Tropical Weather Discussion
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AXNT20 KNHC 071752

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1252 PM EST Thu Dec 7 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
1530 UTC.



A cold front extends from the Tampa Bay area of Florida to 27N87W
then transitions to a stationary front that extends through a
1014 mb low centered near 25N93W to 18N95W. Strong high pressure
building NW of the frontal system over the Gulf of Mexico supports
gale force winds over the NW Gulf today. The gale force winds
will spread to the SW Gulf this afternoon, with peak winds of 40
kt expected this evening and then again on Fri morning as a reinforcing
push of cooler and drier air moves into the region. Wave heights
will peak near 16 ft today, and 19 ft on Monday. Please read the
latest NWS High Seas Forecast under AWIPS/WMO headers
MIAHSFAT2/FZNT02 for more details.


The Monsoon trough extends across the Africa coast near 09N14W and
extends to the E Atlantic near 07N20W. The Intertropical
Convergence Zone axis extends from 07N20W to 04N25W to 04N40W to
03N46W. A surface trough extends from 08N37W to the ITCZ axis near
05N41W. Scattered moderate convection is from 02N to 06N between
the Prime Meridian and 33W, and from 05N to 11N between 36W and


A cold front extends from the Tampa Bay area of Florida to 27N87W
then transitions to a stationary front that extends through a
1014 mb low centered near 25N93W to 18N95W. Strong high pressure
building NW of the frontal system supports gale force winds over
the NW Gulf today. Please refer to the special features section
for more details on this gale. Strong to near gale force winds are
elsewhere NW of the front. Scattered showers are within 60 nm of
either side of the front. The combination of low to mid level
moisture and the subtropical jetstream is supporting numerous
showers over the NW and N central Gulf. Mainly gentle to moderate
winds are south of the front. Over the next 24 hours the low and
front will move very slowly to the SE. Thereafter, the upper
trough supporting the frontal system will dig farther south, and
allow the low to accelerate NE and bring the cold front across the
remainder of the Gulf basin Friday afternoon and Friday night.


Deep moisture over the SW Caribbean is interacting with diffluent
flow aloft and a surface trough from 16N83W to 10N82W to support
scattered moderate convection from 11N to 20N W of 81W. The tail
end of a dissipating cold front extends from the central Atlantic
to the Lesser Antilles near 16N61W to 16N67W, supporting scattered
showers and isolated thunderstorms within 90 nm of the frontal
boundary. Generally fair weather covers the remainder of the
Caribbean. Atlantic high pressure supports strong winds S of 18N
between 68W and 80W over the central Caribbean. Mainly moderate to
fresh NE to E trades are over the remainder of the basin. The
strong winds over the central Caribbean will diminish through the
weekend as the high pressure north of the region shifts NE, while
a frontal system crosses the Gulf of Mexico. This cold front will
reach the NW Caribbean early Saturday and cross the NW Caribbean
through Saturday night with strong to near gale force winds behind
the front. Gale force winds will then be possible along the coast
of Nicaragua Sunday and Sunday night as the front surges
southward across the area.


Isolated thunderstorms are expected over the higher terrain this
afternoon and evening due to daytime heating. This activity will
weaken overnight. This afternoon thunderstorm pattern is expected
to repeat again Friday.

A cold front has exited the Florida coast and extends from 31N78W
to 29N81W. A pre-frontal trough extends from 31N75W to 28N79W.
Fresh to strong northerly winds and scattered showers are
confined NW of the front. Elsewhere over the SW N Atlantic, a
1023 mb high is centered near 29N61W supporting generally fair
weather. Farther east, a cold front enters the area of discussion
near 31N34W and extends to 22N40W to 16N50W. A pair of surface
troughs surround the northern portion of this front. The
westernmost trough is the reflection of an upper low and extends
from 31N40W to 25N42W. The easternmost trough is a pre-frontal
trough that extends from 29N32W to 21N37W. Scattered moderate
convection with numerous thunderstorms are within 210 nm east of
the cold front N of 23N. Scattered thunderstorms are between the
western trough and the cold front N of 26N. Scattered showers and
thunderstorms are also within 90 nm of either side of the cold
front W of 55W. Over the next 24 hours the cold front will stall
off of Florida, before accelerating SE on Saturday. A new surface
low pressure area will develop under the upper low over the
central Atlantic and will move SW over our area of discussion this

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