000 AXNT20 KNHC 140004 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 804 PM EDT Tue Jun 13 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 in the E Atlc with axis extending from 10N19W to 02N19W. CIRA LPW imagery show the wave is in a very moist environment from the surface to 850 mb, that along with favorable wind shear and upper level divergence support scattered heavy showers from 01N to 08N between 18W and 27W and from 03N to 07N E of 17W. A tropical wave is in the central Atlc with axis extending from 13N31W to 04N33W, moving west at 15 kt within the last 24 hours. CIRA LPW imagery show the wave is in a moderate moist environment, with some patches of dry air. The wave coincides with a diffluent environment at the middle levels and a col of low pressure in the upper levels, and is in a region of favorable wind shear. However, enhanced satellite imagery show Saharan dry air in the wave environment, which seems to be the major factor for lack of convection at the moment. A tropical wave is in the W Atlc just SE of the Lesser Antilles with axis extending from 15N57W to 07N58W, moving west at 20 kt within the last 24 hours. CIRA LPW imagery show the wave is in a moderate moist environment, with some patches of dry air. Enhanced satellite imagery confirms the presence of Saharan dry air. Unfavorable wind shear and dry air support lack of convection at the time. A tropical wave is in the central Caribbean with axis extending from 15N72W to inland Colombia near 07N72W, moving westward at 10 kt within the last 24 hours. CIRA LPW imagery show shallow moisture with patches of dry air in the wave environment that along with unfavorable wind shear support lack of convection at the time. ...MONSOON TROUGH/ITCZ... The Monsoon Trough extends from 06N21W to 07N31W to 07N40W. The ITCZ continues from 07N40W to the coast of Guyana near 06N57W. Three tropical waves are embedded within the monsoon trough/ITCZ. Most of the convective activity is associated with the above mentioned tropical waves. ...DISCUSSION... GULF OF MEXICO... High pressure of 1020 mb located over the SE CONUS extends a ridge across the eastern Gulf region, thus supporting moderate to locally fresh SE flow. Shallow moisture being advected from the Caribbean along with the presence of a nearly stationary upper level trough in the E basin support scattered showers E of 86W, including the Florida peninsula and the Florida straits. Otherwise, the remnants of a weak low over the W Bay of Campeche are analyzed as a surface trough along the coast of SE Mexico from 23N97W to 18N96W, which support isolated showers over the Bay of Campeche. Looking ahead, a broad area of low pressure is expected to form over the western Caribbean Sea or Central America late this week or this weekend. Some gradual development of this system is possible thereafter while it moves slowly northwestward into the Gulf region. Computer model indicates that southeast winds will increase over the southwest Gulf by late Saturday ahead of the aforementioned low pressure area expected to approach the region through northern Central America. CARIBBEAN SEA... Shallow moisture and an upper level diffluent environment support scattered heavy showers along Cuba and scattered to isolated showers over the NW basin. A former tropical wave in the SW Caribbean has merged with the broad monsoonal flow in the EPAC and now is being analyzed as a surface trough off the coast of Nicaragua from 13N82W across southern Costa Rica to 07N83W. Heavy showers and isolated tstms are associated with this trough S of 14N W of 80W. Scattered showers are elsewhere S of 14N E of 80W. An upper level trough in the SW Atlc extends S to a base over southern Hispaniola coastal waters. This is supporting lifting of moist warm air and the development of scattered heavy showers and tstms over central Haiti and the NW Dominican Republic. A tropical waves moves across the central Caribbean, however no convection is associated with it. Please see the tropical waves section for more details. Scatterometer data show moderate to fresh trades across the east and central Caribbean, except for fresh to strong winds near Colombia as well as in the Gulf of Honduras. Gentle to moderate winds are over the NW Caribbean. This wind pattern will persist through Wednesday. Winds will diminish into Thursday as the high pressure north of the area lifts farther to the north. Looking ahead, a broad are of low pressure is forecast to develop across central America and the NW Caribbean by the end of the week. ...HISPANIOLA... An upper level trough in the SW Atlc extends S to a base over southern Hispaniola coastal waters. This is supporting lifting of moist warm air and the development of scattered heavy showers and tstms over central Haiti and the NW Dominican Republic. This shower activity is forecast through Wednesday morning as the upper trough moves east to the N of Puerto Rico. ATLANTIC OCEAN... Three tropical waves are moving westward between the coast of Africa and the Lesser Antilles. Please refer to the Tropical Waves section above for details. A surface trough moved to inland Florida supporting showers across the peninsula and Atlc waters W of 76W. Another surface trough extends from 29N59W to 23N63W lacking convection. Farther east, another surface trough extends from a very weak 1021 mb low near 27N37W to 24N39W. Otherwise, broad high pressure covers the Atlantic from the Azores to the Carolinas. Moderate to locally fresh trades are around the southern periphery of the ridge between the Windward Islands and 30W. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos