000 AXNT20 KNHC 270922 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 406 AM EST Sat Jan 27 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 0600 UTC surface analysis and satellite imagery through 0915 UTC. ...SPECIAL FEATURES... Atlantic and Gulf of Mexico Gale Warning: The pressure gradient has significantly tightened between a cold front that extends from 32N49W to 27N54W to 24N63W where it becomes a weakening cold front to 23N65W, then and a dissipating stationary front to 22.5N74W and very strong high pressure of 1040 mb centered N of the area at 36N73W. This tight pressure gradient has induced a large area of near gale to minimal gale force NE to E winds over the waters between the front and the Bahamas S of about 27N. Seas are in the range of 12 to 16 ft with these winds, and are forecast to build slightly higher today through Sun. As of late Fri night, a new gale warning was issued for frequent gusts for the waters W of the Bahamas including the Straits of Florida and far eastern Gulf of Mexico near 83W. Ascat and ship data from late last night indicated that winds over the affected gale winds waters had increased to near gale force with frequent gusts. Seas associated with these gale force winds are in the 10 to 15 ft range. Strong NE to E winds are elsewhere W of the front, including through the Atlantic passages in the Bahamas. The latest model guidance indicates that these winds will be slow in diminishing, and as per the latest issued forecasts, these winds are forecast to lessen to just below gale force on Sun afternoon over the waters E of the Bahamas to the frontal system mentioned above. The gale force winds W of the Bahamas that include the Straits of Florida and far eastern Gulf of Mexico are forecast to diminish late on Sat to strong NE to E winds. Seas will still be on the high range possibly reaching up to 14 ft at that time. By late Sun, these winds and seas diminished considerably. Please see the latest NHC High Seas Forecast under AWIPS/WMO headers Misfit/FZNT02 KNHC for more details on this event. Caribbean Gale Warning: The combination of very strong high pressure centered E of the mid-Atlantic states and lower pressure over South America is bringing minimal gale force NE to E winds near the coast of Colombia. These conditions will persist late at night into the early morning hours through Mon. Please see the latest NHC High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details on this event. Far E Atlantic Gale Warning: Another very strong high pressure system, this one of 1041 mb is centered NE of the Azores near 40N21W. The tight pressure gradient to its SE and S is allowing for NE gale force winds that reach to strong gale force over Meteo France marine zones of Agadir, Tarfaya and to near gale force NE winds over Canarias except for strong gale force winds over the eastern portion of that zone. NE winds are reaching near gale force at times over zone Cap Blanc. These conditions are expected through Sat evening. With the tight gradient not expected to slacken in the short term, the gale conditions for Agadir, Tarfaya and the near gale to gale for Canarias are forecast to continue through Sun night. Please refer to Meteo France Weather Bulletins for more information. ...MONSOON TROUGH/ITCZ... The Monsoon Trough axis extends from the coast of Africa at 06N10W to 05N14W where the latest scatterometer data indicates the ITCZ begins and continues to 02N23W to 01N30W to just below the Equator at 34W. Scattered strong convection is within 120 nm S and 60 N of the axis between 32W-34W, and W of the axis S of 01N between 34W-40W. Scattered moderate isolated strong convection is within 120 nm S and 180 N of the axis between 12W-19W, and also between 22W-29W. Scattered moderate convection is within 150 nm S and 120 N of the axis between 25W- 28W. Scattered moderate convection is within 120 nm either side of the axis between 10W- 12W. ...DISCUSSION... GULF OF MEXICO... Please see the SPECIAL FEATURES section above for details about regarding the gale conditions in the far SE Gulf. Strong surface high pressure centered near the northeastern United States is supporting a large area of strong E winds over much of the eastern and central Gulf of Mexico. The exception is in the far SE Gulf and Straits of Florida where strong E winds are gusting frequently to gale force. These winds are forecast to diminish late on as the strong ridging over the eastern Gulf begins to weaken some. A surface trough has become evident over the far NW portion from 28N95W to 26N95.5W in response to an upper shortwave trough that is beginning to swing northeastward around the base of a longwave trough that is moving through the central U.S. Scattered showers and isolated thunderstorms along with patches of rain have increased over much of the gulf during the overnight hours. This activity is quickly moving east- northeastward. Scattered showers and isolated thunderstorms have recently developed over the SW Gulf just to the E of a surface trough that extends from 21N96W to 19N92W. Strong winds are expected to continue over the eastern Gulf today. A rather progressive upper level pattern will bring surface low pressure southeastward towards the area of southeastern Louisiana or southwestern Mississippi early tonight, with a trailing cold front across the NW Gulf waters. The low is forecast to rapidly move across the NE Gulf on Sun while pushing the cold front across the eastern gulf waters through early on Mon. Expect widespread rain along with scattered showers and isolated thunderstorms with system. CARIBBEAN SEA... Please see the SPECIAL FEATURES section above for details about regarding the gale conditions near the coast of Colombia. The Ascat pass from late last night clearly revealed an impressive swath of strong to near gale force NE winds to the lee of Cuba. Fresh to strong trades are occurring elsewhere across the basin, except for the gale force winds near the coast of Colombia as described above under SPECIAL FEATURES. Latest satellite imagery shows scattered showers and isolated thunderstorm over the far western Caribbean Sea close to the coasts of Honduras including the Gulf of Honduras. Similar activity is over the waters between Jamaica and 82W. Isolated showers and thunderstorms are noted over the Yucatan Peninsula, northern and eastern Honduras and eastern Nicaragua. Since the surface pattern is expected to change very little through Sun, strong trade wind flow is forecast to continue during the next couple of days. Strong to near gale force NE winds are likely to occur through the Windward Passage next week. Expect increasing low-level moisture along with scattered showers to impact the NE Caribbean and islands in that location including Puerto Rico through Sun night as a decaying frontal boundary over the central Atlantic drops southward towards the NE Caribbean and strong to near gale force NE winds advect the associated moisture and shower activity towards that section of the Caribbean. ATLANTIC OCEAN... Please see the SPECIAL FEATURES section above for details about the gale conditions over portions of the waters between the Bahamas and a central Atlantic cold front. A cold front enters the discussion area through 32N49W to 27N54W to 24N63W where it becomes a weakening cold front to 23N65W, then and a dissipating stationary front to 22.5N74W. Meanwhile, very strong high pressure of 1040 mb is centered within about 110 nm E of the northern coast of N Carolina. The resultant tight gradient has increased the NE to E winds between the front and the Bahamas to the ranges of near gale to minimal gale force and along with large seas. These conditions are expected to continue into early Sun afternoon. Scattered showers are within 60 nm either side of the front. The stationary portion of the front is forecast to continue to weaken through the weekend. The frontal remnants will drift southward towards the NE Caribbean Sea islands, most likely as a shearline. Precipitable water GFS model guidance indicates that moisture and precipitation will increase for the NE Caribbean islands through the weekend. before diminishing late Sun. Farther east, a 1041 mb high pressure system centered near 40N21W dominates the area E of the cold front maintaining rather stable weather over much of the central and eastern sections of the area, except for the far eastern portion S of 24N and E of 40W where abundant mid and upper level clouds are streaming eastward towards Africa ahead of a mid to upper level trough located N of 15N between 30W and 40W. For additional information please visit http://www.hurricanes.gov/marine $$ Aguirre