[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 151758
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Fri Sep 15 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 1200 UTC surface analysis and satellite imagery through
1530 UTC.

...SPECIAL FEATURES...

Hurricane Lee is centered near 36.0N 66.9W at 15/1500 UTC or 345
nm SSE of Nantucket, Massachusetts and moving NNE at 16 kt.
Estimated minimum central pressure is 962 mb. Maximum sustained
winds are 70 kt with gusts to 85 kt. Peak seas are around 45 ft
near the center. Scattered moderate convection is near and up to
200 nm in a northern semicircle from the center. Lee will continue
a general northward motion with an increasing forward speed and
approach the coast of New England and Atlantic Canada through
Saturday. Afterward, Lee is expected to turn toward NE northeast
and move across Atlantic Canada Saturday night and Sunday. Little
change in strength is expected through this evening, then followed
by a gradual weakening trend. Lee is forecast to remain a large
and dangerous extratropical storm when it reaches eastern New
England and Atlantic Canada. Please read the latest High Sea
Forecast issued by the Ocean Prediction Center at website -
https://www.ocean.weather.gov/shtml/NFDHSFAT1.php for more
information.

Tropical Storm Margot is centered near 36.3N 38.2W at 15/1500 UTC
or 545 nm W of the Azores, and moving SE at 4 kt. Estimated
minimum central pressure is 990 mb. Maximum sustained winds are 55
kt with gusts to 65 kt. Seas are peaking around 22 ft near and
just SW of the center. Scattered moderate convection is near and
up to 125 nm NE of the center. Margot is expected to make a slow
clockwise loop during the next day or two, the followed by an
increase in forward speed toward the NE by Monday. A gradual
weakening trend will continue during the next couple of days. Please
read the latest High Sea Forecast issued by the Ocean Prediction
Center at website - https://www.ocean.weather.gov/shtml/NFDHSFAT1.php
for more information.

Newly formed Tropical Depression (TD) Fifteen is centered near
14.4N 43.8W at 15/1500 UTC or 1015 nm E of the Lesser Antilles,
and moving NW at 10 kt. Estimated minimum central pressure is 1007
mb. Maximum sustained winds are 30 kt with gusts to 40 kt. Seas
are peaking around 12 ft near and just N of the center. Widely
scattered moderate convection is seen from 10N to 16N between 40W
and 51W. Scattered moderate convection is present farther
northeast from 16N to 21N between 35W and 44W. TD Fifteen will
continue it current motion for the next few days. Gradual
strengthening is anticipated for the next couple of days. It
is expected to become a tropical storm later this evening, and
might become a hurricane this weekend. Please read the latest
HIGH SEAS FORECAST issued by the National Hurricane Center at
website - https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more
information.

For the latest NHC Forecast/Advisory and Public Advisories on all
three system, please visit www.hurricanes.gov for more details.

...TROPICAL WAVES...

An eastern Atlantic tropical wave is near 25W from 12N southward,
and moving west at 5 to 10 kt. Widely scattered moderate convection
is evident from 03N to 11N between 18W and 26W.

...MONSOON TROUGH/ITCZ...

A monsoon trough enters the Atlantic just south of Dakar, Senegal
then extends westward through 12N25W to 12N32W. Widely scattered
moderate convection is noted near and south of the trough from 04N
to 12N between 26W and 37W, There is no ITCZ based on the latest
analysis.

The eastern end of the East Pacific monsoon trough is triggering
numerous showers and scattered thunderstorms across the Caribbean
waters north of Costa Rica and Panama.

...GULF OF MEXICO...

A modest stationary front extends eastward from a 1012 mb low near
Pasadena, Texas across New Orleans, Louisiana to the Georgia-
Florida border. Widely scattered showers and isolated
thunderstorms are occurring near and up to 60 nm north of this
feature. A surface trough is producing similar convection at the
central Bay of Campeche. Otherwise, a 1015 mb high over the
central Gulf is providing light to gentle with locally moderate
winds and seas of 1 to 3 ft across the entire Gulf.

