000 AXNT20 KNHC 260004 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 804 PM EDT Thu May 25 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 2345 UTC. ...TROPICAL WAVES... A tropical wave came off Africa earlier today. Its axis extends from 10N19W to 01N19W and is forecast to move at 10-15 kt within the next 24 hours. The wave is in a favorable wind shear environment and CIRA LPW imagery show mainly a moderate moist environment with some patches of dry air as the wave is being engulfed by the Saharan Air Layer. Upper level diffluence supports scattered showers from 0N-07N between 17W and 30W. A tropical wave is in the west Atlc with axis extending from 13N44W to 04N47W, moving westward at around 20 kt within the last 24 hours. The latest scatterometer data at the time of the analysis showed the inverted-v wind pattern associated with the wave axis. The wave is in an unfavorable wind shear environment and very dry Saharan air engulfs it. CIRA LPW imagery show shallow moisture near the center of the wave axis and dry air in the rest of the wave environment. Upper level divergence supports scattered moderate convection from 07N-11N between 43W-49W. A tropical wave is in the western Atlc with axis extending from 14N51W to 04N53W, moving W at 20 kt over the last 24 hours. Unfavorable wind shear and Saharan dry air across the wave environment hinder convection at the time. A tropical wave is over the southwest Caribbean with axis extending from 14N77W across Panama to EPAC waters near 03N79W, moving W at 20 kt within the last 24 hours. Some dry air is depicted by CIRA LPW ahead of the wave axis, but mostly shallow moderate moisture is in its vicinity. Unfavorable wind shear and dry air subsidence from aloft hinder convection in the Caribbean basin. However, abundant moisture and favorable wind shear in the EPAC support heavy rainfall and scattered tstms there. A tropical wave is moving across the Yucatan Peninsula and Guatemala. The wave axis extends from 20N89W to 11N92W, moving W at 20 kt within the last 24 hours. Scattered showers and tstms associated with this wave are inland. The wave will move to EPAC waters Friday. ...ITCZ/MONSOON TROUGH... The Monsoon Trough enters the tropical Atlantic near 11N16W and continues to 06N15W to 05N19W. The ITCZ begins near 04N23W and extends to 07N39W. Aside from the convection associated with the tropical waves, scattered moderate convection is from 0N-06N between 23W-31W. ...DISCUSSION... GULF OF MEXICO... Strong dry air subsidence allows for clear skies across most of the Gulf behind a cold front that extends from the southern Florida Peninsula near 25N81W to 23N85W to 22N88W where it starts to weaken and transitions to a stationary front to 21N92W. Scattered showers are within 210 nm east of the front, including the Florida straits and the Yucatan Channel. This front is forecast to exit the basin on Friday morning, leaving the basin with weak surface high pressure and light to gentle variable flow through Friday. Return moderate to fresh flow will dominate across the basin the remainder of the weekend. CARIBBEAN SEA... A tropical wave is over the SW Caribbean, however due to strong wind shear and strong dry air subsidence from aloft no convection is associated with it. Please refer to the Tropical Waves section for more details. Scattered showers are over the far NW basin N of 20N W of 78W associated with a cold front moving across South Florida and the SE Gulf of Mexico. These showers will continue through Friday morning as the front moves to SW N Atlc waters. Otherwise, high pressure over the central Atlantic extends a ridge toward the SW across the eastern Caribbean Sea supporting fresh to strong easterly winds across the east and central Caribbean and near gale force winds along the coast of Colombia. Moderate to fresh southeast winds are over the western part of the basin. Visible satellite imagery and Saharan Air layer from UW-CIMSS reveal the presence of Saharan dry air across much of the Caribbean, thus supporting hazy conditions in the Lesser Antilles, Puerto Rico and Hispaniola. Fresh to near gale winds will persist over the central Caribbean through Friday, then diminish on Saturday. Pulsing fresh easterly winds are expected across the Gulf of Honduras at night through Monday night. ...HISPANIOLA... Mostly dry and hazy conditions will prevail across the island under the influence of a ridge. Model guidance continue to show limited moisture across the region through Saturday evening when shallow moisture may enhance showers. Fair weather is expected Sun except again for afternoon/evening showers. ...ATLANTIC OCEAN... A cold front enters the forecast area in the SW N Atlc near 30N75W and extends SW to southern Florida near 26N80W. A band of showers and thunderstorms is ahead of the front across the northern and central Bahamas as well as the Great Bahama Bank. Fresh to strong winds are on either side of the front, but mainly north of 27N. A 1026 mb high pressure centered near 31N46W currently dominates the remainder of the western Atlantic and central Atlantic. A weaker cold front is in the NE forecast waters extending from 30N18W to 27N27W where it becomes stationary to 21N44W. This front will continue to weaken and dissipate Saturday. Three tropical waves are between 19W and 55W. Please refer to the tropical waves section for more details. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos