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000
AXNT20 KNHC 060947
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Mon Dec 6 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 0945 UTC.


...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic Ocean through the coast of Sierra Leone, then continues SW to near 05N18W. The ITCZ extends from 05N18W to 03N30W to the coast of Brazil near 02N50W. Scattered moderate convection is noted from 02N-07N between 25W- 50W. Similar convection is from 03N-06N between 08W-12W.

GULF OF MEXICO...

A ridge extends across Florida into the Gulf of Mexico. Recent scatterometer data indicate moderate to fresh southerly winds over the western Gulf, particularly N of 22N and W of 92W while gentle to moderate winds prevail elsewhere. Seas are 3-4 ft in association with the strongest winds, and 1-3 ft elsewhere. Multilayered clouds, with possible showers, are observed over the NW and north-central Gulf. These clouds are the result of strong SW winds aloft.

For the forecast, a ridge will dominate most of the Gulf waters through Fri producing generally gentle to moderate anticyclonic flow. A weak cold front will reach the NW Gulf late today into the evening hours. Fresh to locally strong northerly winds will follow the front forecast to stall before retreating inland Tue. The next cold front is forecast to move off the Texas coast on Sat. Moderate to fresh southerly return flow is expected over the NW and north-central Gulf ahead of the front Fri and Fri night.

CARIBBEAN SEA...

Satellite derived wind data provide observations of fresh to strong winds over the south-central Caribbean, and moderate to fresh trade winds across the remainder of the E and central Caribbean. A pair of altimeter passes indicate seas of 8-10 ft over the south-central Caribbean where the strongest winds prevail. Seas of 6-7 ft are noted elsewhere S of 18N and E of 80W. Seas of 4-6 ft can be found in the NW Caribbean, except in the lee of Cuba, and in the Gulf of Honduras. Scattered showers and thunderstorms are near 20N85W just ahead of a short-wave trough that crosses the SE Gulf of Mexico into the Yucatan Channel. Moisture in this area is forecast to move westward while dissipating. Shallow moisture embedded in the trade wind flow is seen elsewhere across the basin producing isolated to scattered passing showers.

For the forecast, high pressure located north of the Caribbean Sea combined with the Colombian low will support fresh to strong trade winds over the south-central Caribbean and in the Gulf of Venezuela through the week. Moderate to fresh trades will prevail elsewhere except in the NW Caribbean where mainly gentle to moderate winds are expected. Moderate to locally fresh easterly winds are also forecast in the Gulf of Honduras beginning tonight.

ATLANTIC OCEAN...

A surface ridge extends from Bermuda to near the border of Georgia and Florida. Gentle to moderate E to SE winds are noted across the SW N Atlantic per scatterometer data. Seas are 2 to 4 ft north of 27N and west of 77W, and 4 to 6 ft elsewhere N of 27N and W of 65W. Seas of 5 to 7 ft are S of 27N and E of the Bahamas.

For the forecast west of 65W, a ridge will dominate most of the forecast waters through Fri. A weak cold front will push off NE Florida Tue before stalling and retreating northwest through Tue night. Another cold front will move across the north waters on Thu while weakening. Moderate to fresh NE to E winds are expected along the southern periphery of the ridge, especially south of 22N, including approaches to the Windward Passage, through the week.

Over the central Atlantic, a stationary front extends from a weak 1022 mb low pressure located near 31N52W to 25N54W. Scattered to numerous showers and are ahead of the front affecting mainly the waters from 24N-30N between 48W- 51W. Fresh to strong NE winds and seas of 7-9 ft are seen in the wake of the front. Farther E, a strong high pressure of 1036 mb remains in place over the Azores. Fresh to strong NE winds are blowing N of 23N and E of 32W, including the Canary Island. Moderate to fresh trades are observed across much of the Atlantic N of the ITCZ and E of 50W. Seas of 8-10 ft are within this area of winds. Moderate to fresh NE to E winds dominate the waters E of the Lesser Antilles with seas of 6-9 ft based on altimeter data and buoy observations. An upper- level low situated W of the Canary Islands is generating some shower activity just S of the islands.

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/. The latest advisory states that low ash concentration is expected W of the volcano.

$$ GR

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