[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 042341
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
741 PM EDT Fri May 4 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 1800 UTC surface analysis and satellite imagery through
2315 UTC.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic ocean near the Sierra
Leone/Liberia border and continues to the Equator at 26W. The
Intertropical Convergence Zone stretches from 00N26W to 02S32W to
01S39W to NE Brazil near 02S45W. A cluster of moderate to isolated
strong convection is from 03N to 07N between 11W and 16W. Scattered
moderate to isolated strong convection is noted within about 120
nm S of the ITCZ axis W of 30W.

...DISCUSSION...

GULF OF MEXICO...

A surface ridge extends east to west from the western Atlantic
along the northern Gulf coast to eastern Louisiana, with a 1022
mb high pressure center over southern Georgia. Gentle to moderate
anticylonic flow is noted across the Gulf waters under the influence
of the ridge. A cold front is approaching the coast of Texas. It
is forecast to enter the NW Gulf late tonight, and dissipate from
southern Louisiana to southern Texas by Sat night.

Farther south, a thermal trough will develop over the northwest
coast of Yucatan during the evening, and drift westward across the
SW Gulf before dissipating later in the morning. A surge of fresh
to occasionally strong NE to E winds will accompany this trough.
This pattern will repeat each evening through the period.

For the forecast, moderate to fresh winds over the southeast Gulf
and the Straits of Florida will back more to the NE through early
Sat ahead of the trough moving from the western Atlc across
Florida. Scattered showers and thunderstorms will accompany the
trough as it moves into the eastern Gulf early Sun before stalling
and weakening. The ridge will weaken as well and high pressure
will shift west through the lower Mississippi Valley, allowing
moderate northerly flow and 2 to 4 ft seas through mid week.

CARIBBEAN SEA...

Scattered to numerous showers and tstms have flared up this
afternoon across eastern Cuba, and parts of Hispaniola and
Jamaica, including also the Windward Passage. This convective
precipitation is associated with a surface trough extending
across the SE Bahamas and eastern Cuba to near 18N75W, and a
prominent mid/upper cyclonic circulation center, currently
centered over eastern Cuba. Abundant tropical moisture combined
with atmospheric instability associated with the mid/upper level
low will provide more thunderstorm potential to parts of Cuba, the
Bahamas, Hispaniola and Jamaica on Sat.

Winds have increased across the eastern Caribbean in the wake of
the trough axis. Latest scatterometer data indicate fresh E-SE
winds across the eastern Caribbean, and moderate to locally fresh
NE winds in the lee of eastern Cuba ahead of the trough. Only
moderate winds are noted near the coast of Colombia. Fresh easterly
winds will prevail in the eastern Caribbean and tropical N Atlantic
waters on Sat. The trough will move westward reaching Florida on
Sat.


ATLANTIC OCEAN...

The main weather maker continues to be a mid/upper level cyclonic
circulation center that is on top of central Cuba, that is
supporting a surface trough that extends from 28N72W across
eastern Cuba to near 18N75W. The most recent scatterometer data
indicate fresh to strong E-SE winds of 20-25 kt E of the trough
axis to about 60W, with seas to 9 ft. Fresh to strong NE winds of
20-30 kt are ahead of the trough. The strongest winds are between
the trough axis and the Bahamas. Tropical moisture, transported
by the SE winds in the wake of the trough combined with the
mid/upper level low, continue to support scattered to numerous
showers across the Bahamas and the Turks and Caicos Islands.

The trough will sharpen and elongate as it moves westward,
reaching Florida this Sat, increasing the likelihood of showers
and tstms over South Florida and the Florida Keys. Doppler radar
shows now the first round of showers approaching SE Florida from
the NW Bahamas. Strong to near gale force winds will accompany
the trough, as well as numerous showers and scattered thunderstorms
across the Bahamas through Sat. Scattered thunderstorms are
possible across the Bahamas and adjacent waters into Sun as the
upper low slowly drifts south-southwestward. Winds and seas will
start to diminish Sun through early next week as through lifts
northward to off the northeast coast of Florida through Mon, and
the ridge weakens, but hold in place along roughly 28N/29N.

The remainder of the Atlantic is under the influence of a 1028 mb
high pressure located E of Bermuda near 32N56W. This system is
producing moderate to fresh trade winds across the deep tropics,
where seas are reaching 6 to 8 ft in NE to E swell.

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

$$
GR/MT
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