000 AXNT20 KNHC 030946 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 546 AM EDT Sun Sep 3 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 0945 UTC. ...SPECIAL FEATURES... Hurricane Irma is centered near 18.0N 47.5W at 03/0900 UTC or about 820 nm E of the Leeward Islands moving W at 13 kt. Estimated minimum central pressure is 969 mb. Maximum sustained wind speed is 100 kt with gusts to 120 kt. Numerous strong convection is from 16N to 20N between 44W and 49W. Scattered moderate convection is elsewhere from 15N to 21N between 38W and 52W. Some strengthening is forecast during the next 48 hours. See the latest NHC Forecast/Advisory under AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more details. ...TROPICAL WAVES... A tropical wave is in the E Atlc associated with a 1012 mb low located near 09N30W. The wave axis extends from 15N30W to the low to 06N30W, moving W at 10 kt. The wave is in a region of low vertical wind shear, however enhanced IR imagery show some Saharan dry air and dust in the wave environment. CIRA LPW imagery at the lower levels confirm the presence of dry air in the vicinity of the wave. Shallow moisture and diffluence aloft support scattered showers and tstms from 02N to 13N between 20W and 38W. A tropical wave is in the E Caribbean with axis extending from 21N67W to 11N69W, moving W at 15-20 kt. The wave is in a region of low vertical wind shear, however it continues being affected by dry air subsidence from aloft. Shallow moisture support scattered to isolated showers over the NE Caribbean, Puerto Rico, the Mona Passage and Hispaniola. ...ITCZ/MONSOON TROUGH... The monsoon trough extends from the African coast near 12N16W to 09N30W to 11N40W to 12N45W. Aside from the convection associated with the tropical wave in the E Atlc, scattered moderate convection is from 04N to 09N E of 20W. ...DISCUSSION... GULF OF MEXICO... Water vapor imagery indicates a middle to upper level trough extending over the E CONUS S to a base just N of the Bay of Campeche. The trough supports a dissipating stationary front extending across the Florida panhandle to near 29N91W. A pre- frontal surface trough extends from 26N81W to 23N85W. Another surface trough is in the western Bay of Campeche extending from 24N97W to 18N95W. Upper level diffluent flow to the SSE of the trough base along with abundant low level moisture across the southern basin continue to support scattered showers and tstms generally S of 26N E of 91W and S of 22N W of 91W. Otherwise, mostly light to gentle variable wind is noted across the Gulf with locally moderate E flow mainly in the W half of the basin. Generally, surface lower pressure will persist in the SW Gulf in the form of a trough the next two days while a weak ridge will build over the eastern half of the basin. CARIBBEAN SEA... Upper level diffluent flow to the SSE of a trough base located N of the Bay of Campeche in the Gulf of Mexico continue to support numerous heavy showers and tstms over Guatemala, Belize, the western half of Honduras and the Gulf of Honduras. Fresh to strong winds are in the Gulf of Honduras due to the strong convection. In the SW basin, the E extension of the EPAC monsoon trough support isolated showers S of 12N W of 80W and scattered showers and tstms S of 10N between Panama and Colombia. A tropical wave is moving across E Caribbean waters, thus supporting scattered to isolated showers in the NE basin as well as Puerto Rico and Hispaniola. See the tropical waves section above for further details. Water vapor imagery show dry air aloft across the remainder basin, which subsidence is supporting fair weather conditions. Otherwise, moderate to fresh trades are basin-wide. Looking beyond today, Hurricane Irma is forecast to approach 60W Tuesday night. ...HISPANIOLA... Isolated showers and tstms are expected to continue through the day today as a tropical wave moves across the Island. The wave is expected to pass west of the island by early Monday morning with conditions gradually improving into Tuesday. ATLANTIC OCEAN... Hurricane Irma remains on the southwestern periphery of a ridge anchored by a 1026 mb high centered SW of the Azores near 34N32W. See special features section for further details. A middle to upper level trough progressing over the E CONUS supports isolated showers over the far western SW North Atlc waters, including interior portions of Florida. Farther east, an upper level low continue to support a stationary front extending from 30N59W SW to 26N66W with isolated showers occurring within 60 nm either side of the boundary. The stationary front is forecast to weaken and dissipate by late tonight. For additional information please visit http://www.hurricanes.gov/marine $$ Ramos