Tropical Weather Discussion
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472
AXNT20 KNHC 211650
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1150 AM EST Wed Feb 21 2018

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
1630 UTC.

...SPECIAL FEATURES...

Caribbean Sea Gale Warning: Strong high pressure over the western
Atlc and low pressure over South America are combining to maintain
a tight surface pressure gradient over the Caribbean. This
pattern is supporting winds reaching gale force strength along the
coast of Colombia from 10N to 13.5N between 73W and 77.5W. Wave
heights within the area of gale force winds are currently ranging
between 10 feet and 16 feet. This synoptic setup is expected to
remain in place through Fri morning. Low pres moving E from New
England will weaken the ridge over the western Atlc and allow the
gales to subside Sat and Sun. Please read the latest NHC High
Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for
more details.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through coastal sections of Sierra
Leone near 08N13W to 03N18W. The ITCZ continues from 06N16W,
crossing the Equator near 23W, to 02S28W, to near the coast of
Brazil near 03S38W. Convection: Scattered moderate and isolated
strong convection is present from 01N to 06N between 07W and 15W.
Scattered moderate convection is noted from 02S to 02N between
20W and 29W and from 04S to 00N between 29W and 39W.

...DISCUSSION...

GULF OF MEXICO...

Broad deep layer ridging extending SW from the western Atlc over
Florida to the SW Gulf dominates the basin. The ridging is
currently suppressing convection over all of the basin except
along the coasts of NE Texas and SW Louisiana. This convection is
associated with a frontal boundary that is stalling over southern
Texas. The front is expected to begin retreating northward on Thu
night.

The strong ridge of high pressure will support a dry weather
pattern over the Gulf for the next several days. Moderate to
fresh ESE to SE return flow will prevail basin wide during this
time frame. Winds could be locally strong over the Straits of
Florida and just N of the Yucatan Peninsula this afternoon.
Another weak cold front will move slowly into the far NW waters
on Sunday, then stall there Sunday night.

CARIBBEAN SEA...

Please read the SPECIAL FEATURES section for details concerning
the Gale Warning for the waters adjacent to the coast of Colombia.

A surface ridge passes across central Cuba, to 19N82W in the NW
corner of the area, to southern Costa Rica.

Strong high pressure centered N of Bermuda will maintain fresh-
to strong trade winds over the Caribbean Sea and the Tropical N
Atlantic waters through Friday. Winds will pulse to gale force off
the coast of Colombia during the nocturnal maximum. A shear line
sinking southward from 20N will augment winds and seas N of 15N
and E of 70W as it sinks slowly S during the next couple of days.
High pressure over the western Atlc will weaken Sat and Sun,
leading to diminishing winds and seas.

ATLANTIC OCEAN...

An upper level trough extends SW through 32N34W to 23N53W to
24N48W, to 18N62W. A cold front passes through 32N28W, to 24N36W
and 20N53W. A dissipating cold front continues from 20N53W to
19N65W. The front is transitioning into a shear line W of 50W.
Broken to overcast low level clouds and scattered rainshowers are
occurring along and up to 60 nm NE of this boundary.

Broad high pres will persist over the western Atlc through the
end of the week. The ridge will be weakened slightly on Sat and
Sun as low pres moves E from new England. Gentle to moderate winds
will generally prevail N of 25N with fresh to strong winds
generally expected S of 25N through Friday. Winds and seas will be
highest along and N of the shear line as it sinks slowly S.
Persistent deep-layer low pres centered over the eastern Atlc near
the Azores will weaken the subtropical ridge E of 40W, resulting
in moderate NE winds for the waters S of 25N for the next few
days. Winds and seas will be higher for the waters E of 40W and N
of 25N for the next couple of days.

For additional information please visit
http://www.hurricanes.gov/marine

$$
McElroy



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