000 AXNT20 KNHC 282352 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN JUL 28 2013 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... A TROPICAL WAVE...THE REMNANTS OF DORIAN...EXTENDS FROM 12N61W TO 23N60W MOVING W AT 15 KT. THE WAVE CORRESPONDS WITH A MID- LEVEL TROUGH ALONG 61W AND A MID-LEVEL VORTICITY MAXIMUM IN THE VICINITY OF 21N62W. WHILE NO SURFACE CIRCULATION IS APPARENT AT THIS TIME...THE DYNAMICS ALOFT CONTINUE TO SUSTAIN WIDELY SCATTERED MODERATE CONVECTION FROM 18N-24N BETWEEN 58W-65W. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 10N29W TO 19N32W MOVING W AT 5 KT. THE WAVE AND ENERGY ASSOCIATED WITH IT ARE WRAPPED UP IN A MONSOONAL GYRE FOCUSED AROUND A BROAD AREA OF LOWER PRESSURE NOTED AS A 1014 MB LOW CENTERED NEAR 11N30W ALONG THE MONSOON TROUGH AXIS. CONVECTION REMAINS VERY LIMITED WITH THE WAVE N OF 11N...HOWEVER CONVERGENT SOUTHWESTERLY SURFACE WINDS ARE GENERATING AN AREA OF ISOLATED MODERATE CONVECTION FROM 07N-12N BETWEEN 23W-29W ON THE SOUTHEAST PERIPHERY OF THE GYRE. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO 12N23W TO 11N30W TO 09N34W TO 08N40W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N40W TO 10N55W. NO SIGNIFICANT DEEP CONVECTION IS NOTED ON SATELLITE IMAGERY ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL WAVE AND MONSOONAL GYRE AS DESCRIBED ABOVE. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL ANTICYCLONIC CIRCULATION INFLUENCES MUCH OF NORTHERN MEXICO...THE SOUTHWESTERN CONUS...AND SOUTHERN U.S. PLAINS CENTERED NEAR 29N104W THAT IS PROVIDING MUCH OF THE GULF WITH NORTH-NORTHEASTERLY FLOW ALOFT W OF 86W. WATER VAPOR IMAGERY ALSO INDICATES THAT THE UPPER LEVEL RIDGE WEAKENS OVER THE NE GULF WATERS AS AN UPPER LEVEL TROUGH AXIS EXTENDS FROM 32N82W TO 27N86W. THE TROUGHING SUPPORTS A WEAKENING FRONTAL BOUNDARY EXTENDING FROM SOUTHERN GEORGIA TO SOUTHEASTERN TEXAS. LOW-LEVEL CONVERGENCE AND MIDDLE TO UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED SHOWERS AND TSTMS 25N BETWEEN 80W-89W... INCLUDING INLAND PORTIONS OF THE FLORIDA PENINSULA. OTHERWISE... AT THE SURFACE...A 1018 MB HIGH CENTERED NEAR 26N87W CONTINUES TO PROVIDE MOSTLY FAIR CONDITIONS FOR A LARGE PORTION OF THE SOUTHERN AND WESTERN GULF WITHIN LIGHT AND BROAD ANTICYCLONIC WINDS. THE RIDGING IS FORECAST TO SLOWLY DRIFT EASTWARD THROUGH EARLY MONDAY AS E-SE WINDS RE-ESTABLISH ACROSS THE WESTERN GULF IN THE RANGE OF 10-20 KT ON MONDAY. CARIBBEAN SEA... AN UPPER LEVEL LOW IS CENTERED OVER THE NW CARIBBEAN NEAR 18N83W AND WATER VAPOR SHOWS THIS UPPER LEVEL FEATURE HAS A LARGE AREA OF DRY AIR AND STABILITY ASSOCIATED WITH IT NORTH OF 15N WEST OF 75W. THE ONLY EXCEPTION TO FAIR WEATHER IS SCATTERED SHOWERS AND TSTMS OCCURRING THIS EVENING ACROSS THE ISLAND OF CUBA DUE TO PEAK DAYTIME HEATING AND INSTABILITY. THIS CONVECTION IS EXPECTED TO DIMINISH OVER THE NEXT FEW HOURS. FARTHER SOUTH... SCATTERED SHOWERS AND TSTMS ARE OCCURRING S OF 15N BETWEEN 80W- 87W...INCLUDING PANAMA...COSTA RICA...AND NICARAGUA. THIS CONVECTION IS LIKELY ENHANCED DUE TO THE