[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 230610
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
110 AM EST Sat Nov 23 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 0000 UTC surface analysis and satellite imagery through
0545 UTC.

...SPECIAL FEATURES...

Tropical Storm Sebastien is centered near 27.0N 52.2W at 23/0300
UTC or 920 nm NE of the Northern Leeward Islands moving ENE at 13
kt. Estimated minimum central pressure is 998 mb. Maximum
sustained wind speed is 55 kt with gusts to 65 kt. Numerous
moderate with isolated strong convection is from 25N to 30N
between 49W and 55W. Gradual weakening is anticipated, and
Sebastien is forecast to dissipate by early next week. The Public
Advisories for Sebastien are available via AWIPS/WMO headers
MIATCPAT5/WTNT35 KNHC. The Forecast/Advisories for Sebastien are
available via the AWIPS/WMO headers MIATCMAT5/WTNT25 KNHC.

...TROPICAL WAVES...

A tropical wave is in the central Atlc from 00N to 10N with axis
near 38W, moving W at 10-15 kt. Scattered moderate isolated strong
convection is from 05N to 10N between 36W and 40W.

A tropical wave is to the SE of the Windward Islands from 04N to
15N with axis near 56W, moving W around 10 kt. Scattered showers
are S of 09N to the Guyana coast.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal plains of Sierra
Leone near 06N11W to 06N12W. The ITCZ continues from 06N12W to
04N26W to 03N37W, then continues W of a tropical wave from 03N40W
to 01N50W. Scattered moderate to strong convection is seen north
of the ITCZ from 05N-09N between 24W-36W and along the ITCZ from
15W-30W. For information on convection, see the Tropical Waves
section.

GULF OF MEXICO...

Cold front has moved off the Texas coast into the NW Gulf
extending from 29N93W to a 1012 mb low pressure in South Texas.
A mix of low and mid level clouds and patchy fog are present ahead
of the front. Scattered showers and isolated tstorms are developing
ahead of the front from 24N-29N and west of 93W. Except for
isolated showers and patchy fog along the NW Gulf coast, the
remainder basin is under fair weather conditions being supported
by a deep-layered anticyclone centered near the Yucatan Peninsula
in the middle to upper levels. At the surface, the ridge is anchored
by a 1020 mb high over the SW N Atlc and provides gentle to fresh
return flow to the gulf as seen in the latest ASCAT pass.

A surface ridge will prevail across the eastern area through
tonight, with fresh SE return flow persisting over the western
Gulf. The front will cross the northern and central waters this
weekend, then weaken and stall over the southern Gulf Sun night
into Mon. High pressure will build in from the W behind the front
Sat night through Sun night, move E across the Gulf Mon into Tue,
then persist into Wed night. The next cold front is expected to
move into the northwest Gulf by Tue night into Wed night.

CARIBBEAN SEA...

A surface trough, remnants of a former tropical wave, is over
the NW Caribbean waters extending from 18N85W to Nicaragua
adjacent waters. Isolated showers are in the vicinity of this
trough. The remnants of a former cold front are analyzed as a
shearline extending from Guadeloupe SW to 15N61W to 14N72W.
Scattered to isolated tstorms are within 60 nm either side of the
shearline. This line of showers and tstms will gradually move SSE
through Sat and then dissipate. Otherwise, the pressure gradient
between T.S. Sebastien in the central Atlc and high pressure
building over the SW N Atlc waters is supporting a swath of fresh
winds N of 14N between the Mona Passage and the Dominican Republic.
These winds will diminish Sat as Sebastian is expected to continue
a NE track, which will weaken the pressure gradient.

Easterly trades will freshen across the south-central Caribbean
early next week, increasing to strong Tue into Tue night.

ATLANTIC OCEAN...

Please, see the Special Features section above for details on
T.S. Sebastien.

A 1020 mb high pressure is in the SW N Atlantic near 29N76W
extending to 29N61W. To the east a cold front is present just
west of the T.S. Sebastein extending from 31N47W to 28N52W then
transitions to a stationary front to 22N55W, then extends as a
front to 16N60W. Scattered showers and isolated tstorms are seen
along the boundary. A surface trough is 110 nm ahead of the front
from 16N57W to 23N52W with scattered moderate convection extending
180 nm E of the trough axis. Further E, a 1024 mb high pressure is
in control over the NE Atlantic.

High pressure in the wake of the front will dominate the forecast
waters through Sat, then shift eastward Sat night. The next cold
front will cross the region Sun through Mon, weakening near 70W
Mon night through Tue night. High pressure will build in from the
W over the region by mid week. Otherwise, surface ridging
dominatesthe northeastern Atlc waters.

$$
MMT
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