000 AXNT20 KNHC 141049 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT THU APR 14 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...ITCZ... ITCZ AXIS IS ANALYZED ALONG 04N07W 02N10W 03N25W CROSSING THE EQUATOR NEAR 35W...THEN INTO NE BRAZIL NEAR 03S39W. ISOLATED MODERATE TO STRONG CONVECTION IS OCCURRING WITHIN 90 NM EITHER SIDE OF A LINE FROM THE EQUATOR AND 01W TO 06N19W TO 04N27W. ...DISCUSSION... GULF OF MEXICO... NW FLOW ALOFT IS ACROSS MUCH OF THE GULF DUE TO A RATHER LARGE UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER SOUTHERN MEXICO NEAR 16N97W. THE RIDGE AXIS ALOFT EXTENDS N-NE OVER THE WESTERN GULF CRESTING OVER THE OHIO RIVER VALLEY NEAR 37N87W. WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL TROUGH OVER THE W ATLC BETWEEN 70W-80W THAT SUPPORTS A WEAK 1014 MB LOW CENTERED NEAR 26N80W WITH A STATIONARY FRONT DRAPED ACROSS THE FLORIDA STRAITS TO THE NW COAST OF CUBA NEAR 23N83W TO 25N88W. THE FRONT CONTINUES ON A WEAKENING TREND AND REMAINS FAIRLY BENIGN CONVECTIVELY...HOWEVER...RECENT SHIP...BUOY...AND LAND-BASED OBSERVATIONS INDICATE A DRIER AIRMASS IN PLACE OVER THE NE GULF AND ACROSS MUCH OF THE FLORIDA PENINSULA AS A 1017 MB HIGH LOCATES NEAR 28N86W. THE SURFACE RIDGE IS FORECAST TO SHIFT SLOWLY NE OVER THE NEXT 24 HOURS AS S-SE RETURN FLOW ESTABLISHES ITSELF ACROSS THE ENTIRE BASIN THROUGH EARLY FRIDAY AHEAD OF THE NEXT COLD FRONT FORECAST TO EMERGE OFF THE TEXAS GULF COAST SHORTLY AFTER SUNRISE FRIDAY. CARIBBEAN SEA... AN AMPLIFIED MIDDLE TO UPPER LEVEL TROUGH IS LOCATED OVER THE WESTERN CARIBBEAN WITH AXIS EXTENDING FROM THE SW NORTH ATLC NEAR 24N74W S-SW OVER THE WINDWARD PASSAGE TO EASTERN PANAMA NEAR 08N79W. STRONG SUBSIDENCE AND DRY AIR ACCOMPANY THIS UPPER LEVEL FEATURE AND THESE FACTORS CONTINUE TO PROVIDE OVERALL CLEAR SKIES AND FAIR CONDITIONS ACROSS THE WESTERN CARIBBEAN W OF 70W THIS MORNING. EAST OF THE TROUGH AXIS HOWEVER...SW FLOW IS ADVECTING A STREAM OF MIDDLE TO UPPER LEVEL MOISTURE ACROSS THE SE CARIBBEAN AND LESSER ANTILLES NE INTO THE TROPICAL NORTH ATLC. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING E OF A LINE FROM CURACAO TO THE US/UK VIRGIN ISLANDS WITH THE MOST INTENSE ACTIVITY OVER THE SE CARIBBEAN S OF 13N BETWEEN 62W-66W. A SURFACE TROUGH CONTINUES TO DRIFT WESTWARD AND IS ANALYZED FROM SW HISPANIOLA NEAR 18N73W TO ACROSS NORTHERN COLOMBIA NEAR 10N74W. WHILE BECOMING MORE AND MORE EMBEDDED UNDERNEATH THE PREVIOUSLY MENTIONED STRONG SUBSIDENCE ALOFT IN ASSOCIATION WITH THE UPPER LEVEL TROUGH...THE SURFACE FEATURE WILL GRADUALLY WEAKEN OVER THE NEXT 6 TO 12 HOURS WITH EASTERLY TRADES REMAINING LIGHT DUE TO A RELAXED PRESSURE GRADIENT ACROSS THE ENTIRE BASIN. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL TROUGH IS OVER THE W ATLC BETWEEN 70W-80W WHICH SUPPORTS A COLD FRONT ANALYZED INTO THE DISCUSSION AREA NEAR 32N72W EXTENDING SW TO THE NW BAHAMAS THEN INTO A WEAK 1014 MB LOW CENTERED OFFSHORE OF THE SE FLORIDA PENINSULA NEAR 26N80W. A LACK OF SIGNIFICANT MOISTURE TO WORK WITH IS NOTED WITH THE FRONT AS ONLY ISOLATED SHOWERS ARE OCCURRING WITHIN 60 NM EAST OF THE FRONT. WEAK HIGH PRESSURE IS BUILDING IN BEHIND THE FRONT AND IS EXPECTED TO PROVIDE LIGHT EASTERLY FLOW THROUGH EARLY FRIDAY AS THE FRONT MOVES NE OF 30N70W. THE REMAINDER OF THE W ATLC WEST OF 50W IS UNDER THE INFLUENCE OF A SURFACE RIDGE EXTENDING FROM E-NE OF BERMUDA NEAR 34N54W TO NORTH OF HISPANIOLA NEAR 20N70W. FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED NEAR 27N37W IN THE CENTRAL ATLC AND CONTINUES TO SUPPORT A 1013 MB LOW CENTERED NEAR 26N40W. A SURFACE TROUGH EXTENDS FROM THE LOW ALONG 25N38W TO 21N41W THEN WESTWARD AS A SHEAR LINE TO 20N56W. WIDELY SCATTERED SHOWERS ARE OCCURRING EAST OF THE SURFACE TROUGH FROM 23N-29N BETWEEN 34W-40W. STRONG HIGH PRESSURE IS EXPECTED TO BUILD IN OVER THE CENTRAL ATLC BY LATE THURSDAY AND DISSIPATE ANY REMNANTS OF THE LOW AND SURFACE TROUGH. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN