000 AXNT20 KNHC 172321 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 721 PM EDT Mon Apr 17 2017 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 2300 UTC. ...SPECIAL FEATURES... A gale force low is centered over the central Atlantic near 32N45W. Over the discussion waters, gale force winds are N of 28N between 42W-52W. Very large seas of 17-25 ft can be found coincident with the area of gale force winds. Winds are forecast to diminish below gale later this evening. Please refer to the high seas forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details. ...ITCZ/MONSOON TROUGH... The monsoon trough extends across the western Africa coast near 06N10W and continues to 03N20W. The intertropical convergence zone continues from 03N20W to 00N44W to 01S48W. Scattered moderate convection is S of the monsoon trough from 03N-05N between 08W- 16W. Widely scattered moderate convection is along the ITCZ from 01S-03N between 38W-46W. ...DISCUSSION... ...GULF OF MEXICO... A 1025 mb high is centered over the W Atlantic near 30N67W with a surface ridge extending across northern Florida to the northern Gulf of Mexico along 30N. 10-20 kt E to SE flow is over the Gulf with strongest winds over the Straits of Florida. An embedded surface trough is over the SW Gulf from 23N95W to 17N93W. Some isolated showers may be possible in the vicinity of the trough. Elsewhere, radar imagery shows isolated thunderstorms over the SE Gulf including the Straits of Florida. Scattered showers and thunderstorms are inland over S Louisiana and Mississippi, and along the Texas coast W of 95W. In the upper levels, a broad ridge is over the Gulf with the axis just to the E along 80W. Upper level moisture is over most of the Gulf. Ongoing convection will persist during the next few hours, then should diminish somewhat after sunset with the loss of daytime heating. Little change in marine conditions is expected during the next 48 hours, with a nocturnal surge of 20-25 kt winds expected W of the Yucatan Peninsula each night. CARIBBEAN SEA... Mainly 10-20 kt tradewinds are over the Caribbean Sea, except pulsing and local 20-25 kt winds NW of the coast of Colombia, across the approach to the Windward Passage, and S of Hispaniola. Scattered moderate to strong convection is developing from western Colombia to across Panama and southern Costa Rica. Additional afternoon convection developed along coastal portions of the remainder of the Caribbean. In the upper levels, a broad ridge is over the Caribbean Sea with axis extending from the SE Caribbean to across Hispaniola. Strong subsidence is over portions of the NW Caribbean behind a trough which extends roughly along 81W. Expect little change over the next 48 hours. ...HISPANIOLA... Scattered showers and isolated thunderstorms developed during the afternoon with daytime heating, supported by an approaching upper trough to the west, and with upper level diffluence which has been over the island and is now retreating. Activity should diminish shortly with the loss of daytime heating, with similar conditions possible tomorrow. ATLANTIC OCEAN... A 1025 mb high is centered over the W Atlantic near 30N67W. A gale force low is centered over the central Atlantic near 32N45W. Please see the special features section above for more information on the associated gale warning. A cold front wraps into the low extending into the discussion waters from 32N36W to 20N41W to 15N60W. Scattered moderate convection is N of 25N within 180-240 nm ahead of the front. In the upper levels, a large upper level low is centered directly over the gale force surface low with a ridge aloft building in its wake between 50W-55W. The surface low is forecast to move SE during the next 24 hours, reaching 31N44W by Tuesday afternoon. Also expect the associated Atlantic cold front to drift E while weakening. For additional information please visit http://www.hurricanes.gov/marine $$ Lewitsky