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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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