735 AXNT20 KNHC 071155 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 755 AM EDT Tue Aug 7 2018 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 1145 UTC. ...SPECIAL FEATURES... A Gale Warning is in effect for the south-central Caribbean. A strong Atlantic ridge west of 60W is tightening the pressure gradient in the south-central Caribbean. Scatterometer data has confirmed the existence of gale-force winds in the Gulf of Venezuela, and 30 kt winds along the coast of Colombia near 13N71W. Gale-force winds are forecast for the Gulf of Venezuela on overnight and along the coast of Colombia by Wed night. Please see the Atlantic High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for further details. ...TROPICAL WAVES... A tropical wave axis in the eastern Atlantic extends from 19N37W to 08N41W, moving W at 10-15 kt. Scatterometer data depicts a distinct shift in wind direction along the convergence zone axis west of the wave. The northern part of the wave is affected by Saharan dry air intrusion, limiting convection to the area south of 14N between 36W and 44W. A tropical wave in the equatorial central Atlantic extends from 02N-14N along 52W, moving W at 10-15 kt. The wave continues to be affected by intrusion of Saharan dry air and dust. Shallow moisture in the vicinity of the ITCZ supports scattered showers convection mainly S of 08N. A tropical wave axis in the central Caribbean extends south of 22N along 74W, moving W at 10-15 kt. The wave is in a moist environment at the lower levels as indicated by LPW and water vapor imagery, and under a diffluent environment between an elongated upper-level low over the central basin and S-SW flow to the east, which is supporting scattered showers N of 18N between 70W-73W. A tropical wave is in the western Caribbean with axis S of 21N along 84W, moving W at 10-15 kt. LPW imagery shows shallow moisture in the vicinity of the wave, and interaction with the monsoon trough supports scattered moderate convection mainly S of 12N between 80W-85W. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the eastern Atlantic near 20N17W and extends southwestward to 13N25W then westward to 18N39W. The ITCZ begins W of a tropical wave near 10N41W and continues to 06N51W, then resumes near 08N53W to 09N61W. Aside from the convection related to the tropical waves, scattered moderate convection is observed along the ITCZ between 40W-50W. ...DISCUSSION... GULF OF MEXICO... A broad area of high pressure extends from the western Atlantic into the northern Gulf. Scattered convection is observed just W of the Florida peninsula, a remnant of evening thunderstorms over land. Return flow associated with the surface ridge continues to advect shallow moisture from the Caribbean into the Gulf, supporting scattered moderate convection in the Yucatan Channel and south-central Gulf waters between 84W-90W. A surface trough is in the NE Gulf from the Florida Big Bend to 29N84W with associated convection over land at this time. Expect convection to fire up again across the basin later today. A nocturnal thermal trough that will emerge off the Yucatan Peninsula each night, and enhance the NE winds off the W Yucatan Peninsula. Surface ridging will prevail elsewhere through Sat. CARIBBEAN SEA... Enhanced satellite imagery continues to show a thin layer of Saharan dust moving across most of the basin where deep-layer wind shear prevails. This environment continues to suppress the development of significant convection across the basin. Shallow moisture is present south of Cuba, supporting scattered showers. The monsoon trough in the SW Caribbean supports convection near Panama. Fresh to near-gale force winds in the south-central Caribbean are forecast to increase to gale-force gusts in the Gulf of Venezuela and off the coast of Colombia by tonight, then sustained gale-force winds will develop through midweek. See the Special Features section for further details. ATLANTIC OCEAN... Two tropical waves are moving across the basin. See above for details. A subtropical low pressure system centered near 35N48W interacting with a broad upper-level low has organized showers and thunderstorms N of its center. Environmental conditions are expected to be marginally conducive for it to acquire tropical characteristics, and chances for tropical cyclone development are low. A surface trough extends S and SE from it to 24N57W supporting scattered showers and tstms N of 30N between 40W-50W. Aside from the tropical waves, the remainder of the Atlc is under the influence of surface high pressure that supports fair weather. For additional information please visit http://www.hurricanes.gov/marine $$ Mundell/ERA