[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121023
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Mon Jul 12 2021

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 31N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through
1010 UTC.

...TROPICAL WAVES...

An Atlantic tropical wave is along 36W from 12N southward and
moving W at 15 to 20 kt. Scattered moderate convection is seen
from 07N to 10N between 35W and 37W.

Another weaker Atlantic tropical wave is near 47W from 11N
southward and moving W near 15 kt. No significant convection is
found near this wave.

A robust Caribbean tropical wave extends from Haiti to northeast
Colombia, moving W at 10 to 15 kt. Aided by upper- level
divergent winds, scattered to numerous showers and thunderstorms
are present across the Turks and Caicos Islands, Dominican
Republic and the northeastern Caribbean south of Puerto Rico and
the Virgin Islands.

Another Caribbean tropical wave over Honduras, Nicaragua and
Costa Rica is moving W at 10 to 15 kt. No significant convection
is observed over the Caribbean associated with this tropical wave.
This wave is entering the E Pacific and will be included in the
Pacific Discussion.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the African coast near the
Senegal/Guinea-Bissau border at 12N16W to 08N30W to 07N35W.
The ITCZ then continues from 07N35W to 07N45W. In addition to the
convection listed in the Tropical Wave section, scattered
moderate to isolated strong convection is evident near the
monsoon trough from 06N to 14N between 15W and 30W, and from
Scattered moderate convection is evident from 07N to 10N between
40W and 45W.

...GULF OF MEXICO...

A surface ridge extends west-southwestward from northern Florida
across the northern Gulf to South Texas. This pattern is
supporting mostly gentle to moderate E to SE winds over the basin,
except for fresh NE to E winds over the eastern Bay of Campeche
and off the west coast of the Yucatan Peninsula. Seas are 2 to 4
ft in most areas, except 3 to 5 ft in the eastern Bay of Campeche.
A few showers and thunderstorms are noted over the Straits of
Florida, and over the warmer Loop Current of the south-central
Gulf. No other significant shower or thunderstorm activity is
evident at this time across.

For the forecast, the gentle to moderate SE winds will persist
across most of the Gulf, south of the surface ridge. The ridge
will lift just north of the area through today, maintaining gentle
to moderate winds and slight to moderate seas through Fri. The
exception will be fresh to occasionally strong winds off the
northwest Yucatan Peninsula and eastern Bay of Campeche during
overnight hours through mid week, related to the surface trough
that forms during the late afternoon each day.

...CARIBBEAN SEA...

Please refer to the Tropical Waves section above for details on
convection in the basin.

Scatterometer data from 0430 UTC depicted fresh to strong trade
winds across the south-central Caribbean, as well as over the Gulf
of Honduras and into the northern approaches of the Windward
Passage, where concurrent altimeter data showed wave heights near
8 ft. Maximum seas are estimated to be 9 ft in the south-central
Caribbean, mainly off the coast of Colombia, and to 8 ft over the
eastern Caribbean where fresh tradewinds follow the tropical wave
moving across the basin. Moderate E to SE winds and 3 to 5 ft seas
are noted over the northwest Caribbean. In addition to the
convection mentioned in the Tropical Wave section, scattered
moderate to isolated strong convection is ongoing off eastern
Panama.

For the forecast, the tropical wave reaching from Haiti to
northeast Colombia will move quickly across the central Caribbean
through today, and then move west of the basin into mid week. High
pressure centered north of the region will build in the wake of
the tropical wave, supporting strong tradewinds and building seas
into Wed, including strong nocturnal NE winds across the Windward
Passage Tue night into Wed. Winds and seas will diminish through
Fri.

...ATLANTIC OCEAN...

Please see the Tropical Waves and Monsoon Trough/ITCZ sections
above for information on convection across the basin.

A surface ridge extends from the central Atlantic across Bermuda
to the central Florida coast. This pattern is supporting mostly moderate
to fresh tradewinds south of 25N west of 35W with 6 to 9 ft seas,
and gentle to moderate E to SE winds north of 25N west of 35W with
3 to 5 ft seas over open waters. Strong E winds are noted of
Hispaniola toward the approaches to the Windward Passage, with
seas near 8 ft. Divergence aloft associated with an upper low now
centered over Grand Bahama Island is supporting clusters of
scattered moderate to isolated strong convection over the Cay Sal
area of the Bahamas and across the southern Bahamas and Turks and
Caicos Islands.

For the forecast, the surface ridge will lift northward to along
32N through Tue. The tropical wave over Haiti will move quickly
westward across the central Caribbean and bring a surge in wind
and waves to the Atlantic waters north of Hispaniola and Cuba and
across the Turks and Caicos Islands and southern Bahamas late
today and Tue. Strong winds will continue to pulse off Hispaniola
and into the Windward Passage Tue night into Wed. Winds and seas
will diminish across the region through Fri as the high pressure
weakens.

Farther east, north of 27N east of 35W, fresh to strong NE winds
and 5 to 8 ft seas are following a westward moving trough
analyzed from 25N to 30N between 35W and 38W. South of 27N east of
35W gentle to moderate N to NE breezes and 3 to 5 ft seas are
evident.

$$
Christensen
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