Tropical Cyclone Discussion
178 WTNT44 KNHC 091454 TCDAT4 Hurricane Isaias Discussion Number 12 NWS National Hurricane Center Miami FL AL092026 1000 AM CDT Fri Oct 09 2026 An Air Force Reserve Hurricane Hunter aircraft currently investigating Isaias measured a peak 700-mb flight-level wind of 120 kt within the eastern eyewall a few hours ago, prompting an upgrade of the hurricane to major hurricane status with estimated surface winds of 105 kt. Based on the last several dropsondes released in the eye, the central pressure appears to have leveled off around 959 mb. On the last pass through the eastern eyewall, just about a half hour ago, the plane measured a flight-level wind of 111 kt, suggesting that the peak winds may have also leveled off. The eye itself has become cloud filled in visible satellite imagery, but it is now moving into range of several WSR-88D radars along the northern Gulf coast. Strong deep-layer shear has definitely increased as forecast, with various analyses now showing 30-40 kt out of the southwest. However, the shear vector is nearly aligned with the storm's motion, which limits its adverse effects, and upper-level divergence is also increasing over the hurricane. This setup has likely allowed the hurricane to intensify this morning, and the hurricane regional models (HAFS-A, HAFS-B, and HWRF), as well as the statistical-dynamical models (SHIPS and LGEM), all suggest that Isaias could maintain major hurricane intensity up until its landfall this evening. Therefore, the NHC official forecast depicts Isaias with 100-kt winds just offshore the western Florida Panhandle this evening. Weakening will occur after landfall, but sustained hurricane-force winds will likely occur near and along Isaias's track up to 100 miles inland from the coast into southern Alabama, and gusts to hurricane force could extend even farther north into central Alabama. Isaias is likely to lose its tropical characteristics by 36 hours when it is over northern Alabama. Aircraft fixes indicate that Isaias has drifted a bit east of the previous forecast track. NHC's track forecast leans on the eastern side of the guidance envelope, closest to the latest HCCA and GDMI guidance, and implies a potential landfall along the extreme western Florida Panhandle coast this evening. After moving inland, the center of Isaias is expected to continue northward through Alabama, before turning northeastward over the Tennessee and Ohio Valleys (as a post-tropical remnant low) on Sunday. Now that the eye has become visible in WSR-88D coastal radars, hourly Tropical Cyclone Updates will be issued beginning at 11 AM CDT (1600 UTC). 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 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, and significant river flooding, are possible. 5. The tornado potential will increase this afternoon and 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 09/1500Z 27.7N 87.3W 105 KT 120 MPH 12H 10/0000Z 29.7N 86.8W 100 KT 115 MPH 24H 10/1200Z 32.1N 87.1W 55 KT 65 MPH...INLAND 36H 11/0000Z 34.2N 87.2W 35 KT 40 MPH...POST-TROP/INLAND 48H 11/1200Z 36.5N 85.0W 25 KT 30 MPH...POST-TROP/INLAND 60H 12/0000Z 39.1N 81.0W 20 KT 25 MPH...POST-TROP/INLAND 72H 12/1200Z...DISSIPATED