000 AXNT20 KNHC 122343 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT APR 12 2008 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 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 7N12W 2N25W...ALONG THE EQUATOR BETWEEN 30W AND 40W THEN INLAND OVER NE BRAZIL NEAR 2S48W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 31W-40W. CLUSTERS OF MODERATE TO STRONG CONVECTION ARE THE COAST OF BRAZIL NE OF A LINE FROM 6N43W TO 1N54W. SIMILAR CONVECTION IS OBSERVED INLAND OVER SIERRA LEONE AND WESTERN GUINEA. ...DISCUSSION... GULF OF MEXICO... A MID TO UPPER LEVEL TROUGH EXTENDING FROM THE GREAT LAKES REGION SW TO CENTRAL TEXAS SUPPORTS A RATHER STRONG COLD FRONT FOR THIS TIME OF YEAR THAT IS MOVING ACROSS THE GULF OF MEXICO EARLY THIS EVENING. AS OF 2100 UTC...THE FRONTAL BOUNDARY STRETCHES FROM N FLORIDA TO THE BAY OF CAMPECHE WHERE IT BECOMES STATIONARY THEN CONTINUES INLAND OVER MEXICO. A ROPE LINE DELINEATES THE LEADING EDGE OF THE FRONT MAINLY OVER THE EASTERN GULF. DOPPLER RADAR INDICATES SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE FLORIDA PANHANDLE AND SE GEORGIA. AN EARLIER ASCAT PASS SHOWED NE WINDS OF 20 TO 25 KT BEHIND THE FRONT AND OVER THE NW QUADRANT OF THE GULF. WINDS ARE EXPECTED TO REACH MINIMAL GALE FORCE IN THE SW GULF WATERS ON SUN. A WARNING IS ALREADY IN EFFECT. AHEAD OF THE FRONT...PATCHY CLOUDS ARE FOUND UNDER THE INFLUENCE OF AN UPPER RIDGE ANCHORED OVER CENTRAL AMERICA AND STRONG SUBSIDENCE. LIGHT SOUTHERLY RETURN FLOW AROUND A SFC RIDGE DOMINATES THE EASTERN GULF...BUT EXPECT THE WINDS TO SHIFT N AND INCREASE FOLLOWING THE FRONTAL PASSAGE. THE COLD FRONT IS FORECAST BY THE COMPUTER MODELS TO EXIT THE REGION BY SUN AFTERNOON WHILE HIGH PRES WILL BUILD IN USHERING A MUCH COOLER AND DRIER AIRMASS. CARIBBEAN SEA... STRONG SUBSIDENCE AND DRY STABLE CONDITIONS ALOFT CONTINUE TO DOMINATE THE CARIBBEAN PREVENTING ANY DEEP CONVECTION FROM DEVELOPING. PATCHY CLOUDS AND LOW-TOPPED TRADE WIND SHOWERS ARE MOVING WESTWARD ACROSS THE REGION...PARTICULARLY N OF 14N. UPPER LEVEL DIVERGENCE IS ENHANCING CONVECTION JUST E OF THE LESSER ANTILLES CAUSING A FEW SHOWERS TO MOVE OVER THE WINDWARD ISLANDS. A TROUGH WAS ANALYZED ON THE 18Z SFC MAP WITHIN AROUND 300 NM SE OF TRINIDAD AND TOBAGO ISLANDS. THE POSITION OF THIS TROUGH WAS BASED ON SATELLITE IMAGERY AND AN EARLIER ASCAT PASS. MOISTURE ASSOCIATED WITH THIS TROUGH WILL CONTINUE TO AFFECT THE WINDWARD ISLANDS AND NE VENEZUELA ON SUN. A DIFFLUENT PATTERN ALOFT IS ENHANCING SCATTERED MODERATE TO ISOLATED STRONG CONVECTION OVER NORTHERN CENTRAL AMERICA ESPECIALLY OVER PARTS OF GUATEMALA AND WESTERN HONDURAS. BRISK EASTERLY TRADE WINDS PERSIST ACROSS MUCH OF THE CARIBBEAN...WITH THE STRONGEST WINDS OF 20 TO 25 KT JUST OFFSHORE THE COLOMBIAN COAST. EXPECT THE COLD FRONT IN THE GULF OF MEXICO TO ENTER THE NW CARIBBEAN BY LATE SUN. ATLANTIC OCEAN... FAIR CONDITIONS PREVAILS OVER THE WESTERN ATLC THANKS TO THE PRESENCE OF A 1022 MB SFC HIGH CENTERED NEAR 31N60W. A SECOND... BUT WEAKER SFC HIGH IS FARTHER EAST NEAR 29N49W. EXPECT THESE TWO FEATURES TO MERGE WITHIN THE NEXT 24 HOURS. A COLD FRONT OVER THE EASTERN SEABOARD WILL MOVE OFFSHORE GEORGIA AND INTO THE W ATLC LATER TONIGHT. LIGHT TO MODERATE SOUTHERLY WINDS WILL INCREASE AND SHIFT NW FOLLOWING THE FRONTAL PASSAGE. IN THE CENTRAL ATLC...A COLD FRONT ENTERS THE REGION NEAR 31N34W THEN CONTINUES SW TO NEAR 25N47W. A SURFACE RIDGE ANCHORED BY A 1027 MB HIGH N OF THE REGION COVERS THE EASTERN ATLC. TIGHT PRES GRADIENT BETWEEN THIS ANTICYCLONE AND LOWER PRES OVER AFRICA IS PRODUCING A SWATH OF NE WINDS OF 20 TO 30 KT SE OF LINE FROM 31N14W TO 19N23W. ALOFT...A RIDGE DOMINATES THE W ATLC WHILE AN UPPER LEVEL TROUGH EXTENDS ACROSS THE CENTRAL ATLC ENTERING THE CARIBBEAN SEA THROUGH THE LEEWARD ISLANDS. SWLY FLOW...BETWEEN THIS TROUGH AND A RIDGE COVERING THE DEEP TROPICS...ADVECTS UPPER-LEVEL MOISTURE/HIGH CLOUDS ACROSS THE N TROPICAL ATLANTIC FROM SOUTH AMERICA TO THE NW COAST OF AFRICA. $$ GR