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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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