000 AXNT20 KNHC 281205 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 705 AM EST Sun Jan 28 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 1145 UTC. ...SPECIAL FEATURES... Atlantic Gale Warning: A very tight pressure gradient exists between a cold front that enters the discussion area at 32N41W to 22N52W, where it becomes a dissipating stationary front to 20N59W and a shearline from there to just N of the coast of Hispaniola, and strong high pressure of 1038 mb centered N of the area near 37N59W. This continues to produce a large area of near gale to minimal gale force NE to E winds over the waters N of the front and from 20N to 24N between 57W and 76W. Given the long duration of these winds across an expansive fetch area, the resultant seas have build to the range of 12 to 16 ft. These conditions are forecast to continue through early this evening, at which time the gradient should slacken enough to allow for the winds to diminish to strong category, however, seas are forecast to remain quite high in the 12 to 14 ft range with these winds. Fresh to strong NE to E winds are elsewhere W of the front, including through the Atlantic passages in the Bahamas except for strong to near gale force winds across the Straits of Florida. These winds will become fresh S to SW winds Sun night. Please see the latest NHC High Seas Forecast under AWIPS/WMO headers FZNT02 KNHC for more details on this event. Central Atlantic Gale Warning: A storm center of 1012 mb N of the area near 36N44W moving southward will reach near 30.5N45W by early on Mon. A tight gradient between the low and strong high pressure to its NW will bring minimal gale force northerly winds to the waters N of 29N between 48W and 52W early on Mon. Seas are forecast to be very large, 16 to 21 ft in N swell within the area of gale force winds. By late Mon night, the low is forecast to reach near 26N48W late Mon night while the ridge to its NW weakens. The northerly winds at that time are then forecast to be drop to just below gale force N of 25N between 48W and 55W, with seas in the 12 to 15 ft range. Caribbean Gale Warning: The combination of very strong high pressure centered over the NW Atlantic and lower pressure over South America is bringing minimal gale force NE to E winds near the coast of Colombia, with seas in the 12 to 15 ft range. These conditions will persist late at night and into the early morning hours through Tue, and possibly well into next week. Please see the latest NHC High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details on this event. Gulf of Mexico Gale Warning for the far SW portion: A weak 1018 mb low over southern Mississippi as of 09Z this morning will rapidly track northeastward across the NE Gulf today, and push a cold front through the eastern waters into early on Mon. Strong high pressure ridging will surge southward in the wake of the front over the western waters of the gulf. A tight pressure gradient will set up in the far SW Gulf on Mon leading to strong gale force NW to N winds that will affect the waters S of about 21N and W of 95W to along the coast of Veracruz. These winds are expected to last into early Tuesday morning, with seas building to the range of 9 to 13 ft. With the strong ridging then forecast to weaken through the middle of next week, expect for these strong gale force winds to significantly diminish along with seas subsiding. ...MONSOON TROUGH/ITCZ... The Monsoon Trough axis extends from the coast of Africa near 07N11W to 03N17W where scatterometer data indicates the ITCZ begins and continues to 02N59W and along 01N westward to 44W. Scattered moderate isolated strong convection is S of the axis between the coast of Africa and 15W. Scattered moderate convection is N of the axis within 60 nm of line from 02N31W to 02N38W, and also within 60 nm N of the axis between 42W-44W. ...DISCUSSION... GULF OF MEXICO... Please see the SPECIAL FEATURES section above for details in reference to an upcoming gale event in the SW Gulf. A tight pressure gradient between strong high pressure over the eastern gulf waters and lower pressure to the W of there continues to sustain a large area of fresh to strong E to SE winds E of about 90W. The exception is in the Straits of Florida where E winds are reaching up to 30 kt, however, these winds will diminish further on Sun as strong ridging over the eastern Gulf begins to weaken. An amplified upper level pattern is taking shape across the region. A mid/upper level short-wave trough moving across the NW and N central Gulf has aided in the development of a weak 1018 mb low over southeastern Louisiana and related stationary frontal boundary that trails from it southwestward to just E of Brownsville. A surface trough is just to the SE of the stationary front from 28N90W