[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121755
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Mon Apr 12 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
1745 UTC.

...SPECIAL FEATURES...

Windward Islands Ashfall Advisory: La Soufriere volcano on the
island of Saint Vincent near 13.3N 61.2W is currently undergoing
frequent eruptions. Volcanic ash may be reaching the ocean
surface and low level visibility may be reduced. Mariners
traveling within the area 18N39W to 08N40W to 10N50W to 15N62W
to 17N45W to 18N39W are urged to exercise caution, especially
west of 50W where the densest ash is being observed. If mariners
encounter volcanic ash or floating volcanic debris, you are
urged to report the observation to the National Hurricane Center
by calling 305-229-4424.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends southward from the coast of
Sierra Leone near 08N12W to 03N20W, where overnight
scatterometer data indicates that it transitions to the ITCZ to
03N20W and to 01N35W to the coast of Brazil near 00N47W.
Scattered moderate mainly along the ITCZ from 04S-04N between
26W-34W and from 00N-03N between 36W-45W. Wave height range
between 4-6 ft with latest altimeter and ship obs data from
south of 18N to the Equator.

GULF OF MEXICO...

A weak cold front extends from South Florida south-southwest
to near 25N84W, where it transitions to a weakening stationary
front to 26N94W. An overnight ASCAT pass indicated gentle wind
speeds on both sides of the front. A surface trough extends 60
nm southeast of the cold front from 27N75W to 24N84W with showers
and thunderstorms extending across the Florida Keys into the
Florida Straits. A weak surface trough is located in the SW Gulf
of Mexico with its axis analyzed from 24N87W to inland Mexico at
17N91W. Wave heights are in the range of 3-5 ft across the Gulf
of Mexico, except for lower wave heights of 1-3 ft in the
southern Bay of Campeche.

The weak front will reach from the southeastern Gulf to the
central Gulf this afternoon and evening and to just SE of the
Gulf tonight. An upper-level shortwave trough, in combination
with a surface trough along South Florida, will continue to
bring scattered showers and thunderstorms over the Straits of
Florida today. Some of this activity may contain frequent
lightning and strong gusty winds. Another cold front will enter
the northern Gulf Wed, reach from north-central Florida to
southern Texas Thu and become stationary through Fri night.

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. Recent ASCAT data highlighted
moderate to fresh trade winds over the central Caribbean and
fresh to strong southeast winds in the Gulf of Honduras. It
revealed moderate trade winds elsewhere across the basin. Mainly
fair weather conditions are in place across the basin, except
for isolated shower and thunderstorm activity that is occurring
over the far southwestern Caribbean along the coast of Panama.
Wave heights are in the 4-6 ft range across most of the basin,
except up to 7 ft in some locations in the south-central
Caribbean near the Colombian low pressure near 10N75W.

For the forecast, moderate to fresh southeast winds will continue
over the far northwestern Caribbean through the period, pulsing
to strong speeds in the Gulf of Honduras. Pulses of strong NE to
E winds are forecast mainly along Colombia coastal waters during
the afternoons and at night through Thu. Northerly winds behind
a cold front that will move over the Bahamas will funnel across
the Windward Passage Tue night through Wed night supporting
fresh to locally strong NE winds. Fresh NE winds are also
expected over southern Cuba adjacent waters. Elsewhere,
generally moderate to fresh east winds will change little
through Fri 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 satellite imagery shows scattered moderate convection
ahead of the surface trough from 27N75W to 24N84W. A cold front
60 nm behind the trough extends from 30N75W to 26N79W and across
Florida into the Gulf of Mexico. The scattered moderate
convection extends from the Bahamas across the Florida Straits
into the Gulf. ASCAT data pass detects an area of fresh to
locally strong south to southwest winds from 22N to 31N and to
the east of 74W. A 1021 mb high pressure center is analyzed near
26N21W southeast of the Canary Islands and extends westward
across the central Atlantic to  A ridge extends to 22N64W. Light
to moderate anticyclonic winds prevail in this region. Wave
heights are 6-8 ft north of the Bahamas between 70W-77W.

For the forecast west of 65W, fresh to strong southwest winds NE
of the Bahamas will shift eastward today ahead of a cold front.
The front will reach from near 31N73W to the northern Bahamas
and to South Florida early this afternoon, from near 31N67W to
the southeastern Bahamas and to eastern Cuba by late tonight and
the southeastern waters on Tue. The front will move east of the
forecast waters on Wed as weak high pressure builds in behind it
and as another cold front approaches the far northwest waters.
This front will move across the water N and NE of the Bahamas
from late Wed night through Fri night. Fresh to strong southwest
winds are expected ahead of this front. Scattered showers and
thunderstorms will continue to move offshore the South Florida
coast into the Great Bahama Bank today.

A surface trough is analyzed west of the high from 26N30W to
19N46W and a second trough from 25N45W to 21N54W. Scattered
showers are seen with the first trough from 22N to 31N between
21W-34W. Seas range between 8 to 12 ft from 17N to beyond 31N
between 28W-40W. Northerly swell over the central Atlantic will
diminish today as the low moves toward the northeast and
weakens.

$$
MTorres
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