000 AXNT20 KNHC 151717 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Wed Dec 15 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 1200 UTC surface analysis and satellite imagery through 1700 UTC. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Sierra Leone near 08N13W to 07N16W. The ITCZ continues from 07N16W to 04N30W to the coast of Brazil near 03N50W. Scattered moderate convection with embedded thunderstorms is noted from 01N to 12N between 13W and 50W. GULF OF MEXICO... A surface trough in the Bay of Campeche is generating scattered showers and thunderstorms in the area. High pressure dominating the eastern US is extending a ridge across the area generating moderate to fresh anticyclonic flow across the basin with 4 to 6 ft seas. Recent scatterometer data indicates fresh easterly winds in the Florida Straits. For the forecast, high pressure will prevail across the northern forecast waters through Sat, supporting moderate to locally fresh winds. A cold front is forecast to enter the basin Saturday night into early Sunday. Fresh to strong winds and building seas will prevail west of the front. CARIBBEAN SEA... A surface trough over NE Honduras and northern Nicaragua is generating scattered showers and thunderstorms extending 420 nm eastward from the coast into the central Caribbean. Similar convection is noted over the Gulf of Honduras including the Bay Islands. Scattered showers and isolated thunderstorms are also noted 60 nm north of Aruba. The gradient between high pressure over the western Atlantic combined with low pressure over the Colombian Basin is maintaining fresh to locally strong easterly trade-winds over the majority of the Caribbean Sea. Recent altimiter data confirms seas are predominatley 6 to 8 ft. For the forecast, strong high pressure will prevail over the western Atlantic through the forecast period. This will support fresh to strong trade-winds over the eastern and central Caribbean through the weekend. Moderate to fresh trades are expected elsewhere. ATLANTIC OCEAN... A surface trough extends from south-central Florida to 29N79W. This sytem is enhanced by an upper level trough and is generating scattered showers and thunderstorms from the east coast of Florida to about 77W and over the NW Bahamas. Recent scatterometer data confirms fresh to strong northeast winds are noted along the northern poriton of this feature. Another trough is noted from 29N67W to 25N65W. Recent scatterometer data indicate a wind shift associated with the trough and fresh to strong winds along the northern portion of the feature. Low-level clouds with embedded showers are also associated with the trough. The remainder of the western Atlantic is under the influence of high pressure centered over the eastern US. Moderate to fresh winds dominate the majority of the western Atlantic with 6 to 8 ft seas south of 27N and east of the Bahamas and 4 to 6 ft north of 27N. For the forecast west of 65W, high pressure north of the area is supporting moderate to fresh winds over the forecast waters. The area of high pressure will build southward, bringing an increase in winds and seas. East of 65W, A dissipating cold front extends from 31N45W to 27N55W. Isolated showers are possible near the frontal boundary. A surface trough extends from a low pressure located south of the Madeira Islands near 31N18W through the Canary Islands near 28N15W and into Western Sahara. A ridge exists between the front and the trough producing gentle anticyclonic flow north of 20N. South of 20N and north of the ITCZ moderate to locally fresh trade winds prevail. As of December 15 at 1246Z METEO-FRANCE issued the final advisory on the La Palma volcano in the Canary Islands, which had been erupting since 19 September 2021. No ash concentrations are observed and this is the final advisory expected. $$ FLYNN