000 AXNT20 KNHC 041034 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT THU JUL 04 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...TROPICAL WAVES... TROPICAL WAVE OVER THE CAPE VERDE ISLANDS EXTENDS FROM 22N24W TO 11N25W MOVING W NEAR 10 KT. WAVE REMAINS WITHIN A SURGE OF MODERATE MOISTURE AS DEPICTED BY THE TOTAL PRECIPITABLE WATER IMAGERY. A SWATH OF DRIER AIR IS BEING INTRODUCED ALONG THE WAVE BY THE MID LEVEL SWIRL THAT IS CENTERED NEAR 18N25W. NO ASSOCIATED DEEP CONVECTION. TROPICAL WAVE IN THE CENTRAL TROPICAL ATLC EXTENDS FROM 18N38W TO 7N49W MOVING W-NW 15-20 KT. WAVE REMAINS EMBEDDED WITHIN A SURGE OF DEEP MOISTURE AS DEPICTED BY THE TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120 NM EITHER SIDE OF THE WAVE AXIS. TROPICAL WAVE EXTENDS FROM 22N64W THROUGH THE MONA PASSAGE TO 15N68W IN THE E CARIBBEAN MOVING W-NW NEAR 15 KT. WAVE IS MOVING INTO AN AREA OF MODERATE MOISTURE AS DEPICTED BY THE TOTAL PRECIPITABLE WATER IMAGERY. SHOWER ACTIVITY OVER THE E CARIBBEAN IS BEING ENHANCED BY THIS TROPICAL WAVE. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 11N15W AND CONTINUES ALONG 9N18W TO 7N25W WHERE THE ITCZ BEGINS AND CONTINUES ALONG 8N32W 12N38W TO 13N42W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 120/150 NM OF LINE FROM THE COAST OF SW AFRICA NEAR 6N10W TO 7N29W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 4N TO S OF THE EQUATOR BETWEEN 43W-50W. ...DISCUSSION... GULF OF MEXICO... AN UPPER TROUGH COVERS THE GULF N OF 21N W OF 88W EXTENDING FROM AN UPPER LOW OVER THE MISSOURI/KANSAS BORDER AND SUPPORTING A SURFACE TROUGH THAT AT 04/0900 UTC EXTENDS INTO THE GULF FROM NEAR PENSACOLA FLORIDA ACROSS THE MISSISSIPPI DELTA ALONG 28N91W TO 26N95W. ISOLATED SHOWERS/THUNDERSTORMS ARE POSSIBLE WITHIN 60/75 NM EITHER SIDE OF THE TROUGH THE S PORTION OF THIS SURFACE TROUGH HAS REMAINS OVER THE S GULF AND THE BAY OF CAMPECHE EXTENDING FROM 24N90W TO S MEXICO NEAR 18N94W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 90/120 NM EITHER SIDE OF THE TROUGH. AN UPPER RIDGE EXTENDS FROM THE YUCATAN PENINSULA ALONG 25N85W TO OVER NE FLORIDA TO SOUTH CAROLINA AND IS PROVIDING DIFFLUNCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS E OF 90W. THE SURFACE RIDGE OVER THE ATLC BASIN COVERS THE FAR E GULF. N GULF SURFACE TROUGH WILL DRIFT INTO THE W GULF THROUGH THE WEEKEND IN PHASE WITH ANOTHER TROUGH IN THE BAY OF CAMPECHE. WEAK SURFACE LOW WILL FORM ALONG THE TROUGH OVER THE BAY OF CAMPECHE THROUGH LATE TODAY THEN MOVE W ACROSS THE FAR SW GULF AND INTO THE COAST OF VERACRUZ THROUGH LATE FRI. VERY ACTIVE WEATHER WILL CONTINUE OVER THE CENTRAL AND E GULF THROUGH SAT. A SECOND SURFACE LOW MAY