Hurricane Gilma Forecast Discussion

556 
WTPZ42 KNHC 251445
TCDEP2

Hurricane Gilma Discussion Number  30
NWS National Hurricane Center Miami FL       EP072024
500 AM HST Sun Aug 25 2024

Over the last 6 hours, Gilma's eye has continued to be present on 
most of the infrared and proxy vis images. However, the eye has 
become a bit more cloud-filled, and the convection over the 
southwestern eyewall is slightly less robust. Although the CI 
numbers from TAFB and SAB are still T-6.0/115 kt, the respective 
Final T numbers are lower than that. Recent UW-CIMSS objective 
intensity estimates range from 84 to 113 kt. Based on a blend of the 
subjective and objective intensity estimates, the initial intensity 
is nudged down slightly to 110 kt for this advisory.

Gilma is currently moving very near the 26C isotherm and is located 
in an environment of low vertical wind shear. The middle troposphere 
is fairly dry in the environment surrounding Gilma, but the cyclone 
has been able to prevent the dry air from entraining into the center 
enough to significantly disrupt the hurricane. The environmental 
conditions are not forecast to become more conducive for 
strengthening. Westerly vertical wind shear is forecast to increase 
slightly by late tonight or early Monday. SSTs should decrease 
slightly along the path of Gilma by late Monday or Monday night. 
Based on these factors, only slow weakening is forecast for the next 
24 h followed by more steady weakening after that. The confidence in 
the intensity forecast seems slightly below average in the 
short-term while Gilma straddles the 26C SST isotherm and remains in 
relatively low shear. In the 24 to 96 h time frame, Gilma should be 
weakening, but the rate at which it weakens is a bit uncertain. By 
day 4, vertical wind shear increases to moderate to strong, making 
it likely that Gilma should be significantly weaker in the 4- to 
5-day time frame. Gilma is forecast to lose its convection and 
become a remnant low by day 5. The NHC intensity forecast is similar 
to the previous one, perhaps showing a slightly slower rate of 
weakening in the 36-72 h period, closer to the latest intensity 
consensus guidance.

Gilma's initial motion is estimated to be westward, or 275/8 kt. A 
strengthening mid-tropospheric subtropical ridge situated to the 
north of the hurricane should steer Gilma on a westward to 
west-northwestward track through the forecast period. The official 
forecast is nearly unchanged from the previous advisory and is close 
to a blend of the TVCE and GFEX.


FORECAST POSITIONS AND MAX WINDS

INIT  25/1500Z 18.0N 133.5W  110 KT 125 MPH
 12H  26/0000Z 18.1N 134.8W  105 KT 120 MPH
 24H  26/1200Z 18.3N 136.5W   95 KT 110 MPH
 36H  27/0000Z 18.5N 138.3W   85 KT 100 MPH
 48H  27/1200Z 18.7N 140.1W   75 KT  85 MPH
 60H  28/0000Z 18.9N 142.0W   65 KT  75 MPH
 72H  28/1200Z 19.2N 143.8W   55 KT  65 MPH
 96H  29/1200Z 20.0N 147.4W   40 KT  45 MPH
120H  30/1200Z 20.6N 151.0W   30 KT  35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Hagen/Pasch