[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 280425
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
102 PM EST Sat Jan 27 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 and Gulf of Mexico Gale Warning: A very tight pressure
gradient between a cold front extending from 30N47W to 23N61W
where it stalls while it weakens to the southern Bahamas, and
very strong high pressure of 1040 mb centered N of the area. This
tight pressure gradient has induced a large area of near gale to
minimal gale force NE to E winds over the waters between the front
and the Bahamas S of about 27N. Seas are in the range of 10 to 16
ft with these winds. A gale warning prevails for the waters W of
the Bahamas including the Straits of Florida and far eastern Gulf
of Mexico near 83W. Fresh to strong NE to E winds are elsewhere W
of the front, including through the Atlantic passages in the
Bahamas. Latest model guidance indicates these winds will
diminish to just below gale force on Sun morning near sunrise. Gale
force winds W of the Bahamas that include the Straits of Florida
and far eastern Gulf of Mexico are forecast to diminish to strong
NE to E winds this evening. Please see the latest NHC High Seas
Forecast under AWIPS/WMO headers Misfit/FZNT02 KNHC for more
details on this event.

Caribbean Gale Warning: The combination of very strong high
pressure centered E of the mid-Atlantic states and lower pressure
over South America is bringing minimal gale force NE to E winds
near the coast of Colombia. These conditions will persist late at
night into the early morning hours through Mon. Please see the
latest NHC High Seas Forecast under AWIPS/WMO headers
MIAHSFAT2/FZNT02 KNHC for more details on this event.

Far E Atlantic Gale Warning: Another very strong high pressure
system, this one of 1041 mb is centered NE of the Azores near
40N20W. The tight pressure gradient to its SE and S is allowing
for NE gale force winds that reach to strong gale force over Meteo
France marine zones of Agadir, Tarfaya and to near gale force NE
winds over Canarias except for strong gale force winds over the
eastern portion of that zone. NE winds are reaching near gale
force at times over zone Cap Blanc. These conditions are expected
through this evening. With the tight gradient not expected to
slacken in the short term, the gale conditions for Agadir, Tarfaya
and the near gale to gale for Canarias are forecast to continue
through Sun night. Please refer to Meteo France Weather Bulletins
for more information.

...MONSOON TROUGH/ITCZ...

The Monsoon Trough axis extends from the coast of Africa near
06N10W to 04N14W where the ITCZ begins and then continues along
01N20W to 0N30W to 0N40W to 01S50W. Scattered moderate convection
is within 210 nm either side of the axes.

...DISCUSSION...

GULF OF MEXICO...

Strong surface high pressure centered over the NW Atlc is
supporting a large area of fresh to strong E winds E of 90W. The
exception is in the far SE Gulf and Straits of Florida where
strong E winds are gusting frequently to gale force. These winds
are forecast to diminish early Sunday morning as strong ridging
over the eastern Gulf begins to weaken. An upper level short-
wave supports a 1021 mb low off the Texas coast from where a
stationary front extends NE to SE Louisiana near 29N91W and then
E to 29N85W. Radar data show scattered heavy showers and tstms N
of 27N W of 90W associated with these features. Scattered
showers and isolated thunderstorms are in the SE Gulf from 23N
to 28N between 84W and 89W being supported by upper level
diffluent flow. A rather progressive upper level pattern will
bring surface low pressure southeastward towards the area of
southeastern Louisiana or southwestern Mississippi early
tonight, with a trailing cold front across the NW Gulf waters.
The low is forecast to rapidly move across the NE Gulf on Sun
while pushing the cold front across the eastern gulf waters
through early on Mon. Expect widespread rain along with
scattered showers and isolated thunderstorms with system.

CARIBBEAN SEA...

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

Fresh to strong NE winds prevail at the lee of Cuba. Fresh to
strong trades are occurring elsewhere across the basin, except for
the gale force winds near the coast of Colombia as described
above under SPECIAL FEATURES. A surface trough along the eastern
Yucatan Peninsula and Belize continue to support scattered
showers and isolated thunderstorm over the Gulf of Honduras.
Isolated showers and thunderstorms are noted over Hispaniola
being supported by upper level diffluent flow. Strong to near
gale force NE winds are likely to occur through the Windward
Passage next week. Expect increasing low-level moisture along with
scattered showers to impact the NE Caribbean and islands in that
location including Puerto Rico through Sun night as a decaying
frontal boundary over the central Atlantic drops southward towards
the NE Caribbean and strong to near gale force NE winds advect
the associated moisture and shower activity towards that section
of the Caribbean.

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

A cold front enters the discussion area through 30N46W to 23N61W
where it becomes a weakening stationary front to the southern
Bahamas. Meanwhile, very strong high pressure of 1040 mb is over
NW Atlc waters. The resultant tight gradient support near gale to
minimal gale force winds along with large seas in the SW N Atlc S
of 27W. These conditions are expected to continue into Sun morning.
Scattered showers are within 175 nm E of the front N of 25N. The
stationary portion of the front is forecast to continue to weaken
through the weekend. The frontal remnants will drift southward
towards the NE Caribbean Sea islands, most likely as a shearline.
Precipitable water GFS model guidance indicates that moisture and
precipitation will increase for the NE Caribbean islands through
the weekend. before diminishing late Sun.

Farther east, a 1041 mb high pressure system centered near 40N20W
dominates the area E of the cold front maintaining rather stable
weather over much of the central and eastern sections of the area,
except for the far eastern portion S of 24N and E of 40W where
abundant mid and upper level clouds are streaming eastward towards
Africa ahead of a mid to upper level trough located N of 15N
between 30W and 40W.

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

$$
Ramos
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