Tropical Weather Discussion
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AXNT20 KNHC 181042

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
642 AM 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 0600 UTC surface analysis and satellite imagery through
1030 UTC.


The monsoon trough extends from the coast of Africa near 08N13W
to 03N25W. The intertropical convergence zone continues from that
position to the coast of Brazil near 03N51W. Scattered moderate
convection is within 90 on either side of the ITCZ between 25W
and 35W.



A surface ridge extending from southwest Florida to the Texas
coast is maintaining generally fair weather over the region. A
few platforms over the northwest Gulf continue to report sea fog
with visibilities 4 to 6 nm, but otherwise visibilities remain
unrestricted and 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 is maintain moderate to fresh
trade winds over the south central Caribbean, and gentle to
moderate E to SE winds over the northern Caribbean. An
altimeter satellite pass from 23 UTC indicated seas in excess of
8 ft off Colombia, an indication trade winds are stronger off
northeast Colombia, and will possibly reach near gale force
through early morning due to the added effect of drainage flow.
Seas are 2 to 4 ft in the northwest Caribbean, and 4 to 6 ft
Regional radar in the eastern Caribbean shows a few small showers
in the trade wind flow over the Windward Islands, 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 31N50W to 27N63W to 30N70W will exit
east of the area later today. While strong winds are no longer
evident north of the front, recent buoy observations and
altimeter satellite data indicate seas 8 to 11 ft, likely in NW
swell. Elsewhere, 1019 mb high pressure is centered near 27N70W,
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, 1023 mb high pressure centered near
29N35W 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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