000 AXNT20 KNHC 291000 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 600 AM EDT THU SEP 29 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 0600 UTC surface analysis and satellite imagery through 1000 UTC. ...SPECIAL FEATURES... Tropical Storm Matthew at 29/0900 UTC is centered near 14.0N 64.7W or about 278 NM SSE of San Juan Puerto Rico moving west at 14 KT. Maximum sustained winds are 55 KT with gusts to 65 KT. Estimated minimum central pressure is 1002 mb. Numerous heavy showers associated with it are happening from 12N to 16N between 60W and 65W. Scattered moderate convection is elsewhere from 11N to 18N between 59W and 65W. Matthew is forecast to become a hurricane tonight or early Friday morning. Please refer to the NHC forecast/advisory under AWIPS/WMO headers WTNT24 KNHC/TCMAT4, or visit the NHC website at http://hurricanes.gov for additional details. ...TROPICAL WAVES... A tropical wave is in the E Atlantic extending from 07N to 17N with axis near 24W, moving at 15 kt over the past 24 hours according to satellite and global model guidance. This wave is newly introduced based on global tropical waves diagnostic guidance and latest passes of scatterometer data. Abundant moderate to high low level moisture and a diffluent wind environment at the middle and upper levels support numerous moderate to isolated strong convection from 12N to 16N between 21W and 27W. Scattered moderate convection is elsewhere from 10N to 17N E of 29W. A tropical wave is in the Central Atlc extending from 08N to 16N with axis near 33W moving W at 15 kt over the past 24 hours. This is a low amplitude wave in a region of unfavorable deep layer wind shear. CIRA LPW imagery and Meteosat enhanced imagery show dry air in the northern wave environment that along dust support lack of convection at the time. Scattered showers are from 09N to 12N between the wave axis and 39W. A tropical wave is in the Central Atlc extending from 05N to 14N with axis near 45W expected to move at 15 kt over the next 24 hours. Unfavorable deep layer wind shear is in the northern wave environment supporting lack of convection N of 12N. CIRA LPW imagery show a moderate moist environment elsewhere with pockets of dry air mainly W the wave axis where isolated showers are observed to 50W. Scattered moderate to isolated strong showers are from 08N to 12N between 38W and 44W. A tropical wave is in the W Caribbean extending from 09N to 20N with axis near 86W moving W at 15 KT over the past 24 hours. The wave is in a region of abundant low level moisture and favorable deep layer wind shear that support isolated heavy showers and tstms S of 20N between 81W and 87W. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends over Africa reaching the east Atlantic near 12N17W through 07N30W to 07N43W. Aside from the convection associated with the tropical waves, scattered heavy showers are from 04N to 10N E of 22W. ...DISCUSSION... GULF OF MEXICO... Weak low pressure dominates across the Gulf in the wake of an already dissipated cold front in the NE basin and the presence of a surface trough off the E coast of Mexico extending from 25N97W to 18N95W. These features are providing the basin with gentle variable wind flow. Aloft, a broad anticyclone covers the western portion of the basin while an upper trough extends over the eastern waters and Florida. Diffluent flow between these two upper level features along with low level moisture in the southern basin support scattered to isolated showers over the SE Gulf while the surface trough generates heavy showers and tstms from 20N to 25N W of 96W. A reinforcing cold front will move across the Gulf waters Thu becoming stationary from N Florida to the central basin to Tampico Mexico on Friday and dissipating Saturday. CARIBBEAN SEA... The main feature of concern in the Caribbean is T.S. Matthew located over the E basin. Numerous heavy showers associated with it are happening from 12N to 16N between 60W and 65W. Scattered moderate convection is elsewhere from 11N to 18N between 59W and 65W. See special features for further details. Over the NW basin, a tropical wave with axis near 86W generate isolated heavy showers and tstms S of 20N between 81W and 87W. See the tropical waves section for more details. Strong dry air subsidence and unfavorable deep layer wind shear support fair weather elsewhere. Fresh to strong winds are from 11N to 13.5N between 72W and 76W. Gentle to moderate trades are elsewhere, except in the vicinity of T.S. Matthew. Matthew is forecast to become a hurricane tonight or early Friday morning. ...HISPANIOLA... Currently fair weather conditions prevail across the Island. T.S. Matthew is forecast to pass south of Hispaniola as a hurricane Friday through Sunday. Cloudiness associated with Matthew is expected to spread over the island today with an increase in showers and thunderstorms late tonight into FRI. The heaviest rain is expected Sunday, especially for W Hispaniola. The large envelope of Matthew may result in the potential for locally heavy rains over Hispaniola. This will greatly depend on the ultimate track of Matthew. For additional information on Matthew please refer to the special features section above. ATLANTIC OCEAN... A broad middle-level trough extends across the SE CONUS and covers Atlc waters W of 68W, supporting scattered showers and tstms in that area N of 22N. The remainder basin is being dominated by a broad surface ridge anchored by a 1035 mb high in the north central Atlantic near 40N42W. For additional information please visit http://www.hurricanes.gov/marine $$ RAMOS