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Tropical Storm Gilma Discussion Number  43
NWS Central Pacific Hurricane Center Honolulu HI   EP072024
1100 AM HST Wed Aug 28 2024
 
The satellite presentation of Gilma has changed little since 
yesterday evening. Deep convection continues to pulse within the 
northern semicircle, periodically revealing an exposed low-level 
circulation. Subjective Dvorak estimates ranged from 2.0/30 kt from 
JTWC to 3.0/45 kt out of HFO, and CIMSS ADT recently came in at 33 
kt. Given an overnight ASCAT pass with many 40 kt wind retrievals 
and the pulsing nature of the convection, the initial intensity of 
Gilma for this advisory has been held at 40 kt, which could be 
generous.

Gilma's motion estimate remains unchanged at 280/12 kt. A low-level 
ridge north of Gilma will continue to steer the increasingly 
shallow cyclone toward the west to west-northwest until it 
dissipates near the Hawaiian Islands this weekend. The track 
forecast was changed very little from the prior advisory and lies in 
the middle of a tightly clustered guidance envelope near TVCN and 
HCCA.

Gilma is expected to gradually degenerate to a remnant low as it 
passes close to the Hawaiian Islands Friday and Saturday. With the 
system traversing under a broad col region aloft today, vertical 
wind shear is expected to relax by around 5 kt. Though SSTs along 
the track will remain marginal, around 25.5 to 26C, the reduced 
vertical wind shear could cause deep convection to briefly 
redevelop around the center in the short term. As Gilma approaches 
an upper level trough parked over Hawaii, vertical wind shear will 
increase tonight through Friday, which should cause the cyclone to 
weaken to a tropical depression sometime Thursday and a remnant low 
on Friday. The intensity forecast has been changed little from 
recent advisories, and is near HCCA and SHIPS on the weaker side of 
the guidance envelope beyond Thursday.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  28/2100Z 19.0N 147.0W   40 KT  45 MPH
 12H  29/0600Z 19.4N 148.8W   35 KT  40 MPH
 24H  29/1800Z 19.9N 151.1W   35 KT  40 MPH
 36H  30/0600Z 20.5N 153.5W   30 KT  35 MPH
 48H  30/1800Z 21.1N 155.8W   30 KT  35 MPH...POST-TROP/REMNT LOW
 60H  31/0600Z 21.9N 158.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  31/1800Z 22.8N 160.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  01/1800Z...DISSIPATED
 
$$
Forecaster Wroe
 
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