000 AXNT20 KNHC 021759 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI MAY 02 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 2N10W 2N20W EQUATOR AT 34W THEN 1N43W INTO NE BRAZIL. CLUSTERS OF MODERATE/ISOLATED STRONG CONVECTION COVER THE AREA FROM 3N TO 9N EAST OF 20W TO THE AFRICAN COAST. A SFC TROUGH WAS ANALYZED IN THIS AREA ALONG 15W/16W ON THE 12Z SFC MAP. THERE SEEMS TO BE ENOUGH EVIDENCE TO SUGGEST THAT THIS COULD BE A TROPICAL WAVE. SATELLITE IMAGERY SHOWS A WELL DEFINED INVERTED V-PATTERN. THE HOVMOLLER DIAGRAM ALSO INDICATES THE WWD PROPAGATION OF THIS SYSTEM DURING LAST TWO DAYS...AND THE BAMAKO SOUNDING SHOWED THE PASSAGE OF THIS TROUGH/WAVE BETWEEN APRIL 30 AND MAY 1ST. BASED ON THIS DATA AND THE TIME OF THE YEAR...A TROPICAL WAVE WILL BE INTRODUCED ON THE 18Z MAP. ...DISCUSSION... GULF OF MEXICO... AN UPPER-LEVEL HIGH LOCATED ON PACIFIC SIDE NEAR 12N93W EXTENDS A RIDGE NWD COVERING MEXICO AND THE ENTIRE GULF. STRONG SUBSIDENCE AND A DRY STABLE AIR MASS IS IN PLACE OVER MOST OF THE GULF REGION WITH ONLY A FEW CLOUDS. A JET STREAM BRANCH WITH CORE WINDS OF 90 KT EXTENDS FROM THE DEEP SOUTH TO THE SE PORTION OF THE GULF AND WESTERN CUBA WHILE A SHORT WAVE TROUGH IS MOVING ACROSS THE SE CONUS. AT THE SFC...A RIDGE ALSO DOMINATES THE REGION EXTENDING FROM THE W ATLC ANCHORED BY A 1026 MB OFF THE NORTH CAROLINA COAST. THIS HIGH WILL KEEP A BRISK SE TO S FLOW ACROSS THE GULF THROUGH TONIGHT BEFORE DIMINISHING SAT. A COLD FRONT IS CURRENTLY MOVING ACROSS SOUTH-CENTRAL TEXAS A NORTHERN COAHUILA MEXICO. THIS FRONT IS FORECAST TO ENTER THE NW GULF WATERS LATE SAT AFTERNOON...AND SHOULD EXTEND FROM THE FLORIDA BIG BEND TO JUST SOUTH OF CORPUS CHRISTI TX SUN MORNING. CARIBBEAN SEA... BROAD UPPER RIDGE COVERS THE WESTERN CARIBBEAN AND CENTRAL AMERICA BETWEEN COSTA RICA AND GUATEMALA. ANOTHER UPPER-LEVEL RIDGE OVER NORTHERN SOUTH AMERICA EXTENDS WWD TO PANAMA. IN BETWEEN...AN UPPER-LEVEL TROUGH FROM THE ATLC ENTERS THE CARIBBEAN SEA THROUGH THE WINDWARD PASSAGE AND EXTENDS SW TO THE SW CARIBBEAN. UPPER LEVEL TROPICAL MOISTURE IS BEING DRAWN FROM SOUTH AMERICA TO OVER THE CENTRAL AND EASTERN CARIBBEAN WITH SOME HIGH CIRRUS CLOUDS. THE TAIL END OF A COLD FRONT OVER THE ATLC REACHES THE DOMINICAN REPUBLIC PRODUCING SOME CLOUDINESS WITH EMBEDDED SHOWERS PARTICULARLY ALONG THE N COAST. THE SAN JUAN DOPPLER RADAR IS DETECTING PART OF THIS ACTIVITY SHOWING SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS THE ATLANTIC WATERS NORTHWEST OF PUERTO RICO AS WELL AS SCATTERED TO NUMEROUS SHOWERS AND TSTMS ACROSS THE INTERIOR AND WESTERN SECTIONS OF PUERTO RICO. MOISTURE ASSOCIATED WITH THE FRONT IS FORECAST BY THE COMPUTER MODELS TO AFFECT PUERTO RICO AND THE VIRGIN ISLANDS THIS UPCOMING WEEKEND KEEPING THE LIKELIHOOD OF RAIN OVER THOSE ISLANDS. SFC OBSERVATIONS ACROSS THE LESSER ANTILLES THIS MORNING INDICATED PRETTY WELL THE PRESENCE OF A SFC TROUGH THAT RUNS FROM 19N60W TO 14N63W. THIS TROUGH HAS AN AREA OF CLOUDINESS WITH SOME TURNING AND SCATTERED SHOWERS JUST E OF TROUGH AXIS. HIGH PRES OVER THE SW ATLC OFF THE NORTH CAROLINA COAST IS PRODUCING 20 TO 25 KT NE WINDS THROUGH WINDWARD PASSAGE. AN EARLIER QUIKSCAT PASS CONFIRMED THESE WINDS. LIGHT TO MODERATE TRADE WINDS ARE BLOWING ACROSS THE BASIN. ATLANTIC OCEAN... SURFACE RIDGE COVERS THE W ATLC INTO THE E GULF ANCHORED BY A 1026 MB HIGH LOCATED OFF THE NORTH CAROLINA COAST. THIS FEATURE IS PROVIDING MOSTLY FAIR WEATHER FOR THE W ATLC WATERS. A WEAK UPPER LEVEL TROUGH EXTENDS FROM A CLOSED CYCLONIC CIRCULATION NEAR 36N56W TO THE WINDWARD PASSAGE. THIS UPPER TROUGH SUPPORTS A WEAK COLD FRONT THAT ENTERS THE FORECAST AREA NEAR 31N47W THEN CONTINUES SW TO THE DOMINICAN REPUBLIC WHERE IS GENERATING SOME SHOWER ACTIVITY. A SFC TROUGH...REMNANTS OF AN OLD FRONTAL BOUNDARY CONTINUES TO LINGER OVER THE E-CENTRAL ATLC ALONG 31N26W 24N40W 17N52W. THE TAIL END OF THIS TROUGH LOOKS TO BREAK-UP AND IS NOW OVER THE LESSER ANTILLES. A WEAK 1018 MB HIGH IS AHEAD OF THIS TROUGH CENTERED NEAR 21N30W. A MAINLY ZONAL FLOW DOMINATES THE REMAINDER OF THE ATLANTIC DISCUSSION AREA WHILE AN UPPER RIDGE IS INLAND OVER WESTERN AFRICA... ESPECIALLY AT MIDDLE LEVELS. $$ GR