000 AXNT20 KNHC 111748 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED MAY 11 2011 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. ...ITCZ... ITCZ AXIS IS ALONG 07N13W 02N30W CROSSING THE EQUATOR NEAR 38W THEN ALONG THE EQUATOR TO 51W. WIDELY SCATTERED MODERATE CONVECTION IS FROM THE EQUATOR TO 05N BETWEEN 24W-51W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL RIDGE IS LOCATED OVER THE WESTERN GULF WITH AXIS EXTENDING FROM SOUTHERN MEXICO NORTHWARD ALONG 93W TO OVER THE OHIO RIVER VALLEY AND GREAT LAKES REGION. THE UPPER LEVEL RIDGE IS SUPPORTIVE OF OVERALL FAIR WEATHER AND CLEAR SKIES THIS AFTERNOON AS A 1016 MB HIGH IS CENTERED IN THE SW NORTH ATLC NEAR 27N76W WITH A RIDGE AXIS EXTENDING W-NW TO COASTAL ALABAMA AND MISSISSIPPI. WHILE GENERALLY LIGHT AND VARIABLE WINDS ARE OVER THE NE CORNER OF THE GULF IN THE VICINITY OF THE BIG BEND OF FLORIDA...THE REMAINDER OF GULF OBSERVATIONS CONTINUE TO INDICATE SE WINDS IN THE RANGE OF 10 TO 20 KT...WITH STRONGEST FLOW EXPECTED W OF 90W. THE HIGH PRESSURE RIDGE IS FORECAST TO SHIFT WESTWARD INTO THE NE GULF WATERS OVER THE NEXT 24 TO 36 HOURS WITH SOUTHERLY RETURN FLOW PERSISTING UNTIL THE NEXT COLD FRONT EMERGES OFF THE TEXAS COAST LATE FRIDAY INTO EARLY SATURDAY. CARIBBEAN SEA... NW FLOW ALOFT IS NOTED ON WATER VAPOR IMAGERY OVER THE NW CARIBBEAN AND THIS DRY AIR AND SUBSIDENCE IS PROMOTING CLEAR SKIES AND OVERALL FAIR CONDITIONS THIS AFTERNOON N OF 15N W OF 80W. THE REMAINDER OF CARIBBEAN SEA IS UNDER THE INFLUENCE OF SOUTHWESTERLY UPPER LEVEL FLOW ON THE NW PERIPHERY OF AN ANTICYCLONIC CIRCULATION CENTERED IN THE TROPICAL ATLC NEAR 06N44W. THIS UPPER LEVEL FLOW IS ADVECTING MIDDLE TO UPPER LEVEL MOISTURE OVER MUCH OF THE BASIN E OF 80W. WHILE TOTAL PRECIPITABLE WATER VALUES HAVE LOWERED SLIGHTLY OVER THE PAST 24 HOURS...REMAINING LOW-LEVEL MOISTURE IS ASSOCIATED WITH A SURFACE TROUGH ANALYZED FROM TROPICAL NORTH ATLC NEAR 22N54W TO 18N63W TO 16N69W. VISIBLE SATELLITE IMAGERY SHOWS ISOLATED SHOWERS OCCURRING N OF 17N E OF 68W...INCLUDING PORTIONS OF PUERTO RICO AND THE US/UK VIRGIN ISLANDS. EASTERLY TRADES IN THE RANGE OF 10 TO 20 KT PERSIST AND LOW-LEVEL CONVERGENCE OF THIS SURFACE FLOW ACROSS THE SW CARIBBEAN CONTINUES TO GENERATE SCATTERED SHOWERS AND ISOLATED TSTMS S OF 14N W OF 76W. ATLANTIC OCEAN... AN UPPER LEVEL LOW IS CENTERED IN THE WESTERN NORTH ATLC NEAR 37N64W THAT SUPPORTS A COLD FRONT ENTERING THE DISCUSSION AREA NEAR 32N53W EXTENDING SW ALONG 26N57W 22N68W TO 22N75W. ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE FRONT. MEANWHILE WEST OF THE FRONT...A HIGH PRESSURE RIDGE IS BUILDING SOUTHWARD ACROSS WESTERN PORTIONS OF THE SW NORTH ATLC ANCHORED BY A 1016 MB HIGH CENTERED NEAR 27N76W. A CONVECTIVE COMPLEX OF SCATTERED SHOWERS AND TSTMS MOVED OFF THE CAROLINA COAST EARLIER THIS MORNING AND CONTINUES TO IMPACT THE WATERS N OF 28N BETWEEN 76W-80W. THIS AREA OF SIGNIFICANT CONVECTION IS EXPECTED TO CONTINUE MOVING SOUTHEASTWARD THROUGH WEDNESDAY EVENING. SE OF THE COLD FRONT...A SURFACE TROUGH IS ANALYZED FROM 22N54W TO 18N63W TO 16N69W WITH SCATTERED SHOWERS AND ISOLATED TSTMS FROM 19N-25N BETWEEN 47W-55W. ELSEWHERE E OF 55W WITHIN 60 NM SOUTH AND 150 NM NORTH OF THE SURFACE TROUGH...ISOLATED SHOWERS ARE OCCURRING AND EXPECTED OVER THE NEXT 24 HOURS AS THE COLD FRONT TO THE NW CONTINUES MOVING EASTWARD. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF SURFACE RIDGING ANCHORED BY A 1021 MB HIGH CENTERED NEAR 29N38W. A WEAK SURFACE TROUGH ANALYZED FROM 23N38W TO 17N43W IS EMBEDDED WITHIN THE SURFACE RIDGE AND CONTINUE TO DRIFT SLOWLY WESTWARD. POSSIBLE ISOLATED SHOWERS ARE FROM 20N-24N BETWEEN 37W-42W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN