000 AXNT20 KNHC 091108 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 608 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 0600 UTC surface analysis and satellite imagery through 0945 UTC. ...SPECIAL FEATURES... A cold front extends from the Tampa Bay region near 28N83W S-SW to the coast of the Yucatan peninsula near 21N87W and across to peninsula to near 18N93W. 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 gusts are expected off the coast of the Yucatan peninsula and Belize and 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 09N13W to 06N19W. The Intertropical Convergence Zone axis extends from 06N19W to the Equator near 44W. Widely scattered moderate convection is from the Equator to 05N between the Prime Meridian and 15W. ...DISCUSSION... GULF OF MEXICO... The main feature across the basin is the Special Features cold front extending across eastern Gulf and central Florida peninsula this morning. Aside from the near gale to gale force wind field... scattered showers and tstms are occurring generally within 150 nm E 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 to SE 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 northwestern 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 W of 76W this morning focused on a pre-frontal surface trough analyzed from 16N87W to 23N85W. This area of troughing will linger across the western 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...isolated showers are possible E of 74W 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 morning 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 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 Special Features cold front which extends from a 1005 mb low centered off the coast of the Carolinas near 33N77W. The front extends SW to the Florida peninsula near 29N81W. Scattered showers and tstms are occurring generally within 120-150 nm E 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 31N56W. Lastly...water vapor imagery indicates a cut-off middle to upper level low centered near 27N37W supporting a nearly collocated 1012 mb low centered near 26N37W. A surface trough extends from the low to 26N34W to 23N34W to 15N40W. Scattered showers and tstms are occurring from 20N-31N between 27W-39W near and E of the low center. The low is forecast to gradually weaken through late Saturday night and then drift westward as a surface trough across the central Atlc through Monday. For additional information please visit http://www.hurricanes.gov/marine $$ HUFFMAN