Hurricane Gilma Forecast Discussion

000
WTPZ42 KNHC 250832
TCDEP2

Hurricane Gilma Discussion Number  29
NWS National Hurricane Center Miami FL       EP072024
1100 PM HST Sat Aug 24 2024

After a brief period of rapid strengthening earlier this evening, 
Gilma's intensity has leveled off.  Conventional GOES-18 satellite 
imagery shows that the deep inner core convection has eroded 
considerably in the western half of the cyclone.  The initial 
intensity is set at 115 kt and is based on a blend of the 
subjective Dvorak intensity estimates and various UW-CIMSS 
objective techniques.  Although the current intensity is higher 
than noted in the previous advisory, Gilma likely peaked a few 
hours ago based on earlier ADT intensity estimates of 115-119 kt 
and the 0000 UTC constrained Data-T 6.5 subjective estimates from 
both TAFB and SAB.

Although Gilma's period of rapid intensification has likely ended, 
some intensity fluctuations, common in major hurricanes,  are 
possible in the short term, and the official forecast indicates 
little intensity change through Sunday.  Afterward, the cyclone is 
expected to traverse cooler oceanic surface temperatures and move 
into a thermodynamically inhibiting dry and stable marine layer by 
the middle-part of the forecast.  Early next week, the statistical 
SHIPS intensity guidance shows an increase in west-southwesterly 
shear spreading east of the Big Island of Hawaii. These negative 
intensity contributions should result in a weakening trend through 
the remainder of the forecast period.  The NHC intensity forecast 
has been nudged upward slightly from the previous one and is based 
on a blend of the Decay SHIPS statistical aid and the IVCN consensus 
model.

Gilma's initial motion is estimated to be west-northwestward, or 
285/8 kt.  A strengthening mid-troposphere subtropical ridge 
situated to the north of the hurricane should steer Gilma on a 
generally west-northwest or west track through day 5.  The official 
track forecast is a little bit slower than the previous advisory 
beyond day 3 and is a compromise of the HCCA and TVCE consensus 
guidance.

Gilma's wind radii have been adjusted based on a 0530 UTC METOP-B
ASCAT overpass.


FORECAST POSITIONS AND MAX WINDS

INIT  25/0900Z 18.0N 132.5W  115 KT 130 MPH
 12H  25/1800Z 18.1N 133.8W  115 KT 130 MPH
 24H  26/0600Z 18.3N 135.5W  100 KT 115 MPH
 36H  26/1800Z 18.5N 137.3W   85 KT 100 MPH
 48H  27/0600Z 18.7N 139.1W   75 KT  85 MPH
 60H  27/1800Z 18.9N 141.0W   65 KT  75 MPH
 72H  28/0600Z 19.2N 142.8W   55 KT  65 MPH
 96H  29/0600Z 20.0N 146.6W   40 KT  45 MPH
120H  30/0600Z 20.6N 150.1W   30 KT  35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Roberts