[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 112329
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Tue Sep 12 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 23.6N 64.2W at 11/2100 UTC
or 330 nm N of the Northern Leeward Islands, moving WNW at 6 kt.
Estimated minimum central pressure is 948 mb. Maximum sustained
wind speed is 100 kt with gusts to 120 kt. Lee continues to exhibit
a double eyewall structure as reported by the Air Force Hurricane
Hunters and seen in recent microwave images. Numerous moderate to
strong convection is noted within 120 nm N and 150 nm S semicircles
of the center of Lee. Seas in excess of 12 ft reach as far as
330 nm in the northern semicircle, and 270 nm in the SE quadrant
and 300 nm in the SW quadrant with maximum seas of 48 ft. On the
forecast track, Lee is expected to pass near, but to the west, of
Bermuda in a few days. Lee is a category 3 hurricane on the
Saffir- Simpson Hurricane Wind Scale. Little change in strength
is forecast during the next couple of days. 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 have begun to affect portions of
the southeastern U.S. coast, and these conditions are forecast to
spread northward along much of the U.S. East Coast during the
next day or two. Please consult products from your local weather
office.

Margot becomes the fifth hurricane of the 2023 Atlantic Hurricane
Season. At 11/2100 UTC, Hurricane Margot is centered near 27.0N
39.8W or 1100 nm NW of the Cabo Verde Islands, moving N at 10 kt.
Estimated minimum central pressure is 988 mb. Maximum sustained
wind speed is 65 kt with gusts to 80 kt. Scattered moderate to
isolated strong convection is evident within 90 nm of the center
of Margot. Seas in excess of 12 ft reach as far as 210 nm of the
center, except 150 nm SW quadrant with maximum seas of 22 ft.
Margot is moving toward the north, and this motion is expected to
continue for the next several days. Further strengthening is
forecast during the next 48 hours.

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 (AL98) located over the far eastern tropical
Atlantic between the Cabo Verde Islands and the west coast of
Africa is producing disorganized showers and thunderstorms. Its
axis is along 21W/22W S of 18N. Environmental conditions appear
conducive for gradual development of this system, and a tropical
depression could form by the weekend while it moves westward to
west-northwestward at 15 to 20 kt over the central tropical
Atlantic. Currently, this system has a low chance of tropical
cyclone formation through 48 hours, and a medium chance through
7 days.

A weak area of low pressure (AL97) located several hundred miles
west-southwest of the Cabo Verde Islands is producing disorganized
shower and thunderstorm activity. This low is along a tropical
wave with axis along 32W and S of 18N. Development of this system
is unlikely before it merges with the tropical wave (AL98) incoming
from the east during the next couple of days. As a result, there
is a low chance of tropical cyclone formation during the next 7
days.

Refer to the latest NHC Tropical Weather Outlook at
www.hurricanes.gov for more details on AL97 and AL98.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic Ocean through the coast
of Mauritania near 18N16W, then continues southwestward to a
1012 mb low pressure (AL97) near 12.5N32W to 14N50W. The ITCZ
extends from 09N52W to 10N61W. Scattered moderate convection is
noted from 08N to 16N between 22W and 30W, and within about 100
nm W of the weak area of low pressure (AL97).

...GULF OF MEXICO...

A surface trough reaches from off the mouth of the Mississippi
River in the north-central Gulf to near 24N94W. A weak 1014 mb
low pressure is along the trough axis near 27N92W. Farther east,
a weak ridge extends from the western Atlantic into the
northeastern Gulf. This pattern is supporting only light to
gentle winds and slight seas across the basin. A band-like of
scattered showers and thunderstorms is evident across the NE and
central Gulf, affecting mainly the waters N of 26N E of 87W, and
from 22N to 27N between 87W and 92W.

For the forecast, a weak ridge will dominate the Gulf waters
throughout the forecast period supporting light to gentle winds.
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.

An area of showers, with embedded thunderstorms is over the NW
Caribbean and western Cuba, including the Isle of Youth. A
surface trough is analyzed from central Cuba to near 14N82W. A
diffluent pattern aloft is helping to induce this convective
activity. scattered showers and thunderstorms are also noted over
parts of eastern Cuba and Jamaica. The subtropical ridge that is
normally present north of the basin is being disrupted in part
by Hurricane Lee. This pattern is supporting gentle to moderate
winds. Seas of 7 to 9 ft generated by Major Hurricane Lee are
propagating across the NE Caribbean passages E of La Mona
Passage. Seas of 6-8 ft are likely between the northern Leeward
Islands and St. Croix. Elsewhere 3-4 ft seas prevail, except 1-3
ft in the NW Caribbean, higher near thunderstorms.

For the forecast, moderate to locally fresh trade winds will
continue in the central and eastern Caribbean through this
evening before Lee in the Atlantic disrupts the pressure pattern.
The large easterly swell across the adjacent Atlantic will
gradually become NE and then N today through Thu, and move
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 night through Fri.

...ATLANTIC OCEAN...

Please see the Special Features section for information about

Hurricane Lee and Hurricane Margot.

Outside of the weather conditions associated with the tropical
waves and tropical cyclones, no significant convection is noted
across the basin. Weak low pressure near 14.5N48W is producing a
few showers. The most recent scatterometer satellite pass
indicated the cyclonic circulation related to this weak low
with mainly gentle to moderate winds around it, and only 5 to 10
kt near the center. The scatterometer passes also revealed a
band of moderate E to SE winds over the eastern Atlantic from the
coast of Western Sahara toward Hurricane Margot. A weak 1019 high
pressure is near 29N27W. Gentle winds are noted elsewhere across
the Atlantic outside of the areas near Lee and Margot, with
combined seas of 4 to 6 ft in mixed swell.

For the forecast west of 55W, Hurricane Lee is expected to maintain
a slow NW motion and strengthen modestly through Tue, then begin
a gradual turn toward the N on Wed. Lee will move to 24.0N 65.1W
Tue morning, 24.6N 66.1W Tue afternoon, 25.3N 66.9W Wed morning,
26.5N 67.5W Wed afternoon, 28.3N 67.8W Thu morning, and 30.3N
67.9W Thu afternoon. Lee will change little in intensity as it
moves N of the area Fri afternoon. Large E to SE swell dominating
the waters east of 78W will continue to propagate westward
across the Atlantic, reaching the Florida coast Tue afternoon.
Large swell from Lee will dominate regional waters Tue night
through Fri.

$$
GR
This weather bulletin was brought to you by:
www.nashvilleweather.net