[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291754
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
155 PM EDT Wed Jul 29 2020

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.

...SPECIAL FEATURES...

Potential Tropical Cyclone Nine is centered near 16.2N 64.7W at
29/1800 UTC, or about 90 nm S of St. Croix, moving WNW at 20
kt. Estimated minimum central pressure is 1006 mb. Maximum
sustained wind speed is 40 kt with gusts to 50 kt. Scattered
strong convection extends out 240 nm from the center in the NE
quadrant and 150 nm SW quadrant. Scattered moderate isolated
strong convection is elsewhere within 360 nm NE, 180 nm SE,
270 nm SW and 210 nm NW of the center. Heavy rain may lead to
life-threatening flash flooding over the Leeward Islands,
Virgin Islands, Puerto Rico and the Dominican Republic today
into Thu. A recent ASCAT pass shows that tropical storm force
winds of 35-40 kt exist in the NE quadrant in the area between
150-270 nm NE of the center. These winds are likely currently
affecting the northern Leeward Islands, and will be spreading
to the Virgin Islands early this afternoon. The highest seas
this afternoon and evening are expected on the Atlantic Ocean
side of the northern Leeward and Virgin Islands, with peak seas
of 18 ft.

PTC Nine is forecast to remain at tropical storm strength as it
interacts with Hispaniola on Thursday, and Cuba and the Bahamas
on Friday. Please read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT4.shtml and Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT4.shtml for
more details.

...TROPICAL WAVES...

A tropical wave has been added to the analysis with axis along
20W from 03N-18N, moving W at 15 kt. Numerous moderate scattered
strong convection is within 120 nm W and 180 nm E of the wave
axis from 09N-13.5N.

An Atlantic tropical wave is along 33W from 03N-21N, moving W at
20 kt. Isolated moderate convection is seen from 12N-14N between
28W-30W and from 03N-08N between 33W-37W.

A Caribbean Sea tropical wave is along 76W from 04N-20N, moving W
at 20 kt. Isolated moderate convection is near eastern Panama
where the wave axis meets the east Pacific monsoon trough.

The northern portion of a tropical wave has moved inland over
Belize along 89W from 18N southward. Scattered showers and
tstorms associated with this wave over the Gulf of Honduras will
end later today.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal sections of
Mauritania near 19N16W to 13N23WW to 07N41W to 08N45W. The ITCZ
continues from 08N45W to 09N53W. Numerous moderate isolated
strong convection is observed from 08N-11N between 24W-27W and
from 04N-08N between 38W-45W.

GULF OF MEXICO...

A ridge extends across the northern Gulf supporting gentle to
moderate E to SE winds and 2 to 4 ft seas across the basin,
except for fresh winds and 3 to 5 ft seas off the west coast of
the Yucatan peninsula. An upper-level low over NE Mexico is
generating upper-level diffluence over the west-central Gulf,
enhancing scattered moderate showers and tstorms over the
western Gulf, west of 95W.

For the forecast, surface ridging will dominate the Gulf waters
through Fri, supporting mainly gentle to moderate return flow.
Beyond that, much will depend on the track and intensity of
Potential Tropical Cyclone Nine, currently located over the
eastern Caribbean. Nine may approach the Florida Straits and
far southeast Gulf by Sat and Sun.

CARIBBEAN SEA...

Potential Tropical Cyclone Nine is currently affecting the
eastern Caribbean, east of 69W and north of 13N. See Special
Features section above for the current details on Nine.
Several stations on Guadeloupe and Martinique reported
24-hour rainfall amounts ending at 29/1200 UTC between 3 and
4 inches. For the forecast, seas as high as 10-15 ft are
forecast through tonight for portions of the NE Caribbean in
the waters south of Puerto Rico. Tropical storm force winds
are forecast to be in the Mona Passage tonight, near
Hispaniola Thu, and in the Windward Passage late Thu and Thu
night. The NW Caribbean should monitor the progress of Nine
in case the track shifts farther south. Winds and seas will
largely diminish over the eastern Caribbean Fri, except for
an area of swell to at least 8 ft that will penetrate
through the Mona Passage.

Elsewhere, scattered showers and tstorms related to the east
Pacific monsoon trough are over the far SW Caribbean off the
coast of Panama through southern Nicaragua. A recent ASCAT
pass shows fresh trades in the central Caribbean and in the
Gulf of Honduras, with moderate winds elsewhere in the
western Caribbean. Fresh to strong NE winds are expected tonight
through Thu night across the Windward Passage and Cuba adjacent
waters. Fresh trade winds will prevail over Colombia adjacent
waters and in the Gulf of Honduras through tonight.

ATLANTIC OCEAN...

A small upper-level trough off the SE coast of the U.S. is
inducing upper-level divergence to the SE of the trough. This
is enhancing scattered moderate convection east of Florida and
north of the NW Bahamas, from 27N-32N between 75W-80W. A
surface ridge extends across the Atlantic from a 1023 mb high
near 33N28W to a 1025 mb high near 31N55W to a 1020 mb high
over central Florida. Convection related to PTC Nine is
currently occurring south of 23N between 58W-67W. The ASCAT
pass from around 1300 UTC this morning showed that winds over
25 kt associated with the circulation of PTC Nine were
confined to areas south of 24N between 56W-66W at that time.

The swath of dangerous winds and seas associated with PTC Nine
will occur over the waters north of Puerto Rico and Hispaniola
to 25N through Thu, reaching the SE Bahamas and Windward
Passage late Thu and into the central and NW Bahamas through
Fri to include the adjacent offshore waters. Tropical storm
force winds are also expected over the Old Bahama Channel Fri
and Florida Straits Saturday.

$$
Hagen
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