Hurricane Gilma Forecast Discussion

000
WTPZ42 KNHC 232035
TCDEP2

Hurricane Gilma Discussion Number  22
NWS National Hurricane Center Miami FL       EP072024
1100 AM HST Fri Aug 23 2024

The satellite appearance of Gilma has decayed a little more since 
the previous advisory, although a cloud-filled eye is still 
present.  The various objective and subjective satellite intensity 
estimates are in the 80-100 kt range, and the initial intensity is 
thus reduced to 90 kt in best agreement with the estimates from SAB 
and CIMSS satellite consensus technique.  The cyclone remains in an 
environment of light shear with good anticyclonic outflow in all 
directions.

The initial motion is now 275/8 kt.  Gilma is slipping west of the 
axis of the deep-layer trough near the west coast of the United 
States, and a ridge is expected to build north of the cyclone during 
the next few days as the trough lifts out.  The track guidance is in 
good agreement with a general westward or just north of westward 
motion through the forecast period.  However, the guidance has again 
shifted a little southward, and the official forecast track will 
again be nudged southward.  While the guidance is in good agreement 
on the direction, there is a notable spread in forward speed between 
the faster GFS and the slower ECMWF.  The new NHC track lies near 
the consensus models, which split the difference in forward speed 
between these two models.

Gilma's more westward motion is keeping it over warmer water for a 
little longer in the short term, so little change in strength is 
likely during the next 12 h.  After that, the hurricane is expected 
to cross the 26C isotherm in about 36 h while moving into a drier 
and more stable airmass.  This combination should lead to gradual 
weakening, and the rate of weakening should increase after 48-60 h 
when Gilma is expected to encounter westerly shear.  The new 
intensity forecast follows the general trend of the intensity 
guidance with a faster rate of decay after 48 h than seen in the 
previous forecast.  The forecast still calls for the cyclone to 
degenerate to a remnant low by 120 h.


FORECAST POSITIONS AND MAX WINDS

INIT  23/2100Z 17.3N 127.7W   90 KT 105 MPH
 12H  24/0600Z 17.5N 128.9W   90 KT 105 MPH
 24H  24/1800Z 17.8N 130.6W   85 KT 100 MPH
 36H  25/0600Z 18.1N 132.3W   80 KT  90 MPH
 48H  25/1800Z 18.4N 134.0W   75 KT  85 MPH
 60H  26/0600Z 18.7N 136.0W   65 KT  75 MPH
 72H  26/1800Z 19.0N 138.1W   50 KT  60 MPH
 96H  27/1800Z 19.8N 142.8W   35 KT  40 MPH
120H  28/1800Z 20.5N 148.0W   30 KT  35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Beven