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Atlantic Tropical Weather Discussion

AXNT20 KNHC 131717

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Tue Apr 13 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.


Windward Islands Ashfall Advisory: An Ashfall Advisory remains
in effect for La Soufriere Volcano that is on the island of St. 
Vincent near 13.3N 61.2W. The volcano currently is undergoing 
light emissions from its summit. It is possible that ash that was 
released earlier may be reaching the surface of the ocean, and 
low-level visibility may be reduced. Mariners who are transiting 
the waters under the emitted ash advisory should exercise caution.
Mariners who encounter volcanic ash or floating volcanic debris, 
are urged to report the observation to the National Hurricane 
Center, by calling 305-229-4424.


The monsoon trough axis passes through the coastal sections of 
Guinea near 09N13W to 04N22W, where scatterometer data indicates 
that it transitions to the ITCZ near 42N22W and to the delta of 
the Amazon river near 00N49W. Scattered moderate to isolated 
strong convection is within 00N to 05N between 22W to 34W and 
scattered showers along the ITCZ between 34W to 49W. Seas range 
between 4 to 6 ft within 200 nm on either side of both boundaries.


Broad surface anticyclonic flow covers the Gulf of Mexico. Broken
to overcast low clouds are along and inland the Texas coastal 
plains. Patches of fog, some dense, are over the NW Gulf. Latest 
ship obs and altimeter data show wave heights ranging between 2 to
4 ft across the basin. 

For the forecast, weak high pressure has settled in over the 
area. This high pressure will shift eastward through Wed in 
response to an approaching cold front. The cold front will move 
across the northern Gulf Wed night, reach from north-central 
Florida to southern Texas Thu and become stationary and weaken 
through Fri night. Mainly moderate northeast to east winds will 
follow in behind the front. A stronger cold front is expected to 
move over the NW Gulf late Fri night, and reach from north-central
Florida to the west- central Gulf by late Sat. Fresh to strong 
northeast winds will follow in behind this front.


A cold front extends from the western Atlantic across central 
Cuba into the western Caribbean Sea to 21N84W. The front is 
weakening with a few showers still lingering near the boundary. 
Further south, scattered showers are moving across Honduras and 
Nicaragua east to Hispaniola. Moderate easterly trades prevail 
with wave heights between 2 to 4 ft across the basin. 

On the forecast, moderate to fresh SE winds will continue over 
the far NW Caribbean through the period, except for pulsing strong
winds in the Gulf of Honduras. Elsewhere, generally moderate to 
fresh trade winds will persist through this week.


A cold front is analyzed from near 30N57W to across central Cuba.
Broken to overcast multilayered clouds, with scattered moderate 
convection are noted to the east of the front from 23N to 32N 
between 47W-60W. Fresh to strong southwest winds are noted ahead 
of the front with the latest ASCAT pass. Further east, a 1023 mb 
high pressure centered near 25N33W remains in control across the 
east with broad anticyclonic flow covering north of 26N. 

An Ashfall Advisory is in effect for La Soufriere Volcano on the 
island of St. Vincent near 13.3N 61.2W. Mariners transiting the 
Tropical N Atlantic waters south of 15N between 43W-55W should be 
aware of the possibility for the existence of volcanic ash.

For the forecast, the cold front will move eastward and pass east
of the forecast waters on Wed. A secondary cold front or low 
pressure trough will cross the northern waters later today through
early Wed, with strong winds and building seas expected N of 27N 
and E of 75W. Yet another cold front will move off the 
southeastern U.S. coast later this week and over the northern 
offshore waters Thu night and Fri, then stall north of the Bahamas
this weekend.