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Tropical Storm Gilma Discussion Number   5
NWS National Hurricane Center Miami FL       EP072024
800 AM PDT Mon Aug 19 2024

Recent AMSR and SSMIS imagery indicate that Gilma's center is 
located near the northeast edge of its deep convection, with little 
deep convection present in its northeast quadrant. This is due, at 
least in part, to upper-level easterly winds that are causing some 
shear across the cyclone. A consensus of objective and subjective 
intensity estimates from SAB, TAFB, and UW-CIMSS support an initial 
intensity of 45 kt for this advisory, which also agree well with 
earlier ASCAT data.

The aforementioned wind shear is expected to persist for at least 
another day or two, which should limit the potential for 
strengthening. After around 36 h, global models indicate the shear 
will begin to decrease, which should allow for more strengthening. 
The exact timing of this strengthening is still highly uncertain, 
with several global models suggesting it could begin near the 36 h 
mark, while the HWRF indicates it won't begin to strengthen until 
closer to 60 h. Regardless, there is a good chance that Gilma will 
become a hurricane at some point before the end of the week. No 
significant changes were made to the intensity forecast, which 
follows the HCCA and IVCN intensity models. 

The track forecast is also largely unchanged from the previous NHC 
advisory. Gilma is currently moving west near 12 kt. A ridge 
extending westward from the southwest United States should keep 
Gilma on a similar heading today. After that, the tropical storm 
may interact with another disturbance to its west, while a trough 
off the U.S. west coast will begin to erode the ridge slightly. All 
models indicate that Gilma will generally slow down and turn 
west-northwestward in response to these steering changes, but there 
is unusually high spread in the guidance on the exact track the 
cyclone will take. The NHC track forecast follows the consensus 
aids, but confidence in the specifics of the forecast is lower than 
normal due to the high model spread.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  19/1500Z 15.1N 116.0W   45 KT  50 MPH
 12H  20/0000Z 15.3N 117.6W   50 KT  60 MPH
 24H  20/1200Z 15.8N 119.3W   50 KT  60 MPH
 36H  21/0000Z 16.5N 121.0W   50 KT  60 MPH
 48H  21/1200Z 17.0N 122.6W   55 KT  65 MPH
 60H  22/0000Z 17.5N 123.7W   65 KT  75 MPH
 72H  22/1200Z 18.0N 124.7W   70 KT  80 MPH
 96H  23/1200Z 19.0N 127.0W   70 KT  80 MPH
120H  24/1200Z 20.0N 129.0W   60 KT  70 MPH
 
$$
Forecaster D. Zelinsky
 
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