000 AXNT20 KNHC 140548 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...ITCZ... ITCZ AXIS IS ANALYZED ALONG 06N10W 02N30W CROSSING THE EQUATOR NEAR 35W...THEN INTO NE BRAZIL NEAR 03S40W. ISOLATED MODERATE CONVECTION IS FROM THE EQUATOR TO 05N BETWEEN THE PRIME MERIDIAN AND 12W...AND FROM 02N-06N BETWEEN 19W-28W. ...DISCUSSION... GULF OF MEXICO... NW FLOW ALOFT IS ACROSS MUCH OF THE GULF DUE TO A RATHER LARGE UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER THE WEST- CENTRAL COAST OF MEXICO NEAR 17N101W. THE RIDGE AXIS ALOFT EXTENDS N-NE OVER THE WESTERN GULF CRESTING NEAR THE MIDDLE MISSISSIPPI RIVER VALLEY NEAR 36N92W. WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL TROUGH OVER THE W ATLC BETWEEN 70W-80W THAT SUPPORTS A STATIONARY FRONT ANALYZED AT 14/0300 UTC FROM THE FLORIDA STRAITS NEAR 24N80W W-NW TO 26N90W. THIS EVENING THE FRONT CONTINUES ON A WEAKENING TREND AND REMAINS FAIRLY BENIGN CONVECTIVELY...HOWEVER...RECENT SHIP...BUOY...AND LAND-BASED OBSERVATIONS INDICATE A MUCH DRIER AIRMASS IN PLACE OVER THE NE GULF AND ACROSS MUCH OF THE FLORIDA PENINSULA AS A 1018 MB HIGH LOCATES NEAR 29N86W. 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 BY EARLY FRIDAY AHEAD OF THE NEXT COLD FRONT FORECAST TO EMERGE OFF THE TEXAS GULF COAST BY LATE 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 24N73W S-SW OVER THE WINDWARD PASSAGE TO WESTERN PANAMA NEAR 08N82W. STRONG SUBSIDENCE AND DRY AIR ACCOMPANY THIS UPPER LEVEL FEATURE AND THESE FACTORS CONTINUE TO PROVIDE OVERALL CLEAR SKIES AND FAIR CONDITIONS FOR THE WESTERN CARIBBEAN W OF 72W. EAST OF THE TROUGH AXIS HOWEVER...MOIST SOUTHWESTERLY FLOW IS ADVECTING MIDDLE TO UPPER LEVEL MOISTURE ACROSS THE EASTERN CARIBBEAN AND LESSER ANTILLES. ISOLATED SHOWERS ARE POSSIBLE THROUGH THE OVERNIGHT AND MORNING HOURS E OF 70W. A SURFACE TROUGH CONTINUES TO DRIFT WESTWARD AND IS ANALYZED FROM SOUTHERN HISPANIOLA NEAR 18N72W TO NORTHERN COLOMBIA NEAR 09N74W. WHILE BECOMING MORE AND MORE EMBEDDED UNDERNEATH THE DRIEST AIR AND SUBSIDENCE ALOFT ASSOCIATED WITH THE UPPER LEVEL TROUGH...THE SURFACE FEATURE WILL GRADUALLY WEAKEN OVER THE NEXT 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 32N73W EXTENDING SW TO THE NW BAHAMAS THEN TO 24N80W AND WESTWARD INTO THE SE GULF OF MEXICO. A LACK OF SIGNIFICANT MOISTURE ACCOMPANIES THE FRONT WITH ONLY ISOLATED SHOWERS OCCURRING WITHIN 60 NM EAST OF THE FRONT N OF 29N. 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 EAST OF BERMUDA NEAR 32N57W TO NORTH OF HISPANIOLA NEAR 20N70W. FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED NEAR 28N39W IN THE CENTRAL ATLC AND CONTINUES TO SUPPORT A 1013 MB LOW CENTERED NEAR 28N42W. A SURFACE TROUGH EXTENDS FROM THE LOW ALONG 26N40W TO 21N45W THEN WESTWARD AS A SHEAR LINE TO 21N56W. WIDELY SCATTERED SHOWERS ARE OCCURRING EAST OF THE SURFACE TROUGH FROM 23N-30N BETWEEN 35W-42W. 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