[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 261748
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1248 PM EST Tue Dec 26 2017

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
1715 UTC.

...ITCZ/MONSOON TROUGH...
The monsoon trough enters the Atlantic Ocean through Nigeria,
Africa, and extends to 03N06W. The Intertropical Convergence Zone
axis continues from 03N06W to 05N25W to the Equator near 50W.
Scattered moderate convection is from 02N-07N between 24W-43W.

...DISCUSSION...

GULF OF MEXICO...
A weak low pressure has developed along a frontal boundary over
the NW Gulf. As of 1500 UTC...the low center is located near
28N96W with a warm front extending eastward to near 26N91W. The
Mosaic Doppler Radar from the SE U.S. shows scattered showers
over the NW Gulf and parts of Louisiana and esatern Texas. Broken
to overcast low clouds and possible isolated showers are observed
across the northern Gulf waters, particularly N of 27N. A recent
ASCAT pass provided observations of moderate to fresh easterly
winds just N of the warm front, and mainly gentle to moderate
SE-S winds across the remainder of the western half of the Gulf.
A trough also extends from the low center across the far western
Gulf to near 21N96W. The remainder of the Gulf is under the
influence of a surface ridge anchored by a 1033 mb high currently
centered over North Carolina. The ridge is providing gentle to
moderate easterly winds across the eastern half of the Gulf. The
area of weak low pressure across the NW Gulf will drift eastward
over the next couple of days. The pressure gradient between the
low and high pressure N of area will bring a slightly stronger
N-NE winds on Tuesday night into Wednesday across the NW Gulf
eventually becoming more diffuse by Thursday as the frontal wave
weakens across the north-central and NE Gulf waters. The next
strong cold front is expected to emerge off the Texas and
Louisiana coasts Sunday evening followed by gale force winds.

CARIBBEAN SEA...
The most recent scatterometer data show fresh to strong winds
across the south-central Caribbean near the coast of Colombia, and
fresh to strong winds across the remainder of the central Caribbean.
Moderate to fresh trades are noted elsewhere across the basin.
Patches of low level moisture embedded in the trade wind flow are
producing isolated to scattered passing showers across the Greater
and Lesser Antilles from time to time. A larger patch of low
clouds is noted over the NW Caribbean S of 20N W of 85W. Little
change in this weather pattern is expected during the next couple
of days. Strong trades will persist over the Central and SW
Caribbean through Thursday, with near gale-force nocturnal winds
near the coast of Colombia tonight. Fresh to locally strong NE
winds are expected through the Windward Passage this evening.
Large E swell, in the form of 7 to 9 ft seas, will reach the E
Atlantic passages this evening, and continue through Thu evening.

...HISPANIOLA...
Low-topped trade wind showers will continue to move across the
island from time to time. Mostly dry and stable conditions are
expected to persist during the next couple of days under the
influence of a middle to upper level ridge and associated strong
subsidence.

ATLANTIC OCEAN...
A cold front enters the discussion area near 31N65W extending SW
to 29N71W, then becomes stationary to the NW Bahamas across the
Florida Keys and into the SE Gulf of Mexico. Mainly low clouds
with embedded isolated showers are associated withthe frontal
boundary. The cold front is expected to drift eastward through
Wednesday, and begin to stall and weaken on Thursday. The remainder
of central and eastern Atlantic is under the influence of a
surface ridge anchored by a 1034 mb high centered SW of the
Azores near 36N31W. This system will undergo occasional intensity
fluctuations, resulting in a rather tight pressure gradient
across the waters north of the ITCZ/monsoon trough between the
coast of Africa and the Lesser Antilles through at least
Wednesday. The high will move SE and weaken some on Thursday.
Recent ASCAT passes indicate moderate to fresh winds around the
southern periphery of the ridge east of the Lesser Antilles. Seas
are in the 8-11 ft range within this area of winds based on several
altimeter passes.

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

$$
GR
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