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Hurricane Hilda Discussion Number  11
NWS National Hurricane Center Miami FL       EP082021
200 AM PDT Mon Aug 02 2021

SSMIS microwave data received just after the previous advisory 
indicate that Hilda's structure may have improved slightly, with a 
closed mid-level eye noted in the 85-GHz channel.  However, the 
microwave data also showed that the low- and mid-level centers 
remain offset from each other by about 15 n mi due to continued 
moderate easterly shear.  The initial intensity remains 70 kt, which 
is a blend of the latest final-T Dvorak numbers from TAFB and SAB.
 
Hilda has begun to turn to the right and slow down, and the initial 
motion is west-northwestward (295 degrees) at 7 kt.  Although the 
subtropical ridge remains positioned to the north of Hilda, the 
hurricane's close proximity to Tropical Depression Ten-E and the 
remnants of Tropical Depression Nine-E is expected to cause some 
binary interaction over the next couple of days, with Hilda likely 
to slow down further and turn toward the northwest later today and 
continue on that heading through Wednesday.  In fact, the newest 
track guidance has trended to the northeast during the first 48 
hours, and the updated NHC forecast has therefore been shifted a 
bit to the right during that period.  However, it should be noted 
that the track adjustment is conservative, and does not show a 
turn quite as sharp as that shown by the TVCE and HCCA consensus 
aids.  Low-level ridging should play a more prominent role in about 
3 days, causing Hilda to turn back toward the west-northwest and 
then west by the end of the forecast period.  No significant track 
changes were required during the day 3-5 time period.
 
Moderate east-northeasterly shear is expected to continue for the 
next 36 hours or so, with Hilda also heading toward cooler waters 
during that time.  Therefore, gradual weakening is expected to 
commence later today, and the NHC intensity forecast is close to 
the HCCA and ICON consensus aids for the next day or so.  Sub-26 
degree Celsius waters are likely to cause quicker weakening from 36 
hours onward, and the NHC intensity forecast has been nudged 
downward during that period.  This new forecast is lower than the 
statistical-dynamical models but not nearly as low as the latest 
HCCA solution.  Hilda is now forecast to weaken to a tropical 
depression by day 3 and degenerate into a remnant low by day 4, 
although the HCCA scenario suggests that these transitions could 
occur as much as a day earlier.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  02/0900Z 15.3N 122.1W   70 KT  80 MPH
 12H  02/1800Z 15.8N 122.7W   70 KT  80 MPH
 24H  03/0600Z 16.7N 123.5W   65 KT  75 MPH
 36H  03/1800Z 17.8N 124.3W   55 KT  65 MPH
 48H  04/0600Z 18.9N 125.5W   45 KT  50 MPH
 60H  04/1800Z 19.8N 127.0W   35 KT  40 MPH
 72H  05/0600Z 20.5N 128.8W   30 KT  35 MPH
 96H  06/0600Z 21.2N 132.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  07/0600Z 21.5N 136.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Berg
 
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