[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111804
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Sun Apr 11 2021

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
1650 UTC.

...SPECIAL FEATURES...

Windward Islands Ashfall Advisory: La Soufriere volcano on the
island of Saint Vincent near 13.3N 61.2W is undergoing frequent
eruptions. Satellite imagery shows the volcanic ash plume
spreading well to the east and northeast of St. Vincent, roughly
in an area from 10N-18N between 40W-62W, which includes Barbados.
Violent volcanic eruptions may occur suddenly without warning.
Volcanic ash may be reaching the ocean surface east northeast of
St. Vincent. Mariners should exercise caution, and report
volcanic
ash or floating debris to the National Weather Service by calling
305-229-4424.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends southward from the coast of
Guinea-Bissau near 12N16W to 04N22W, where it transitions to the
ITCZ to 01N30W to 02S43W. Scattered moderate convection is
within 240 nm south of the ITCZ between 21W-26W.

GULF OF MEXICO...

A cold front is slowly moving east across the NW Gulf. As of 15
UTC the front stretches from the western edge of the Florida
Panhandle to northeast Mexico near 25N97W, and the latest
scatterometer pass revealed moderate N-NE winds behind the front.
Ahead of the boundary, a cluster of thunderstorms continues to
move across the NE Gulf and Northern Florida north of 27N and east
of 88W. With a rather potent upper-level trough located over the
eastern Gulf and ample available moisture in place at the low-
levels from persistent fresh southerly winds along with daytime
heating, expect additional clusters of strong to severe
thunderstorms to develop over the NE Gulf and over central
Florida. The main hazards associated with these storms are likely
to be wind gusts of 35-45 kt and frequent lightning. The storms
will propagate east-southeastward during the day.

Elsewhere in the Gulf, a 1006 mb low is along a surface trough
is located near 22N94W in the southwest Gulf. Gentle to moderate
winds are in the southern Gulf around the low. Seas across the
basin are 3-5 ft.

The cold front over the northern Gulf will move
eastward, reaching from north Florida to the east-central Gulf by
late tonight. It will weaken further to a trough as it reaches
the southeastern Gulf Mon and dissipates late Mon. An upper-
level trough will help generate scattered showers and
thunderstorms over most of the eastern Gulf waters today. Some of
this activity may contain frequent lightning and strong gusty
winds.

CARIBBEAN SEA...

See the Special Features section above for details on an Ashfall
Advisory issued for ongoing volcanic eruptions on St. Vincent.

The latest surface analysis depicts a rather weak pressure
gradient across the basin. ASCAT data shows fresh trades over
most of the basin, while fresh to strong east-southeast winds in
the Gulf of Honduras as well as the Yucatan Channel. Mainly fair
weather conditions are in place across the basin. Wave heights are
in the 3-6 ft range, except for slightly higher wave heights of
5-7 ft in the central Caribbean area and within the Gulf of
Honduras.

For the forecast, fresh southeast winds will continue over the
northwestern Caribbean through this afternoon, while fresh to
strong east to southeast winds continue in the Gulf of Honduras.
Winds will pulse to strong speeds over a small area near the coast
of Colombia during the afternoons and at night through Wed.
Elsewhere, generally moderate to fresh east winds will change
little through Thu night.

ATLANTIC OCEAN...

See the Special Features section above for details on an Ashfall
Advisory issued for ongoing volcanic eruptions on St. Vincent.

The latest scatterometer data shows fresh to strong southerly
winds west of 73W. Numerous showers and thunderstorms are moving
E-SE across the Florida Peninsula. Storms are currently offshore
northern Florida north of 26N and west of 76W. Storms will bring
frequent lightning and strong gusty winds to the coastal waters
between Florida and the Bahamas later today and tonight.

For the forecast, fresh to strong southerly winds east of
Florida will shift eastward through Mon ahead of a cold front
that will move off the southeastern U.S. coast tonight. The front
will reach from near 31N75W to east-central Florida early Mon,
from near 31N70W to the central Bahamas and to east-central Cuba
Mon evening and the southeast waters by late Tue. The front will
move east of the forecast waters on Wed as weak high pressure
builds in behind it. Another cold front is expected to cross the
northwest and north- central waters beginning Tue. Fresh to strong
southwest winds are expected to precede this front. Scattered to
numerous showers and thunderstorms, some strong to severe, are
expected to push off the Florida coast today.

Farther east, a large area of fresh to strong west winds
associated with a low pressure system north of our discussion
area continues to affect waters north of 26N between 27W-51W. Seas
are 11-17 ft in this area. Northerly swell from this system, with
seas in excess of 8 ft, is affecting most of the central Atlantic
north of 21N between 26W-63W. Fast-moving small cells of showers
and thunderstorms are seen rotating cyclonically in the southern
semicircle of this low. This activity is brushing the waters north
of 29N between 39W- 48W. Cold air instability aloft is helping to
sustain this activity. South of the low, weak surface trough is
analyzed from 30N30W to 15N62W. Upper-level diffluence to the east
of the northeastern portion of the surface trough is aiding an
area of scattered moderate convection east of the trough from
about 24N to 32N between 23W-31W. High pressure ridging and gentle
anticyclonic flow dominates the waters east of the trough.


$$
Mora
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