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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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