[Tropical] Tropical Weather Discussion

Tue Nov 23 05:00:28 CST 2021

AXNT20 KNHC 231100
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Tue Nov 23 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
1030 UTC.

...SPECIAL FEATURES...

Atlantic Ocean Gale Warning: A strong cold front will move from
offshore of Florida toward Bermuda through tonight. Strong to
gale-force NW-N winds and seas of 10 to 13 ft will follow the
front north of 29N late this morning through this evening. Winds
will continue to be fresh to strong through Wednesday near the
front with seas 10-13 ft. Please see the latest NWS High Seas
Forecast issued by the National Hurricane Center at
website://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more
information.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal plains of
Guinea-Bissau near 12N15W to 09N21W. The ITCZ extends from 09N21W
to 04N30W to 02N40W to 00N49W. Isolated moderate convection is
noted within 360 nm either side of the axes between Africa and
South America.

GULF OF MEXICO...

At 0900 UTC, a cold front extends from Naples, Florida to 22N96W,
then stationary to Veracruz, Mexico. Isolated showers are along
the boundary. High pressure is quickly building in behind the
front with strong winds in the northeast Gulf and fresh elsewhere
north of the front. Seas are 5 to 8 ft within 180 nm north of the
front and 3 to 5 ft elsewhere.

For the forecast, the cold front will move SE of the Gulf of
Mexico this afternoon. Fresh to strong N to NE winds are expected
through this morning in the NE Gulf. High pressure will build
north of the area behind the front, maintaining moderate to fresh
winds through Wed night. Winds will briefly diminish across the
basin Thu ahead of the next cold front forecast to move off the
coast of Texas by Thu evening. This front will reach from the
Florida Big Bend to Veracruz Mexico late Fri before weakening.
Fresh to strong winds are expected behind the front over the far
western Gulf Thu night and Fri, with near gale force winds
possible in the nearshore waters between Tampico and Brownsville.

CARIBBEAN SEA...

At 0900 UTC, a cold front extends from Cuba near 22N81W to 19N86W.
Isolated moderate showers and tstorms are noted between the front
and the Cayman Islands. A westward moving surface trough extends
along 75W from 11N-18N. Scattered moderate convection is noted
from 16N-18N between 73W-77W. The monsoon trough in the SW
Caribbean is inducing scattered moderate to strong convection
south of 12.5N between 71W-82W, including over NW Venezuela and N
Colombia. Fresh N winds are likely occurring over the NW Caribbean
north of the cold front, where seas are likely 4 to 6 ft. Gentle
to moderate winds prevail across the remainder of the basin with 2
to 4 ft seas.

For the forecast, the front will be reinforced by a second front
that will move into the NW Caribbean this afternoon. This front
will reach from the Windward Passage to E Honduras on Wed and from
the Mona Passage to E Honduras Thu before weakening and
dissipating Fri. Behind the front, fresh N to NE winds are
expected, with locally strong NE winds possible Thu in the
Windward Passage and south of Hispaniola. The front will enhance
showers and tstorms for portions of Hispaniola and Puerto Rico
late this week. Moderate northerly swell will affect the NE
Caribbean passages beginning Thu afternoon and continuing through
the weekend.

ATLANTIC OCEAN...

Please see the Special Features section above for more details on
the gale-force wind event expected today over the SW N Atlantic,
north of 29N between Bermuda and 75W.

At 0900 UTC, a cold front extends from 31N70W to the N coast of
Cuba near 23N80W. A second cold front extends from 31N73W to Ft.
Lauderdale, Florida to the south-central Gulf of Mexico. A pre-
frontal trough east of the first front extends from 31N69W to E
Cuba near 21N75.5W. Numerous moderate, with embedded isolated to
scattered strong thunderstorms are within 90 nm either side of the
pre-frontal trough, north of 22.5N. Strong NW winds are occurring
just off of NE Florida behind the second front, where seas are
likely 7 to 8 ft. Strong to near-gale force SW winds are occurring
east of the first front to 64W, north of 28N, where seas are
likely 8 to 10 ft.

Farther east, a surface trough extends from 30N40W to 25N49W. A
cold front extends from 31N26W to 26N35W. Another surface trough
is analyzed ahead of this front from 29N23W to 23N33W. These
surface features reside within a broad area of upper-level
cyclonic flow, with a large upper-level low centered north of the
area. Three pockets of scattered moderate convection are noted,
from 25N-31N between 33W-43W, from 25N-31N between 21W-31W, and
from 18N-22N between 30W-34W. Generally moderate to fresh winds
prevail across this area. A surface ridge axis with light to
gentle winds extends from the Canary Islands southwestward to
17N45W. Seas of 8 to 10 ft are likely occurring north of 27N
between 42W-54W, with seas of 5 to 6 ft farther south, in the
tropics.

The Cumbre Vieja volcano on the island of La Palma in the Canary
Islands, has been erupting since 19 September 2021. 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, the two cold fronts in the west Atlantic will
combine by this evening from 31N64W to eastern Cuba. The merged
front will reach from 31N59W to the Windward Passage early Wed,
and from 31N50W to the Mona Passage early Thu as the southern
portion becomes nearly stationary. Strong to near gale force SW
winds are occurring E of the initial cold front, mainly N of 28N.
Strong to near gale force NW to N winds are developing early this
morning behind the reinforcing cold front. A period of NW to N
gales is expected N of 29N, to the SW of Bermuda, late this
morning through this evening. Swell from this system will extend
down to Puerto Rico and the Tropical N Atlantic waters later this
week. In the wake of the front, high pressure will build in off
the coast of Georgia and northern Florida on Thu. The next cold
front is likely to bring fresh winds Fri and Fri night to waters
north of 29N.

$$
Hagen
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