Tropical Weather Discussion
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000
AXNT20 KNHC 191731
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1231 PM EST Sun Feb 19 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 Liberia and
extends to 04N15W. The ITCZ continues from this point to 04N30W
then crosses the Equator at 38W to 01S42W to 01N50W. Scattered
moderate to isolated strong convection is noted from 01N-05N
between 24W and 28W. Scattered moderate convection can be found
from 01N-05N between 30W-40W.

...DISCUSSION...

GULF OF MEXICO...

The pressure gradient between a high pressure system over the
western Atlantic and lower pressures over Texas and NE Mexico is
supporting mainly gentle to moderate SE-S winds across most of
the Gulf region. The most recent ASCAT pass showed moderate to
fresh southerly winds across the NW Gulf. Winds will increase in
the western half of the Gulf tonight as the pressure gradient
tightens between a ridge extending south across Florida and lower
pressures over eastern Mexico. Dense fog was noted this morning
along the coastline from Louisiana to the Florida Panhandle, and
across the west coast of Florida and parts of south Florida.
Parchy fog were seen along the coast of Texas and over the NW
Gulf. Computer model suggests that a low pressure system and
associated trough will move eastward across the Gulf Tuesday and
Wednesday, with a band of moisture extending from SE Louisiana to
the Yucatan Peninsula by Tuesday night, reaching the SE Gulf on
Wednesday. This will bring an increase in showers across the area
with the potential of some thunderstorms. Aloft, SW flow, ahead
of a sharp trough over NW Mexico, is transporting mid-upper level
moisture across the western Gulf.

CARIBBEAN SEA...

The San Juan Doppler radar shows a band of showers affecting the
north coast of the island and regional Atlantic waters. This band
of showers extends into Dominican Republic and is associated with
a weakening cold front located north of Puerto Rico. Moisture
associated with this front will persist across the Puerto Rico and
Dominican Republic through Monday. Another band of moisture is
forecast to approach these islands by Monday night in association
with a frontal trough currently located east of Florida. Patches
of moisture, with embedded passing showers, are noted over
southern Haiti and parts of Jamaica. High pressure north of area
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. Gentle to moderate trades will persist elsewhere
through Tuesday. A cold front moving across the SW N Atlantic
Monday and Tuesday will bring northerly winds across Cuba and the
Windward passage Monday and Tuesday. These winds will transport
some shower activity. Looking ahead...a band of moisture forecast
to move across the Gulf of Mexico Tuesday and Wednesday is
forecast by the computer model to reach western Cuba and the NW
caribbean on Wednesday. In the upper levels, a westerly flow is
noted over Cuba and the NW Caribbean while W-NW winds dominate the
remainder of the basin. Mid-upper level moisture is over the NW
Caribbean, and Cuba. Strong subsidence is seen on water vapor
imagery elsewhere.

...HISPANIOLA...

Patches of moisture, with embedded passing showers, are noted
over southern Haiti. The proximity of a weakening frontal boundary
will produce isolated to scattered showers today. Moisture is
forecast to persist across the island on Monday with the risk of
showers.

ATLANTIC OCEAN...

A frontal trough extends from a 1015 mb low pressure located near
31N77W to 27N80W. A sharp short-wave trough supports this feature.
A band of showers and thunderstorms is ahead of the trough axis.
Lightning data indicate very active weather within this band. The
low pressure is forecast to move SE across the forecast area
reaching a position near 29N69W by early Monday morning. At that
time, the associated frontal trough will extend from the low
center to the SE Bahamas. High pressure will build across Florida
in the wake of this frontal trough bringing a drier air mass. A
cold front enters the discussion area near 31N43W, then extends SW
to the waters north of Puerto Rico. A 1022 mb high pressure
located near 28N64W follows the front and extends a ridge toward
the SE Bahamas and Turks and Caicos Islands. Moderate to fresh NE
winds are observed, per scatterometer data, within about 150 nm
north of the front between 56W-63W. In about 24 hours, the high
pressure will move NE as the aforementioned low pressure system
moves SE into the forecast region. 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 strong high pressure and the front over the central Atlantic
supports fresh to strong southerly winds ahead of the front but
mainly north of 28N.

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

$$
GR



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