000 AXNT20 KNHC 241749 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU MAR 24 2011 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...ITCZ... ITCZ AXIS IS ANALYZED FROM 06N11W TO THE EQUATOR NEAR 23W THEN TO 03S31W AND INTO NE BRAZIL NEAR 03S39W. ISOLATED MODERATE CONVECTION IS FROM THE EQUATOR TO 04N BETWEEN 24W-32W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL SHORTWAVE TROUGH IS MOVING OFF THE MID-ATLC SEABOARD AND EXTENDS A WEAK COLD FRONT ACROSS SOUTH CAROLINA AND GEORGIA INTO NORTHERN PORTIONS OF THE GULF FROM PANAMA CITY FLORIDA TO THE NEW ORLEANS LOUISIANA AREA THEN STATIONARY TO THE TEXAS COAST NEAR GALVESTON BAY. LACK OF STRONG UPPER LEVEL SUPPORT AND MOISTURE ARE LIMITING IMPACTS WITH THE FRONT TO A FAIRLY BENIGN WIND SHIFT AND A MORE APPARENT MOISTURE/DEW POINT CONTRAST ACROSS THE BOUNDARY. RELATIVELY HIGHER DEWPOINTS IN THE UPPER 60S AND LOWER 70S ARE OBSERVED ON SHIPS AND BUOYS ACROSS THE GULF WATERS WHILE CONSIDERABLY DRIER AIR LOCATES NORTH OF THE FRONT OVER THE GULF COASTAL PLAINS WITH DEWPOINTS REACHING INTO THE LOWER 40S. THE FRONT IS FORECAST TO GRADUALLY DISSIPATE OVER THE NEXT 24 HOURS. THE REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF A SURFACE RIDGE WHICH EXTENDS FROM THE SW NORTH ATLC ALONG 24N TO THE FLORIDA STRAITS THEN W-NW TO A 1016 MB HIGH CENTERED NEAR 26N88W. SKIES REMAIN MOSTLY CLEAR THIS AFTERNOON DUE TO STRONG MIDDLE TO UPPER LEVEL SUBSIDENCE AND MODERATELY DRY AIR ALOFT. SOUTHERLY RETURN FLOW IS EXPECTED TO INCREASE ACROSS THE WESTERN GULF LATE FRIDAY INTO SATURDAY AHEAD OF THE NEXT FRONT FORECAST TO EMERGE OFF THE NW GULF COAST MONDAY. CARIBBEAN SEA... A RIDGE OF HIGH PRESSURE LIES NORTH OF THE CARIBBEAN SEA BASIN ALONG 24N THAT IS PRODUCING 15-25 KT TRADEWIND EASTERLIES THIS AFTERNOON. SURFACE WINDS JUST NORTH OF COLOMBIA ARE SOMEWHAT ENHANCED BY THE LOCAL TOPOGRAPHY...AS IS TYPICALLY SEEN. NO DEEP CONVECTION IS CURRENTLY OBSERVED ACROSS THE CARIBBEAN...HOWEVER SOME LOW-TOPPED SHOWERS ARE OCCURRING ALONG THE EASTWARD FACING SLOPES OF CENTRAL AMERICA AND AN AREA WITHIN 90 NM SURROUNDING GRAND CAYMAN ISLAND. IN THE UPPER LEVELS...STRONGLY SUBSIDENT ZONAL FLOW DOMINATES. LITTLE CHANGE IS EXPECTED OVER THE NEXT 24 HOURS. ATLANTIC OCEAN... DEEP LAYER TROUGHING IS LOCATED N OF 28N ACROSS THE WESTERN NORTH ATLC WITH MOSTLY NORTHWESTERLY AND MODERATELY SUBSIDENT FLOW ALOFT DOMINATING W OF 50W. AT THE SURFACE...CONDITIONS REMAIN FAIRLY BENIGN WITH LIGHT ANTICYCLONIC FLOW AROUND A RIDGE AXIS EXTENDING ALONG 24N STEMMING FROM A 1022 MB HIGH CENTERED IN THE CENTRAL ATLC NEAR 24N44W. STRONGER SOUTHWESTERLY SURFACE FLOW IS NOTED N OF 30N WITH MOST OF THE ACTIVE CONVECTION ASSOCIATED WITH A SURFACE TROUGH AND COLD FRONT LOCATED N OF 34N BETWEEN 55W-70W. OVER THE EASTERN ATLC WEDGED WITHIN THE SUBTROPICAL RIDGE IS A WEAK 1018 MB LOW CENTERED NEAR 26N33W. SURFACE TROUGHING EXTENDS S-SW TO 20N36W WITH A SHEAR LINE CONTINUING S OF 20N ALONG 18N40W TO 13N52W. ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE BOUNDARIES SOUTH OF THE LOW CENTER. A STATIONARY FRONT EXTENDS E-NE FROM THE LOW ALONG 28N30W TO 28N25W AND CONNECTS WITH A COLD FRONT EXTENDING INTO THE DISCUSSION AREA NEAR 32N20W. THE UPPER LEVEL PATTERN ASSOCIATED WITH THIS COLD FRONT REMAINS UNFAVORABLE FOR ANY DEEP CONVECTION...HOWEVER ISOLATED SHOWERS ARE OCCURRING OVER THE AREA FROM 26N-29N BETWEEN 21W-33W AND WITHIN 60 NM EAST OF THE COLD FRONT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN