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Hurricane Hilda Discussion Number  10
NWS National Hurricane Center Miami FL       EP082021
800 PM PDT Sun Aug 01 2021

Hilda's satellite appearance is showing effects of easterly vertical 
wind shear this evening. Recent imagery shows a sharp edge to the 
upper-level outflow on the eastern side of the system. A 2130 UTC 
AMSR2 microwave pass reveals that the eyewall is no longer closed, 
as the inner core convection has been eroded on the eastern side of 
the circulation. Microwave data also indicate the vortex has become 
vertically tilted, with the mid-level center displaced about 10-15 n 
mi to the west-northwest of the low-level center. Thus, the initial 
intensity is lowered slightly to 70 kt for this advisory, in best 
agreement with the objective UW-CIMSS Dvorak estimates.

Hilda is still moving west-northwestward at 285/8 kt, to the south 
of a ridge over the western U.S. and northern Mexico. A turn to the 
northwest is expected on Monday as the ridge weakens, likely in 
response to T.D. Ten-E located to the east-northeast of Hilda. A 
northwestward motion should continue through midweek before the 
ridge becomes reestablished and Hilda turns westward through the 
rest of the forecast period. There is greater track uncertainty 
later in the week due to possible interaction with another system 
that could redevelop from the remnants of T.D. Nine-E. The official 
NHC track forecast has been adjusted to the right of the previous 
one at 48 h and beyond based on the latest guidance, but it still 
lies slightly left of the multi-model consensus aids TVCE and HCCA.

Environmental conditions are not expected to become any more 
favorable for strengthening during the next couple days, so Hilda's 
intensity has likely peaked. Moderate northeasterly shear is 
forecast to persist for the next 36-48 h, and the NHC forecast track 
brings Hilda north of the 26 deg C isotherm by the time these 
upper-level winds subside. Once over cooler waters, Hilda is 
forecast to quickly spin down and weaken to a tropical depression by 
96 h. The NHC intensity forecast has again been lowered by 5-10 kt 
from the previous one at all forecast times, but it still lies 
slightly above the IVCN and HCCA consensus aids through 72 h. The 
system is forecast to degenerate to a remnant low by day 5.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  02/0300Z 15.1N 121.6W   70 KT  80 MPH
 12H  02/1200Z 15.5N 122.5W   70 KT  80 MPH
 24H  03/0000Z 16.2N 123.4W   65 KT  75 MPH
 36H  03/1200Z 17.3N 124.3W   60 KT  70 MPH
 48H  04/0000Z 18.4N 125.3W   50 KT  60 MPH
 60H  04/1200Z 19.5N 126.6W   40 KT  45 MPH
 72H  05/0000Z 20.3N 128.3W   35 KT  40 MPH
 96H  06/0000Z 21.0N 132.3W   25 KT  30 MPH
120H  07/0000Z 21.5N 136.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Reinhart/Pasch
 
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