000 AXNT20 KNHC 040602 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 102 AM EST Thu Jan 4 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 0000 UTC surface analysis and satellite imagery through 0545 UTC. ...SPECIAL FEATURES... As of 04/0300 UTC, a vigorous middle to upper level trough is noted on water vapor imagery over the eastern Gulf of Mexico and the SW N Atlc waters supporting a deepening and complex area of low pressure focused on a 997 mb low near 31N74W and a 993 mb low near 31N76W. A cold front extends from the easternmost low SW to the northern Bahamas near 25N76W through central Cuba continuing to eastern Honduras. A warm front also extends E from the eastern low to near 31N52W. The eastern low is forecast to merge with the western low as it continues to rapidly intensify while moving to the NE. Storm force winds are currently in place N of the Bahamas from 28.5N to 31N west of the cold front with seas to 18 ft. Hurricane- force winds will develop off the east coast of the US north of the discussion area within the next 24 hours. The complex low will continue to move N-NE 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 before sunrise today. 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 05N20W. The Intertropical Convergence Zone axis extends from 05N20W SW to the coast of Brazil near 03S39W. Scattered moderate convection is from the Equator to 09N between 16W-30W. ...DISCUSSION... GULF OF MEXICO... Aside from the near gale to gale force conditions mentioned above, a surface ridge prevails across the Gulf anchored by a 1030 mb high centered near Tampico, Mexico. 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 between the base of an upper level trough over the northwestern Caribbean, and an upper level ridge anchored east of the Windward Islands. The trough aloft supports a cold front analyzed across central Cuba from 21N79W to the eastern Gulf of Honduras near 16N85W. Isolated showers are possible within 60 nm either side of the front. South of Jamaica, a 1009 mb low is analyzed near 13N78W with a trough extending northward from the low to the Windward Passage. This elongated area of low pressure is underneath diffluent flow aloft, which is supporting scattered heavy showers and scattered tstms N of the low between 71W and 80W. including the Windward Passage and Hispaniola. Similar convection is S of the low to the coast of Panama and Costa Rica. This convection is being influenced by the EPAC surface trough and divergent flow in the upper levels. 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 today into Friday with fresh to near gale force winds expected W of the boundary through the upcoming weekend. ...HISPANIOLA... Increased cloudiness and scattered to isolated showers are across Hispaniola due to an elongated area of low pressure centered south of Jamaica. A cold front currently across central Cuba and the NW Caribbean Sea will begin to approach from the west on today 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 surface trough extends from 29N56W to 22N70W supporting scattered showers and isolated tstms within 150 nm either side of the boundary. The remainder of the central and eastern Atlc is under the influence of a surface ridge anchored by a 1033 mb high centered W-SW of the Iberian peninsula near 36N13W. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos