000 AXNT20 KNHC 152330 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN APR 15 2012 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE WEST AFRICAN COAST OF LIBERIA NEAR 6N10W TO 3N17W...WHERE THE ITCZ CONTINUES ALONG THE EQUATOR NEAR 30W TO THE COAST OF BRAZIL NEAR 3S40W. SCATTERED WEAK TO ISOLATED MODERATE CONVECTIVE PRECIPITATION IS WITHIN 150-200 NM ON EITHER SIDE OF THE ITCZ. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY DISPLAYS DRY AIR AND STRONG SUBSIDENCE ALOFT ACROSS THE DISCUSSION AREA THIS EVENING...ANCHORED BY A STRONG 1029 MB CENTERED OVER THE WRN ATLC BASIN. THE SURFACE RIDGE AXIS ASSOCIATED TO THIS HIGH PRESSURE SYSTEM EXTENDS WSW INTO THE AREA...AND TOGETHER WITH A STRONG LOW PRESSURE SYSTEM OVER THE GREAT PLAINS...IS GENERATING A MODERATE E-W PRESSURE GRADIENT OVER THE GULF WITH 15-25 KT SSE WINDS ACROSS THE BASIN WITH JUST A LINE OF HEAVY SHOWERS AND ISOLATED THUNDERSTORMS IS HEADING N AGAINST THE COAST OF THE WRN FLORIDA PANHANDLE AND ALABAMA. SHORT RANGE COMPUTER MODELS SUGGEST THE PRESSURE GRADIENT BETWEEN THE STRONG SURFACE LOW AND RIDGE ACROSS THE GULF WILL PERSIST UNTIL MONDAY WHEN THE GRADIENT WILL BEGIN TO RELAX GRADUALLY DUE TO A WEAK FRONTAL BOUNDARY EMERGING OFF THE TEXAS AND LOUISIANA COASTS. WEAK FRONTAL TROUGHING WILL REMAIN ACROSS THE NORTHERN GULF THROUGH TUESDAY INTO WEDNESDAY WITH WINDS GENERALLY IN THE RANGE OF 10 TO 15 KT. CARIBBEAN SEA... WATER VAPOR IMAGERY SHOWS MODERATE TO STRONG SUBSIDENCE AND DRY AIR ALOFT OVER A GREAT PORTION OF THE DISCUSSION AREA THIS EVENING. HOWEVER...THE SRN EXTENSION OF A COLD FRONT ENTERS THE NE BASIN ACROSS THE LEEWARD ISLANDS THROUGH THE ISLAND OF MONTSERRAT...AND QUICKLY BECOMES A SHEAR AXIS EXTENDING TO THE NRN COASTAL WATERS OF COLOMBIA NEAR 13N74W. MODERATE TO HEAVY SHOWERS AND ISOLATED THUNDERSTORMS ARE WITHIN 75 NM ON EITHER SIDE OF THE AXIS. SIMILAR CONVECTION IS NOTICED S OF JAMAICA FROM 14N TO THIS ISLAND BETWEEN 75W-81W. OTHERWISE...ENE TRADEWIND FLOW OF 10-20 KTS IS REPORTED ACROSS THE AREA...WITH STRONGER NE FLOW FILTERING THROUGH THE WINDWARD AND MONA PASSAGES AS THE PRESSURE GRADIENT STRENGTHENS TO THE NORTH OVER THE SW NORTH ATLC. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH CONTINUES TO MOVE ACROSS THE CENTRAL ATLC THIS EVENING. WATER VAPOR IMAGERY SHOWS A VIGOROUS SHORTWAVE EMBEDDED AT THE BASE OF THE UPPER TROUGH SUPPORTING AN OCCLUDED 1012 MB LOW CENTERED NEAR 31N51W. A COLD FRONT EXTENDS SSW FROM ITS TRIPLE POINT INTO THE DISCUSSION AREA ALONG 32N48W 24N51W INTO THE FAR NE CENTRAL CARIBBEAN SEA ALONG THE ISLAND OF MONTSERRAT. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 80-150 NM AHEAD OF THE COLD FRONT...BECOMING STRONGER N OF 23N WHERE LOW LEVEL CONVERGENCE AND UPPER LEVEL DIFFLUENCE IS MAXIMIZED. HIGH PRESSURE CONTINUES TO BUILD BEHIND THE FRONT AS A 1029 MB HIGH CENTERED NEAR 32N70W IS FORECAST TO REMAIN IN CONTROL THROUGH WEDNESDAY. COMPUTER MODELS SUGGEST THE FRONT WILL CONTINUE TO EXPAND E OVER THE NEXT 24 HOURS AND BEGIN TO STALL DURING THE NEXT 24-48 HOURS. FAIR WEATHER CONDITIONS ARE FOUND ELSEWHERE AHEAD OF THE FRONTAL CONVECTION...ASSOCIATED TO A STRONG SURFACE RIDGE ANCHORED BY A 1033 MB HIGH CENTERED N OF THE AZORES NEAR 40N27W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA