000 AXNT20 KNHC 120556 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT TUE APR 12 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 05N09W 02N22W CROSSING THE EQUATOR NEAR 27W THEN INTO NE BRAZIL NEAR 05S36W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 02N-07N BETWEEN 16W-27W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL TROUGH CONTINUES TO PROGRESS ACROSS THE LOWER MISSISSIPPI RIVER VALLEY THIS EVENING SUPPORTING A COLD FRONT THAT AT 12/0300 UTC ENTERS THE GULF OF MEXICO NEAR CAMERON LOUISIANA THEN S-SW ALONG 27N95W TO 23N97W THEN INLAND ACROSS EAST-CENTRAL MEXICO NEAR 21N97W. WATER VAPOR IMAGERY INDICATES FAIRLY DRY CONDITIONS AND OVERALL STRONG SUBSIDENCE ALOFT OVER MUCH OF THE GULF SO CONVECTION WITH THE FRONT IS LIMITED TO A PRE-FRONTAL SQUALL LINE EXTENDING FROM MOBILE BAY NEAR 31N88W TO 30N90W IMPACTING THE COASTAL WATERS BETWEEN 87W-91W. MOST OF THE STRONGER AND MORE INTENSE CONVECTION IS LOCATED OVER INTERIOR PORTIONS OF SE ALABAMA AND WEST-CENTRAL GEORGIA. GLOBAL MODEL GUIDANCE INDICATES STRONGER NE WINDS TO 20 KT ARE EXPECTED BY SUNRISE TUESDAY NW OF THE FRONT DUE TO AN INCREASED PRESSURE GRADIENT ACROSS THE NW GULF...HOWEVER SEVERAL MODELS INCLUDING THE GFS...ECMWF...AND NAM ALL SHOW THOSE THIS WIND FIELD TO REMAIN BRIEF LASTING ONLY UNTIL AROUND 12/1500 UTC. A 1021 MB HIGH CENTERED OVER WEST TEXAS NEAR ABILENE IS FORECAST TO CREATE THIS INCREASE GRADIENT AND SHIFT EASTWARD THROUGH EARLY WEDNESDAY PROVIDING THE GULF WITH LIGHT ANTICYCLONIC WINDS. CARIBBEAN SEA... DRY AIR AND STRONG SUBSIDENCE IS NOTED ON WATER VAPOR IMAGERY ACROSS MUCH OF THE WESTERN CARIBBEAN IN ASSOCIATION WITH BROAD TROUGHING EXTENDING FROM THE SW NORTH ATLC REGION. THE UPPER LEVEL TROUGH AXIS EXTENDS FROM AN UPPER LEVEL LOW CENTERED NORTH OF HISPANIOLA NEAR 21N71W TO NORTHERN PANAMA NEAR 08N80W. THIS VERY DRY AIR ALOFT IS SUPPORTIVE OF CLEAR SKIES W OF 70W AND IS EXPECTED TO REMAIN IN PLACE THROUGH THURSDAY AS THE UPPER LEVEL TROUGH AMPLIFIES SLIGHTLY. HIGHER POTENTIAL CONVECTIVE WEATHER REMAINS EAST OF THE TROUGH AXIS ALONG 70W. E OF 70W...E-NE TRADES CONTINUE WITH A SURFACE TROUGH ANALYZED FROM 11N66W TO MONTSERRAT NEAR 17N62W. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING E OF A LINE FROM THE US/UK VIRGIN ISLANDS NEAR 18N65W TO ARUBA NEAR 12N70W. THIS AREA IS FORECAST TO REMAIN NEARLY STATIONARY THROUGH EARLY WEDNESDAY AS A FRONTAL BOUNDARY TO THE NORTH OVER THE W ATLC SHIFTS NE OF THE AREA OVER THE NEXT 24 TO 36 HOURS. TOTAL PRECIPITABLE WATER VALUES REMAIN HIGH OVER THE SE CARIBBEAN AND THIS ADDED LOW-LEVEL MOISTURE WILL CONTINUE TO SUPPORT SCATTERED SHOWER ACTIVITY E OF 70W OVER THE NEXT COUPLE OF DAYS. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL TROUGH IS OVER THE CENTRAL ATLC THAT SUPPORTS A COLD FRONT ENTERING THE DISCUSSION AREA NEAR 32N44W EXTENDING SW TO 30N49W THEN CONTINUES W-SW AS A STATIONARY FRONT ALONG 28N60W TO 22N69W. THE STRONGEST UPPER LEVEL DYNAMICS ARE EVIDENT ON WATER VAPOR IMAGERY N OF 27N WITH SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING FROM 28N-33N BETWEEN 43W-49W. SOUTH OF THE FRONT ACROSS THE SW NORTH ATLC...A WEAK 1016 MB LOW AND SURFACE TROUGH IS NEAR 22N61W WITH VERY LITTLE ASSOCIATED SHOWER ACTIVITY. THE REMAINDER OF THE ATLC E OF 45W IS UNDER THE INFLUENCE OF A SURFACE RIDGE EXTENDING FROM THE AZORES NEAR 38N27W TO 22N45W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN