000 AXNT20 KNHC 031044 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Sat Oct 3 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 0600 UTC surface analysis and satellite imagery through 1000 UTC. ...SPECIAL FEATURES... Tropical Storm Gamma is centered near 19.4N 86.9W at 03/0900 UTC or 70 nm S of Cozumel Mexico moving NW at 8 kt. Estimated minimum central pressure is 992 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Strong thunderstorms are evident across the inner core of Gamma and in a prominent band to north of the center impacting northern Quintana Roo. Another strong band is moving northwest toward western Cuba. Given the size and relatively slow movement of Gamma across the northeastern portion of the Yucatan peninsula through tonight, the main threat continues to be heavy rainfall that could result in life- threatening flash flooding over portions of the Yucatan Peninsula, far western Cuba and well away from the center in the Mexican states of Campeche, Tabasco, and northern Chiapas. Please monitor local weather advisories for more details. For marine interests, strong winds and seas at least as high as 13 ft will impact the Yucatan Channel through tonight. In the south- central Gulf, a long fetch of persistent near-gale force NE winds is already causing seas to 12 ft off the north coast of Yucatan, along with rough surf conditions. Adverse marine conditions will persist into mid week in the south-central Gulf due to the expected track of Gamma. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT5.shtml and Forecast/ Advisory at https://www.nhc.noaa.gov/text/MIATCMAT5.shtml for more details. ...TROPICAL WAVES... An Atlantic Ocean tropical wave is along 42W from 18N southward, moving W at 10-15 kt. A broad area of disorganized area of scattered moderate to isolated strong convection is noted from 08N-16N between 33W-44W. A Caribbean Sea tropical wave is along 70W from 18N southward, moving W at 10 kt. Numerous moderate to scattered strong convection is evident over the entrance to the Gulf of Venezuela, to the west of the wave axis. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through coastal sections of Senegal near 14N17W to 07N30W. The ITCZ continues from 07N30W to 07N40W, and from 06N43W to the coast of Brazil near 03N51W. Convection near the ITCZ is associated with the tropical wave along 42W, described above. GULF OF MEXICO... At 0300 UTC, a stationary front extends from southwest Florida near 26N81W to 22N90W. Another stationary front farther north extends off the Tampa Bay, Florida coast near 26N84W. In the far southwest Gulf, a surface trough is analyzed off the coast of Veracruz. An earlier scatterometer satellite pass indicated strong to near- gale force NW winds funneling between the trough and the coast, south of 21N. Large area of strong to near-gale force NE winds are noted over the south-central Gulf, between Gamma to the southeast and high pressure north of the area. A recent altimeter satellite pass indicated seas were reaching 12 ft off the Yucatan coast. Moderate NE winds and 3 to 5 ft seas persist elsewhere over the northern Gulf. Seas over the southern Bay of Campeche are likely up to 9 ft, in a combination of mixed NW and NE swell. For the forecast, Gamma will enter the south-central Gulf and reach near 21.7N 88.0W Sun afternoon, then move to 21.8N 88.4W Mon morning, 21.6N 89.3W Mon afternoon, and 21.2N 90.5W Tue morning. Gamma is expected to change little in intensity as it moves across the eastern Bay of Campeche through early Wed. Meanwhile a weak stationary front reaching from SW Florida to the south-central Gulf will dissipate late by today ahead of Gamma. Another stationary front from central Florida to the central Gulf will dissipate late Sun into Mon. A cold front will move into the northern Gulf Mon and stall over the central Gulf through mid week. CARIBBEAN SEA... Please see the Special Features section on information regarding T.S. Gamma and the tropical waves section regarding the tropical wave in the central Caribbean. A few showers and thunderstorms are noted off the southern coast of the Dominican Republic this morning, likely due to overnight drainage flow converging off the coast, but also near where the northern portion of the tropical wave is passing. Strong E winds are noted off the southern coast of Haiti as well, with seas likely reaching 8 ft. Moderate to fresh trade winds and 5 to 7 ft seas are noted elsewhere east of 75W, and north of 18N particularly between Jamaica and eastern Cuba. Light to gentle breezes and modest seas are noted over the southwest Caribbean. For the forecast, Gamma will move to 20.2N 87.4W this afternoon, inland to 21.1N 87.9W Sun morning, then into the south-central Gulf of Mexico through Sun afternoon. Winds and seas will gradually diminish over the far northwest Caribbean through Mon. Elsewhere, fresh to strong trades are expected over the eastern and central Caribbean through Sun night. Winds and seas will subside through mid week across the basin as Gamma moves farther west and high pressure north of the area weakens slightly. ATLANTIC OCEAN... A stationary front extends from 31N73W to 26N80W. A surface trough is analyzed south of the front, reaching from the northern Bahamas to central Cuba. A few showers are active over the northern Bahamas where the trough and front intersect. Another stationary front is analyzed farther north, from 31N78W to 28N80W. No significant weather is associated with that front. A broad surface ridge extends from 1033 mb high pressure near 40N37W to just east of the fronts. The gradient on the southwest side of this ridge is supporting fresh to strong E winds off the north coast of Hispaniola. Fresh winds and a few showers are also noted north of a surface trough embedded in the ridge along 48W from 23N to 28N. Fresh winds are also associated with the tropical wave near 42W. In the eastern Atlantic, Fresh to strong NE winds and seas to 9 ft are active off the African coast of Mauritania in Elsewhere, generally moderate trade winds persist across the Atlantic with mostly 5 to 7 ft seas. For the forecast for waters west of 65W, the stationary front extending from 31N73W to 26N80W will gradually dissipate late today or tonight. The other stationary front extending from 31N78W to 28N80W will dissipate through late Sun. Meanwhile, the high pressure north of our area will support moderate to fresh trades south of 22N, occasionally pulsing to strong north of Hispaniola during the overnight hours through Sun night. Looking ahead, a third weak front will move over the Atlantic waters east of NE Florida late Sun or early Mon, drift south through Tue then stall from 31N73W to near W Palm Beach Florida by mid week. $$ Christensen