Tropical Weather Discussion
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AXNT20 KNHC 182351

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
751 PM EDT Sun Mar 18 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
2345 UTC.


The monsoon trough extends from the coast of Africa near 08N13W
to 04N20W. The intertropical convergence zone continues from that
position to 03N30W to the coast of Brazil near 03N51W. Scattered
moderate convection is within 90 nm either side of the ITCZ
between 23W and 38W.



A surface ridge extending from southwest Florida to the Texas
coast is maintaining generally fair weather over the region.
There is no significant rain or shower activity. Winds are nearly
calm over the northeast Gulf near the center of the high pressure
with gentle to moderate southeast winds elsewhere. Seas are 1 to
3 ft in the eastern Gulf, and 3 to 5 ft in the western Gulf.

The ridge over the northern Gulf will shift E through tonight
ahead of a cold front moving off the Texas coast Mon. The front
will extend from the Florida Big Bend area to Veracruz Mexico
early Tue, just as a reinforcing push of cold air moves off the
Texas coast. The reinforcing front overtakes the first front late
Tue, accompanied by strong winds and building seas over the
northern Gulf. The merged front sweeps southeast of the Gulf by
early Wed. Winds and seas diminish across the Gulf through late
Wed as high pressure follows the front across the northern Gulf.


The undersea volcano Kick`em Jenny, located north of Grenada near
12.18N 61.38W, is in a state of unrest. The government of Grenada
advises mariners to observe a 5 km/ 3.1 nm exclusion zone around
Kick`em Jenny. Please see for further information.

High pressure east of the Bahamas and a low over N Colombia is
tightening the surface pressure gradient and maintaining moderate
to fresh trade winds over the south central Caribbean, and gentle
to moderate E to SE winds over the northern Caribbean. 25 kt winds
and seas of 8 to 9 ft are off the coast of N Colombia. Scattered
showers in the tradewind flow are S of Jamaica, but otherwise no
significant rainfall is noted.

High pressure north of the region will continue to support fresh
to locally strong trades across the south central Caribbean the
next several days, except increasing to near gale force along the
northwest coast of Colombia during the overnight hours. A
weakening cold front will pass through the Yucatan Basin late Tue
night. The pressure gradient will tighten ahead of the front,
allowing fresh to strong E to SE winds off the central coast of
Honduras by Mon night.


A cold front extending from 31N44W to 25N59W will dissipate over
our area tonight. Seas are 8 to 11 ft in NW swell in vicinity of
the front. Elsewhere, 1016 mb high pressure is centered near
23N76W, maintaining light to gentle breezes from 22N to 28N, with
fresh SW winds north of 28N.

The SW winds north of 28N will increase tonight ahead of another
front moving across the waters north of 28N Mon. Southerly winds
will increase to fresh to strong off northeast Florida and north
of the Bahamas late Mon, then increasing further to near gale to
gale force north of 28N with building seas late Tue through Wed
as low pressure moves off the Carolina coast. A trailing cold
front will sweep eastward, reaching from Bermuda to eastern Cuba
by Wed night. Looking ahead, the front will drift east through
late week, with 7 to 9 ft NW swell propagating across most of the
open waters east of 55W.

Over the eastern Atlantic, 1024 mb high pressure centered near
30N27W is maintaining gentle to moderate flow over the subtropics
and moderate to fresh trades over the deep tropics. Persistent
long period NW swell continues to propagate into the region from
the north central Atlantic, maintaining 8 to 12 ft seas mainly
east of 55W, as noted in recent altimeter satellite passes. An
upper trough reaching from roughly the Canary Islands through the
Cabo Verde Islands to 06N30W is interacting with trade wind
convergence in the lower levels to support scattered showers and a
few thunderstorms within 90 nm of the intertropical convergence
zone between 25W and 35W.

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