[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201750
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1250 PM EST Wed Nov 20 2019

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1200 UTC surface analysis and satellite imagery through
1720 UTC.

...SPECIAL FEATURES...

Tropical Storm Sebastien is near 21.1N 61.7W at 20/1500 UTC, or
about 191 nm NNE of the northern Leeward Islands. Sebastien is
moving W at 6 kt. The estimated minimum central pressure is 1002
mb. Maximum sustained winds are 45 kt with gusts to 55 kt.
Numerous moderate with scattered strong convection extends outward
to 200 nm in the SE quadrant. Scattered moderate convection is
elsewhere within 300 nm in the SE quadrant. Sebastian will turn to
the north later today, then turn to the northeast with an increase
in forward speed is expected tonight and Thursday. Some strengthening
is forecast during the next 48 hours. Sebastien is expected to
become an extratropical cyclone in a couple of days and be
absorbed by a cold front on Friday. The Public Advisories for
Sebastien are available via the WMO header WTNT35 KNHC and the
AWIPS header MIATCPAT5. The Forecast/Advisories are available via
the WMO header WTNT25 KNHC and the AWIPS header MIATCMAT5 or visit
www.hurricanes.gov.

...TROPICAL WAVES...

An Atlantic Ocean tropical wave is along 44W from 14N southward,
moving W at 10-15 kt. Scattered showers are noted from 07N-12N
between 41W- 46W.

A Caribbean Sea tropical wave is along 74W from 20N southward,
moving W at 5-10 kt. Isolated showers are seen in SW Haiti near
the wave axis.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal plains of southern
Sierra Leone near 07N12W to 05N18W. The ITCZ continues from
05N18W to 04N29W to 07N43W, then W of a tropical wave near 07N45W
to the coast of Suriname near 06N55W. Scattered moderate
convection is seen from 02N- 09N between 10W- 28W.

GULF OF MEXICO...

A 1021 mb surface high is near 27N87W and is ridging across the
basin. As such, relatively dry air covers most of the area. The
latest ASCAT pass shows that gentle to moderate anticyclonic winds
cover the basin.

High pressure over the central Gulf will shift eastward today.
Fresh to locally strong SE return flow will develop over the NW
Gulf tonight into Thursday ahead of a cold front moving over
Texas. The front will move into the NW Gulf late Friday night,
cross the region Saturday through Sunday, then weaken and stall
over the southern Gulf Sunday night.

CARIBBEAN SEA...

A surface trough extends across eastern Honduras into the NW
Caribbean, from 16N84W to 19N85W. Showers are seen within 70 nm on
either side of the trough. Meanwhile, a 1012 mb low is located
over the Turks and Caicos Islands near 21N71W with a trough that
extends along the low from 18N76W to 24N67W. Scattered showers and
thunderstorms are seen along this trough, including over
Hispaniola, the Windward Passage, and just east of Jamaica.
Isolated showers are seen moving across the Lesser Antilles,
Puerto Rico and the USVI. Strong upper level ridging will inhibit
any deep convection. The latest ASCAT pass shows moderate to fresh
northerly winds in the western Caribbean, with calm to light
trades across the rest of the basin.

Tropical Storm Sebastien will turn northward later today and move
away from the area. Fresh NE winds will prevail across most of
the western Caribbean through Friday morning, with the strongest
winds expected through the Windward and Mona passages Thursday
night as high pressure builds north of the region.

ATLANTIC OCEAN...

A cold front enters the forecast waters near 31N67W and stretches
southwestward toward the central Bahamas near 25N76W to northwest
Cuba near 23N82W. Showers are within 50 nm of this boundary. A
pre-frontal trough is noted from 26N69W to 35N61W. Scattered
moderate convection is ahead of this trough from 27N-38N between
56W-65W. An upper level low is noted near 17N41W. With support
from the ITCZ, scattered showers are noted from 09N-16N between
21W-41W. The latest ASCAT pass shows fresh to strong NW winds in
the western Atlantic, N of 28N and W of 68W.

In the far NE portion of the area, a cold front extends
southwestward from a 1016 mb low near 31N16W to 27N30W. Scattered
showers are seen within 50 nm of the front. Latest ASCAT pass
shows gentle to moderate N winds behind the front. Surface ridging
dominates the rest of the area from a 1028 mb high near 32N42W.

Tropical Storm Sebastien will turn northward later today and move
to 22.0N 61.7W this evening, 23.7N 60.2W Thu morning, 26.3N 57.2W
Thu evening, then become extratropical as it merges with a cold
front near 29.8N 52.5W Friday morning. Elsewhere, the cold front
in the western/central Atlantic will continue moving
southeastward across the region through Thursday. High pressure
will build across the northern waters Thursday through Saturday,
then shift eastward Saturday night through Sunday as the next
cold front moves off the SE U.S. coast.


$$

AKR
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