000 AXNT20 KNHC 242347 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE APR 24 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN SECTIONS OF SOUTH AMERICA...AND THE 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 9N10W 2N20W EQ30W INTO NE BRAZIL NEAR 4S44W. SCATTERED MODERATE/ ISOLATED STRONG CONVECTION FROM 1N-6N BETWEEN 12W-20W. SIMILAR CONVECTION IS WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN 32W-38W...AND OVER NE BRAZIL. ...DISCUSSION... GULF OF MEXICO... THE LEADING EDGE OF CLOUDS ASSOCIATED WITH A FRONTAL BOUNDARY OVER TEXAS AND NORTHERN COAHUILA IN MEXICO IS BEGINNING TO AFFECT THE NW CORNER OF THE GULF WHERE DOPPLER RADAR IS SHOWING SOME SHOWER ACTIVITY. A CUT-OFF LOW OVER THE SW US AND ITS ASSOCIATED UPPER LEVEL TROUGH SUPPORTS THIS FRONTAL SYSTEM. THIS UPPER TROUGH WILL MOVE EWD ENTERING THE W GULF TOMORROW. AN UPPER RIDGE DOMINATES THE GULF WITH THE AXIS EXTENDING FROM THE YUCATAN PENINSULA TO THE SE U.S..THE E HALF OF THE GULF AND THE FLORIDA PENINSULA IS DOMINATED BY MODERATE/STRONG SUBSIDENCE WHILE UPPER LEVEL MOISTURE IS ON INCREASE OVER THE W PART OF THE GULF STREAMING ACROSS NE MEXICO BY SWLY UPPER LEVEL WINDS. THE COLD FRONT IS EXPECTED TO MOVE OFF THE TEXAS COAST EARLY THU. THIS SCENARIO WOULD THEN ONLY SUPPORT SCATTERED SHOWERS/TSTMS OVER THE FAR NRN GULF WED THROUGH FRI AS THE MAIN ENERGY ASSOCIATED WITH THE FRONT SKIRTS BY TO THE N. SE RETURN FLOW OF 20 TO 25 KT WILL CONTINUE TO BLOW ACROSS THE WESTERN GULF TONIGHT AND WEDNESDAY. CARIBBEAN... AN UPPER LEVEL TROUGH LOCATED OVER THE W/CENTRAL ATLC DRAPES SW INTO THE W CARIBBEAN FROM THE WINDWARD PASSAGE SW TO NICARAGUA AND HONDURAS. STRONG CONFLUENCE INTO THE TROUGH AXIS IS PRODUCING VERY STRONG SUBSIDENCE FROM THE CAYMAN ISLANDS TO BEYOND THE SOUTHERN BAHAMAS. TO THE E...BROAD SW FLOW ALOFT LIES AHEAD OF THE TROUGH AND IS TRANSPORTING SLIGHTLY MORE MOIST AIR UP FROM SOUTH AMERICA TO THE NE CARIBBEAN. A WEAKENING SURFACE TROUGH REMAINS OVER THE AREA EXTENDING FROM THE VIRGIN ISLANDS SW TO 15N74W. SCATTERED SHOWERS AND ISOLATED TSTMS LIE TO THE N OF THE TROUGH...SOME OF WHICH ARE AFFECTING PUERTO RICO AND THE VIRGIN ISLANDS...HISPANIOLA...AND JAMAICA. SIMILAR CONVECTION IS OBSERVED OVER NORTHERN COLOMBIA AND E PANAMA...PARTLY AIDED BY A DIFFLUENT PATTERN ALOFT. SE OF THE TROUGH...DRIER LOW-LEVEL AIR AND SUBSIDENCE IN THE MID/UPPER LEVELS IS PRODUCING MAINLY FAIR WEATHER CONDITIONS ACROSS THE SRN LEEWARD AND WINDWARD ISLANDS AS WELL AS ACROSS THE VENEZUELA COAST...WITH THE EXCEPTION OF SOME SHOWERS NEAR LAKE MARACAIBO. WEATHER CONDITIONS ARE EXPECTED TO IMPROVE OVER THE NE CARIBBEAN AS THE SFC TROUGH CONTINUES TO WEAKEN AND THE UPPER TROUGH MOVES EWD AND AWAY FROM THE REGION. ATLANTIC... A 1026 MB HIGH IS CENTERED OVER THE W ATLC JUST SE OF BERMUDAS WITH A RIDGE ALIGNED FROM BERMUDA TO N FLORIDA. AN UPPER LEVEL TROUGH IS LOCATED OVER THE SAME AREA WITH THE AXIS FROM 31N60W TO THE WINDWARD PASSAGE...AND THIS IS PRODUCING MAINLY DRY CONDITIONS AT ALL LEVELS OF THE ATMOSPHERE. THIS UPPER TROUGH HAVE SUPPORTED THE DEVELOPMENT OF A WEAK SFC LOW ALONG THE STATIONARY FRONTAL BOUNDARY WHICH HAS BEEN OVER THE CENTRAL ATLC AND THE NE CARIBBEAN FOR A FEW DAYS. THIS FRONT EXTENDS SW FROM A 1018 MB SFC LOW NEAR 31N50W TO THE VIRGIN ISLANDS. A WIDE BAND OF MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS IS ASSOCIATED WITH THE FRONT. TO THE E OF THE LOW...THE FRONT HAS MOVED N AS A WARM FRONT. OVER THE E ATLC...A STRONG MID-LEVEL HIGH IS CENTERED NEAR 20N40W WHICH IS KEEPING MOST OF THE HIGH CLOUDINESS SPREADING N OF THE AREA TOWARDS THE AZORES...AND MODERATE/STRONG SUBSIDENCE SWD TO 6N. AT THE SURFACE...A RIDGE DOMINATES THE REGION GENERATING MODERATE TRADE WINDS. ONLY FRAGMENTS OF LOW LEVEL MOISTURE ARE FOUND UNDER THE INFLUENCE OF THIS RIDGE. $$ GR