[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 231454
TCDAT4

Tropical Depression Nine Discussion Number   2
NWS National Hurricane Center Miami FL       AL092022
1100 AM EDT Fri Sep 23 2022

The depression remains highly sheared this morning. Visible
satellite imagery and data from an Air Force Reserve Hurricane
Hunter aircraft indicate the center of the system is still exposed
to the east of the associated deep convection. The center also
appears a bit elongated, with a couple of low-level swirls evident
in satellite imagery that appear to be rotating around a mean
center. The aircraft winds and a blend of the latest satellite
estimates support an initial intensity of 30 kt for this advisory.

The long-term motion of the depression is still west-northwestward
at 12 kt. The cyclone is expected to move more westward over the
next 24-36 h as a narrow low- to mid-level ridge builds to the north
of the system. Then, an amplifying deep-layer trough over the
eastern U.S. is forecast to weaken the ridge beginning on Sunday,
which should cause the cyclone to turn northwestward and northward
as it approaches western Cuba early next week. There is increased
spread in the guidance for this portion of the track forecast, with
day 5 positions that span from the eastern Gulf to east of the
Florida peninsula. The latest NHC track forecast lies near the
center of the guidance envelope and closely follows the IVCN and
HCCA aids. This prediction is very similar to the previous one,
with only slight westward adjustments at days 3-5 to reflect the
latest model consensus trends.

The moderate to strong deep-layer northeasterly shear over the
cyclone is expected to persist through tonight, so only slight
strengthening is forecast through early Saturday. But once the shear
decreases to less than 10 kt this weekend, more significant
intensification is forecast as the cyclone moves over SSTs in excess
of 30 deg C. The latest NHC intensity forecast has been increased
from the previous one and explicitly calls for rapid intensification
as the cyclone crosses the northwestern Caribbean Sea. The system
is forecast to approach the Cayman Islands and Cuba as a
strengthening hurricane, with additional intensification likely once
it emerges over the warm waters of the southeastern Gulf of Mexico.
In fact, this forecast calls for the system to approach the Florida
peninsula as a major hurricane by day 5, which is supported by the
latest IVCN and HCCA aids.

Key Messages:

1. The depression is expected to produce heavy rainfall and
instances of flash flooding and possible mudslides in areas of
higher terrain in Aruba, Bonaire, and Curacao. Heavy rains are also
likely to spread into Jamaica, the Cayman Islands, and Cuba in the
coming days.

2. The depression is expected to approach Jamaica as a tropical
storm on Sunday and the Cayman islands as a hurricane on Monday.
Watches for these locations may be required later today or on
Saturday.

3. Early next week the system is forecast to move near or over
western Cuba as a strengthening hurricane and then approach the
Florida peninsula at or near major hurricane strength, with the
potential for significant impacts from storm surge, hurricane-force
winds, and heavy rainfall. While it is too soon to determine the
exact magnitude and location of these impacts, residents in Cuba,
the Florida Keys, and the Florida peninsula should ensure they have
their hurricane plan in place and closely monitor forecast updates
through the weekend.


FORECAST POSITIONS AND MAX WINDS

INIT  23/1500Z 14.2N  70.1W   30 KT  35 MPH
 12H  24/0000Z 14.5N  71.7W   35 KT  40 MPH
 24H  24/1200Z 14.7N  74.1W   35 KT  40 MPH
 36H  25/0000Z 15.1N  76.3W   40 KT  45 MPH
 48H  25/1200Z 16.1N  78.3W   45 KT  50 MPH
 60H  26/0000Z 17.8N  79.9W   60 KT  70 MPH
 72H  26/1200Z 19.8N  81.4W   75 KT  85 MPH
 96H  27/1200Z 23.5N  82.8W   90 KT 105 MPH
120H  28/1200Z 26.7N  82.1W  100 KT 115 MPH

$$
Forecaster Reinhart
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