For the forecast, the 1012 mb high will continue to dominate the
region through Tue, supporting mainly moderate or weaker winds
along with slight seas. Winds will pulse to between moderate and
fresh WNW of the Yucatan Peninsula each evening.

...CARIBBEAN SEA...

Refer to the Monsoon Trough/ITCZ section for convection in the
basin. The presence of Hurricane Lee at the northwestern Atlantic
is supporting a modest trade- wind pattern across much of the
basin. Fresh to locally strong easterly winds and seas of 5 to 7
ft are evident at the south- central basin north of Colombia and
northwestern Venezuela. Moderate to locally fresh ENE to ESE winds
and 2 to 4 ft seas are found at the north- central basin. Light
to gentle winds and seas at 1 to 3 ft are present north of Costa
Rica and Panama. Gentle to moderate ENE to ESE winds and 3 to 5 ft
seas prevail for the rest of the basin.

For the forecast, northerly swell affecting the NE Caribbean
Passages will gradually subside today, then may build again early
next week due to newly formed Tropical Depression Fifteen which is
forecast to remain NE of the area. Otherwise, moderate to fresh
trade winds will dominate the central and western portions of the
basin through Tue. Gentle to locally moderate winds are forecast
elsewhere.

...ATLANTIC OCEAN...

Please, read the SPECIAL FEATURES section, for details about
Hurricane Lee, Tropical Storm Margot, and newly formed Tropical
Depression Fifteen.

Convergent southerly winds feeding toward Hurricane Lee are
causing scattered moderate convection north of Puerto Rico and
the Virgin Islands from 20N to 28N between 60W and 67W. An
elongated upper-level low near 24N55W is generating widely
scattered moderate convection from 19N to 30N between 46W and 53W.
Refer to the Monsoon Trough/ITCZ and Tropical Waves sections for
additional weather in the Atlantic Basin.

North of 27N, moderate to fresh with locally strong SW to NW
winds and seas of 10 to 15 ft are noted between 57W and 75W, and
gentle to moderate NE to NW winds and seas at 7 to 10 ft are seen
between 75W and the Georgia-Florida coast. Farther south, light to
gentle winds and 5 to 8 ft seas in moderate to large northerly
swell dominate from 20N to 27N between 60W and the Bahamas. At the
central and eastern Atlantic outside the direct impact of
Tropical Depression Fifteen, moderate to fresh easterly winds and
seas of 8 to 10 ft exist from 17N to 23N between 35W and 50W.
Otherwise, gentle to locally moderate NNE to E winds and 5 to 7 ft
seas in mixed northerly and northeasterly swells are seen from
north of 14N between the Africa coast and 50W, including the
Canary and Cabo Verde Islands. Gentle to moderate S to SW winds
and seas of 5 to 7 ft in moderate southerly swell are evident from
the Equator to 17N between the central Africa coast and 50W. Light
to gentle winds and seas at 5 to 8 ft in moderate NW swell prevail
for the rest of the Atlantic Basin.

For the forecast W of 55W, Hurricane Lee will continue to move N
away from the area today, while associated large northerly swell
gradually decays through the weekend. Newly formed Tropical
Depression Fifteen is expected to strengthen to a tropical storm
near 15.5N 44.7W this evening, and move to 17.2N 46.0W Sat
morning, It will then move to near 18.9N 47.9W Sat evening and
20.5N 49.6W Sun morning, then strengthen to a hurricane near
22.0N 51.2W Sun evening, and tracks to near 23.4N 52.9W Mon
morning. Fifteen will change little in intensity as it moves to
26.0N 56.8W early Tue. Otherwise, high pressure will prevail
across the waters through the weekend. A weak cold front may move
off the SE U.S. coast early next week.

$$

Forecaster Chan
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