000 AXNT20 KNHC 112352 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 752 PM EDT Thu May 11 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 is over the central Atlc with axis extending from 01N36W to 09N36W, moving westward at 15 kt over the past 24 hours. Unfavorable wind shear and Saharan dry air is in the northern wave environment, coinciding with lack of convection. However, from 02N to 06N, favorable wind shear, deep layer moisture and upper diffluence support scattered moderate to isolated strong convection in this region east of the wave axis to 28W. Similar convection is ahead of the wave from 0N to 04N between 39W and 51W. A tropical wave is over the western tropical Atlantic with axis extending from 13N56W to inland western Suriname, moving westward at 10 kt over the past 24 hours. The wave is mainly in an unfavorable wind shear environment N of 09N and is embedded in a moderate moist region as shown by both CIRA LPW and water vapor imagery. Upper level diffluent flow ahead of the wave axis support scattered moderate convection from 08N to 13N between 57W and 61W. A tropical wave is moving from western Venezuela to Colombia, moving west at 15 kt over the past 24 hours. Convection associated with this wave is inland. ...ITCZ/MONSOON TROUGH... The monsoon trough crosses the western African coast near 14N17W and extends to 06N20W. The ITCZ begins near 06N20W and continues to 06N34W, then resumes west of a tropical wave near 02N38W and continues to 00N48W. Aside from the convection associated with the tropical waves, scattered moderate convection is from 01S-08N between 39W-52W. ...DISCUSSION... THE GULF OF MEXICO... Fair weather and very stable conditions prevail across most of the basin being supported by middle to upper level ridging and surface high pressure being anchored by a 1017 mb high centered in the NE basin near 28N85W. Water vapor and CIRA LPW imagery show dry air nearly basin-wide, which is allowing for clear skies except for the SW basin S of 23N where shallow moisture being advected from the Caribbean support scattered to isolated showers. A light to gentle breeze is across the eastern gulf while moderate return flow dominates the western basin. Locally fresh N-NE flow is over the NW Yucatan Peninsula associated with a thermal trough in the eastern Bay of Campeche from 22N89W to 18N92W. The center of high pressure is forecast to dissipate tonight leaving the basin with return flow ahead of the next cold front to come off the coast of Texas and Louisiana Friday afternoon. CARIBBEAN SEA... A middle to upper level trough prevails over the W Atlc extending S to a base over the eastern Caribbean. The trough aloft along with shallow moisture continue to support scattered heavy showers across southern Puerto Rico and coastal waters as well as in southern Dominican Republic. Heavy showers and isolated tstms are also occurring in the Leeward Islands and adjacent waters N of 15N E of 65W. A surface trough extending from 20N62W to 14N67W enhances this convection. In the SW Caribbean, the eastern extension of the Pacific Ocean monsoon trough continue to support scattered showers and isolated tstms S of 12N. Otherwise, gentle to moderate trades are basin-wide. Showers will continue for the northeast Caribbean through Friday morning. ...HISPANIOLA... Under the presence of a middle to upper level trough and shallow moisture, scattered showers and isolated thunderstorms prevail over southern Dominican Republic. Model guidance indicate rainshowers will continue to tonight. ATLANTIC OCEAN... A surface ridge anchored by a 1016 mb high pressure center near 25N74W dominates the southwestern north Atlantic waters W of 64W. A middle to upper level trough prevailing over the W Atlc extending S to a base in the E Caribbean supports a cold front from 30N53W to 25N60W with scattered moderate convection within 120 nm ahead of the boundary. Scattered heavy showers and isolated tstms are from 16N to 26N between 54W and 64W. The remainder central and eastern Atlc is under the influence of a surface ridge centered by a 1020 mb high near 27N41W, which will remain nearly stationary within the next 24 hours. The cold front will continue to move over north-central Atlc waters where it will stall early Friday before dissipating Saturday. A new cold front will clip the northern discussion waters of the central Atlantic Friday night. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos