[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 122348
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Wed Sep 13 2023

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 1800 UTC surface analysis and satellite imagery through
2300 UTC.

...SPECIAL FEATURES...

Major Hurricane Lee is centered near 25.0N 66.5W at 13/0000 UTC
or 450 nm SSW of Bermuda, moving NW at 6 kt. Estimated minimum
central pressure is 946 mb. Maximum sustained wind speed is 100
kt with gusts to 120 kt. Numerous moderate to strong convection
is noted within about 90 nm of center. Seas in excess of 12 ft
extend within 390 nm in the N semicircle, 300 nm SE quadrant and
360 nm SW quadrant of the center of Lee with maximum seas of 44
ft. Air Force Hurricane Hunter finds that Lee is growing in size.
While the core of the hurricane is forecast to pass west of
Bermuda, the large wind field of the storm is likely to bring
storm force winds and heavy rainfall to the island by Thu. Lee is
a category 3 hurricane on the Saffir-Simpson Hurricane Wind
Scale. Some slow weakening is forecast during the next 48 hours
though the wind field is forecast to remain large. Lee is
expected to turn toward the north on Thursday and increase in
forward speed. Swells generated by Lee are affecting portions of
the Lesser Antilles, the British and U.S. Virgin Islands, Puerto
Rico, Hispaniola, the Turks and Caicos Islands, the Bahamas, and
Bermuda. These swells are likely to cause life-threatening surf
and rip current conditions. Dangerous surf and rip currents are
affecting portions of the southeastern U.S. coast, and these
conditions are forecast to spread northward along much of the
U.S. East Coast and Atlantic Canada during the next couple of
days. Please consult products from your local weather office.

Hurricane Margot is centered near 31.7N 39.6W at 12/2100 UTC or
730 nm WSW of the Azores, moving N at 12 kt. Estimated minimum
central pressure is 977 mb. Maximum sustained wind speed is 70
kt with gusts to 85 kt. Numerous moderate to isolated strong
convection is evident within 30 nm of center. Seas in excess of
12 ft extend within 230 nm NE, 150 nm SE, 120 nm SW and 160 nm SW
quadrants of the center of Margot with maximum seas of 29 ft.
Margot is moving toward the north. A turn toward the north-
northwest at a slower forward speed is expected beginning
tomorrow. A meandering northward motion is then expected on
Thursday and Friday. Margot's track beyond Friday is unusually
uncertain, but a slow meandering motion is generally expected
into the weekend. Slight fluctuations in intensity, up or down,
are possible during the next several days. Swells generated by
Margot will begin to affect the Azores on Wednesday. These swells
are likely to cause life-threatening surf and rip current
conditions. Please consult products from your local weather
office.

Please read the latest HIGH SEAS FORECAST issued by the National
Hurricane Center at website -
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest NHC
Forecast/Advisory and Public Advisory on Lee and Margot at
www.hurricanes.gov for more details.

...TROPICAL WAVES...

A tropical wave is along 24W south of 17N, moving west at 10 kt.
A 1009 mb low pressure is along the wave axis near 12N24W. No
significant convection is noted near this wave.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic Ocean through the coast
of Senegal near 14N17W, then continues to 1009 mb low pressure
near 12N24W to a broad 1010 mb low pressure area near 12N32W
AL97 and AL98) to 1012 mb low pressure near 14N48W. Scattered
moderate convection is noted within about 60 nm S of a line from
11N28W to 08N32W to 07N39W. Scattered moderate isolated strong
convection is observed from 16N to 18N between 31W and 35W.

...GULF OF MEXICO...

High pressure of 1017 mb located over the NE Gulf dominates the
basin. This pattern is maintaining light winds and slight seas
across the Gulf waters. Scattered showers and isolated thunderstorms
are evident in the Gulf at this time. This convective activity is
more concentrated over the NE Gulf and adjacent Gulf states.
Scattered showers and thunderstorms are also affecting the State
of Florida while numerous showers and thunderstorms have flare-up
over the Yucatan Peninsula.

For the forecast, the ridge will dominate the Gulf waters throughout
the forecast period supporting mainly light to gentle winds. Moderate
return flow will develop across the W and SW Gulf Thu night. Scattered
thunderstorms can be expected across the western Yucatan and eastern
Bay of Campeche each late afternoon and evening.

...CARIBBEAN SEA...

Please read the Special Features section about large swell generated
by Major Hurricane Lee impacting the northeast Caribbean islands.

The subtropical ridge that is normally north of the region is disrupted
by Hurricane Lee, resulting in gentle to moderate trades across
the basin. Northerly swell, with seas of 5-8 ft, generated by Lee
continues to propagate across the Anegada and Mona Passages,
with plumes of 4 to 6 ft combined seas extending south of
passages across the northeast Caribbean. Seas of 2-4 ft are noted
elsewhere. An outer band of Lee appears to enhance showers and
thunderstorms over eastern Dominican Republic and across the
Atlantic waters N of Puerto Rico. The San Juan Doppler Radar
confirms the presence of this band of convective activity.

For the forecast, Hurricane Lee will move slowly NW and farther
away from Caribbean waters through tonight then turn N on Wed.
Large N swell across the adjacent Atlantic will gradually become
NNW tonight through Thu, moving through the Caribbean Passages
and into the Caribbean waters between the Leeward Islands and the
Mona Passage. Seas across these Caribbean Passages and waters will
diminish significantly Thu through Fri. Moderate to locally fresh
trade winds will return to the Caribbean Fri.

...ATLANTIC OCEAN...

Please see the Special Features section for information about
Major Hurricane Lee and Hurricane Margot.

A recent scatterometer satellite pass indicated that a broad
area of 1010 mb low pressure is centered along the monsoon trough
over the eastern Atlantic near 12N32W. The NHC is analyzing this
feature as two separate invest areas in the eastern Atlantic
(AL97 and AL98). This system is expected to consolidate, with a
low on the western side becoming dominant over the next day or
two. Gradual development of the low is expected after that, and a
tropical depression is likely to form by this weekend while the
system moves west-northwestward or northwestward at about 15 mph
across the central tropical Atlantic. There is a low chance of
tropical cyclone development through the next couple of days,
but high chance through the next seven days.

Elsewhere, no significant convection is evident across the
subtropical or tropical North Atlantic outside of the immediate
area near Lee and Margot. Seas in excess of 8 ft due to Lee cover
the area between 55W and 75W, and due to Margot N of 25N between
33W and 50W. Gentle to moderate winds are noted elsewhere with 4
to 6 ft combined seas in mixed swell.

For the forecast west of 55W, Hurricane Lee will move to 25.4N
67.0W Wed morning, 26.7N 67.6W Wed afternoon, 28.6N 68.1W Thu
morning, 30.7N 68.2W Thu afternoon, 33.4N 67.6W Fri morning, and
pass W of Bermuda Fri afternoon. Large E to SE swell dominating
the waters east of 80W will reach the Florida coast this evening.
Large swell from Lee will dominate the regional waters through
Fri.

$$
GR
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