[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 210539
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Thu Sep 21 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 0000 UTC surface analysis and satellite imagery through
0545 UTC.

...SPECIAL FEATURES...

Hurricane Nigel is centered near 39.0N 50.4W at 21/0300 UTC or
480 nm SSE of Cape Race Newfoundland, moving NE at 22 kt.
Estimated minimum central pressure is 973 mb. Maximum sustained
wind speed is 80 kt with gusts to 100 kt. Peak seas N of our
area are currently around 39 ft. Numerous moderate to strong
convection is evident within 150 nm in the NE semicircle of
Nigel. Hurricane Nigel is expected to accelerate northeastward
over the next day or two. Weakening is forecast during the next
couple of days, and Nigel is forecast to become a post-tropical
cyclone by Friday. Swells generated by Nigel currently affecting
Bermuda will gradually subside through Thursday. 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
Nigel NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

Atlantic Gale Warning: The pressure gradient between low
pressure that is expected to develop along a stationary front
N of the Bahamas and high pressure over the southeastern U.S.
will result in frequent wind gusts to gale force N of 30N and W
of 75W starting Thu afternoon, then N of 29N and W of 76W by late
Thu night. Seas with these winds are forecast to be 9 to 12 ft
and could be locally higher. Please see the latest NWS High Seas
Forecast issued by the National Hurricane Center at website
https://www.nhc.noaa.gov/text/MIAHSFAT2 for further details.

...TROPICAL WAVES...

A tropical wave is in the far eastern Atlantic Ocean near 22W,
moving W through the Cabo Verde Islands at 5 to 10 kt. Scattered
moderate to strong convection is evident from 12N to 16N between
23W and 26W.

A tropical wave in the central Atlantic is centered near 37W,
from 18.5N southward, moving W at around 15 kt. Scattered
moderate to isolated strong convection is evident from 03N to
17N between 32W and 40W.

A western Atlantic tropical wave is near 51W, from 15N
southward, moving W at 5 to 10 kt. No significant convection is
depicted in association with this tropical wave.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends off the coast of Senegal near
16N17W to 9.5N31W to 10N50W. The ITCZ axis extends from 10N52W to
10N60W. Nearby significant convection is discussed in the
TROPICAL WAVES section above.

...GULF OF MEXICO...

A slowly dissipating stationary front extends from near Sarasota,
Florida, to 28N87W. Scattered moderate convection is noted north
and south of this boundary. Moderate to fresh SE winds are
present N of the front, with seas up to 4 ft. A weak surface
trough is noted in the eastern Bay of Campeche, with locally
fresh NE winds. No significant convection is noted in
association with the trough. Elsewhere, mainly gentle winds,
with seas 1-3 ft prevail.

For the forecast, high pressure will be in control of the weather
pattern across the Gulf waters allowing for generally gentle to
moderate east to southeast winds and slight seas, except pulsing
to moderate to fresh offshore the western Yucatan Peninsula in
the evenings. Developing low pressure east of Florida will
tighten the pressure gradient over the NE Gulf bringing moderate
to locally fresh NE winds across the NE Gulf Thu night into Fri.
A frontal trough associated with the aforementioned low pressure
will move across the southeastern Gulf and the Straits of
Florida Thu night into Fri.

...CARIBBEAN SEA...

A deep layer trough E of the Yucatan Peninsula is inducing
scattered moderate convection in the NW Caribbean Sea. A weak
pressure gradient sustains mainly moderate to fresh easterly
trade winds in the central Caribbean. However, strong winds are
occurring just off the N Colombia and NW Venezuelan coasts. Seas
in the central Caribbean are in the range of 4-7 ft. Elsewhere,
gentle to moderate winds and seas of 2-5 ft prevail.

For the forecast, long period north to northeast swell moving
through the Tropical N Atlantic waters and Caribbean passages
will subside Thu. Moderate to fresh trade winds in the central
Caribbean will change little through the next few days.
Northeast to east trade winds will pulse to fresh to strong
speeds offshore northern Colombia and northwest Venezuela during
the afternoons and at night into early next week.

...ATLANTIC OCEAN...

Please read the SPECIAL FEATURES section for details on Hurricane
Nigel and on an Atlantic Gale Warning. In addition, please read
the TROPICAL WAVES and MONSOON TROUGH/ITCZ sections for details
on convection in the Atlantic Ocean.

A stationary front extending from just south of Bermuda to
29N73W and to inland Florida near Daytona Beach, Florida. The
combination of this front and a very sharp upper- level trough
over its vicinity is leading to numerous moderate to strong
convection from 24N to 31N between 71.5W and 74W and west of
79W. A surface trough extends from around 28N73W through the NW
Bahamas, locally enhancing convection further. Moderate to fresh
NE to E winds are N of the front. Another surface trough extends
from 31N50W to 24N58W, but is not producing any convection.
Otherwise, weak ridging dominates W of 50W. To the E, an upper
level trough is producing a cluster of showers and thunderstorms
near 19N48W. Moderate to fresh trades are evident from 17N to
27N between the coast of Africa and 55W between a ridge N of
that area and three tropical waves along the monsoon
trough/ITCZ. Locally strong winds are occurring off the coast of
Western Sahara. Seas in the broad zone of tradewinds are 7-9 ft.
Across the remainder of the basin, gentle to moderate winds and
4-7 ft seas prevail, except 6-9 ft seas in northerly swell
related to Nigel N of 28N between 48W and 65W.

For the forecast W of 55W, the aforementioned stationary front
will lift northward on Fri as low pressure develops along it to
the east of northern Florida, and where frequent gusts to gale
force are possible Thu night into Fri. This non-tropical low
pressure system could acquire some subtropical characteristics
on Fri while it moves generally northward. In its wake, high
pressure ridging will build from E to W just north of the
forecast waters into early next week.

$$
KRV
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