000 AXNT20 KNHC 150926 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 526 AM EDT Tue Aug 15 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 0600 UTC surface analysis and satellite imagery through 0915 UTC. ...SPECIAL FEATURES... Hurricane Gert is centered near 31.8N 72.5W at 15/0900 UTC or about 375 nm W of Bermuda moving N at 11 kt. Estimated minimum central pressure is 986 mb. Maximum sustained wind speed is 65 kt with gusts to 80 kt. Numerous moderate to strong convection is from 30N-32N between 70W-73W. Scattered moderate convection is elsewhere from 28N-33N between 70W-74W. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMAT3/WTNT23 KNHC for more details. ...TROPICAL WAVES... A tropical wave is W of the Cape Verde islands associated with a 1012 mb low pressure located near 14N28W. The wave axis extends from 18N27W to the low to 09N28W and has been moving W at 10 kt. The wave is in a region of low vertical wind shear, however intrusion of Saharan dry air and dust to the wave environment limit deep convection. Shallow moisture confined to the vicinity of the monsoon trough and upper level diffluent wind support scattered moderate convection SW of the low center from 10N-14N between 28W-33W. Slow development of this system is anticipated during the next day or two, but conditions are forecast to become a little more conducive for tropical cyclone formation by later in the week while the system moves westward over the tropical Atlantic. A tropical wave is in the central Atlc with axis extending from 20N51W to 09N53W, moving W at 25 kt. The wave is entering a region of moderate to strong vertical wind shear and is being severely affected by extensive Saharan dry air and dust, which is hindering convection at the time. A tropical wave is in the E Caribbean with axis extending from 20N64W to 10N66W, moving W at 25 kt. The wave is in a region of strong vertical wind shear and dry air subsidence, which is hindering deep convection at the time. Shallow moisture observed in CIRA LPW imagery and upper level diffluent flow ahead of the wave axis in the N-central Caribbean support isolated showers over northern Puerto Rico and adjacent waters as well as the Mona Passage and E Dominican Republic. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the coast of W Africa near 12N16W to 14N28W to 11N42W. The Intertropical Convergence Zone axis extends from 11N43W to the coast of Venezuela near 09N60W. Numerous heavy showers and scattered tstms are coming off the W African coast associated with the next tropical wave. The convection extends from 05N to 11N E of 18W. Scattered moderate convection is from 06N to 15N between 34W and 46W associated with a 1012 mb low located near 11N39W. ...DISCUSSION... GULF OF MEXICO... Weak surface ridging prevails across the basin, which along with dry air subsidence support mainly fair weather conditions. A broad upper level low is centered just N of the Yucatan Peninsula, which supports isolated showers there and in the Yucatan Channel. Diffluent flow in the NW periphery of the low support similar shower activity off the SE coast of Louisiana and Mississippi. Winds are gentle to moderate and from the S-SE in the western half of the basin and light variable elsewhere. The ridge will remain in place across the Gulf waters the next couple of days. A surface trough will develop each evening across the Yucatan Peninsula shifting W to the Bay of Campeche during the overnight hours. Locally higher winds can be expected west of the trough axis. CARIBBEAN SEA... A tropical wave is moving through the eastern Caribbean. Please see section above. The tropical wave will continue to propagate westward over Puerto Rico this morning, then will move over central Caribbean waters tonight. Isolated showers are occurring ahead of the wave axis over northern Puerto Rico and adjacent waters, the Mona Passage and E Dominican Republic. This convection is mainly due to shallow moisture and a diffluent wind environment aloft associated with an upper level low over central Atlc waters. A broad upper level low centered just N of the Yucatan Peninsula support isolated showers in the Yucatan Channel extending to NW Caribbean waters N of 17N W of 80W. Scattered heavy showers and tstms are over Belize and northern Guatemala associated with the passage of a tropical wave with axis currently moving across the Gulf of Tehuantepec, Mexico. Otherwise, fresh to near gale force winds are in the south-central basin forecast to continue through Thursday. ...HISPANIOLA... An upper level low over the central Atlc will drift WSW to the north and across the Island over the next couple of days. This low aloft along with the passage of a tropical wave will support scattered to isolated showers over the Island and adjacent waters through Thursday. ATLANTIC OCEAN... Scattered showers and tstms are N of 28N between 70W and 74W associated with the rainbands of Hurricane Gert centered north of the area. See Special features for further details. Otherwise, the remainder basin generally N of 20N is under the influence of the Azores high, which supports fair weather. For information about tropical waves, see section above. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos