000 AXNT20 KNHC 032352 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 652 PM EST Wed Jan 3 2018 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 2230 UTC. ...SPECIAL FEATURES... As of 03/2100 UTC, a vigorous middle to upper level trough is noted on water vapor imagery over the eastern Gulf of Mexico and Florida panhandle supporting a deepening and complex area of low pressure focused on a 997 mb low near 31N78W and a 998 mb low near 29N77W. An occluded front extends from the northern low to the southern low, with a cold front continuing through the central Bahamas into central Cuba. A warm front also extends E from the southern low to near 29N69W. The southern low is forecast to merge with the northern low as it continues to rapidly intensify while moving to the NE. Gale force winds currently in place NE of the Bahamas will increase to storm force within 150 nm in the SW semicircle of the complex low in the discussion waters later this evening, and eventually develop hurricane-force winds off the east coast of the US north of the discussion area. Nearby ships recently reported 45-50 kt NE of the northern low and N of the discussion waters, as did a dropsonde from a NOAA research mission. The complex low is forecast to move N offshore of the east coast of the US reaching Nova Scotia, Canada by Thursday night. See the latest NWS NHC High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC and NWS OPC High Seas Forecast under AWIPS/WMO headers HSFAT1/FZNT01 KWBC for more details. A tight pressure gradient and reinforcing cold air filtering in across the western Gulf of Mexico continues to support near gale to gale force N-NW winds generally within 60 nm of the coast of Veracruz, Mexico. These winds are forecast to diminish below gale force by Thursday morning. 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 06N10W to 06N17W. The Intertropical Convergence Zone axis extends from 06N17W to the Equator near 36W. Widely scattered moderate convection is from the Equator to 03N between the Prime Meridian and 07W, and from the Equator to 06N between 12W-27W. ...DISCUSSION... GULF OF MEXICO... Aside from the near gale to gale force conditions mentioned above, a surface ridge prevails across the Gulf this evening anchored by a 1036 mb high centered just NW of Laredo, Texas near 28.5N100W. Fresh to strong northerly winds are expected to persist through Thursday morning. Thereafter, the ridging will weaken gradually relaxing the pressure gradient and winds will diminish into moderate breeze levels for the upcoming weekend. CARIBBEAN SEA... Southwesterly flow aloft prevails over the Caribbean basin this evening between an upper level trough moving from the southeastern Gulf of Mexico into the northwestern Caribbean, and an upper level ridge anchored over northern Venezuela. The troughing supports a cold front analyzed across western Cuba from 22N81W to the eastern Gulf of Honduras near 16N86W. Isolated showers are possible across the NW Caribbean waters in the vicinity of the front as the cooler and drier airmass NW of the front filters southward across the western Caribbean through tonight. Farther SE, broad surface troughing and a 1009 mb low centered offshore of central Panama near 11N80W continues to provide focus for scattered to numerous showers and scattered tstms S of 18N between 73W-83W, and S of 12N between 81W-84W. Otherwise, the eastern Caribbean remains under fair skies within moderate to occasional fresh trades. As the Special Features low pressure area across the SW North Atlc waters moves northward, the associated cold front will move across the western Caribbean to 78W and become stationary across the Windward Passage and Hispaniola Thursday into Friday with fresh to near gale force winds expected W of the boundary through the upcoming weekend. ...HISPANIOLA... Increased cloudiness and isolated showers are expected through tonight across Hispaniola as broad surface troughing and lower pressure focuses on the Bahamas, Greater Antilles, and central Caribbean Sea. A cold front currently across western Cuba and the NW Caribbean Sea will begin to approach from the west on Thursday with NE winds increasing through the Windward Passage region and persisting through early next week. ATLANTIC OCEAN... Outside of the Special Features deepening area of low pressure across the SW North Atlc, a cold front enters the discussion area across the central Atlc near 32N50W to 31N52W becoming stationary to 30N62W to 28N72W and linking up with the Special Features warm front boundary. Scattered showers and isolated tstms are occurring within 240 nm either side of the boundary, with the strongest activity S of the boundary. The remainder of the central and eastern Atlc is under the influence of a surface ridge anchored by a 1036 mb high centered W-SW of the Iberian peninsula near 36N16W. For additional information please visit http://www.hurricanes.gov/marine $$ Lewitsky