[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 150536
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Thu Jul 15 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 0000 UTC surface analysis and satellite imagery through
0500 UTC.

...TROPICAL WAVES...

A new tropical wave is added to the 0000 UTC analysis/surface map
near the west coast of Africa along 17W/18W based on satellite
imagery, the Hovmoller Diagram that shows the westward propagation
of the wave, and the Tropical Wave Diagnostics. Scattered moderate
convection is noted near the southern end of the wave axis from
06N-10N between 12W-18W.

A tropical wave is in the Atlantic Ocean along 35W from 15N
southward, moving W at around 15 to 20 kt. Scattered moderate
convection is seen behind the wave axis from 09N-12W between
30W-34W. The northern portion of the wave is surrounded by SAL.

Another tropical wave is in the Atlantic Ocean near 58W from 15N
southward crossing near the Suriname/Guyana border. It is moving
W at around 15 kt. The wave is helping to induce some convective
activity over parts of Suriname and southern Guyana. Moisture
associated with this wave will reach the Windward Islands today
increasing the likelihood of showers.

A tropical wave is over the eastern Bay of Campeche and SE Mexico
along 92W extending into the eastern Pacific region. It is moving
W at around 10 to 15 kt. The wave is generating scattered moderate
convection over the eastern Bay of Campeche, and parts of SE Mexico
and Guatemala. This tropical wave could help to develop a tropical
cyclone on the eastern Pacific region through five days.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic Ocean from Guinea-Bissau
near 12N16W to 09N34W. The ITCZ continues from 09N37W to 07N55W.
Scattered moderate convection is observed from 05N-10N between
25W-30W, and from 05N-08N between 46W-55W.

GULF OF MEXICO...

A ridge over the SE of United States extends into the Gulf waters.
Gentle to moderate E-SE flow prevails across most of the basin
based on recent scatterometer data. Seas are mainly in the 2 to 4
ft range across the Gulf. Scattered showers and thunderstorms are
over the Bay on Campeche in association with the above mentioned
a tropical wave currently moving across the area. Similar convective
activity is also noted over west-central Florida and coastal waters,
and in the Florida Big Bend.

For the forecast, a ridge will prevail across the Gulf region
through the forecast period and will support mainly gentle to
moderate E to SE winds. A surface trough will develop each day
over the Yucatan peninsula and shift westward into the SW Gulf.
This will support fresh NE to E winds off the northwest Yucatan
Peninsula and eastern Bay of Campeche during the overnight hours
through tonight.

CARIBBEAN SEA...

An upper level trough extends from the Atlantic Ocean, across
Hispaniola into the south-central Caribbean. Dry, subsident
northerly flow aloft is suppressing showers and thunderstorms
across much of the central and western Caribbean Sea. Shallow
moisture embedded in the trade wind flow is noted across the
eastern Caribbean producing isolated to scattered passing showers.

Recent satellite-derived wind data provide observations of fresh
to strong trade winds over the south-central Caribbean and in the
vicinity of the Gulf of Honduras. Moderate trades prevail
elsewhere, with fresh NE winds across the Windward Passage. Seas
are mainly in the 4 to 6 ft range across the basin, except 8 to
10 ft in the south-central Caribbean based on an altimeter pass.

For the forecast, high pressure north of the region is supporting
fresh to locally strong tradewinds in the south-central Caribbean
and in the Gulf of Honduras. These conditions will prevail in the
south-central Caribbean through Fri and then increase in areal
coverage reaching Hispaniola adjacent waters Fri night through Mon
night as high pressure builds again N of the Caribbean Sea. Moderate
to fresh winds in the lee of Cuba and in the Windward Passage
will diminish this morning.

ATLANTIC OCEAN...

Two tropical waves are moving westward between the west coast of
Africa and the Lesser Antilles. Please refer to the Tropical Waves
section above for details.

Gentle to moderate anticyclonic wind flow covers most of the Atlantic
forecast waters. Moderate easterly winds are noted over the Bahamas
as well as just N of Hispaniola, including approaches to the
Windward Passage. Fresh to strong N-NE winds are occurring between
the Canary Islands due to a locally tight pressure gradient.

A pair of surface high pressure centers are just north of the area,
one of 1024 mb located mid-way between Bermuda and the coasts of
South Carolina and Georgia, and the second one of 1025 mb over the
central Atlantic near 32N46W. Seas of 3 to 6 ft dominate the waters
west of 30W. Seas are 6 to 9 ft near the fresh to strong winds
off the coast of Africa.

A large upper-level trough extends from 31N57W to Hispaniola. The
surface reflection of this upper level trough is analyzed as a
trough that extends from 29N61W to 22N63W. A few showers are near
the trough axis that is well defined on scatterometer data.

For the forecast for the waters west of 65W, a ridge will continue
to dominate the SW N Atlantic while the surface trough will drift
westward W of 65W through Sat. By Sat night, the Bermuda-Azores
high is forecast to strengthen, extending a ridge westward over
Florida and the SE of United States.

$$
GR
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