000 AXNT20 KNHC 201016 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 616 AM EDT MON JUN 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 0600 UTC surface analysis and satellite imagery through 1015 UTC. ...SPECIAL FEATURE... Tropical Depression Four is located near 20.2N 95.9W at 0900 UTC and is moving west at 6 kt. The estimated minimum central pressure is 1009 mb. Maximum sustained winds are near 30 kt with gusts to 40 kt. Numerous heavy showers and scattered thunderstorms are S of 22N west of 94W. Scattered showers are elsewhere S of 26N W of 90W. The center of the depression is expected to move inland over eastern Mexico later today or tonight. However, some strengthening is still expected, and the depression could become a tropical storm before it makes landfall in Mexico later today. See the latest NHC Intermediate Public Advisory under AWIPS/WMO headers MIATCPAT4/WTNT34 KNHC and the full Forecast/Advisory under AWIPS/WMO headers MIATCMAT4/WTNT24 KNHC for more details. ...TROPICAL WAVES... A tropical wave is in the tropical central Atlantic with axis near 33W from 03N-13N, moving W at 15-20 kt during the last 24 hours. The wave coincides with weak 700 mb troughing between 25W and 35W according to the GFS model. Saharan dry air and dust are in the northern wave environment as well as strong deep layer wind shear. This is limiting the convection to scattered showers from 06N-07N between 30W and 34W. A tropical wave is in the tropical central Atlantic with axis near 41W from 02N-11N, moving W near 15 kt. The wave coincides with broad 500 mb troughing between 30W and 54W according to the GFS model. Saharan dry air and dust are in the northern wave environment. In the southern wave environment, weak deep layer wind shear, moderate moisture and diffluent wind at the upper levels support scattered showers from 03N-07N between 35W and 46W. A tropical wave is in the eastern Caribbean with axis near 66W from 09N-19N, moving W at 20 kt during the past 24 hours. The wave is associated with abundant moisture as indicated by SSMI TPW imagery and is under a diffluent environment aloft that supports numerous showers and isolated tstms from 12N-18N between 59W and 67W. A tropical wave is in the central Caribbean with axis near 70W from 11N-19N, moving W at 20 kt during the past 24 hours. The wave has not moved much during the last few hours and it is possible that it will merge with the wave in the eastern Caribbean, which is advancing W faster. The wave is associated with moderate moisture, however strong deep layer wind shear in this region of the basin limits the convection to isolated showers and tstms N of 15N between 67W and 72W. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 10N14W to 04N23W. The ITCZ axis begins near 04N23W and continues to 04N39W. It then resumes W of a tropical wave from 05N43W to 06N57W. Besides the convection associated with the tropical waves, a cluster of heavy showers and tstms is from 07N-10N E of 15W. ...DISCUSSION... GULF OF MEXICO... The main concern in the basin is T.D. Four currently centered over the western Bay of Campeche, which is expected to intensify to a T.S. later today or tonight. Numerous heavy showers and scattered thunderstorms are S of 22N west of 94W. Scattered showers are elsewhere S of 26N W of 90W. Seas in its vicinity are near 12 ft. See the special features section above for more details. The tail of a stationary front currently over SW N Atlc waters extends from 24N80W to 24N81W and support isolated showers across the Florida straits. Surface ridging has built across the remainder basin. Scatterometer data show fresh to occasionally strong easterly winds within 90 nm off the western Florida peninsula coast and mainly moderate easterlies elsewhere. CARIBBEAN SEA... The main features across the basin are two tropical waves, one with axis near 70W and the other in the eastern Caribbean with axis near 66W. The easternmost wave is generating numerous heavy showers and isolated tstms currently affecting the Lesser Antilles, Virgin Islands and adjacent waters. Scattered showers and tstms are across Puerto Rico and will increase in coverage as the wave continues to move fast westward to possibly merge with the wave near 70W later this morning. Moderate to fresh easterlies are behind this wave axis. See the tropical waves section above for further details. In the SW basin, the monsoon trough continues to support scattered heavy showers and tstms S of 12N as indicated by GOES lighting density data. Strong pres gradient between ridging NE of the basin and lower pres in the central, eastern and SW Caribbean continue to support fresh to strong easterlies from 11N to 15N between 72W and 79W, with possible near gale-force winds along the coast of Colombia. ...HISPANIOLA... A tropical wave with axis near 70W currently supports scattered showers mainly across the Dominican Republic southern adjacent waters. This wave has nearly stalled during the last few hours, but is expected to merge with a much faster wave to the E that will bring heavy showers across the Island today. See tropical waves section for further details. ATLANTIC OCEAN... An upper level low over the NW Atlc and associated trough extending S to a base over the south-central Caribbean support a 1015 mb low near 29N67W, from which a stationary front extends along 24N72W to the Florida straits near 24N81W. GOES lighting density data indicate the presence of scattered to isolated heavy showers and tstms within 140 nm ahead of the front. Similar convection is farther east from 23N to 28N between 61W-64W. Scattered showers are S of 21N between 61W and 66W associated with a tropical wave that moves across the eastern Caribbean. The remainder basin is under the influence of a surface ridge, anchored by a 1031 mb high near the Azores islands. The stationary front is forecast to weaken today. For additional information please visit http://www.hurricanes.gov/marine $$ RAMOS