000 AXNT20 KNHC 200605 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 205 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 0000 UTC surface analysis and satellite imagery through 0545 UTC. ...SPECIAL FEATURE... Tropical Depression Four is located near 20.1N 95.4W at 0300 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. Scattered showers and thunderstorms are S of 26N west of 89W. The center of the depression is expected to move inland over eastern Mexico on Monday. However, some strengthening is expected, and the depression is forecast to become a tropical storm early Monday. 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 32W from 03N-12N, 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 05N-07N between 30W and 33W. A tropical wave is in the tropical central Atlantic with axis near 40W from 02N-12N, moving W near 10 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 45W. A tropical wave is in the eastern Caribbean with axis near 64W from 10N-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 11N-20N between 60W and 67W. A tropical wave is in the central Caribbean with axis near 69W from 11N-19N, moving W at 20 kt during the past 24 hours. The wave has not moved much during the last several 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 14N between 67W and 71W. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 10N13W to 04N23W. The ITCZ axis begins near 04N23W and continues to 03N38W. For information about convection, see the tropical waves section above. ...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 this morning. Scattered showers and thunderstorms are S of 26N west of 89W and seas in its vicinity are near 12 ft. See the special features section above for more details. The tail of a cold front currently over SW N Atlc waters extends from 25N81W to 25N82W and generates scattered 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 69W and the other in the eastern Caribbean with axis near 64W. 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 69W later this morning. Moderate to fresh easterlies are behind this wave axis mainly N of 13N. 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 and SW Caribbean continue to support fresh to strong easterlies from 11N to 16N between 70W and 80W, with near gale-force winds along the coast of Colombia. ...HISPANIOLA... A tropical wave with axis near 69W currently supports scattered to isolated showers and tstms mainly across the Dominican Republic. This wave has nearly stalled during the last several hours, but is expected to merge with a much faster wave to the E that will bring heavy showers across the Island Monday. 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 29N68W, from which a cold front extends along 25N74W to southern Florida near 25N80W. GOES lighting density data indicate the presence of scattered to isolated heavy showers and tstms within 120 nm ahead of the front. Similar convection is farther east S of 23N between 60W and 65W 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 1033 mb high near the Azores islands. The cold front is forecast to stall near sunrise today. For additional information please visit http://www.hurricanes.gov/marine $$ RAMOS