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Tropical Depression Hilda Discussion Number  24
NWS National Hurricane Center Miami FL       EP082021
800 AM PDT Thu Aug 05 2021
 
After an earlier brief burst of thunderstorm activity northeast of 
the center around 0600Z, associated convection since then has been 
on a rapid decline and warming of the cloud tops which now barely 
reach -30 deg C near the center. The initial intensity has been 
lowered to 30 kt based on a blend of Dvorak T- and CI-numbers of 
T2.5 and T1.5 from both TAFB and SAB, and an objective satellite 
intensity estimate of 2.0/30 kt from UW-CIMSS ADT, making Hilda a 
tropical depression. Further weakening is expected now that Hilda is 
located over sub-23 deg C sea-surface temperatures and moving into a 
drier and more stable air mass. The cyclone is forecast to 
degenerate into a remnant low later today and open up into a trough 
by the weekend, well east of the Hawaiian Islands.
 
The initial motion estimate is 305/11 kt, which is faster and a 
little to the right of the previous advisory motion. This is likely 
due to the low- and upper-level circulations having decoupled now, 
owing to the lack of significant convection. The weakening cyclone 
should be steered west-northwestward for the next 48 hours by a 
sprawling subtropical ridge located to the north. The new NHC 
forecast track is similar to the previous advisory track and lies 
down the middle of the tightly packed consensus models.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  05/1500Z 21.0N 130.2W   30 KT  35 MPH
 12H  06/0000Z 21.7N 131.8W   25 KT  30 MPH
 24H  06/1200Z 22.5N 133.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
 36H  07/0000Z 23.2N 136.1W   20 KT  25 MPH...POST-TROP/REMNT LOW
 48H  07/1200Z 23.9N 138.3W   15 KT  15 MPH...POST-TROP/REMNT LOW
 60H  08/0000Z...DISSIPATED
 
$$
Forecaster Stewart
 
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