[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 210005
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 PM EDT Wed Jun 20 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
2300 UTC.

...TROPICAL WAVES...

An Atlantic Ocean tropical wave is along 18W/19W from 11N. Broken
to overcast multilayered clouds and rainshowers cover the area
that is from 02N to 11N between Africa and 23W.

A second Atlantic Ocean tropical wave is along 27W/28W from 11N
southward, moving W 20 knots. Widely scattered to scattered
moderate rainshowers are in the ITCZ.

A third Atlantic Ocean tropical wave is along 38W/39W from 11N
southward, moving W 15 knots. African dust surrounds the wave
limiting convection. The wave is well depicted in the moisture
product. Widely scattered moderate rainshowers are in the ITCZ.

A fourth Atlantic Ocean tropical wave is along 56W/57W from 14N
southward, moving W 10 knots. Isolated moderate rainshowers cover
the area from 08N to 13N between 53W and 60W. The wave will move
across the eastern Caribbean from tomorrow Thursday afternoon
through Friday night. The associated moisture is forecast by the
GFS computer model to reach Puerto Rico on Friday.

A Caribbean Sea tropical wave is 70W/71W from the Dominican
Republic southward. widely scattered rainshowers are in the NW
corner of the Dominican Republic. Scattered moderate to isolated
strong rainshowers are in NW Venezuela and the Guajira Peninsula
of Colombia. Moisture and instability related to this wave will
affect Hispaniola today and Thursday, reaching eastern Cuba by
late Thursday.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal sections of Sierra
Leone near 08N13W to 06N27W. The ITCZ continues from 06N27W to
06N38W to 05N54W in French Guiana. Widely scattered moderate to
isolated strong rainshowers are from 02N to 09N between 19W and
42W. isolated moderate rainshowers are from 10N southward between
43W and 60W.

...DISCUSSION...

GULF OF MEXICO...

A 1005 mb low pressure centered inland in the Deep South of Texas
near 27N98W continues to produce a large area of showers and tstms
over the western Gulf coast. Similar convective activity is flared
up over the west-central Gulf, particularly N of 21N W of 95W.
This slow moving system will continue to deliver heavy rainfall
and flooding along the coast of Texas into Louisiana. A widespread
3 to 5 inches of rainfall is possible over this region through
Thu morning, with isolated pockets of heavier amounts expected.

A 1016 mb high pressure is analyzed over the eastern Gulf near
27N86W. The pressure gradient between the high pressure and the
low over southern Texas will support fresh SE winds in the NW Gulf
through this evening. Abundant tropical moisture will persist
across the northern Gulf, from Texas to Florida, through late
Thu.

Low pressure in southern Texas will support strong winds,
numerous showers and scattered thunderstorms over the NW Gulf this
evening. Winds and seas for the NW Gulf will subside tonight and
Thu as the low weakens. A surface trough will develop over the
Yucatan Peninsula each afternoon, then move westward across the SW
Gulf during overnight hours, accompanied by fresh east to
southeast winds.

CARIBBEAN SEA...

A tropical wave is moving across the eastern Caribbean. Another
tropical wave is forecast to reach the Windward Islands by Thu
morning. Please, see Tropical Waves section for details. Expect
increasing showers and isolated thunderstorms in association with
the passage of these tropical waves.

High pressure N of area is forecast to strengthen over the next
couple of days while moving westward. As a result, the trade winds
across the south-central Caribbean will strengthen on Thursday,
then expand in coverage across the basin this weekend. Strong
winds will also affect the Gulf of Honduras tonight, then return
Fri night through Sun night.

An upper-level trough extends from a cyclonic circulation located
over the western Atlantic near 27N65W to another cyclonic
circulation over the NW Caribbean. This feature is called a TUTT
(Tropical Upper-Tropospheric Trough) that extends from the
Atlantic into the Caribbean Sea during May to October. They are
cold-core systems that exist mostly above 500 hPa. They are also
sources of clouds and precipitation. Currently, a SW flow on the
SE side of this upper-level trough that also crosses eastern Cuba
is helping to induce some shower and thunderstorm activity over
the coast of Nicaragua and regional waters, just S of Hispaniola,
and over Puerto Rico and the Virgin Islands.

The Hispaniola tropical wave will support scattered showers and
isolated thunderstorms N of 16N between 65W and 75W tonight.
The 56W/57W tropical wave will bring showers and thunderstorms to
the Lesser Antilles Thu and Fri. Strong winds will affect the
Gulf of Honduras tonight, then return Fri night through Sun night.
Trade winds across the south-central Caribbean will strengthen on
Thursday, then expand in coverage across the basin this weekend.

ATLANTIC OCEAN...

An upper-level trough extends from a cyclonic circulation
centered near 27N65W to eastern Cuba. A surface trough is analyzed
from 28N60W to 27N70W to the NW Bahamas. Scattered showers and
tstms are noted S of the trough to about 20N between 60W and 70W.
A diffluent pattern aloft between the aforementioned upper-level
trough and an anticyclonic circulation located E of the Lesser
Antilles is helping to induce this convective activity.


A weakening trough extending ENE from Andros Island
to near 27N69W will dissipate tonight. High pressure over the
central Atlantic will build westward over the region through Sun
night. Fresh to strong E to SE winds will develop over the waters
S of 23N on Sat.

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

$$
MT
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