to 25N93W. As of 03Z, a cold front has reached the Texas coast from near Corpus Christi northeastward to inland around Galveston. Latest radar displays reveal scattered showers and thunderstorms with frequent lightning along and within 120 nm of the Texas coast and within 180 nm S of the Louisiana coast. More concentrated scattered shower and thunderstorm is related to the 1019 mb low and attendant stationary front. This activity is occurring to the N of 26N and E to a line from the Florida Big Bend to 26N88W. This activity is more directly being driven by the short-wave trough as well as by the moist E to SE surface to low-level flow across the eastern gulf. An area of scattered showers and isolated thunderstorms are seen over the S central waters S of 25N between 85W and 89W, while isolated showers and thunderstorms are elsewhere over the eastern gulf and near to within 60 nm of the NW portion of the Yucatan Peninsula. The latest forecast calls for the low to quickly track across the NE Gulf today, sending a cold front through the eastern waters into early on Mon. Strong high pressure ridging will surge southward in the wake of the front over the western waters of the gulf. Until this upcoming weather scenario is over, expect for scattered showers and thunderstorms to plague much of the gulf through Mon. CARIBBEAN SEA... Please see the SPECIAL FEATURES section above for details regarding the gale conditions near the coast of Colombia. Fresh to strong NE winds prevail at 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. A surface trough along the eastern Yucatan Peninsula and Belize continue to support scattered showers and isolated thunderstorm over the Gulf of Honduras. Similar activity has developed over and just S of the Yucatan Channel, and is lifting northward into the S central Gulf of Mexico. Isolated showers and thunderstorms are noted over Hispaniola being supported by upper level diffluent flow. Fresh to strong NE winds will occur to the lee of Cuba, and through the Windward Passage through early on Mon. Expect for low-level moisture along with related scattered showers to continue to impact the NE Caribbean, including Puerto Rico and nearby islands through at least Mon as strong to near gale force NE winds with a shearline that is located just to the N of the Greater Antilles act to advect the moisture and shower activity towards that part of the Caribbean. ATLANTIC OCEAN... Please see the SPECIAL FEATURES section above for details about the gale conditions over a portion of the southern waters between the Bahamas and a central Atlantic cold front. A cold front enters the discussion area through 32N41W to 23N51W, Where it becomes a dissipating stationary front to 21N60W and a shearline from there to just N of the coast of Hispaniola. Meanwhile, strong high pressure of 1038 mb is located well N of the area at 39N60W. The resultant tight gradient support near gale to minimal gale force winds along with large seas in the SW N Atlc from the front N to 24N and between 57W and 76W. These conditions are expected to continue through early this evening. Latest satellite imagery shows areas of rain and scattered showers within 120 nm E of the front N of 28N, and isolated showers and weak isolated thunderstorms within 90 nm SE of the front from 24N to 28N. Scattered showers are within 120-150 nm of the shearline and stationary front portions. This shower activity, as stated above under Caribbean Sea, will continue to press west- southwestward towards the NE Caribbean through Mon. Over the far western portion of the area, deep layer moisture is increasing N of the Bahamas and W of 78W as the Gulf of Mexico weak low pressure over southeastern Louisiana advances northeastward, and new cold front along the Texas coast makes headway across the Gulf of Mexico. Areas of rain along with scattered showers are noted from along the central and NE Florida coasts eastward from there for about 90-120 nm. The moisture, in the form of mid/upper level overcast clouds will trend to spread eastward through Mon in advance of the next cold front. This cold front is expected to move offshore the SE United States coast on Mon, and reach from near 32N73W southwest across the NW Bahamas to the Straits of Florida on Mon night, then from 32N63W to eastern Cuba by Tue night. Strong NW winds and building seas will follow in the wake of this front. Over the far eastern portion of the area, a ridge that extends from a 1039 mb high pressure system centered near 43N18W 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 16N and E of 31W where abundant mid and upper level clouds are streaming eastward towards Africa ahead of a mid to upper level trough located N of 10N between 30W and 40W. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos