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Tropical Depression Hilda Discussion Number 25
NWS National Hurricane Center Miami FL EP082021
200 PM PDT Thu Aug 05 2021
Stubborn Hilda refuses to go away. Convection has been pulsing since
the previous advisory with cloud tops fluctuating between -30C and
-60C in the northeastern quadrant. However, this convection hasn't
mixed higher winds downward into the boundary based on a 1634Z
ASCAT-A scatterometer pass, which showed 30-31-kt wind vectors north
of the center and outside of the convection. The initial intensity
is being maintained at 30 kt for this advisory based on the
aforementioned ASCAT surface wind data. Gradual weakening should
occur now that Hilda is firmly located over sub-23 deg C sea-surface
temperatures and will be moving into a drier and more stable air
mass. Visible satellite imagery already shows an extensive field of
cold-air stratocumulus clouds being entrained into much of the
low-level circulation. Hilda is forecast to degenerate into a
remnant low tonight or early Friday, and open up into a trough by
the weekend, well east of the Hawaiian Islands.
The initial motion estimate is 300/11 kt. Hilda should continue on
a west-northwestward trajectory for the next couple of days, being
steered by a deep-layer subtropical ridge to the north. The latest
NHC track forecast is essentially just an update of the previous
advisory track, and lies down the middle of the tightly packed
consensus models.
FORECAST POSITIONS AND MAX WINDS
INIT 05/2100Z 21.5N 131.2W 30 KT 35 MPH
12H 06/0600Z 22.2N 132.8W 25 KT 30 MPH
24H 06/1800Z 23.0N 135.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 07/0600Z 23.7N 137.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 07/1800Z 24.4N 139.3W 15 KT 15 MPH...POST-TROP/REMNT LOW
60H 08/0600Z...DISSIPATED
$$
Forecaster Stewart
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