT44 KNHC 092052 TCDAT4 Hurricane Isaias Discussion Number 13 NWS National Hurricane Center Miami FL AL092026 400 PM CDT Fri Oct 09 2026 Deep-layer shear from the southwest has increased to 30-40 kt, and the hurricane's structure is responding accordingly. WSR-88D radar data shows that the structure is becoming increasingly asymmetric, with very intense convection mainly confined to the northern eyewall. Tail Doppler radar data from the NOAA P-3 has also shown that the circulation is becoming tilted with height. That said, some impressive winds were measured at flight-level--136 kt by the Air Force Reserve at 10,000 feet and 126 kt by NOAA at 8,000 ft. While these winds themselves would normally support a higher intensity, several dropsondes released in the eyewall showed that there is a sharp drop-off of winds at the ocean surface, with layer-averaging suggesting a surface intensity of 90-95 kt. In addition, recent Doppler radar data from Mobile show winds of 100-110 kt at about 10,000 feet in the northern eyewall. Combining all this data together, the maximum surface winds appear to be around 100 kt, although it's very likely that Isaias will be a gustier-than-normal hurricane when it makes landfall. Isaias has turned northward and is accelerating with a current motion of 010/15 kt. The track guidance has honed in on a landfall over the western Florida Panhandle near the Pensacola area sometime this evening. A northward motion is expected to continue through Saturday, bringing Isaias's center through Alabama, followed by a northeastward trajectory across the Tennessee and the central Appalachians on Sunday. The circulation is expected to dissipate by hour 60. The high-resolution hurricane regional models (HAFS-A, HAFS-B, and HWRF), as well as the statistical-dynamical models (SHIPS and LGEM) indicate that Isaias is likely to be at or near major hurricane strength at landfall this evening. After landfall, fast weakening is expected, with some caveats. As mentioned previously, Isaias is likely to be a gusty hurricane, and its fast motion could bring strong hurricane-force gusts well inland. Simulated satellite imagery from global model guidance indicates that Isaias is likely to transition to a post-tropical cyclone over Alabama by Saturday afternoon, although it could still be producing tropical-storm-force gusts, especially in areas of higher terrain. Key Messages: 1. A life-threatening storm surge is expected from the Mouth of the Mississippi River to Suwannee, Florida. Residents under evacuation orders should leave immediately and follow advice from local officials. 2. Extremely dangerous and damaging hurricane force-winds are expected over portions of the Florida Panhandle, southern Alabama, and southern Mississippi where a Hurricane Warning is in effect. Residents in these areas should have a safe room to ride out the storm and prepare for long-duration power outages. 3. Damaging wind gusts are likely over a large portion of the southeastern United States from western and northern Georgia and the southern Appalachians, westward over much of central and northern Alabama, southern middle Tennessee, and Mississippi, especially in areas of higher terrain. Residents should secure loose outdoor items, avoid driving high-profile vehicles, prepare for power outages, and be aware of the potential for falling trees. 4. Isaias will bring areas of heavy rainfall to the central U.S. Gulf coast and much of the Southeast through the weekend. Considerable flash and urban flooding, along with significant river flooding, will be possible. Landslides are also possible across the Southern Appalachians. 5. The tornado potential will continue through tonight. The greatest risk will be east of the center, particularly across the Florida Panhandle into southern Georgia. This risk will continue spreading north-northeast across parts of the Southeast on Saturday. FORECAST POSITIONS AND MAX WINDS INIT 09/2100Z 29.2N 87.0W 100 KT 115 MPH 12H 10/0600Z 31.2N 86.8W 75 KT 85 MPH...INLAND 24H 10/1800Z 33.4N 87.2W 40 KT 45 MPH...POST-TROP/INLAND 36H 11/0600Z 35.6N 86.1W 30 KT 35 MPH...POST-TROP/INLAND 48H 11/1800Z 38.1N 82.5W 25 KT 30 MPH...POST-TROP/INLAND 60H 12/0600Z...DISSIPATED $$ Forecaster Berg

Recorded source facts

