000 AXNT20 KNHC 281804 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 103 PM EST Wed Feb 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 1200 UTC surface analysis and satellite imagery through 1745 UTC. ...SPECIAL FEATURES... A 978 mb low pressure located well to the northeast of the area just east of the Azores Islands near 37N22W. A cold front associated with this low enters the discussion area at 32N10W, and continues to 25N17W to 21N33W and to 19N30W, where it transitions to a weakening stationary front to 19N37W and to 19.5N45W where it becomes a weak trough to 24N52W. As a result, a very tight pressure gradient is analyzed over the far eastern portion of the area to the north of 25N. The Ascat pass from near 1100 UTC this morning confirmed the ongoing gale westerly gale force winds north of about 26N. Please refer to the METEO- FRANCE High Seas Forecast link at WWW.METEOFRANCE.COM/PREVISIONS-METEO-MARINE/BULLETIN/ GRANDLARGE/METAREA2. Gale force winds are forecast for the areas IRVING, MADEIRA, CASABLANCA AND AGADIR. Near gale force S to SW winds over Cadiz are forecast to increase to gale force tonight into early on Thu. The OUTLOOK, for the 24 hours that follow the forecast that is valid until 01/1200 UTC, consists of: the persistence of a cyclonic near gale or gale north of 25N. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends off the coast of Africa through the coastal sections of Liberia near 06N11W and continues southwestward to 02N16W. The ITCZ continues then continues from 02N16W to below the Equator near 190W, and continuing along 01S to 29W where it briefly ends. It resumes at the Equator along 34W and to 02S42W. Scattered moderate isolated strong convection is within 150 nm S of the monsoon trough axis between 10W-15W, and also within 90 nm n of the monsoon trough axis between 12W-14W. Scattered moderate convection is within 30 nm of 01N18W and within 30 nm of 01N21W. Similar activity is S of the ITCZ within 60 nm of line from 04S18W to 04S23W. ...DISCUSSION... GULF OF MEXICO... Isolated showers are seen moving west-northwest across the Straits of Florida spun of from moisture related to the tail-end of a stationary front that is just east of the central Bahamas. The fresh to strong winds observed this morning off the northern coast of the Yucatan Peninsula have diminished to mainly fresh winds as of early this afternoon. Elsewhere, weak ridging from the western Atlantic extends westward over the northern waters. The gradient associated with this ridging is maintaining gentle to moderate east to southeast winds over most of the Gulf with seas in the 1 to 3 ft range. The exception is in the NW Gulf, where fresh southeast winds are noted along with seas of 3 to 5 ft seas. The fresh southeast winds over the NW Gulf will diminish tonight ahead of a cold front moving into the northern Gulf early Thu. Strong northerly winds will follow the front over mainly the western Gulf into Fri. The front will stall from the Straits of Florida to near Veracruz Mexico by late Fri before dissipating Sat. A ridge will build across the Gulf through Sun. CARIBBEAN SEA... Weakening high pressure north of the area is supporting generally moderate to fresh trade winds across the basin this afternoon. The fresh to strong NE winds earlier noted through the Windward Passage have diminished to mainly moderate winds per the Ascat pass from 1416 UTC this morning. Upper level diffluence on the southeastern side of a broad upper trough that extends from just east of Puerto Rico to the along the NW coast of Colombia and to just south of Panama is supporting patches of low-level moisture with isolated showers moving quickly in the trade wind flow over the southeastern and Caribbean and much of the central Caribbean. Elsewhere across the central and western Caribbean, fairly dry conditions are present due to dry sinking air in the wake of the aforementioned upper trough. Reinforcing high pressure to the north of the area will continue to support moderate to fresh trade winds across the basin, with strong winds pulsing at night off Colombia through late week. These winds will diminish by Sat as the high pressure weakens and shifts east ahead of a deep low pressure moving into the western Atlantic. Large swell will impact the tropical Atlantic waters through Sat, with a more significant swell event penetrating the NE Caribbean starting early on Sun. ATLANTIC OCEAN... A cold front extends from a 1002 mb low just north of the area at 33N41W southwestward through 32N44W to 27N60W and to 25N67W, where it transitions to stationary front to 26N70W to just east of the Bahamas near 25N75W. Scattered showers and possible weak isolated thunderstorms are noted from 26N to 29N between 53W-59W aided mainly by an upper short-wave trough that extends from 32N56W to just east of Puerto Rico that is acting upon deep layer moisture present along the front east of 60W. Drier conditions persist elsewhere, but low level clouds persist within 120 nm of the front. Current buoy and recent altimeter data indicate seas of 10 to 15 ft N of the front east of 57W, and 9 to 12 ft N of the front between 57W and 66W. Latest satellite imagery shows cyclonic swirls of broken to mid level clouds with scattered showers along the stationary frontal boundary, with similar clouds over the NW Bahamas. Farther to the south, gentle to moderate winds prevail. Looking ahead, the cold front will stall east of the Bahamas and dissipate through late Thu. Fresh southerly flow will increase late Thu off NE Florida ahead of another cold front moving off the coast Thu night. The front will reach from Bermuda to the Straits of Florida by late Fri, just ahead of a reinforcing front with strong to possibly gale force winds north of 24N related to deep low pressure moving off the Virginia coast. The fronts will merge Sat and reach from 22N65W to the Windward Passage by Sun. A significant swell event and likely the largest of this winter winter season will accompany this system, affecting all waters to the east of north Florida and the Bahamas by the end of the week. Over the far eastern Atlantic, strong to near gale force winds persist north of 20N into the area of gales described in the special features. Recent altimeter satellite data continue to highlight very large seas to the north of about and east of 40W. For additional information please visit http://www.hurricanes.gov/marine $$ Aguirre