000 AXNT20 KNHC 090510 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1210 AM EST Sat Dec 9 2017 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 0000 UTC surface analysis and satellite imagery through 0415 UTC. ...SPECIAL FEATURES... A 1007 mb low is centered NE of the Tampa Bay region near 28N84W with the associated cold front extending S-SW to the coast of the Yucatan peninsula near 22N88W to across northern Guatemala. Strong high pressure is building in west of the front across the western and central Gulf waters maintaining a strong pressure gradient and resulting near gale to gale force NW to N winds generally S of 26N W of the front. As the front moves eastward...the near gale to gale force conditions are expected to persist through late Saturday. Looking ahead...as the front enters the NW Caribbean Sea and then begins to stall across the SW Caribbean waters...near gale to gale force N winds are again forecast W of the front in the offshore waters off the coast of Nicaragua. See the latest NWS High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 10N14W to 06N23W. The Intertropical Convergence Zone axis extends from 06N23W to 03N30W to 03N40W. Widely scattered moderate convection is from the Equator to 06N between the Prime Meridian and 11W. ...DISCUSSION... GULF OF MEXICO... The main feature across the basin is the Special Features 1007 mb low and frontal system that extends across eastern Gulf this evening. Aside from the near gale to gale force wind field... scattered showers and tstms are occurring S of 30N W of the front across the SE Gulf and Florida peninsula. The cold front is expected to clear the basin by late Saturday with strong to near gale NW winds continuing across the southeastern two-thirds... gradually diminishing from the NW through Sunday. Thereafter... gentle to moderate N winds will prevail as high pressure builds in across the western waters early next week. CARIBBEAN SEA... Divergent middle to upper level flow is noted over the western Caribbean between the strong upper level troughing over the western Gulf of Mexico and an upper level anticyclone centered over northern Colombia. Increased moisture and cloudiness continues to support widely scattered showers and isolated tstms generally between 75W-85W this evening focused on a surface trough analyzed from 10N81W to 17N80W. This area of troughing will linger across the SW Caribbean until Saturday night and then likely merge with the cold front that is expected to impact the NW and far western waters Saturday and Saturday night. The front is forecast to stall across the western Caribbean through Tuesday and gradually weaken by mid-week. Farther east...a surface trough extends from 13N59W near Barbados to 15N69W. Isolated showers are occurring within 75 nm either side of the trough axis and will remain embedded within fresh to strong trades on the southern periphery of a ridge anchored across the central Atlc. The trades will weaken gradually across the eastern Caribbean by Sunday as the ridge weakens and retreats northward. ...HISPANIOLA... Fair weather conditions prevail across the island this evening as a surface high centered in the central Atlc extends ridging across the area. Isolated showers however are occurring across the southern adjacent waters in association with a diffuse remnant frontal boundary. ATLANTIC OCEAN... Southwesterly flow aloft is noted on water vapor imagery over the SW North Atlc between a middle to upper level trough over the eastern CONUS and Gulf of Mexico and an upper level ridge anchored over the central and western Caribbean Sea. The troughing supports the 1007 mb Special Features low and frontal boundary centered in the vicinity of the Tampa Bay region...however a stationary front meanders across the northern Florida peninsula and into a 1008 mb low centered near 32N78W. Scattered showers and tstms are occurring generally within 120 nm either side of the front as the entire system moves rapidly off to the NE. Otherwise...the remainder of the SW North Atlc waters are under the influence of a surface ridge anchored by a 1026 mb high centered near 30N57W. Lastly...water vapor imagery indicates a cut-off middle to upper level low centered near 28N36W supporting a nearly collocated 1013 mb low centered near 28N38W. A stationary front extends from the low to 25N34W then to 18N37W becoming a surface trough W-SW to 14N50W to 13N61W. Scattered showers and tstms are occurring from 22N-31N between 28W-40W near the low center...with isolated showers possible within 90 nm either side of the surface trough axis. The low is forecast to gradually weaken through late Saturday night and then drift westward as a surface trough through Monday. For additional information please visit http://www.hurricanes.gov/marine $$ HUFFMAN