Tropical Weather Discussion
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AXNT20 KNHC 172321

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
721 PM EDT Mon Apr 17 2017

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
2300 UTC.


A gale force low is centered over the central Atlantic near
32N45W. Over the discussion waters, gale force winds are N of 28N
between 42W-52W. Very large seas of 17-25 ft can be found
coincident with the area of gale force winds. Winds are forecast
to diminish below gale later this evening. Please refer to the
high seas forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC
for more details.


The monsoon trough extends across the western Africa coast near
06N10W and continues to 03N20W. The intertropical convergence zone
continues from 03N20W to 00N44W to 01S48W. Scattered moderate
convection is S of the monsoon trough from 03N-05N between 08W-
16W. Widely scattered moderate convection is along the ITCZ from
01S-03N between 38W-46W.



A 1025 mb high is centered over the W Atlantic near 30N67W with a
surface ridge extending across northern Florida to the northern
Gulf of Mexico along 30N. 10-20 kt E to SE flow is over the Gulf
with strongest winds over the Straits of Florida. An embedded
surface trough is over the SW Gulf from 23N95W to 17N93W. Some
isolated showers may be possible in the vicinity of the trough.
Elsewhere, radar imagery shows isolated thunderstorms over the SE
Gulf including the Straits of Florida. Scattered showers and
thunderstorms are inland over S Louisiana and Mississippi, and
along the Texas coast W of 95W. In the upper levels, a broad ridge
is over the Gulf with the axis just to the E along 80W. Upper
level moisture is over most of the Gulf. Ongoing convection will
persist during the next few hours, then should diminish somewhat
after sunset with the loss of daytime heating. Little change in
marine conditions is expected during the next 48 hours, with a
nocturnal surge of 20-25 kt winds expected W of the Yucatan
Peninsula each night.


Mainly 10-20 kt tradewinds are over the Caribbean Sea, except
pulsing and local 20-25 kt winds NW of the coast of Colombia,
across the approach to the Windward Passage, and S of Hispaniola.
Scattered moderate to strong convection is developing from
western Colombia to across Panama and southern Costa Rica.
Additional afternoon convection developed along coastal portions
of the remainder of the Caribbean. In the upper levels, a broad
ridge is over the Caribbean Sea with axis extending from the SE
Caribbean to across Hispaniola. Strong subsidence is over portions
of the NW Caribbean behind a trough which extends roughly along
81W. Expect little change over the next 48 hours.


Scattered showers and isolated thunderstorms developed during the
afternoon with daytime heating, supported by an approaching upper
trough to the west, and with upper level diffluence which has
been over the island and is now retreating. Activity should
diminish shortly with the loss of daytime heating, with similar
conditions possible tomorrow.


A 1025 mb high is centered over the W Atlantic near 30N67W. A
gale force low is centered over the central Atlantic near 32N45W.
Please see the special features section above for more information
on the associated gale warning. A cold front wraps into the low
extending into the discussion waters from 32N36W to 20N41W to
15N60W. Scattered moderate convection is N of 25N within 180-240
nm ahead of the front. In the upper levels, a large upper level
low is centered directly over the gale force surface low with a
ridge aloft building in its wake between 50W-55W. The surface low
is forecast to move SE during the next 24 hours, reaching 31N44W
by Tuesday afternoon. Also expect the associated Atlantic cold front
to drift E while weakening.

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