000 AXNT20 KNHC 162342 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED SEP 16 2015 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURES... TROPICAL DEPRESSION NINE IS CENTERED NEAR 15.2N 44.6W AT 16/2100 UTC OR ABOUT 965 NM E OF THE LESSER ANTILLES AND ABOUT 1190 NM W OF THE CAPE VERDE ISLANDS MOVING NW AT 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1009 MB. MAXIMUM SUSTAINED WIND SPEED IS 25 KT WITH GUSTS TO 35 KT. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 14N-16N BETWEEN 41W-44W. WIDELY SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM 13N-22N BETWEEN 37W-44W. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. TROPICAL WAVE EXTENDS FROM A 1010 MB LOW CENTERED ALONG THE MONSOON TROUGH NEAR 11N29W TO 17N29W MOVING WNW AT 10-15 KT. ONGOING CONVECTION LARGELY REMAINS DISORGANIZED...WITH ISOLATED MODERATE OCCURRING FROM 06N-13N BETWEEN 27W-36W. THERE IS A HIGH CHANCE OF TROPICAL FORMATION OVER THE NEXT 48 HOURS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 11N72W TO 20N70W MOVING W AT 10-15 KT. THE WAVE COINCIDES WITH FAIRLY BROAD AND WEAK 700 MB TROUGHING OVER THE CENTRAL CARIBBEAN SEA AND CONTINUES TO INTERACT WITH AN UPPER LEVEL TROUGH WITH AXIS EXTENDING NW OF THE WAVE AXIS FROM 24N70W TO 17N76W. SCATTERED MODERATE CONVECTION IS FROM 16N-21N BETWEEN 68W-73W. TROPICAL WAVE EXTENDS FROM 14N90W TO 21N89W W AT 10-15 KT. A LARGE PORTION OF THE WAVE'S FRACTURED ENERGY CONTINUES TO BE LOCATED TO THE NORTH ACROSS THE EASTERN GULF OF MEXICO...HOWEVER RESIDUAL ENERGY CONTINUES WESTWARD OVER GUATEMALA AND THE YUCATAN PENINSULA WITH ISOLATED MODERATE CONVECTION FROM 14N-19N BETWEEN 89W-93W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 18N16W TO THE 1010 MB SPECIAL FEATURES LOW NEAR 11N29W TO 11N35W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N50W TO 09N61W. ASIDE FROM CONVECTION OCCURRING WITH THE SPECIAL FEATURES LOW AND TROPICAL DEPRESSION NINE...ISOLATED MODERATE CONVECTION IS FROM 06N-12N BETWEEN 13W-20W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES A MIDDLE TO UPPER LEVEL TROUGH OVER THE SE CONUS AND EASTERN GULF OF MEXICO WITH AXIS EXTENDING FROM EAST-CENTRAL ALABAMA S-SW TO A BASE NEAR 25N88W. THE TROUGHING ALOFT REFLECTS AS A SURFACE TROUGH EXTENDING FROM 29N86W TO 23N88W WITH SCATTERED SHOWERS AND TSTMS OCCURRING ACROSS A LARGE PORTION OF THE EASTERN GULF...FLORIDA PENINSULA...AND FLORIDA STRAITS. THE UPPER LEVEL TROUGHING IS FORECAST TO VERY SLOWLY SLIDE EASTWARD THROUGH THE UPCOMING WEEKEND AND LIKELY CONTINUE TO GENERATE PRECIPITATION AND CONVECTION FOR THE EASTERN GULF AND FLORIDA PENINSULA. OTHERWISE...THE WESTERN GULF IS UNDER THE INFLUENCE OF DRY AND STABLE NORTHERLY FLOW ALOFT AND A SURFACE RIDGE EXTENDING FROM THE LOWER MISSISSIPPI RIVER VALLEY TO NE MEXICO. GENERALLY GENTLE TO MODERATE E-NE WINDS ARE EXPECTED EAST OF THE INFLUENCE OF THE SURFACE TROUGH AND ONGOING CONVECTION THROUGH THE OVERNIGHT HOURS. CARIBBEAN SEA... AN UPPER LEVEL RIDGE AXIS EXTENDS FROM OVER THE YUCATAN PENINSULA E-NE OVER CUBA AND INTO THE SW NORTH ATLC BEYOND 26N79W. THE RIDGING ALOFT CONTINUES TO SUPPORT ISOLATED SHOWERS AND TSTMS N OF 20N W OF 79W IN AREAS OF MAXIMIZED DIFFLUENCE THIS EVENING. FARTHER EAST...AN UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY OVER THE WINDWARD PASSAGE REGION. DIFFLUENCE ON THE EASTERN PERIPHERY OF THE TROUGHING AND THE PRESENCE OF A TROPICAL WAVE ALONG 71W IS GENERATING SCATTERED SHOWERS AND TSTMS ACROSS HISPANIOLA AND THE ADJACENT COASTAL WATERS N OF 16N BETWEEN 67W-73W. OTHERWISE...MODERATE TO FRESH TRADES PREVAIL AND GENERALLY ARE EXPECTED TO PERSIST THROUGH THE UPCOMING WEEKEND. ...HISPANIOLA... PRESENTLY SCATTERED SHOWERS AND TSTMS ARE OCCURRING ACROSS HISPANIOLA THIS EVENING DUE TO THE PRESENCE OF A TROPICAL WAVE. AS THE WAVE IS FORECAST TO CONTINUE MOVING WESTWARD DURING THE NEXT 24 HOURS...CONDITIONS ARE EXPECTED TO GRADUALLY IMPROVE THROUGH THURSDAY INTO FRIDAY. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS OVER THE SE CONUS AND EXTENDS OVER PORTIONS OF THE EASTERN GULF OF MEXICO. TO THE EAST OF THE TROUGHING...MIDDLE TO UPPER LEVEL DIFFLUENCE IS MAXIMIZED GENERATING SCATTERED SHOWERS AND TSTMS N OF 23N W OF 74W. TO THE SE...ANOTHER UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY CENTERED OVER THE WINDWARD PASSAGE REGION. WHILE A TROPICAL WAVE IS ACROSS THE CENTRAL CARIBBEAN SEA...MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF THE TROUGH AXIS ALONG WITH POTENTIAL ENERGY FRACTURED NE FROM THE TROPICAL WAVE IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS FROM 20N-24N BETWEEN 60W-70W. ACROSS THE CENTRAL ATLC...A SURFACE TROUGH IS ANALYZED FROM 23N51W TO 29N48W IN RESPONSE TO A SHORTWAVE TROUGH NOTED ON WATER VAPOR IMAGERY IN THE VICINITY OF 26N50W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE BOUNDARY. FINALLY...MOSTLY TRANQUIL CONDITIONS ARE NOTED ACROSS THE EASTERN ATLC FOCUSED AROUND A 1019 MB HIGH CENTERED NEAR 31N35W THAT IS EXPECTED TO SLIDE SOUTHEASTWARD DURING THE NEXT 24 HOURS. 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