000 AXNT20 KNHC 132254 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Sun Dec 13 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 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...SPECIAL FEATURES... Gulf of Mexico Gale Warning: A strong cold front will move into the NW Gulf tonight. Behind this front, strong cold air advection will induce northwest to north gale force winds to 35 kt over the NW Gulf overnight tonight along with seas building to 11 ft. This same surge of cold air will also bring similar northerly gale force winds, but slightly stronger, up to 40 kt, over sections of the western and SW Gulf Mon through Mon evening, with strong north winds elsewhere over the western Gulf. Seas are forecast to reach 11 ft in the SW Gulf. Winds and seas will decrease Tue as high pressure moves over the area. Please read the latest High Seas Forecast at https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends from the coast of Sierra Leone near 08N13W to 05N20W, where latest scatterometer data indicates that it transitions to the ITCZ to 05N20W to 03N43W. Scattered moderate to isolated strong convection is within 90 nm either side of the ITCZ between 20W-43W. GULF OF MEXICO... Please see the Special Features section for details on a forecast Gulf of Mexico gale warning. The cold front over the Florida panhandle transitions to a warm front which now extends from Pensacola westwards across Louisiana coast to northeastern Texas. An area of scattered showers and thunderstorms moving northeastward extends from Texas near Corpus Christi northeastward to the Panama City and offshore for about 60 nm. Moist southerly flow resulting in patches of low clouds and stratus are over the rest of the Gulf. Isolated showers are possible with some of these cloud patches. Otherwise, a 1019 mb high center is analyzed over north-central Florida, with a ridge extending west-southwestward. As for the forecast: The warm front will continue to lift northward today, with fresh southerly winds developing in its wake. A more significant cold front will move into the Gulf tonight, then move across much of the basin Mon into Tue. Strong N winds will spill behind the front and gales will develop over portions of the western and southwestern Gulf Mon and Mon evening. Wind and seas decrease Tue as high pressures builds in. The next front will move into the western Gulf Tue night and across the Gulf by Thu. Northerly gales will briefly occur offshore Veracruz, Mexico Wed afternoon. CARIBBEAN SEA... Upper-level ridging covers the western Caribbean and Central America. Water vapor imagery depicts moderate subsidence inducing dry sinking air and rather stable atmospheric condition across these sections of the sea. An upper-level trough axis extends from near 30N58W to the eastern part of the Caribbean. At the surface, a trough has moved to just inland the northeastern part of the Yucatan Peninsula. Latest partial ASCAT data reveals generally moderate to fresh trades over the central part of the sea, with the exception of fresh to strong trades south of about 14N between 74W-79W and to near the coast of Colombia. Gentle to moderate trades are elsewhere across the sea. Seas are in the range of 4-7 ft, except for higher seas in the range of 6-9 ft in the south-central section of the sea, where the fresh to strong winds are occurring. As for the forecast:Strong NE to E wind will pulse tonight offshore N Colombia, before high pressure weakens early this week and winds and seas subside some. By the latter half of the week, the high will re- strengthen to the north, and strong nightly pulses will redevelop. A weakening cold front will move slowly SE across the Yucatan Channel and western Cuba Thu. ATLANTIC OCEAN... A cold front is analyzed from near 31N19W to 29N29W, then weakening stationary to 28N35W. The boundary then transitions to a shearline to near 26N48W. ASCAT data revealed a large area of fresh to strong northeast to east winds north of stationary front and shearline to 30N and between 45W-58W. Mainly fresh northeast to east winds are east of 45W north of the stationary and cold fronts. A surface trough is along a position from near 27N55W to 17N59W. This feature lies to southeast of a rather robust upper- level trough that stretches from near 32N54W southwestward to 24N60W and to the eastern Caribbean Sea. Upper-level divergence southeast of this feature is helping to promote an increasing area of rain with embedded scattered moderate convection over the area from 19N-29N and between 48W-57W. Weak low pressure is forecast to develop along the surface trough near 24N by early Tue. Elsewhere across the eastern waters, moderate to large northwest swell remains in the waters roughly north of 20N and east of 67W, where seas are in the 8-12 ft. This area of swell is forecast to gradually shrink into the early part of the week as it shifts to the south and southeastward. A surface trough east of northern Florida extends from 30N78W to 27N79W. Light northwest winds are west of the trough. Isolated showers are near this trough. ASCAT data showed moderate to fresh northeast to east winds between 58W-68W, gentle to moderate winds between 68W-75W and light to gentle winds west of 75W. A 1032 mb high center is analyzed north of the area at 35N52W, with a ridge extending west-southwestward to just east of the trough that is east of northern Florida. High pressure covers the discussion area outside the aforementioned described features. As for the forecast: The high pressure ridging east of northern Florida will shift eastward through Mon in response to the next cold front that will move over the northwest waters Mon afternoon. A deep layer trough will remain nearly stationary along about 57W early this week. Strong S winds will develop N of about 28N Mon ahead of a cold front that will move off the FL coast Mon evening. This front will cross the northern basin into mid-week. The next cold front will move into the NW waters Wed night then slide slowly SE through the basin for the end of the week. $$ Torres