Issued at 400 PM CDT Fri Oct 09 2026 000 WTNT44 KNHC 092052 TCDAT4 Hurricane Isaias Discussion Number 13 NWS National Hurricane Center Miami FL AL092026 400 PM CDT Fri Oct 09 2026 Deep-layer shear from the southwest has increased to 30-40 kt, and the hurricane's structure is responding accordingly. WSR-88D radar data shows that the structure is becoming increasingly asymmetric, with very intense convection mainly confined to the northern eyewall. Tail Doppler radar data from the NOAA P-3 has also shown that the circulation is becoming tilted with height. That said, some impressive winds were measured at flight-level--136 kt by the Air Force Reserve at 10,000 feet and 126 kt by NOAA at 8,000 ft. While these winds themselves would normally support a higher intensity, several dropsondes released in the eyewall showed that there is a sharp drop-off of winds at the ocean surface, with layer-averaging suggesting a surface intensity of 90-95 kt. In addition, recent Doppler radar data from Mobile show winds of 100-110 kt at about 10,000 feet in the northern eyewall. Combining all this data together, the maximum surface winds appear to be around 100 kt, although it's very likely that Isaias will be a gustier-than-normal hurricane when it makes landfall. Isaias has turned northward and is accelerating with a current motion of 010/15 kt. The track guidance has honed in on a landfall over the western Florida Panhandle near the Pensacola area sometime this evening. A northward motion is expected to continue through Saturday, bringing Isaias's center through Alabama, followed by a northeastward trajectory across the Tennessee and the central Appalachians on Sunday. The circulation is expected to dissipate by hour 60. The high-resolution hurricane regional models (HAFS-A, HAFS-B, and HWRF), as well as the statistical-dynamical models (SHIPS and LGEM) indicate that Isaias is likely to be at or near major hurricane strength at landfall this evening. After landfall, fast weakening is expected, with some caveats. As mentioned previously, Isaias is likely to be a gusty hurricane, and its fast motion could bring strong hurricane-force gusts well inland. Simulated satellite imagery from global model guidance indicates that Isaias is likely to transition to a post-tropical cyclone over Alabama by Saturday afternoon, although it could still be producing tropical-storm-force gusts, especially in areas of higher terrain. Key Messages: 1. A life-threatening storm surge is expected from the Mouth of the Mississippi River to Suwannee, Florida. Residents under evacuation orders should leave immediately and follow advice from local officials. 2. Extremely dangerous and damaging hurricane force-winds are expected over portions of the Florida Panhandle, southern Alabama, and southern Mississippi where a Hurricane Warning is in effect. Residents in these areas should have a safe room to ride out the storm and prepare for long-duration power outages. 3. Damaging wind gusts are likely over a large portion of the southeastern United States from western and northern Georgia and the southern Appalachians, westward over much of central and northern Alabama, southern middle Tennessee, and Mississippi, especially in areas of higher terrain. Residents should secure loose outdoor items, avoid driving high-profile vehicles, prepare for power outages, and be aware of the potential for falling trees. 4. Isaias will bring areas of heavy rainfall to the central U.S. Gulf coast and much of the Southeast through the weekend. Considerable flash and urban flooding, along with significant river flooding, will be possible. Landslides are also possible across the Southern Appalachians. 5. The tornado potential will continue through tonight. The greatest risk will be east of the center, particularly across the Florida Panhandle into southern Georgia. This risk will continue spreading north-northeast across parts of the Southeast on Saturday. FORECAST POSITIONS AND MAX WINDS INIT 09/2100Z 29.2N 87.0W 100 KT 115 MPH 12H 10/0600Z 31.2N 86.8W 75 KT 85 MPH...INLAND 24H 10/1800Z 33.4N 87.2W 40 KT 45 MPH...POST-TROP/INLAND 36H 11/0600Z 35.6N 86.1W 30 KT 35 MPH...POST-TROP/INLAND 48H 11/1800Z 38.1N 82.5W 25 KT 30 MPH...POST-TROP/INLAND 60H 12/0600Z...DISSIPATED $$ Forecaster Berg