000 AXNT20 KNHC 041047 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Sun Oct 4 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 off the north coast of Yucatan near 22.0N 88.2W at 04/0900 UTC or 100 nm ENE of Progreso Mexico moving N at 4 kt. Estimated minimum central pressure is 995 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Large clusters of showers and thunderstorms are active within 150 nm in the northwest semicircle of Gamma. Additional showers and thunderstorms are observed over the southeast Gulf from 23N to 26N between 83W and 88W. Isolated thunderstorms are also evident over western Cuba. Most of the thunderstorm activity has moved north of the Yucatan Peninsula. Seas are building as Gamma moves farther offshore. A long fetch of persistent NE winds to the north of Gamma is support seas to 16 ft in the south- central Gulf. Gamma is expected to turn toward the north- northwest with decreasing forward speed is expected on Sunday, followed by a turn to the west or west- southwest Sunday night or Monday. On the forecast track, the center of Gamma will pass near or north of the northern coast of the Yucatan Peninsula Monday and Tuesday. Little change in strength is forecast during the next few days. 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. A tropical wave with an axis along 75W southward from 18N moving W at 10 kt is producing scattered moderate convection from 13N- 15N between 71W-77W. Environmental conditions are expected to become more conducive for development, and a tropical depression is likely to form during the next couple of days while the system moves westward or west- northwestward at about 10 to 15 kt across the central and northwestern Caribbean Sea and then into the southern Gulf of Mexico. Locally heavy rainfall and gusty winds will be possible across portions of Hispaniola, Jamaica, Cuba, and the Cayman Islands during the next few days, and interests on those islands should monitor the progress of this disturbance. This system has a medium chance of development through the next 48 hours and a high chance of formation through the next 5 days. ...TROPICAL WAVES... An Atlantic Ocean tropical wave is along 45W from 20N southward, moving W at 10 kt. A 1010 mb low is along the wave near 11N44W. Scattered moderate convection is noted from 11N-17N between 41W- 48W. Some slow development of this system is possible during the next couple of days while it moves west-northwestward or northwestward at 10 to 15 kt. Significant development is not expected beyond that time due to the system moving into a region of strong upper-level winds. This system has a low chance of development over the next 48 hours and the next 5 days. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through coastal sections of Senegal near 14N17W to 06N35W. The ITCZ continues from 06N35W to 06N43W and from 09N47W to the coast of French Guiana near 04N52W. Some scattered moderate convection is moving off the coast of southern Senegal. No other significant convection is observed. GULF OF MEXICO... Please see the Special Features section above for information on T.S. Gamma. A stationary front continues to linger off the SW Florida coast near 26N81W to 24N85W. Scattered moderate convection is within 80 nm of the front. Dry conditions west of 90W is inhibiting convection from occurring over the western Gulf. Moderate to strong N to NW winds span across the eastern and central Gulf, including the eastern half of the Bay of Campeche. Gentle easterly winds are off the coasts of Texas through Alabama. Seas are from 3-5 ft across the northern and western Gulf with 9-16 ft across the south- central Gulf near T.S. Gamma. Tropical Storm Gamma near 22.0N 88.2W 995 mb at 5 AM EDT moving N at 4 kt. Maximum sustained winds 45 kt gusts 55 kt. Gamma will move to 22.6N 88.3W this afternoon, 22.7N 88.6W Mon morning, 22.4N 89.4W Mon afternoon, 22.0N 90.2W Tue morning, 21.5N 90.9W Tue afternoon, and 21.0N 91.6W Wed morning. Gamma will change little in intensity as it moves westward through the eastern Bay of Campeche. A stationary front from SW Florida near 26N81W to the SE Gulf near 24N83W will dissipate later today, ahead of low pressure expected to move from the northern Caribbean across western Cuba into the southeast Gulf Tue, possibly as a tropical depression or tropical storm. A cold front will move into the northern Gulf Mon, then stall and dissipate over the central Gulf through mid week as the low pressure moves northward. CARIBBEAN SEA... Please see the Special Features section on information regarding T.S. Gamma and the tropical wave in the central Caribbean. The monsoon trough extends across the southwest Caribbean from 11N74W to the coast of Costa Rica near 10N82W. Scattered moderate convection is active from 13N- 15N between 71W-77W. Isolated thunderstorms continue to impact the Virgin Islands westward into Puerto Rico. Gentle to moderate trade winds prevail across most of the Caribbean with fresh winds near the Greater Antilles and light winds in the SW Caribbean. Seas are from 3-6 ft across most of the basin with upwards of 8 ft near the low along the tropical wave, and 5 to 7 ft near the Yucatan Channel Gamma will continue to move NW into the south-central Gulf, allowing winds and seas over the Yucatan Channel to diminish through Sun. The focus turns to the development and track of the low pressure south of Haiti There is a high chance this low may form into a tropical depression or tropical storm through next several days as the low moves west- northwest through the northwest Caribbean, south of Cuba. ATLANTIC OCEAN... A stationary front is draped off the Florida coast from 31N79W to the coast near Melbourne, Florida at 29N80W. Another stationary front is farther south extends from 31N74W to near West Palm Beach, Florida at 27N80W. No significant convection is associated with either front. Both stationary front will dissipate through late today or tonight. A broad surface ridge extends from 1030 mb high pressure near 38N37W west of the Azores 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. There may be one more round of fresh to strong winds off Hispaniola tonight. Winds and seas will diminish thereafter as the ridge shifts east ahead of a third weak front that will move over the Atlantic waters east of NE Florida by early Mon, drift south through Tue then stall from 31N73W to near W Palm Beach Florida by mid week. Farther east, fresh winds and a few showers are also noted north of a surface trough embedded in the ridge along 50W from 23N to 30N. Fresh winds are also associated with the tropical wave near 45W. In the eastern Atlantic, fresh to strong NE winds and seas to 9 ft are active off the African coast of Western Sahara and Mauritania. Elsewhere, generally moderate trade winds persist across the Atlantic with mostly 5 to 7 ft seas. $$ Christensen