000 AXNT20 KNHC 211703 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Sat Nov 21 2020 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 32N. 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. ...TROPICAL WAVES... A tropical wave is over the eastern Caribbean along 62W, from 18N southward, moving westward at 10 to 15 kt. Scattered showers are near the wave axis. A second tropical wave is over the central Caribbean along 75W, from 20N southward, moving westward at 10 to 15 kt. The wave combined with a mid-upper level trough is producing scattered moderate convection from 18N-20N between 73W-77W, including the Windward Passage. Another tropical wave is along 88W, from 19N southward, moving westward at 10 to 15 kt. The wave extends southward into the EPAC region. Numerous moderate to isolated strong convection is seen from 16N-19N between 86W-89W. This convective activity is affecting the Gulf of Honduras and parts of Belize and northern Honduras. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coast of Africa near 07N12W to 07N25. The ITCZ continues from 07N25W to 05N40W to near the coast of French Guiana. Scattered moderate to isolated strong convection is noted from 02N-10N between 10W-25W. A diffluent pattern aloft is helping to induce this convective activity. GULF OF MEXICO... A surface ridge dominates the Gulf waters producing moderate to fresh easterly winds across the eastern half of the Gulf and gentle to moderate winds over the western half of the basin. Seas are in the 5-8 ft range based on buoys observations. Patches of low level clouds are noted across the region moving westward. Low level clouds are also banking up against the Sierra Madre Mountains in Mexico. Winds and seas are forecast to diminish across the Gulf region today. A weak cold front will move across the NE Gulf Mon. Another weak cold front may move into the northern Gulf for the middle of next week. CARIBBEAN SEA... Three tropical waves are analyzed in the Caribbean Sea. Please, see Tropical Waves section for details. Recent scatterometer data suggest that the eastward extension of the Pacific Ocean monsoon trough extends into the SW Caribbean. An area of scattered moderate to isolated strong convection is noted over the SW Caribbean just N of the monsoon trough and ahead of a tropical wave axis with axis along 75W. This convective activity covers the waters from 10N-13N between 75W-81W. Mainly moderate trade winds are noted across the basin, with the exception of moderate to fresh NE winds in the lee of eastern Cuba. Winds and seas will diminish across the NW Caribbean through tonight as high pressure north of the area weakens. Large northerly swell will continue to impact the tropical Atlantic waters east of the Lesser Antilles through Mon where fresh to locally strong trades are seen per satellite-derived wind data. In addition, recent altimeter data provided observations of sea heights in the 9-11 ft range within this area. Building high pressure N of the area will bring an increase in winds and seas across the central Caribbean Tue night and Wed. ATLANTIC OCEAN... Moderate to fresh NE winds are noted across the regional waters E of Florida, the Bahamas, and over the Straits of Florida. These winds have been carried patches of low level moisture with embedded showers. In fact, Mosaic Doppler Radar from the SE U.S. shows band of showers parallel to the winds mainly over central Florida and in the Straits of Florida. A surface trough is analyzed from 27N67W to 20N72W. Abundant cloudiness with embedded showers and thunderstorms is noted in association with this trough. Moderate to fresh winds are seen on either side of the trough axis per scatterometer data. This trough will drift westward through late Mon. A non-tropical area of low pressure could form near the northern end of the trough over the western Atlantic early next week. This system would only have a brief time period to develop subtropical characteristics before it merges with a cold front as it accelerates northeastward by the middle of next week. The cold front will move into the NW waters east of northern Florida on Monday. High pressure in the wake of the front will bring another round of fresh NE-E winds across the SW N Atlantic Tue night into Wed. Farther east, another surface trough extends from 30N29W to 23N27W. Recent satellite-derived wind data indicate the wind shift related to the trough axis as well as fresh to strong NE winds near the northern end of the trough. Visible satellite imagery shows a well-defined swirl of low clouds in association with this feature. High pressure dominates the remainder of the Atlantic forecast region. $$ GR