Tropical Weather Discussion
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AXNT20 KNHC 292330

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
729 PM EDT Wed Mar 29 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 1800 UTC surface analysis and satellite imagery through
2315 UTC.


As of 29/1800 UTC, a 992 mb low pressure is analyzed near 31N56W.
A cold front extends from the low center to the Leeward Islands
into the NE Caribbean. A band of showers with isolated thunderstorms
is noted ahead of the front. The low is still producing gale
force winds of 35-45 kt over the discussion area, particularly N
of 28N between the cold front and 60W based on the most recent
scatterometer data. The low will move N of 31N this evening and
away from the forecast region tonight and Thursday. Gale force
winds are still expected ahead of the front over the next 24
forecast. A that time, the front will extend from 31N43W to
23.5N50W to 16.5N62W. Please see the latest NWS High Seas Forecast
under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details.


The Monsoon Trough extends from the African coast near 13N16W to
01N24W. The ITCZ extends from 01N24W to the coast of Brazil near
05S38W. Scattered moderate and isolated strong convection is noted
S of the monsoon trough from 00N-04N between 10W-20W. A cluster of
moderate to strong convection is just south of the Equator between
15W and 18W.



A ridge dominates the Gulf region anchored by a 1019 mb high
pressure located near the central Bahamas. The pressure gradient
between the ridge and lower pressures over eastern Mexico
supports moderate to fresh SE-S winds across the Gulf west of
87W, and gentle to moderate SE winds east of 87W. A dryline is
over eastern Texas followed by a cold front. This cold front will
move off the Texas coast Thursday morning, and across the northern
Gulf through Saturday morning with a band of scattered showers
and thunderstorms. In the upper levels, an upper level trough is
inland over New Mexico and Texas supporting the above mentioned
cold front. An upper level ridge, with axis across Florida,
dominates the Gulf of Mexico. Strong southwesterly winds aloft
are transporting mid-upper level moisture across the western Gulf.


Currently, the pressure gradient across the basin remains fairly
weak and results in mostly gentle to moderate trades, with the
exception of moderate to fresh SE winds across the western
Caribbean, including also the Yucatan Channel and the Gulf of
Honduras. Moderate to locally fresh NE winds are also noted per
scatterometer data across the Windwrad Passage and downwind to
just SE of Jamaica. Weak high pressure building north of the area
will support mainly moderate to fresh winds across most of the
basin, with the exception of fresh to strong winds near the coast
of Colombia, and in the Gulf of Honduras at night. A weak cold front
extends across the Leeward Islands into the NE Caribbean generating
some shower activity. The front is forecast to drift SE and
gradually dissipate across the central Lesser Antilles by Friday.
Patches of low level moisture, embedded in the trade wind flow are
noted across the remainder of the area. A diffluent pattern aloft
is helping to induce convection over parts of Venezuela and
Colombia. SW flow aloft across the eastern Caribbean is advecting
some mid-to-upper level moisture from northern South America across
the eastern Caribbean into the Lesser Antilles.


Strong upper-level subsidence and implied dry air mass is seen on
water vapor imagery over Hispaniola. Shower activity will be
limited over the next 24-48 hours and mainly associated with the
trade wind flow. A surge of moisture is likely expected during the
upcoming weekend.


Main feature in the Atlantic is the low pressure system located
near 31N56W. Please, see Special Features section for details. A
1019 mb high pressure located near 26N74W dominates the Bahamas
and the SW N Atlantic. The high will remain nearly stationary over
the next 24 hours while weakenning. A cold front is forecast to
enter the forecast area W of 65W tonigh and move across the
forecast region on Thursday before stalling along 25N-26N W of 60W
by Friday morning. The remainder of the Atlantic is under the
infuence of a ridge. In the tropics, a surface trough extends
from 08N46W to 01N47W and is generating isolated showers while
moving W.

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