CLOSE PROXIMITY TO THE MONSOON TROUGH AXIS ANALYZED ALONG 09N FROM PANAMA TO SOUTHERN COSTA RICA. OVER THE EASTERN CARIBBEAN...AN UPPER LEVEL LOW IS CENTERED NORTH OF THE BASIN NEAR 23N70W AND EXTENDS A TROUGH AXIS SOUTHWARD ALONG 71W TO A BASE NEAR 17N. LOW TO MIDDLE LEVEL MOISTURE CONTINUES TO ADVECT NORTHWARD ACROSS THE EXTREME NE CARIBBEAN DUE TO AN APPROACHING TROPICAL WAVE...THE REMNANTS OF DORIAN. CONVECTION REMAINS VERY LIMITED AS THE TROPICAL WAVE ALONG 61W PROGRESSES WESTWARD WITH ONLY A FEW ISOLATED SHOWERS AND TSTMS OCCURRING N OF 17N BETWEEN 60W-68W. SCATTERED SHOWERS AND TSTMS ARE ALSO OCCURRING OVER HISPANIOLA THIS EVENING DUE TO FAVORABLE DIFFLUENT MIDDLE TO UPPER LEVEL FLOW AND PEAK DAYTIME HEATING AND INSTABILITY. LOOKING AHEAD...THE REMNANTS OF DORIAN AND THE ASSOCIATED TROPICAL WAVE...WILL MOSTLY SKIRT NORTH OF THE NE CARIBBEAN THROUGH MONDAY WITH SURFACE TROUGHING EXTENDING ACROSS PUERTO RICO AND HISPANIOLA AS THE TROPICAL WAVE PASSES. INCREASED CLOUDINESS AND PRECIPITATION THROUGH EARLY TUESDAY IS EXPECTED ACROSS THE EASTERN GREATER ANTILLES AS OVERALL RE- DEVELOPMENT OF THIS SYSTEM WILL CONTINUE TO BE MONITORED. HISPANIOLA... CURRENTLY SCATTERED SHOWERS AND TSTMS ARE OCCURRING ACROSS THE ISLAND AND THIS ACTIVITY IS EXPECTED TO WANE DUE TO THE LOSS OF PEAK DAYTIME HEATING AND INSTABLITY OVER THE NEXT FEW HOURS. ON THE SYNOPTIC SCALE...AN UPPER LEVEL LOW IS CENTERED N OF HISPANIOLA NEAR 23N70W THAT IS FORECAST TO SLOWLY DRIFT NORTHWESTWARD DURING THE NEXT FEW DAYS. AS THIS OCCURS...THE ISLAND WILL GRADUALLY FALL WITHIN AN AREA OF SOUTHWESTERLY FLOW ALOFT BY EARLY MONDAY THAT WILL PRESENT A HIGHER CHANCE FOR AFTERNOON AND EARLY EVENING SHOWERS AND TSTMS FOR EARLY NEXT WEEK. IN ADDITION...THE REMNANTS OF DORIAN ARE FORECAST TO TRACK NORTH OF THE ISLAND MONDAY INTO TUESDAY...WITH SURFACE TROUGHING EXTENDING SOUTHWARD PROVIDING ANOTHER MECHANISM TO INITIATE SHOWERS AND TSTMS. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH AXIS EXTENDS FROM OVER THE SE CONUS NEAR 32N82W TO 27N86W IN THE NE GULF OF MEXICO GENERATING A LARGE AREA OF MIDDLE TO UPPER LEVEL DIFFLUENCE ACROSS THE SW NORTH ATLC THIS EVENING. SCATTERED SHOWERS AND TSTMS ARE OCCURRING N OF 23N W OF 75W...INCLUDING MUCH OF THE FLORIDA PENINSULA. FARTHER EAST...SURFACE RIDGING REMAINS IN PLACE ACROSS THE REMAINDER OF THE SW NORTH ATLC...HOWEVER AN UPPER LEVEL LOW CENTERED NEAR 23N70W IS PRODUCING ISOLATED SHOWERS AND TSTMS FROM 27N-33N BETWEEN 67W-73W. OTHERWISE...A TROPICAL WAVE ANALYZED ALONG 61W...THE REMNANTS OF DORIAN...CONTINUES TO PROGRESS WESTWARD ON THE SOUTHERN PERIPHERY OF THE SURFACE RIDGING TO THE NORTH ANCHORED BY A 1026 MB HIGH CENTERED NEAR 32N53W. WIDELY SCATTERED SHOWERS AND TSTMS ARE OCCURRING 18N-24N BETWEEN 58W-66W. FINALLY...ACROSS THE EASTERN ATLC...AN UPPER LEVEL LOW IS CENTERED NEAR 32N36W AND SUPPORTS A WEAK SURFACE TROUGH THAT EXTENDS FROM 30N26W SOUTHWESTWARD TO 21N38W. POSSIBLE ISOLATED SHOWERS ARE WITHIN 120 NM EITHER SIDE OF THE BOUNDARY. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN