Tropical Weather Discussion
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000 AXNT20 KNHC 301154 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 AM EDT FRI SEP 30 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... Hurricane Matthew at 30/1200 UTC is centered near 13.8N 70.3W or about 113 nm northwest of Punta Gallinas, Colombia and about 450 nm east-southeast of Kingston, Jamaica moving west-southwest at 12 kt. Maximum sustained winds are 90 KT with gusts to 110 KT. Estimated minimum central pressure is 971 mb. Numerous strong convection is observed from 12N to 16N between 68W and 72W. Scattered moderate convection is elsewhere from 11N to 17N between 64W and 72W. Matthew will continue to strengthen during the next few days as it moves west-northwest over the central Caribbean. 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 8N to 18N with axis near 28W, moving west at 10 kt over the past 24 hours. The wave is in a region of favorable deep layer wind shear and in a region of middle to upper level diffluence. However, both the TPW imagery and Meteosat enhanced imagery show Saharan dry air mainly W of the wave axis, which is limiting the convection to scattered showers from 14N to 16N between 25W and 30W. A tropical wave is in the central Atlantic extending from 7N to 17N with axis near 48W, moving west at 10-15 kt over the past 24 hours. The wave is in a region of unfavorable deep layer wind shear and Saharan dry air is mainly W of its axis, which is limiting convection to scattered showers from 10N-20N between 39W and 47W. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends over Africa reaching the east Atlantic near 12N16W through 12N27W to 08N38W. The ITCZ begins near 08N38W and continues to 08N58W. Aside from the convection associated with the tropical waves, scattered showers are noted off the coast of W Africa from 07N to 14N E of 21W. This convection may be associated with the next tropical wave to move off Africa. ...DISCUSSION... GULF OF MEXICO... A broad deep layered cyclonic circulation centered over Kentucky and associated trough with mean axis along 85W dominates the eastern half of the Gulf of Mexico and provides support for a cold front extending from 28N82W through 25N90W to 24N96W. Strong upper level subsidence is occurring in the wake of the upper trough in the north-central and northeast basin providing fair weather. Unfavorable deep layer wind shear support similar weather conditions in the NW Gulf. A large anticyclone over Mexico dominates the flow over the western Gulf with moderate to strong northwesterly flow aloft spreading mid level moisture across the Bay of Campeche. Diffluent flow aloft between the upper anticyclone and the trough provide support for scattered showers and isolated thunderstorms ahead of the cold front and weaker shower activity within 60 NM either side of a surface trough extending from 24N96W to 20N96W. The cold front will continue to move south across the eastern Gulf during today and then will stall Saturday before dissipating Sunday. Convection will prevail ahead of this boundary affecting the southern Gulf waters. CARIBBEAN SEA... The main feature of concern in the Caribbean is Hurricane Matthew located south of Dominican Republic. Matthew remains embedded within an area of divergent anticyclonic flow aloft as it tracks westward. Please refer to the special features section above for details. An upper-level trough extends across the Florida Peninsula reaching the west Caribbean waters west of 77W. The upper trough support scattered showers and tstms within 120 nm off the SW coast of Cuba while diffluent flow aloft support similar convection within 60 nm off the coast of Honduras. Isolated showers are observed in the SW basin due to the proximity of the EPAC Monsoon Trough. Scatterometer data depicts moderate to fresh northeasterly winds across the basin west of 78W. Expect for Matthew to intensify as it moves WNW over the central basin through Sunday. ...HISPANIOLA... High cloudiness continues to spread across the Dominican Republic in advance of Hurricane Matthew. The forecast track of the hurricane should keep the bulk of the heavy precipitation to the south of Hispaniola. However an increase in the overall moisture could lead to localized heavy rain in orographically favored areas. As Matthew turns northward late SUN or MON, the potential exists for additional heavy rains over Haiti. For additional information on Matthew, please refer to the special features section above. ATLANTIC OCEAN... Two tropical waves are moving across the basin. Please refer to the section above for details. A broad mid-level trough extends across the southeast CONUS and covers the west Atlantic waters W of 75W, supporting scattered showers and thunderstorms between 70W-80W. The remainder of the basin is dominated by a surface ridge anchored by a 1031 mb high in the north central Atlantic near 41N35W. For additional information please visit http://www.hurricanes.gov/marine $$ RAMOS/PAW

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