[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 032353
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
752 PM EDT Thu May 3 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 through the coastal
sections of Liberia, then continues SW to near 02N20W. The ITCZ
stretches from 02N20W to the Equator at 50W. Scattered moderate to
isolated strong convection is from the Equator to 03N between the
Prime Meridiam and 07W. Similar convection is also noted over
parts of Liberia, and from the Equator to 05N between 18W-24W.

...DISCUSSION...

GULF OF MEXICO...

A ridge extends westward along the Gulf coast to SE Louisiana,
and then continues southwestward to NE Mexico. Moderate to fresh
anticyclonic flow is noted across the Gulf waters. Scatterometer
data indicate fresh to locally strong easterly winds across the
Straits of Florida. These winds are the result of the pressure
gradient between the aforementioned ridge and a surface trough
moving slowly across the Bahamas. These winds will persist
tonight across the Straits of Florida and the SE Gulf, with seas
building up to 8-10 ft across the Straits of Florida. Doppler
Radar shows a few showers across the Florida Keys and the Straits
of Florida.

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.

CARIBBEAN SEA...

Persistent high pressure north of the area is supporting fresh to
strong trade winds across the south-central Caribbean, including
the Gulf of Venezuela, with seas to near 8 ft within 90 nm of
coast of Colombia. Moderate to locally fresh trades are noted
elsewhere. Increasing winds and building seas can be expected
across the waters E of the Lesser Antilles first, then across the
eastern Caribbean tonight into Fri due to the pressure gradient
between the ridge to the north and a surface trough moving across
the Bahamas. This weather pattern will keep relatively low winds
of 15 to 20 kt off the coast of Colombia, and 10 to 15 kt
elsewhere over the western Caribbean.

As of 1800 UTC, a surface trough extends over eastern Cuba and
Jamaica. This trough is helping to induce scattered showers and
tstms over parts of eastern Cuba, Jamaica, and near the southern
peninsula of Haiti. Moisture will remain high across easteran
Cuba, Jamaica and Hispaniola through Fri night, and begin to
increase over west-central Cuba, south Florida and the Florida
Keys Fri night into Sat, keeping the likelihood of scattered to
numerous showers and tstms. This unstable weather conditions will
be associated with a surface trough moving westward across the
Bahamas, reflection of a mid/upper-level low located near the
central Bahamas. This mid/upper level low is forecast to drift
southward across eastern Cuba on Fri, where it will remain on Sat,
then reach Jamaica on Sun. A fresh to strong SE wind flow will
follow the trough, transporting abundant tropical moisture.

ATLANTIC OCEAN...

A weakening stationary front extends from 31N52W to 26N70W. A
surface trough extends from this point across the SE Bahamas and
eastern Cuba. Water vapor satellite imagery indicates the presence
of a mid/upper level low over the central Bahamas. A diffluent
pattern aloft on the east side of the low is helping to support a
large area of multi-layer clouds with embedded showers and tstms.
This convective activity is affecting the SE Bahamas, the Turks
and Caicos Islands, and parts of eastern Cuba and Hispaniola.
Ship and buoy reports, along with recent scatterometer data
indicate fresh to strong winds on either side of the frontal
boundary, mainly from 22N-28N between 65W-71W. Gusty winds of 35
to 40 kt will be possible in some of the stronger thunderstorms.

The surface trough is expected to gradually develop into a broad
low pressure system and move WNW between the Bahamas and Cuba
during the next 48 hours, and be near southern Florida by early
Saturday. Active weather spawned by the instability of this large
and complex deep-layer low, along with abundant moisture drawn
northward in a fresh to strong SE wind flow, will result in
numerous showers and thunderstorms steadily developing and
overspreading across most of the Greater Antilles, Bahamas, Turks
and Caicos, and adjacent waters by Fri, and gradually spread
westward across the Straits of Florida and into the Florida
peninsula over the weekend. Fresh to strong NE winds are expected
ahead of the trough, and fresh to strong SE winds will follow the
trough, impacting mainly the waters S of 27N-28N and W of 65W.

The remainder of the Atlantic is under the influence of a 1030 mb
high pressure located near the Azores. 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
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