Tropical Weather Discussion
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AXNT20 KNHC 181733

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
132 PM EDT Wed Apr 18 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
1700 UTC.


The monsoon trough extends from the coast of Africa near 08N13W
to 03N13W to 02N24W. The ITCZ continues from 02N24W to 03N35W to
0N49W. Scattered to numerous moderate showers and thunderstorms
are ocurring along and within 150 nm south of the monsoon trough
east of 25W. Scattered showers and isolated thunderstorms are
occuring along and within 120 nm north of the ITCZ west of 35W.



SE return flow winds of 15-20 kt are occuring over the northwestern
Gulf and up to the Texas coast. Seas are 5 to 7 ft in this area,
with 2 to 4 ft seas elsewhere across the Gulf. No shower or
thunderstorm activity is noted, and none is expected through
Thursday due to very stable conditions. Visibility is expected to
remain unrestricted across the basin through Thursday.

A narrow high pressure ridge over the northern Gulf will gradually
weaken and shift eastward ahead of a cold front currently moving
southward through the southern Plains and southeastern United
States, resulting in the currently southeasterly flow becoming
northerly by Thursday morning over the northwestern Gulf, and becoming
northeast to easterly flow on Friday. The front will enter the northern
Gulf tonight or early Thursday and stall over southern Florida to
south Texas on Friday, before lifting back northward as a warm front
on Saturday ahead of yet another late-season cold front that will
be moving out of the southwestern U.S. and into Texas. The second
front is expected to move across the northwestern Gulf by late
Saturday, and reach from near the western Florida panhandle to the
SW Gulf Sunday night. A warm front will extend eastward along the
northeast Gulf coast out ahead of the cold front.


A few isolated light showers were occurring over the Gulf of
Honduras, and also to the south of the Mona Passage. Otherwise,
generally fair weather conditions and little or no shower activity
were noted eslewhere across the remainder of the Caribbean Sea.
Swells to near 8 ft continue east of Windward Islands, while brisk
easterly trade wind flow continues along and 150 nm north of the
coast of Venezuela and Colombia.

A weak surface trough located over Puerto Rico is expected to move
into the Mona Passage this afternoon, and become diffuse across
eastern Hispaniola by Thursday. Fresh to strong winds currently
over the southern Caribbean will continue through late week, and
expand north and westward into the southwestern Caribbean late Wed
through late Fri as high pressure builds to the north across the
Atlantc. These winds are expected to weaken Saturday afternoon,
before pulsing back up to fresh to strong Sat night into Sunday.


A frontal boundary near 31N63W extended southwestward to the
southern Bahamas and Turks/Caicos Islands. The southern portion of
the frotnal system has stall and weakened. Scattered showers and
isolated thunderstorms were occurring along and within 60 nm
southeast of the front to the east of 71W. Seas of 8 to 10 ft
continue north of 26N and west of front to 75W in NW swell. Seas
in open waters are 4 to 6 ft elsewhere, except 2 to 4 ft off
northeast Florida.

The southern portion of the front should dissipate this afternoon,
and gradually weaken northward through tonight, becoming diffuse
on Friday. The next cold front will move into the western Atlantic
from Florida late Thursday, reaching from Bermuda to south Florida
by late Fri, then stall from near 25N65W to the Straits of Florida
by late Sat. East winds will gradually increase to 20 kt over much
of the waters west of 65W.

Farther east, a 1030-mb high was located over the central Atlantic
near 33N44W. The tail-end of a dissiapting cold front was located
over the far east Atlantic from 21N21W to 29N29W. A large area of
NW swell with wave heights of 8-15 ft will accompany this front
covering a large portion of the area north of 20N and east of 45W
through Friday. Seas will gradually subside to below 8 ft Saturday
into Sunday.

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