FORM OVER THE N/CENTRAL GULF SUN THEN SHIFT N INTO SW LOUISIANA THROUGH MON. CARIBBEAN SEA... AN UPPER RIDGE COVERS THE CARIBBEAN W OF 70W AND IS ANCHORED OVER THE YUCATAN PENINSULA. AN ELONGATED UPPER LOW IS CENTERED OVER THE CENTRAL BAHAMAS AND EXTENDS S TO THE N COAST OF HISPANIOLA AND W CUBA. THE UPPER RIDGE IS PROVIDING DIFFLUNCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 19N W OF 74W AND WITHIN 60 NM ALONG THE COAST OF THE YUCATAN PENINSULA S OF 20N. THE MONSOON TROUGH EXTENDS ACROSS OF PANAMA ALONG 9N GENERATING ISOLATED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS S OF 12N W OF 82W AND S OF 10N E OF 82W. EASTERLY TRADE WINDS ARE USHERING IN SOME SCATTERED LOW LEVEL SHOWERS OVER THE FAR E CARIBBEAN FROM 13N-17N W OF THE TROPICAL WAVE TO THE LESSER ANTILLES AND ARE BEING ENHANCED BY THIS TROPICAL WAVE. TROPICAL WAVE WILL MOVE THROUGH THE CENTRAL CARIBBEAN THROUGH FRI AND ACROSS W CARIBBEAN AND INTO CENTRAL AMERICA THROUGH SAT. ATLC SURFACE RIDGE IS MAINTAINING FRESH TO STRONG TRADE WINDS ACROSS THE CENTRAL CARIBBEAN THIS MORNING BUT WILL DIMINISH SLIGHTLY AHEAD OF THE TROPICAL WAVE THEN INCREASE AGAIN FRI BEHIND THE WAVE. ANOTHER TROPICAL WAVE OVER THE ATLC IS EXPECTED TO REACH THE EASTERN CARIBBEAN EARLY NEXT WEEK. HISPANIOLA... CURRENTLY SKIES ARE CLEAR OVER MOST OF THE ISLAND THIS MORNING. THE EXCEPTION IS N HAITI WHERE ISOLATED SHOWERS ARE POSSIBLE. AN ELONGATED UPPER LOW CENTERED OVER THE CENTRAL BAHAMAS IS N OF HISPANIOLA. GLOBAL MODELS SHOW THAT THIS UPPER LOW WILL CONTINUE TO MOVE NW AWAY FROM HISPANIOLA ALLOWING ANOTHER UPPER LOW TO MOVE IN FROM THE E ON SAT. A TROPICAL WAVE WILL MOVE ACROSS THE ISLAND STARTING THIS MORNING EXITING EARLY FRI INCREASING THE CHANCE OF SHOWERS/THUNDERSTORMS. THE TYPICAL AFTERNOON SHOWERS AND THUNDERSTORMS WILL THEN REMAIN POSSIBLE OVER THE ISLAND THROUGH THE WEEKEND. ATLANTIC OCEAN... THE UPPER RIDGE AXIS THAT EXTENDS FROM THE NW CARIBBEAN OVER THE E GULF OF MEXICO AND CONTINUES TO PROVIDE ENOUGH DIFFLUNCE ALOFT TO GENERATE ISOLATED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 75 NM ALONG THE COAST OF FLORIDA. AN ELONGATED UPPER LOW IS CENTERED OVER THE CENTRAL BAHAMAS AND IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 20N-28N BETWEEN 70W-77W. A LARGE SURFACE RIDGE DOMINATES THE ATLC ANCHORED BY A SERIES OF HIGHS WELL N OF THE DISCUSSION AREA. A COLD FRONT IS APPROACHING THE DISCUSSION AREA OVER THE CENTRAL ATLC. SURFACE RIDGE WILL CHANGE LITTLE THROUGH SAT THEN WEAKEN SUN INTO MON. THE N PORTION OF A TROPICAL WAVE MOVING ACROSS THE E CARIBBEAN WILL MOVE W ACROSS THE SOUTHERN BAHAMAS THROUGH FRI. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW