[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281803
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
103 PM EST Sun Jan 28 2018

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
1745 UTC.

...SPECIAL FEATURES...

Atlantic Gale Warning: A cold front enters the discussion area at
30N41W to 21N49W, where it becomes a dissipating cold front to
20N52W and a shearline from there to just N of the coast of NW
Puerto Rico. A very tight pressure gradient prevails between this
front and strong high pressure of 1038 mb centered N of the area
near 37N58W. This is resulting in a large area of near gale to
minimal gale force NE to E winds over the SW N Atlc waters. Given
the long duration of these winds across an expansive fetch area,
the resultant seas have build to the range of 12 to 18 ft. These
conditions are forecast to continue through early this evening, at
which time the gradient should weaken enough to allow for the
winds to diminish to strong category, however, seas are forecast
to remain quite high in the 12 to 16 ft range with these winds.
Fresh to near gale-force NE to E winds are through the Atlantic
passages in the Bahamas. Please see the latest NHC High Seas
Forecast under AWIPS/WMO headers FZNT02 KNHC for more details on
this event.

Central Atlantic Gale Warning: A storm center of 1016 mb N of the
area near 34N42W moving southward will reach near 30N45W by Monday
morning. A tight gradient between the low and strong high
pressure to its NW will bring minimal gale force northerly winds
to the waters N of 30N between 48W and 52W Monday near sunrise.
Seas are forecast to be very large, 18 to 21 ft in N swell within
the area of gale force winds. By late Mon night, the low is
forecast to reach near 28N47W late Mon night while the ridge to
its NW weakens. The northerly winds at that time are then forecast
to be drop to just below gale force in the NW semicircle of the
low, with seas in the 12 to 18 ft range.

Caribbean Gale Warning: The combination of very strong high
pressure centered over the NW Atlantic and lower pressure over
South America is bringing near to minimal gale force NE to E
winds near the coast of Colombia, with seas in the 12 to 15 ft
range. Winds will increase to gale-force late at night and into
the early morning hours through Tue, and possibly well into next
week. Please see the latest NHC High Seas Forecast under AWIPS/WMO
headers MIAHSFAT2/FZNT02 KNHC for more details on this event.

Gulf of Mexico Gale Warning for the far SW portion: A weak 1017
mb low over southern Mississippi will rapidly track northeastward
across the NE Gulf today, and push a cold front through the
eastern waters into early on Mon. Strong high pressure ridging
will surge southward in the wake of the front over the western
waters of the gulf. A tight pressure gradient will set up in the
far SW Gulf on Monday afternoon leading to strong gale force NW
to N winds that will affect the waters S of about 21N and W of 95W
to along the coast of Veracruz. These winds are expected to last
into Tuesday morning, with seas building to the range of 8 to 12
ft. The strong ridge is then forecast to weaken through late
Tuesday night, thus significantly diminishing the winds and seas.

...MONSOON TROUGH/ITCZ...

The Monsoon Trough axis extends from the coast of Africa near
05N09W to 06N18W where the ITCZ begins and continues along 03N28W
to 02N41W to 01S51W. Scattered moderate convection is from 03N to
07N between 06W and 15W and from 05S to 04N between 26W and 49W.

...DISCUSSION...

GULF OF MEXICO...

Please see the SPECIAL FEATURES section above for details
in reference to an upcoming gale event in the SW Gulf.

A broad middle to upper level trough over the central U.S.A with
base extending to the NW Gulf of Mexico waters supports a cold
front that extends SW from a 1017 mb low off the Mississippi coast
to 26N90W to near Tuxpan, Mexico. Moderate to fresh northerly
winds are behind the front, except for strong northerlies in the
vicinity of Tuxpan. Ahead of the front, a surface trough is in
the eastern Bay of Campeche from 22N90W to 18N92W. A tight
pressure gradient between the front and ridging to the E-NE
continue to support fresh to strong SE-E winds ahead of the front,
including the Straits of Florida. An upper level diffluent
pattern E of 86W support scattered heavy showers in that region,
including scattered showers in the Yucatan Channel. The latest
forecast calls for the low to quickly track across the NE Gulf
today, sending a cold front through the eastern waters into early
on Mon. Strong high pressure ridging will surge southward in the
wake of the front over the western waters of the gulf. Until this
upcoming weather scenario is over, expect for scattered showers
and thunderstorms prevail across much of the E gulf through Mon.

CARIBBEAN SEA...

Please see the SPECIAL FEATURES section above for details regarding
the gale conditions near the coast of Colombia.

Fresh to strong NE to E winds prevail are occurring across the
central and eastern basin with gale force winds developing at
night near the coast of Colombia as described above under SPECIAL
FEATURES. Scatterometer data show light to moderate trades in the
NW basin, except for fresh NE winds in the Windward Passage.
Diffluent flow aloft in the far E Gulf of Mexico support scattered
showers in the Yucatan Channel. Low to middle level water vapor
imagery from GOES-16 show dry, stable conditions elsewhere.
However, shallow moisture associated with the remnants of a cold
front N of the area is supporting isolated showers over Puerto
Rico and Hispaniola. Fresh to strong NE winds will continue across
the Windward Passage through early on Mon. Expect the continuation
of showers in the NE Caribbean, including Puerto Rico and nearby
islands through at least Mon as strong to near gale force NE winds
with a shearline located just to the N acts to advect the
moisture and shower activity towards that part of the Caribbean.

ATLANTIC OCEAN...
Please see the SPECIAL FEATURES section above for details about
gale conditions over a portion of the SW N Atlc between the
Bahamas and a central Atlantic cold front.

A cold front enters the discussion area at 30N41W to 21N49W,
where it becomes a dissipating cold front to 20N52W and a
shearline from there to just N of the coast of NW Puerto Rico. The
shealine is advecting moisture associated with the front to
Hispaniola and Puerto Rico northern adjacent waters. Over the far
eastern Atlc, a ridge that extends from a 1040 mb high pressure
system centered near 44N15W dominates the area E of the cold front
maintaining rather stable weather. A cold front is expected to
move offshore the SE United States coast on Mon, and reach from
near 32N73W southwest across the NW Bahamas to the Straits of
Florida on Mon night, then from 32N63W to eastern Cuba by Tue
night. Strong NW winds and building seas will follow in the wake
of this front.

For additional information please visit http://www.hurricanes.gov/marine

$$
Ramos
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