[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 202349
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
705 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 1800 UTC surface analysis and satellite imagery through
2330 UTC.

...SPECIAL FEATURES...

The center of Tropical Storm SEBASTIEN, at 20/2100 UTC, is near
21.7N 61.5W, or about 230 nm/425 km to the NNE of the northern
Leeward Islands. Sebastien is moving N, or 360 degrees, 5
knots. The estimated minimum central pressure is 1002 mb. The
maximum sustained wind speeds are 45 knots with gusts to 55
knots. Precipitation: scattered to numerous strong within 180 nm
of the center in the E quadrant. The PUBLIC ADVISORIES for
SEBASTIEN are available via the WMO header WTNT35 KNHC, and via
the AWIPS header MIATCPAT5. The FORECAST/ADVISORIES for
SEBASTIEN are available via the WMO header WTNT25 KNHC, and via
the AWIPS header MIATCMAT5.

...TROPICAL WAVES...

An Atlantic Ocean tropical wave is along 45W/46W, from 13N
southward, moving W 10 to 15 knots. Precipitation: isolated
moderate to locally strong within 300 nm to the west of the wave
from 08N to 12N.

A Caribbean Sea tropical wave is along 72W, from 20N southward
moving through the central sections of Hispaniola, moving W 5 to
10 knots. Precipitation: isolated moderate from 16N to 20N
between the Windward Passage and 79W.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the southern coastal plains of
Sierra Leone near 07N12W, to 06N14W. The ITCZ continues from
06N14W, to 04N23W 06N41W, and curving to NE French Guiana.
Precipitation: isolated moderate to locally strong within 200 nm
to the south of the monsoon trough/ITCZ from 40W eastward, and
within 180 nm to the north of the monsoon trough/ITCZ from the
45W/46W tropical wave eastward, and between 48W and 50W.

GULF OF MEXICO...

An upper level ridge is along 93W/94W. Upper level anticyclonic
wind flow spans the Gulf of Mexico.

Broad surface anticyclonic wind flow covers the area. A surface
ridge passes through the Florida Panhandle, into the east
central Gulf of Mexico, to the SW corner of the Gulf of Mexico.

High pressure in the northeast Gulf of Mexico will continue to
shift eastward through the evening. Fresh to locally strong SE
return flow will develop in the NW Gulf of Mexico, from tonight
into Thursday, ahead of a cold front that is moving across
Texas. The cold front will move into the NW Gulf of Mexico by
late Friday. The front will cross the region through the
weekend. The front will weaken and stall in the southern Gulf
of Mexico by late Sunday.

CARIBBEAN SEA...

A cold front passes through the central Bahamas, to NW Cuba.
A surface trough is along 25N67W 20N70W, reaching the north
central coast of Hispaniola, and continuing to the southwestern
corner of Haiti. Precipitation: isolated moderate within 75 nm
on either side of the second surface trough. Multilayered
moisture is within 110 nm on either side of the line that
extends from 16N76W, across Hispaniola from the SW to the NE,
beyond 22N66W in the Atlantic Ocean. The GFS model shows an
upper level trough that passes through the Windward Passage to
Jamaica, middle level anticyclonic wind flow in the same area,
and a narrow 700 mb trough that passes through SE Cuba toward
Belize.

A surface trough curves from eastern Honduras to the east
central coastal sections of the Yucatan Peninsula of Mexico.
Broken multilayered clouds and possible rainshowers are within
75 nm on either side of the surface trough.

The GFS model shows middle level to upper level anticyclonic
wind flow near Nicaragua, and 700 mb NE wind flow on the
southern side of a ridge. Precipitation: isolated moderate in
near Nicaragua: within 150 nm of the coast of Nicaragua to 60 nm
inland, covering the southern 2/3 of the coastal plains and
coastal waters.

Comparatively drier air in subsidence covers much of the rest of
the Caribbean Sea.

Tropical Storm Sebastien near 21.7N 61.5W 1002 mb at 4 PM EST
moving N at 5 kt. Maximum sustained winds 45 kt gusts 55 kt.
Sebastien will move to 22.7N 61.0W Thu morning, 24.5N 59.0W Thu
afternoon, 27.2N 55.5W Fri morning, become extratropical and
move to 30.0N 51.4W Fri afternoon, and dissipate by Sat
afternoon. Fresh NE winds will prevail across most of the
western Caribbean Sea through Friday morning. The fastest wind
speeds are expected through the Windward Passage and the Mona
Passage on Thursday night, as high pressure builds to the north
of the region.

ATLANTIC OCEAN...

A cold front passes through 32N63W, to 26N70W, through the
central Bahamas, to NW Cuba. Precipitation: scattered moderate
to strong within 90 nm to 180 nm to the east of the cold front,
from 30N northward. One surface trough is along 30N62W 28N64W
26N65W. Precipitation: Isolated moderate to locally strong
within 270 nm to the east of the surface trough from 25N to 30N.
A second surface trough is along 25N67W 20N70W, reaching the
north central coast of Hispaniola, and continuing to the
southwestern corner of Haiti. Precipitation: isolated moderate
within 75 nm on either side of the second surface trough.

An upper level cyclonic center is near 19N41W. Upper level
cyclonic wind flow covers the Atlantic Ocean from 11N to 23N
between 32W and 52W. Precipitation: Widely scattered moderate to
isolated strong within 300 nm to 500 nm away from the center in
the SE quadrant.

A cold front passes through 32N10W, across the Canary Islands to
27N20W, to 27N30W. Precipitation: rainshowers are possible
within 200 nm to the NW of the cold front.

Broad surface anticyclonic wind flow spans the Atlantic Ocean,
elsewhere, from 18N northward, between the westernmost part of
the 32N10W-to-27N30W cold front and the cyclonic wind flow that
is moving around T.S. Sebastien.

Tropical Storm Sebastien near 21.7N 61.5W 1002 mb at 4 PM EST
moving N at 5 kt. Maximum sustained winds 45 kt gusts 55 kt.
Sebastien will move to 22.7N 61.0W Thu morning, 24.5N 59.0W Thu
afternoon, 27.2N 55.5W Fri morning, become extratropical and
move to 30.0N 51.4W Fri afternoon, and dissipate Sat afternoon.
A cold front, currently extending from 31N64W to 26N71W to
23N80W, will continue to move southeastward across the region
through Thursday. High pressure will build across the northern
waters from Thursday through Saturday. The high pressure then
will shift eastward, from Saturday night through Sunday, as the
next cold front moves off the SE U.S.A. coast.

$$
mt
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