Central Pacific Basin Tropical Cyclones

Tropical Storm Gilma Forecast Discussion



000
WTPA42 PHFO 290238
TCDCP2

Tropical Storm Gilma Discussion Number  44
NWS Central Pacific Hurricane Center Honolulu HI   EP072024
500 PM HST Wed Aug 28 2024

Even though Gilma is in a low to moderate vertical wind shear 
environment, organized deep convection has failed to redevelop 
today, with only isolated thunderstorms forming in the northern 
semicircle. Subjective Dvorak estimates are down to 35 kt from HFO, 
30 kt from JTWC, and 25 kt from SAB, while CIMSS ADT came in at 33 
kt. Based on expected weakening due to a lack of convection and a 
blend of these inputs, the initial intensity has been lowered to 35 
kt for this advisory.

The forward motion of Gilma remains nearly unchanged during the 
last day at 280/12 kt. A low-level ridge north of Gilma will 
continue to steer the increasingly shallow cyclone toward slightly 
north of due west into Thursday, followed by a turn toward the 
west-northwest Friday until dissipation near the Hawaiian Islands 
this weekend. The official forecast track was nudged slightly north 
from the prior advisory due to an adjustment in center position and 
remains near the middle of a tightly clustered guidance envelope 
near the TVCE.

Gilma is expected to pass close to the Hawaiian Islands as it 
slowly degenerates to a remnant low late Thursday night or Friday. 
For the next 6 to 12 hours, Gilma will remain under a broad col 
aloft that will produce a low to moderate vertical wind shear 
environment of around 15 kt. This will likely be the only window for 
redevelopment of organized convection and for Gilma to maintain 
tropical storm intensity, even though SSTs will remain marginal, 
around 25.5 to 26C. As Gilma approaches an upper level trough 
building over Hawaii, vertical wind shear will increase late tonight 
through Friday, which should cause the cyclone to weaken to a 
tropical depression sometime Thursday and a remnant low Thursday 
night or Friday. The intensity forecast has been changed little from 
recent advisories, and is near the statistical guidance and ICON 
near the middle of the guidance envelope.


FORECAST POSITIONS AND MAX WINDS

INIT  29/0300Z 19.5N 148.3W   35 KT  40 MPH
 12H  29/1200Z 19.8N 150.0W   35 KT  40 MPH
 24H  30/0000Z 20.3N 152.3W   30 KT  35 MPH
 36H  30/1200Z 20.9N 154.7W   30 KT  35 MPH
 48H  31/0000Z 21.7N 157.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 60H  31/1200Z 22.6N 159.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  01/0000Z 23.8N 161.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  02/0000Z...DISSIPATED

$$
Forecaster Wroe



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