000 AXNT20 KNHC 211750 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SUN JUL 21 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 09N12W TO 17N18W MOVING W AT 10-15 KT. THIS WAVE IS BEGINNING TO EMERGE OFF THE COAST OF WEST AFRICA AND EXHIBITS FAVORABLE MID-LEVEL VORTICITY ENERGY IN THE VICINITY OF 12N15W ALONG THE WAVE AXIS. GLOBAL MODELS INDICATE THE WAVE COINCIDES WITH A WEAK 700 MB TROUGH ALONG 16W THAT IS FORECAST TO MOVE WESTWARD ON THE SOUTHERN PERIPHERY OF CENTRAL ATLC RIDGING DURING THE WEEK AHEAD. SCATTERED MODERATE CONVECTION IS FROM 06N-12N BETWEEN 13W-17W. TROPICAL WAVE EXTENDS FROM 12N55W TO 23N53W MOVING W AT 15-20 KT. TOTAL PRECIPITABLE WATER IMAGERY INDICATES THE WAVE LIES WITHIN A POLEWARD EXTENDING MAXIMUM FROM 06N-24N BETWEEN 49W- 59W...HOWEVER THE PRESENCE OF THE SAHARAN AIR LAYER IS PROVIDING FOR AN OVERALL STABLE ENVIRONMENT FOR THE WAVE RESULTING IN A LACK OF DEEP CONVECTION AT THIS TIME. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR 12N17W TO 10N25W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 10N25W TO 07N33W TO 04N38W TO 03N47W TO 06N57W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 07N- 13N BETWEEN 18W-29W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS NOTED ON WATER VAPOR IMAGERY PROGRESSING E-NE OVER MISSISSIPPI THIS AFTERNOON WITH A TROUGH AXIS EXTENDS SOUTHWEST OVER PORTIONS OF THE NW GULF TO 27N94W. WHILE THE PRIMARY SURFACE FEATURE REMAINS A SURFACE RIDGE ANCHORED OVER THE SW NORTH ATLC...THE MIDDLE TO UPPER LEVEL DYNAMICS ARE GENERATING SCATTERED SHOWERS AND TSTMS N OF 27N BETWEEN 89W-97W...INCLUDING INLAND SOUTHERN LOUISIANA AND IMMEDIATELY ALONG THE TEXAS GULF COAST. OTHERWISE...THE REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF THE PREVIOUSLY MENTIONED SURFACE RIDGE WITH AXIS EXTENDING FROM A 1023 MB HIGH CENTERED NEAR 29N66W IN THE SW NORTH ATLC TO EAST-CENTRAL MEXICO NEAR 21N97W. ANOTHER MID-LEVEL SHORTWAVE TROUGH IS NOTED OFF THE COAST OF THE NORTHERN FLORIDA PENINSULA AND IS PROVIDING FOR SCATTERED SHOWERS AND TSTMS PRIMARILY IN THE SW NORTH ATLC REGION...HOWEVER A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING ACROSS THE FLORIDA PENINSULA AND ADJACENT COASTAL EASTERN GULF WATERS S OF 27N E OF 84W. THE SURFACE RIDGE AXIS IS FORECAST TO REMAIN ALONG 26N/27N THROUGH WEDNESDAY. CARIBBEAN SEA... CONDITIONS ACROSS THE NW CARIBBEAN REMAIN TRANQUIL THIS AFTERNOON AS WATER VAPOR IMAGERY INDICATES DRY AIR AND A FAIRLY STABLE ATMOSPHERE ALOFT. VERY FEW CLOUDS ARE NOTED ON SATELLITE IMAGERY AS EAST WINDS PERSIST. A MIDDLE TO UPPER LEVEL DIFFLUENT ATMOSPHERE IS HOWEVER CENTERED OVER THE SW CARIBBEAN WHICH IS GENERATING SCATTERED SHOWERS AND TSTMS...SOME STRONG...S OF 13N BETWEEN 77W-86W...INCLUDING PANAMA...COSTA RICA...AND SOUTHERN NICARAGUA. THIS AREA OF CONVECTION IS LIKELY ENHANCED AS WELL BY THE CLOSE PROXIMITY TO THE MONSOON TROUGH AXIS EXTENDING ALONG 09N. FINALLY...OVER THE EASTERN AND CENTRAL PORTIONS OF THE CARIBBEAN...THE WESTERN PERIPHERY OF AN UPPER LEVEL RIDGE IS PROVIDING FOR SOUTHWESTERLY FLOW ALOFT E OF 76W. HIGH-LEVEL CLOUDINESS IS NOTED ON SATELLITE IMAGERY...WITH ONLY A FEW AREAS OF ISOLATED SHOWERS OCCURRING ACROSS THE LESSER ANTILLES AND AREAS E OF 73W. THE PRIMARY IMPACT THIS AFTERNOON REMAINS MODERATE TO FRESH TRADES WHICH ARE EXPECTED TO PERSIST THROUGH MUCH OF THE WEEK AHEAD. HISPANIOLA... CURRENTLY CONDITIONS ACROSS THE ISLAND REMAIN FAIRLY TRANQUIL AS A RIDGE ANCHORED BY A 1023 MB HIGH TO THE NORTH NEAR 29N66W CONTINUES TO PROVIDE OVERALL STABLE CONDITIONS THIS AFTERNOON. A FEW PASSING ISOLATED SHOWERS ARE POSSIBLE THROUGH THE LATE EVENING HOURS...HOWEVER NO SIGNIFICANT DEEP CONVECTION IS EXPECTED TO IMPACT HISPANIOLA FOR THE NEXT 36 TO 48 HOURS. A FAST MOVING TROPICAL WAVE ANALYZED ALONG 55W IS EXPECTED TO PASS THROUGH LATE MONDAY INTO TUESDAY...WITH ONLY ISOLATED SHOWERS EXPECTED AT THIS TIME DUE TO THE PRESENCE OF A FAIRLY STRONG SAHARAN AIR LAYER WHICH PROVIDES A STABLE ENVIRONMENT AND INHIBITS DEEP CONVECTION. ATLANTIC OCEAN... NORTH-NORTHEASTERLY FLOW ALOFT DOMINATES ACROSS THE SW NORTH ATLC BETWEEN AN UPPER LEVEL LOW CENTERED NEAR 28N70W AND AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER THE EASTERN GULF OF MEXICO NEAR 27N85W. AN EMBEDDED SHORTWAVE TROUGH OVER THIS REGION IN THE VICINITY OF 30N77W IS GENERATING SCATTERED SHOWERS AND TSTMS FROM 25N TO BEYOND 32N BETWEEN 72W-81W. OTHERWISE THE REMAINDER OF THE SW NORTH ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1023 MB HIGH CENTERED SOUTH OF BERMUDA NEAR 29N66W. ASIDE FROM THE TROPICAL WAVE ALONG 55W...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS ALSO UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1023 MB HIGH CENTERED NEAR 29N41W. THE SURFACE RIDGE IS LARGELY THE RESULT OF A STRONG MID-LEVEL RIDGE CENTERED NEAR 29N52W PROVIDING FOR OVERALL STABLE CONDITIONS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN