Forecaster discussion 012a

000
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
 
$$
Forecaster Berg