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Tropical Storm Hilda Discussion Number 16
NWS National Hurricane Center Miami FL EP082021
800 AM PDT Tue Aug 03 2021
There's been little change with the structure of Hilda overnight as
deep convection continues to be mostly south of the center due to
persistent northeasterly shear. The low-level eye feature in 37 GHz
microwave data remains on the latest passes, but it isn't very deep
because of the shear. A blend of the T- and CI-numbers from
TAFB/SAB, plus the UW-CIMSS SATCON, yields 60 kt as the initial wind
speed. Hilda should weaken during the next several days, first
primarily due to shear, then cool water temperatures and a more
stable environment on Wed-Fri. Model guidance is in good agreement
on this scenario, and the latest forecast is close to the previous
NHC advisory and the model consensus. Hilda should decay into a
remnant low by Friday and dissipate as a trough this weekend well
east of the Hawaii.
The initial motion estimate, 315/7 kt, is the same as the previous
advisory. Hilda is maintaining this motion as it is steered by a
mid-level ridge centered over southern California. The global
models are consistently building this ridge westward over the
eastern Pacific during the next several days as a shortwave trough
lifts out along 135W, causing Hilda to turn west-northwestward by
Thursday. The only significant forecast difference is how quickly
the cyclone moves, mostly in the latter stages, with more of the
guidance showing a faster motion, perhaps because the models are
showing a weaker Hilda being steered by the quicker low-level flow.
The new NHC prediction shows that acceleration at long-range as
well, near or just behind the latest model consensus.
FORECAST POSITIONS AND MAX WINDS
INIT 03/1500Z 17.5N 124.5W 60 KT 70 MPH
12H 04/0000Z 18.2N 125.3W 50 KT 60 MPH
24H 04/1200Z 19.1N 126.4W 45 KT 50 MPH
36H 05/0000Z 19.9N 127.7W 40 KT 45 MPH
48H 05/1200Z 20.8N 129.4W 35 KT 40 MPH
60H 06/0000Z 21.6N 131.4W 30 KT 35 MPH
72H 06/1200Z 22.3N 133.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 07/1200Z 23.0N 138.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 08/1200Z...DISSIPATED
$$
Forecaster Blake
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