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Hurricane Gilma Discussion Number  13
NWS National Hurricane Center Miami FL       EP072024
800 AM PDT Wed Aug 21 2024
 
This morning, Gilma's structure on satellite has continued to 
improve, with infrared satellite depicting a banding type eye 
appearing intermittently as convection attempts to wrap around the 
estimated center. In addition, we received a 0933 UTC AMSR2 
microwave pass which showed a developing eyewall on both the 89-GHz 
and 37-GHz channels, though with some vertical tilt. The latest 
subjective Dvorak intensity estimates from TAFB and SAB were both 
T4.5/77-kt, which also matches the latest ADT estimate. Thus, 
Gilma's initial intensity will be raised to 75 kt for this 
advisory. 

Gilma appears to be moving just north of due west, but slower than 
earlier, estimated at 280/6 kt. Over the next few days, a large 
subtropical ridge poleward of the hurricane should continue to steer 
it generally westward to west-northwestward. However, this ridge 
becomes positioned a little farther northwest with time as a subtle 
weakness north of the storm forms, resulting in a 
slower-than-typical forward motion for this part of the Eastern 
Pacific basin. The latest track guidance this cycle is notably 
slower and more equatorward than the previous cycle, and the NHC 
track was shifted in that direction, but not quite as far as the 
reliable track consensus guidance TVCE and HCCA. As mentioned in the 
previous discussion, if these southward trends continue, further 
southward adjustments may be necessary.  

With the improvement of Gilma's inner core structure this morning, 
the hurricane may be poised to intensify more over the next day or 
two. This scenario is shown by the recent hurricane-regional model 
guidance, which shows more intensification than the prior cycle. 
Given the reduction in vertical wind shear noted in the recent SHIPS 
guidance and as Gilma remains over 27-28 C sea-surface temperatures 
for the next 48 h, the NHC intensity forecast now shows 
intensification into a Category 3 hurricane over this time period. 
This intensity forecast is higher than the previous one, but is in 
good agreement with the latest HCCA consensus aid. However there 
remain some hurricane-regional models that show even more 
intensification (e.g., HAFS-A). After 48 h, sea-surface temperatures 
begin to gradually decrease, and slow weakening is expected to begin 
thereafter, though less than the previous advisory due to the 
further south track over warmer ocean waters.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/1500Z 16.0N 122.8W   75 KT  85 MPH
 12H  22/0000Z 16.2N 123.7W   85 KT 100 MPH
 24H  22/1200Z 16.5N 124.8W   95 KT 110 MPH
 36H  23/0000Z 16.8N 125.9W  100 KT 115 MPH
 48H  23/1200Z 16.9N 127.2W  100 KT 115 MPH
 60H  24/0000Z 17.1N 128.5W   95 KT 110 MPH
 72H  24/1200Z 17.3N 130.3W   90 KT 105 MPH
 96H  25/1200Z 17.5N 133.5W   85 KT 100 MPH
120H  26/1200Z 18.0N 137.5W   70 KT  80 MPH
 
$$
Forecaster Papin/Alaka
 
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