Tropical Weather Discussion
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AXNT20 KNHC 201736

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1236 PM EST Mon Feb 20 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.


The Monsoon Trough enters the Atlantic Ocean through Liberia and
extends to 04N14W. The ITCZ continues from this point to 02N22W
00N30W to 01S40W to 01N50W. Scattered moderate to isolated strong
convection is noted from the Equator to 04N between 20W and 29W.
Similar convection is along the Equator between 30W-40W.



The pressure gradient between a ridge across Florida and the
eastern Gulf and a frontal trough across the NW Gulf and NE
Mexico is supporting fresh to strong SE-S winds across the NW Gulf
and moderate to fresh southerly winds elsewhere across the
west and central Gulf. The most recent scatterometer data and
buoys observations confirmed the presence of these winds. Mosaic
Doppler radar from the SE U.S. along with lightning data reveals
a band of showers and thunderstorms in association with this
trough. Winds will continue to increase later today across the
western Gulf as the pressure gradient tightens. The frontal trough
and associated band of showers and thunderstorms will move
eastward reaching from SE Louisiana to the central Bay of Campeche
by early Tuesday morning, and from the Florida Panhandle to the
Yucatan peninsula by Tue night. A weak low is forecast to form
over the NE Gulf along the trough axis Tuesday night into
Wednesday. This weather pattern is currently associated with an
unusually sharp mid-upper level trough crossing central Texas and
Mexico. Then, a cut-off low is forecast to develop at the mid-
levels near the Texas/Louisiana border on Tuesday, with this low
tracking slowly eastward into the NE part of the Gulf on
Wednesday. This system is forecast to move across south Florida
Wednesday night into Thursday producing unsettled weather


High pressure centered over the SE CONUS extends a ridge across
Florida into Cuba and the NW Caribbean. A weakening cold front
is clipping the north-central coast of Cuba with the potential of
few passing showers the rest of today. Moisture associated with
this front will reach the northern coast of Hispaniola and eastern
Cuba by this evening, producing some shower activity. Shallow
moisture, embedded in the trade wind flow, will move across the
remainder of the basin producing isolated to scattered passing
showers. The high pressure centered north of area combined with
Colombian/Panamaniam low will support fresh to strong winds near
the coast of Colombia and in the Gulf of Honduras during the
overnight and morning hours through Tuesday. The frontal trough
forecast to move across the Gulf of Mexico will reach western Cuba
and the NW Caribbean by Wedenesday morning with a band of showers
and thunderstorms. This trough is forecast to extends from
Matanzas Cuba to NE Honduras by Wednesday evening. Fresh to locally
strong NW winds are expected behind the frontal trough. Gentle to
moderate trades will persist elsewhere through Friday. In
addition, the aforementioned cut-off low is forecast to also
affect western Cuba on Wednesday, increasing the likelihood of
showers and thunderstorms. In the upper levels, an anticyclone
centered south of Costa Rica in the EPAC waters extens a ridge
northward across Central America and the NW Caribbean into the
eastern Gulf of Mexico. As a result, mainly a NW flow aloft
dominates the western Caribbean while a westerly flow is noted
over the eastern part of the basin. Strong subsidence is seen on
water vapor imagery across much of the area.


A weakening frontal boundary is approaching from the north and
will reach the coast this evening increasing the risk of showers.
A drier air mass will follow the front on Tuesday.


Visible satellite imagery and recent scatterometer data indicate
the presence of a 1011 mb low pressure located near 29N70W with
the associated cold front extending SW across the Turks and
Caicos Islands into the north-central coast of Cuba. A band of
cloudiness with embedded showers is associated with the front.
Lightning data indicate very active weather within this band north
of 22N. Fresh to strong southerly winds are ahead of the front.
Mainly fresh northerly winds will follow the front. The low
pressure is forecast to move SE across the forecast area reaching
a position near 24N61W by early Tuesday morning as a new cold
front moves south of 30N. This new cold front will reach the SE
Bahamas by late Tuesday. A stationary front extends from 31N72W to
21N56W where it begins to dissipate. The remainder of the Atlantic
is under the influence of a ridge, anchored by a 1035 mb high
pressure located NE of the Azores. The pressure gradient between
this high and a low pressure system over Africa is resulting in
fresh to strong northerly winds between the Madeira and Canary
Islands and the coast of Africa. Looking ahead, the low with the
associated frontal trough forecast to move across the Gulf of
Mexico and Florida is expected to enter the Atlantic waters
Wednesday night, supporting strong to near gale force winds across
the northern Bahamas and the waters E of Florida to about 74W-

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