Atlantic Tropical Weather Discussion (Text)

AXNT20 KNHC 120512

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 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 0000 UTC surface analysis and satellite imagery through 
0430 UTC.


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 18N35W to 14N55W to 13N62W to 10N56W 
to 06N37W to 18N35W are urged to exercise caution. The densest 
ash is west of 48W. If mariners encounter volcanic ash or 
floating volcanic debris, you are urged to report the 
observation to the National Hurricane Center by calling 


The monsoon trough axis extends southward from the coast of 
Senegal near 13N17W to 05N21W. The ITCZ continues from 05N21W to 
00N30W to 00N45W. Scattered moderate and isolated strong 
convection is from 05S-02N between 18W-32W.


A weak cold front extends from a 1005 mb low pressure near 
Apalachicola Florida to 26N90W to 25N95W, then stationary to a 
1000 mb low pressure inland over Mexico near 25N101W. A recent 
ASCAT pass shows gentle wind speeds on both sides of the front. 
The cold front will stall out from central Florida to the Bay of 
Campeche today and dissipate by tonight. A squall line oriented 
east-west off the coast of Naples Florida is producing numerous 
moderate and scattered strong convection from 25N-27.5N between 
81W-86W, as of 0430 UTC. During the last 6 hours, the squall 
line has been moving slowly southeastward at 10 kt while 
changing little in intensity. It has been producing frequent 
lightning and gusts to 40 kt. This activity is being enhanced by 
an upper-level shortwave trough. Expect the thunderstorms over 
the eastern Gulf to weaken later this morning. Scattered 
moderate showers extend eastward from the squall line over South 
Florida. Elsewhere, a weak surface trough is located in the SW 
Gulf of Mexico with axis extending from 25N90W to 21N94W. Seas 
are 3-5 ft across the Gulf of Mexico, except 1-3 ft in the 
southern Bay of Campeche.


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. A recent ASCAT pass shows fresh 
trades over the central Caribbean and Gulf of Honduras, with 
moderate winds elsewhere. Mainly fair weather conditions are in 
place across the basin, except for a few scattered showers off 
the coasts of Costa Rica and Panama. Wave heights are in the 4-6 
ft range across most of the basin, except locally up to 7 ft in 
the south-central Caribbean.

For the forecast, fresh southeast winds are expected over the 
northwestern Caribbean through the 5-day forecast period, with 
fresh to strong east to southeast winds 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 
Thu. Elsewhere, generally moderate to fresh east winds will 
change little through Fri night. 


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

A surface trough extends from 30N74W to the N coast of Cuba near 
23N79W. Upper-level diffluence to the east of Florida is 
enhancing a cluster of moderate to strong thunderstorms 
currently impacting the central Bahamas area, as of 0400 UTC. 
This cluster of storms should weaken later this morning. 
Scattered moderate showers and isolated tstorms are occurring 
elsewhere west of 70W from 23N-32N. ASCAT shows fresh to locally 
strong S to SW winds to the east of Florida, mainly north of 26N 
extending to 70W. A 1016 mb high pressure is centered near 
28N62W. The high extends a ridge axis to the SE Bahamas. ASCAT 
shows moderate anticyclonic winds to the east of the SE Bahamas. 
Seas are 6-8 ft north of the Bahamas between 70W-77W.

For the forecast west of 65W, fresh to strong southwest winds 
east of Florida will shift eastward today ahead of a cold front 
that will move off the southeastern U.S. coast this morning. The 
front will reach from near 31N75W to east-central Florida by 
late this morning and from near 31N70W to the central Bahamas to 
east-central Cuba this evening. The front will move east of 65W 
on Wed as weak high pressure builds in behind it over the 
western Atlantic. Another cold front is expected to cross the 
waters to the north and northeast of the Bahamas on Tue. Fresh 
to strong southwest winds are expected to precede this front.

Farther east, a surface trough extends from 26N45W to 23N57W, 
with isolated showers near its axis. Another surface trough 
extends from 27N30W to 16N52W. Upper-level diffluence is 
sparking scattered moderate showers and tstorms along and east 
of this surface trough axis, mainly east of 42W from 20N-29N. A 
recent ASCAT pass shows fresh to strong W winds north of 29N 
between 30W-42W associated with a low pressure system north of 
our discussion area. Seas are 10-12 ft in this area. Northerly 
swell over the central Atlantic will diminish today as the low 
moves NE and weakens. A 1020 mb high is located over the Canary 
Islands. A surface ridge with light to gentle winds extends from 
this high to 18N47W to 22N59W.


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Page last modified: Monday, 12-Apr-2021 05:13:03 UTC