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Tropical Storm HILDA

Tropical Storm Hilda Discussion Number  15
NWS National Hurricane Center Miami FL       EP082021
200 AM PDT Tue Aug 03 2021
Overnight, Hilda's deep convection has continued to pulse, but 
primarily in the southern semicircle of the circulation as 15-20 kt 
of northeasterly vertical wind shear continues displacing this 
activity downshear. A helpful ASCAT-B pass at 0602 UTC indicated the 
center of Hilda was located on the northern edge of the convective 
cirrus canopy, with the instrument also indicating a peak wind 
retrieval of 53 kt. The most recent microwave imagery concurs with 
this assessment and also indicates the earlier eyewall is no longer 
well-defined. While the 0600 UTC subjective Dvorak estimates from 
TAFB and SAB were both T4.0/65 kt, the most recent objective Dvorak 
estimate from UW-CIMSS was down to T3.5/55 kt. Given the devolving 
convective structure seen on microwave, the initial intensity has 
been reduced to 60 kt, leaning towards the lower intensity 
Hilda continues to move slowly northwestward, at 315/7 kt as it 
remains positioned southwest of a mid-level ridge centered over 
southern California. Over the next several days, this ridge is 
forecast to build westward over the East Pacific as a short-wave 
trough offshore of California lifts out. This synoptic pattern 
should allow Hilda to gradually bend to the west-northwest and 
increase its forward motion slightly over the forecast period. Hilda 
will also become increasingly influenced by low-level ridging, 
steering the cyclone more westward as it becomes a weak and shallow 
cyclone. The latest NHC track forecast is just a touch south of the 
previous forecast track, blending the reliable TVCE and HCCA 
consensus aids.
Northeasterly vertical wind shear, related to the remaining 
convective outflow of Ignacio, is expected to keep Hilda on a 
weakening trend over the next day or so. Even though this shear is 
expected to subside thereafter, Hilda will also be crossing the 25 
degree Celsius sea-surface temperature isotherm in 24 hours. Thus, 
continued weakening is expected. The latest NHC intensity forecast 
follows the HCCA consensus aid closely, showing weakening throughout 
the forecast period. The tropical cyclone is now expected to 
degenerate to a remnant low by Friday, when model guidance suggests 
organized deep-convection will cease. The remnant low is then 
expected to open up into a trough by the weekend, well east of 
INIT  03/0900Z 17.0N 123.9W   60 KT  70 MPH
 12H  03/1800Z 17.6N 124.6W   50 KT  60 MPH
 24H  04/0600Z 18.6N 125.5W   45 KT  50 MPH
 36H  04/1800Z 19.4N 126.7W   40 KT  45 MPH
 48H  05/0600Z 20.2N 128.1W   35 KT  40 MPH
 60H  05/1800Z 21.0N 129.9W   30 KT  35 MPH
 72H  06/0600Z 21.7N 132.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  07/0600Z 22.4N 136.2W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  08/0600Z...DISSIPATED
Forecaster Papin/Brown