[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191804
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Mon Apr 19 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.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal sections of Guinea
near 10N14W to 07N16W and to 04N20W. The ITCZ continues from
04N20W, to the Equator along 29W, and continuing along the
Equator at 34W.  Precipitation: widely scattered moderate to
isolated strong in clusters is from 07N southward from 40W
eastward. Isolated moderate to locally strong is elsewhere from
10N southward from 60W eastward.

GULF OF MEXICO...

A stationary front passes through 31N80W in the Atlantic Ocean,
to 29N82W in Florida, curving into the central Gulf of Mexico
near 26N90W, curving to 23N94W, and reaching the coast of Mexico
near  19N95W. The stationary front continues northwestward in
interior sections of Mexico to 24N100W. A surface trough is
within 60 nm to 180 nm to the southeast of the stationary front.
A second surface trough runs north-to-south, in the Yucatan
Peninsula. Precipitation: widely scattered moderate to isolated
strong is from 25N southward from 87W eastward. Isolated
moderate is elsewhere from 28N southward from 88W eastward.

A nearly stationary front extends from near Tampa Bay, Florida,
to 25N92W, to the western Bay of Campeche. Fresh to strong
winds, occurring to the west of this boundary in the
southwestern Gulf of Mexico, will continue to diminish today.
This front will remain nearly stationary into mid-week, before
reinforcing cool and dry air pushes the front into the far
southeastern Gulf of Mexico, from mid-to-late week.

CARIBBEAN SEA...

The Eastern Caribbean Sea Ashfall Advisory from six hours ago
has ended for the time being. Latest satellite analysis
indicates some faint volcanic aloft removed well to the west and
southwest of the volcano. The Ashfall Advisory has been in
effect for La Soufriere Volcano on the island of St. Vincent
near 13.3N 61.2W off and on for the last 8 days or so. The
volcano remains in an active state. Additional eruptions and ash
plumes are possible at any time. Mariners who are transiting the
nearby waters should exercise caution, and they are encouraged
to report volcanic ash to the National Hurricane Center by
calling 305-229-4424.

Comparatively drier air in subsidence is apparent in water vapor
imagery, from 66W eastward.

An Atlantic Ocean upper-level trough passes through 13N55W,
toward the eastern sections of Venezuela. The trough is
surrounded by the comparatively drier air. Upper-level NW wind
flow is moving toward Venezuela and Colombia, in general. An
upper level anticyclonic circulation center is in Honduras.

The GFS model for 500 mb shows: an anticyclonic circulation
center that is near 24N61W in the Atlantic Ocean. Anticyclonic
wind flow is covering the Caribbean Sea to the east of the line
that runs from SW Haiti to the coast of Venezuela along 68W. The
GFS model for 700 mb shows: an anticyclonic circulation center
is near 26N61W in the Atlantic Ocean. Anticyclonic wind flow is
covering much of the Caribbean Sea. Broad cyclonic wind flow
covers the SW corner of the Caribbean Sea from 14N southward
from 75W westward.

The monsoon trough is along 11N73W in northern Colombia, across
eastern Panama just to the north of the border with Colombia,
beyond 07N84W, into the eastern Pacific Ocean. Precipitation:
widely scattered moderate to isolated strong is within 150 nm to
the west of the line that runs from  10N79W, to 15N84W in
eastern Honduras.

Broken to overcast low-level clouds, and isolated moderate
rainshowers, cover the rest of the Caribbean Sea. The clouds and
isolated moderate precipitation are moving with the surface to
low-level wind flow.

A ridge extends to the north of the basin, across the Atlantic
Ocean, through the central Bahamas. The ridge will shift
eastward, in advance of a weak front moving across the Gulf of
Mexico. This will be allowing for trade winds to increase in
mainly the south central Caribbean Sea, through mid-week.
Looking ahead: The trade winds will diminish by late week, as
the high pressure shifts eastward, although fresh to strong
winds will persist off Colombia.

ATLANTIC OCEAN...

A stationary front passes through extends from a 1006 mb low
pressure center that is near 32N76W to 31N81W to beyond 29N82W
in Florida. Precipitation: scattered moderate to widely
scattered strong is within 240 nm to the south and southeast of
the 1006 mb low pressure center and stationary front, between
69W and 78W. Isolated moderate convection is elsewhere from 25N
northward from 64W westward.

A surface ridge extends from a 1026 mb high pressure center that
is near 35N26W  to 28N36W to 23N50W to 21N65W and to beyond the
coast of Cuba near 23N78W. Surface anticyclonic wind flow covers
the Atlantic Ocean away from the 31N81W-to-Florida 29N82W
stationary front southeastward.

The current weak frontal boundary will remain nearly stationary
off the coast of northeastern Florida, through Tuesday night, as
a ridge extends westward from the central Atlantic Ocean to
the central Bahamas. The ridge will slide eastward on Wednesday,
in response to a cold front that will move off the southeastern
U.S.A. coast. The front will reach from near 31N74W to Stuart in
Florida on Wednesday night, and from near Bermuda to the Straits
of Florida by late Thursday. The front is forecast to begin to
stall near 25N through Friday night, as high pressure builds
between northeastern Florida and Bermuda.

$$
mt/ja
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