000 AXNT20 KNHC 201745 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 145 PM EDT WED JUL 20 2016 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. ...TROPICAL WAVES... Tropical wave came off the coast of West Africa this morning and extends from 9N-18N with axis near 18.5W. Global model guidance indicates the wave will move at 10 kt within the next 24 hours. The wave is being engulfed by Saharan dry air and dust, which is limiting the convection to scattered showers from 7N-14N E of 22W. Tropical wave is east of the Lesser Antilles extending from 10N- 18N with axis near 58W, moving W at 20 kt within the last 24 hours. The wave has been moved further west from the former position per the latest tropical wave diagnostics guidance. Low level moisture convergence supports scattered showers from 11N-16N between 58W and 63W, including the Windward Islands. Strong deep layer wind shear and dry air limits the convection to isolated showers across the Leeward Islands. Tropical wave in the central Caribbean extending from 12N-22N with axis near 77W, moving W at 20 kt within the past 24 hours. Wave coincides with a weak 700 mb trough depicted in global model guidance and is embedded in shallow moisture as indicated by CIRA LPW imagery. Isolated showers and tstms are mainly over southern Cuba adjacent waters. Tropical wave in the Bay of Campeche extending from 11N-22N with axis near 93W, moving W at 15 kt over the past 24 hours. Wave coincides with a 700 mb trough as indicated in global model guidance and is embedded within a surge of moderate moisture at the lower levels according to CIRA LPW imagery. Deep layer wind shear limits the convection to isolated showers S of 25N E of 95W. Scattered showers and isolated tstms are between the wave axis and the eastern coast of Mexico S of Tampico. ...ITCZ/MONSOON TROUGH... The monsoon trough extends across Africa into the east Tropical Atlantic near 16N16W and then continues along 10N24W to 08N40W. The ITCZ begins near 08N40W and then extends to 07N48W to the coast of Guyana near 07N58W. Aside from the convection associated with the tropical waves, scattered moderate convection is within 245 nm south of the monsoon trough east of 35W. ...DISCUSSION... GULF OF MEXICO... Weak surface ridging continues to dominate across the central and northern Gulf waters, thus providing gentle to moderate easterly flow. A tropical wave moves over the SW basin with axis near central Bay of Campeche. Convection associated with this wave lies mainly W of its axis to the eastern coast of Mexico south of Tampico. See tropical waves section for further details. The tropical wave will move inland Mexico and into east Pacific waters by Thursday morning. A surface trough currently over the NW Caribbean will move across the Yucatan Peninsula and then over the SW Gulf by Thu afternoon. Weak ridging will persist elsewhere. CARIBBEAN SEA... A surface trough, remnant of a tropical wave currently over the Bay of Campeche extends from 21N81W to Honduras near 15N85W generating scattered showers W of 80W. Over the central Caribbean, a tropical wave extends from 21N75W to 11N79W generating scattered to isolated showers over eastern Cuba and southern Hispaniola adjacent waters. A third tropical wave is east of the Lesser Antilles with axis near 58W. Moisture associated with this wave and a diffluent environment aloft support scattered showers N of 11N E of 66W, including the Windward and Leeward Islands. The tight pressure gradient between the west Atlantic surface ridge and the lower pressure over South America is producing fresh to strong trade winds across the south-central Caribbean that will continue through the week. The tropical wave E of the Lesser Antilles will move into the eastern Caribbean tonight and into the central basin Friday morning. ...HISPANIOLA... An upper level inverted trough in the central Caribbean and an upper level ridge centered NE of Puerto Rico generate a diffluent environment aloft. This environment in the upper levels along with moisture associated with the passage of a tropical wave currently with axis near 77W support scattered showers and isolated tstms over Hispaniola adjacent waters W of 70W. Showers will increase and extend inland Thursday as a tropical wave moves across the Eastern Caribbean. ATLANTIC OCEAN... A middle to upper level trough along the eastern seaboard with base extending into the SW N Atlc waters along with shallow moisture being advected by southeasterly flow support isolated showers and tstms W of 70W. Otherwise, besides the tropical waves already discussed, surface ridging dominates elsewhere. No major changes are expected in the next two days. For additional information please visit http://www.hurricanes.gov/marine $$ RAMOS