[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211012
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Sun Nov 21 2021

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 0600 UTC surface analysis and satellite imagery through
1000 UTC.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coast of Guinea near
11N15W to 06N20W. The ITCZ continues from 06N20W to 04N30W to
03N50W. Clusters of moderate to isolated strong convection are
noted from 00N-06N between 13W-17W. Scattered moderate convection
is occurring from 01N-10N between 20W-35W.

GULF OF MEXICO...

High pressure of 1030 mb located over the SE of United States
extends a ridge across the Gulf waters. Recent satellite-derived
winds data provided observations of fresh to strong NE winds over
the eastern Gulf, including the Straits of Florida. An earlier
altimeter pass indicates seas of 6-9 ft within this area of winds.
Moderate to locally fresh NE to E winds dominate the remainder of
the Gulf waters, with the exception of E to SE winds across the
NW part of the basin. The remainder of the Gulf region is covered
by seas of 4 to 6 ft, except for 2 to 4 ft in the NW Gulf.

A surface trough is analyzed over the SW Gulf. A few showers are
E of the trough axis. Cloudiness with embedded showers is affecting
the Yucatan peninsula and the SE Gulf into the Straits of Florida.
These clouds are the result of the presence of strong upper-level
SW winds.

For the forecast, a ridge will dominate the Gulf waters today.
The next cold front will enter the basin by early Mon and move
quickly SE, exiting the Gulf region by Mon evening. Fresh to
strong northerly wind will be expected behind the front, but
mainly over the eastern Gulf late Mon into Tue. High pressure is
forecast to build in behind the front. Fresh southerly return flow
will set up across the NW Gulf by the middle of the week ahead of
the next cold front forecast to reach the Gulf of Mexico by Thu
night.

CARIBBEAN SEA...

Recent scatterometer data show mainly gentle to moderate trade
winds across the basin, with the exception of fresh winds near
the coast of Colombia and in the Gulf of Venezuela. Seas of 5-7 ft
prevail in the south-central Caribbean, with 3-5 ft elsewhere,
except in the lee of Cuba and in the Gulf of Honduras where seas
of 1-3 ft are found. Seas of 5-6 ft are likely occurring in the
Yucatan Channel.

Scattered showers are thunderstorms continue to develop over the
Caribbean plains of Nicaragua. A diffluent pattern aloft is
helping to sustain this convective activity. A large patch of
moisture, with embedded showers, covers the Leeward Islands, the
US/UK Virgin Islands and Puerto Rico, and it is moving westward. A
well defined swirl of clouds, with some convective activity, is
noted on satellite imagery over the eastern Caribbean S of Puerto
Rico. This could be related to a surface trough that crossed the
Leeward Islands a couple of days ago. Elsewhere, shallow moisture
embedded in the trade wind flow will continue to move across the
region producing isolated to scattered passing showers.

For the forecast, mainly gentle to moderate trades will prevail
across much of the Caribbean Sea through Mon. A cold front will
reach the Yucatan Channel by Mon evening, and extend from eastern
Cuba to the Gulf of Honduras by late Tue. Fresh to locally strong
winds and building seas are expected across the western Caribbean,
the Windward Passage and Mona Passage likely through Thu as high
pressure builds N of the area in the wake of the front.

ATLANTIC OCEAN...

A weakening stationary front stretches from 31N60W to near West
Palm Beach, Florida. Some shower activity is along the frontal
boundary. The most recent scatterometer data show fresh to strong
NE winds behind the front while a pair of altimeter passes and
buoy observations indicate seas of 8-11 ft in the wake of the
front. Fresh to locally strong NE to E winds are also noted S of
the front to about 25N and W of 70W. This is the result of the
pressure gradient between the front and a 1030 mb high pressure
located over the SE of United States.

Farther east, another cold front enters the Atlantic forecast
waters near 31N25W and extends SW to near 22N40W. A few showers
are observed along the front. Within about 200 nm ahead of the
front there is a trough that runs from 31N21W to 21N31W. Fresh
NW winds are west of the cold front, north of 28N. Seas in NW
swell, generated by a gale center located W of the Azores, are
reaching the forecast waters, building seas to 10-14 ft roughly N
of 29N between 30W and 40W by Sun morning.

The Cumbre Vieja volcano, on the island of La Palma in the
Canary Islands, has been erupting since 19 September 2021.
Medium ash concentration is in the vicinity of the volcano,
while low concentration is elsewhere. Marine and aviation
interests should monitor this ongoing situation by reading the
Volcanic Ash Advisory issued by Meteo-France, at
http://vaac.meteo.fr/volcanoes/la-palma/.

For the forecast W of 65W, the aforementioned stationary front
extending 31N60W to near West Palm Beach, Florida will remain over
the northern forecast waters through tonight, before lifting
north ahead of a strong cold front that will move off the
northeast Florida coast on Mon. The next cold front will reach
from near Bermuda to eastern Cuba late on Tue. Fresh to strong
winds and building seas are expected on either side of the front
beginning on Tue. Winds could reach gale force N of 30N and just W
of the front by Tue evening.

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