[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 032352
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
652 PM EST Wed Jan 3 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 1800 UTC surface analysis and satellite imagery through
2230 UTC.

...SPECIAL FEATURES...
As of 03/2100 UTC, a vigorous middle to upper level trough is
noted on water vapor imagery over the eastern Gulf of Mexico and
Florida panhandle supporting a deepening and complex area of low
pressure focused on a 997 mb low near 31N78W and a 998 mb low near
29N77W. An occluded front extends from the northern low to the
southern low, with a cold front continuing through the central
Bahamas into central Cuba. A warm front also extends E from the
southern low to near 29N69W. The southern low is forecast to merge
with the northern low as it continues to rapidly intensify while
moving to the NE. Gale force winds currently in place NE of the
Bahamas will increase to storm force within 150 nm in the SW
semicircle of the complex low in the discussion waters later this
evening, and eventually develop hurricane-force winds off the
east coast of the US north of the discussion area. Nearby ships
recently reported 45-50 kt NE of the northern low and N of the
discussion waters, as did a dropsonde from a NOAA research mission.
The complex low is forecast to move N offshore of the east coast
of the US reaching Nova Scotia, Canada by Thursday night. See the
latest NWS NHC High Seas Forecast under AWIPS/WMO headers
MIAHSFAT2/FZNT02 KNHC and NWS OPC High Seas Forecast under
AWIPS/WMO headers HSFAT1/FZNT01 KWBC for more details.

A tight pressure gradient and reinforcing cold air filtering in
across the western Gulf of Mexico continues to support near gale
to gale force N-NW winds generally within 60 nm of the coast of
Veracruz, Mexico. These winds are forecast to diminish below
gale force by Thursday morning. See the latest NWS High Seas
Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more
details.

...ITCZ/MONSOON TROUGH...
The monsoon trough extends from the African coast near 06N10W to
06N17W. The Intertropical Convergence Zone axis extends from
06N17W to the Equator near 36W. Widely scattered moderate
convection is from the Equator to 03N between the Prime Meridian
and 07W, and from the Equator to 06N between 12W-27W.

...DISCUSSION...

GULF OF MEXICO...
Aside from the near gale to gale force conditions mentioned
above, a surface ridge prevails across the Gulf this evening
anchored by a 1036 mb high centered just NW of Laredo, Texas near
28.5N100W. Fresh to strong northerly winds are expected to
persist through Thursday morning. Thereafter, the ridging will
weaken gradually relaxing the pressure gradient and winds will
diminish into moderate breeze levels for the upcoming weekend.

CARIBBEAN SEA...
Southwesterly flow aloft prevails over the Caribbean basin this
evening between an upper level trough moving from the southeastern
Gulf of Mexico into the northwestern Caribbean, and an upper
level ridge anchored over northern Venezuela. The troughing
supports a cold front analyzed across western Cuba from 22N81W to
the eastern Gulf of Honduras near 16N86W. Isolated showers are
possible across the NW Caribbean waters in the vicinity of the
front as the cooler and drier airmass NW of the front filters
southward across the western Caribbean through tonight. Farther
SE, broad surface troughing and a 1009 mb low centered offshore
of central Panama near 11N80W continues to provide focus for
scattered to numerous showers and scattered tstms S of 18N
between 73W-83W, and S of 12N between 81W-84W. Otherwise, the
eastern Caribbean remains under fair skies within moderate to
occasional fresh trades. As the Special Features low pressure area
across the SW North Atlc waters moves northward, the associated
cold front will move across the western Caribbean to 78W and
become stationary across the Windward Passage and Hispaniola
Thursday into Friday with fresh to near gale force winds expected
W of the boundary through the upcoming weekend.

...HISPANIOLA...
Increased cloudiness and isolated showers are expected through
tonight across Hispaniola as broad surface troughing and lower
pressure focuses on the Bahamas, Greater Antilles, and central
Caribbean Sea. A cold front currently across western Cuba and the
NW Caribbean Sea will begin to approach from the west on Thursday
with NE winds increasing through the Windward Passage region and
persisting through early next week.

ATLANTIC OCEAN...
Outside of the Special Features deepening area of low pressure
across the SW North Atlc, a cold front enters the discussion area
across the central Atlc near 32N50W to 31N52W becoming stationary
to 30N62W to 28N72W and linking up with the Special Features warm
front boundary. Scattered showers and isolated tstms are
occurring within 240 nm either side of the boundary, with the
strongest activity S of the boundary. The remainder of the
central and eastern Atlc is under the influence of a surface ridge
anchored by a 1036 mb high centered W-SW of the Iberian peninsula
near 36N16W.

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

$$
Lewitsky
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