Hurricane Gilma Forecast Discussion

000
WTPZ42 KNHC 262037
TCDEP2

Hurricane Gilma Discussion Number  35
NWS National Hurricane Center Miami FL       EP072024
1100 AM HST Mon Aug 26 2024

Gilma's eye continues to become more symmetric with a warming eye 
and impressive convection surrounding the eye.  Objective intensity 
estimates from UW-CIMSS have been generally increasing over the last 
several hours, ranging from 85 to 96 kt.  Subjective Dvorak 
estimates are T-5.0/90 kt from TAFB and T-5.5/102 kt from SAB.   The 
initial intensity is set to 95 kt based on a blend of the subjective 
estimates.

Other than the stronger initial intensity, there is no change to the 
environmental conditions that Gilma is expected to traverse through 
the forecast period.  Sea surface temperatures (SSTs) and vertical 
wind shear conditions have been favorable enough for Gilma to 
strengthen over the past 12 h.  By tonight, westerly vertical wind 
shear is predicted to increase to 15 to 20 kt, which should put a 
halt to any additional strengthening, and likely induce a slow 
weakening trend.  Beyond 24 h, Gilma is forecast to reach slightly 
cooler SSTs, which should cause a faster rate of weakening in the 
24-48 h time period.  These factors, combined with the relatively 
dry and stable airmass that Gilma will continue to be embedded in, 
is likely to cause the cyclone to lose its convection and become a 
remnant low in 3 to 4 days, as suggested by the GFS and ECMWF 
simulated satellite imagery.  The global models then show the 
remnant low gradually weakening through day 5, possibly opening up 
into a trough around that time.  The new NHC intensity forecast is 
higher than the previous forecast for the first 24 h due to the 
stronger initial intensity and relatively unchanged after that, and 
lies close to the middle of the guidance envelope.

The initial motion is estimated to be westward, or 280/7 kt.  The 
track guidance is faster this cycle, following the global model 
solutions.  The new NHC forecast is similar to the previous forecast 
through 36 h, then shows a faster motion toward the west-northwest, 
though not as fast as the latest consensus track models.  The cross 
track spread in the guidance remains very low, and the NHC forecast 
is essentially on top of the consensus models.


FORECAST POSITIONS AND MAX WINDS

INIT  26/2100Z 18.4N 137.4W   95 KT 110 MPH
 12H  27/0600Z 18.5N 138.8W   90 KT 105 MPH
 24H  27/1800Z 18.7N 140.9W   75 KT  85 MPH
 36H  28/0600Z 18.9N 143.1W   60 KT  70 MPH
 48H  28/1800Z 19.4N 145.3W   50 KT  60 MPH
 60H  29/0600Z 19.9N 147.4W   45 KT  50 MPH
 72H  29/1800Z 20.3N 149.5W   40 KT  45 MPH
 96H  30/1800Z 21.2N 154.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  31/1800Z 22.8N 158.5W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Hagen/Pasch