000 AXNT20 KNHC 151802 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED APR 15 2009 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 5N9W...CROSSING THE EQUATOR ALONG 18W EXTENDING TO 3S30W AND INTO NE BRAZIL NEAR 4S40W. THE TROPICAL WAVE-LIKE FEATURE THAT WAS ANALYZED AS A SFC TROUGH ON THE SFC MAP IS NO LONGER IDENTIFIABLE BASED ON LATEST SATELLITE IMAGERY. CONVECTION HAS DIMINISHED SINCE YESTERDAY IN THAT AREA. CURRENTLY... SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NOTED FROM THE EQUATOR TO THE AFRICAN COAST BETWEEN THE PRIME MERIDIAN AND 10W. SCATTERED MODERATE CONVECTION IS ALSO FROM THE EQUATOR TO 4N BETWEEN 10W AND 20W. SIMILAR CONVECTION IS NOTED WHERE THE ITCZ AXIS MEETS THE COAST OF BRAZIL. ...DISCUSSION... THE GULF OF MEXICO... AS OF 1500 UTC...A COLD FRONT EXTENDING OVER SOUTH FLORIDA BECOMES STATIONARY OVER THE GULF OF MEXICO ALONG 23N83W 25N86W 23N90W. A QSCAT PASS FROM AROUND 1130 UTC SHOWED VERY WELL THE WIND SHIFT RELATED TO THE FRONT. THE UPPER LEVEL SUPPORT THAT GENERATED STRONG CONVECTION YESTERDAY IN THE VICINITY OF THIS FRONT HAS NOW OUTRUN THE FRONT...WITH ISOLATED SHOWERS AND THUNDERSTORMS OCCURRING ALONG THE FRONTAL BOUNDARY EARLY THIS AFTERNOON. THE FRONT WILL CONTINUE TO DRIFT SOUTHWARD THIS AFTERNOON AND EXTEND FROM THE FLORIDA KEYS TO THE YUCATAN PENINSULA TONIGHT BEFORE WEAKENING ON THU. HIGH PRES WILL BUILD OVER THE SE U.S. BEHIND THE FRONT THROUGH THE WEEKEND. WINDS WILL INCREASE ACROSS THE WESTERN GULF ON FRI DUE TO A TIGHT PRES GRADIENT BETWEEN THE RIDGE OVER THE SE CONUS AND LOWER PRES OVER MEXICO. THE GFS COMPUTER MODEL INDICATES SE WINDS OF 20 TO 25 KT IN THAT AREA. A SFC TROUGH PERSISTS OVER THE BAY OF CAMPECHE AND EXTENDS FROM 22N92W TO 18N93W. ISOLATED SHOWERS ARE ASSOCIATED WITH THIS TROUGH. IN THE UPPER LEVELS...A RIDGE WITH AXIS ALONG 92W DOMINATES MUCH OF THE GULF REGION. THE NEXT COLD FRONT IS FORECAST TO MOVE OFF THE SE TEXAS COAST SAT NIGHT AND EXTENDS FROM SE LOUISIANA TO VERACRUZ SUN AFTERNOON. THE CARIBBEAN SEA... FRESH TRADEWINDS ARE BLOWING ACROSS THE EAST AND CENTRAL CARIBBEAN. WINDS VEER TO THE SE OVER THE WESTERN CARIBBEAN DUE TO THE PRESENCE OF THE FRONTAL ZONE ACROSS THE GULF OF MEXICO. SHALLOW MOISTURE EMBEDDED IN THE TRADE WIND FLOW WILL CONTINUE TO MOVE ACROSS THE BASIN PRODUCING ISOLATED TO SCATTERED PASSING SHOWERS. SOME OF THEM ARE ALREADY AFFECTING TRINIDAD AND TOBAGO IN THE WINDWARD ISLANDS AS WELL AS THE UK/US VIRGIN ISLANDS AND THE EASTERN PORTION OF PUERTO RICO. ALOFT...THE BASE OF AN UPPER-LEVEL TROUGH OVER THE W ATLC REACHES CUBA WITH WLY WINDS DOMINATING THE NW CARIBBEAN. THE REMAINDER OF THE AREA IS UNDER THE INFLUENCE OF A BROAD RIDGE WITH MODERATE TO STRONG SUBSIDENCE. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS. THE ATLANTIC OCEAN... A COLD FRONT ENTERS THE AREA NEAR 31N76W THEN CONTINUES SW ACROSS SOUTH FLORIDA INTO THE GULF OF MEXICO WHERE IT BECOMES STATIONARY. S TO SW WINDS OF 20 TO 25 KT ARE BLOWING AHEAD OF THE FRONT N OF 27N TO NEAR 70W. WINDS SHIFT TO THE W AND THEN NW WITH THE SAME SPEEDS BEHIND THE FRONT. ISOLATED SHOWERS AND POSSIBLE THUNDERSTORMS ARE NOTED ALONG THE FRONTAL BOUNDARY... WHICH IS ASSOCIATED WITH AN UPPER LEVEL TROUGH OVER THE W ATLC. ANOTHER COLD FRONT IS OVER THE CENTRAL ATLC AND ENTERS THE FORECAST AREA NEAR 31N38W EXTENDING SW TO NEAR 25N51W. VIS SATELLITE IMAGERY REVEALS A NARROW BAND OF BROKEN CLOUDS WITH ISOLATED SHOWERS ASSOCIATED WITH THE FRONT. THE REMAINDER OF THE REGION IS UNDER THE INFLUENCE OF TWO HIGH PRESSURE SYSTEMS...A 1027 MB HIGH TO THE WEST OF THE SECOND FRONT CENTERED NEAR 32N51W AND A 1029 MB HIGH TO THE EAST OF THE FRONTAL SYSTEM LOCATED NEAR 32N28W. IN THE UPPER LEVELS...A TROUGH/RIDGE/TROUGH PATTERN IS PRESENT ACROSS MOST OF THE FORECAST REGION WITH THE FIRST TROUGH OVER THE W ATLANTIC W OF 65W...AND THE SECOND TROUGH EXTENDING FROM 30N25W TO NEAR 14N45W. $$ GR