Tropical Storm Gilma Forecast Discussion

428 
WTPZ42 KNHC 192041
TCDEP2

Tropical Storm Gilma Discussion Number   6
NWS National Hurricane Center Miami FL       EP072024
200 PM PDT Mon Aug 19 2024

ASCAT data valid at 1644 UTC showed that Gilma has strengthened 
slightly and its wind field has grown a little. While the tropical 
storm is still sheared, maximum winds measured by the ASCAT were 
between 40 and 45 kt, which after accounting for undersampling 
supports an intensity around 50 kt. An average of the most recent 
Dvorak estimates from TAFB and SAB also yields 50 kt, so that is the 
intensity estimate for this advisory. The maximum extent of 34 kt 
winds is estimated to be around 70 n mi based on the ASCAT data, 
mostly to the southwest in the deep convection.

Although the track forecast spread in the model guidance remains 
unusually high, not much change was made to the NHC forecast, except 
to show a slightly faster forward motion in 24-48 h. Otherwise, 
Gilma is still expected to slow down and turn west-northwestward 
within the next day as the ridge currently steering the storm is 
gradually eroded by a deep-layer trough off the U.S. west coast. 
There is still quite a bit of difference between the models in the 
forward speed of Gilma, so the NHC forecast closely follows the 
consensus throughout the forecast. 

Only small adjustments were made to the intensity forecast. Gilma 
should remain sheared for another day or so, limiting the potential 
for strengthening during that period.  After that, the shear should 
decrease and Gilma should strengthen.  Most models continue to 
indicate that Gilma will approach hurricane strength later this 
week. The NHC intensity forecast remains very close to the various 
intensity consensus aids.


FORECAST POSITIONS AND MAX WINDS

INIT  19/2100Z 15.1N 116.9W   50 KT  60 MPH
 12H  20/0600Z 15.5N 118.2W   55 KT  65 MPH
 24H  20/1800Z 16.2N 120.0W   55 KT  65 MPH
 36H  21/0600Z 16.7N 122.0W   55 KT  65 MPH
 48H  21/1800Z 17.2N 123.6W   60 KT  70 MPH
 60H  22/0600Z 17.8N 124.7W   70 KT  80 MPH
 72H  22/1800Z 18.3N 126.0W   75 KT  85 MPH
 96H  23/1800Z 19.0N 127.5W   75 KT  85 MPH
120H  24/1800Z 20.0N 130.0W   65 KT  75 MPH

$$
Forecaster D. Zelinsky