000 AXNT20 KNHC 132351 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE MAY 13 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. ...TROPICAL WAVES... WEAK TROPICAL WAVE IS ALONG 57W/58W S OF 10N MOVING W 10-15 KT. THE WAVE IS STILL ENHANCING SOME SHOWER/TSTM ACTIVITY OVER THE GUYANAS REGION AND ADJACENT COASTAL WATERS. THE WAVE IS EXPECTED TO ENTER THE FAR SOUTHERN WATERS OF THE EASTERN CARIBBEAN SEA DURING THE NEXT 24 TO 48 HOURS BRINGING SOME INCREASE IN MOISTURE OVER THE SRN WINDWARD ISLANDS. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 7N10W 4N24W 1N35W EQ52W. 1N40W AND INTO NE BRAZIL NEAR 2N51W. CLUSTERS OF MODERATE TO STRONG CONVECTION ARE OVER SW AFRICA. SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 1N-5N BETWEEN 17W-23W. SIMILAR CONVECTION IS FROM THE EQUATOR TO 6N BETWEEN 30W-36W...AND WITHIN 50 NM EITHER SIDE OF AXIS WEST OF 40W. ...DISCUSSION... GULF OF MEXICO... SFC HIGH PRES DOMINATES THE SE CONUS...INCLUDING THE STATE OF FLORIDA AND THE EASTERN HALF OF THE GULF KEEPING THE ATMOSPHERE DRY AND STABLE. AS OF 2100 UTC...A 1018 MB HIGH IS ANALYZED OVER THE FAR NE CORNER OF THE GULF NEAR 29N84W. SOUTHERLY RETURN FLOW HAS DEVELOPED OVER THE WESTERN HALF OF THE GULF AROUND A WEAK RIDGE ANCHORED ON THE ABOVE MENTIONED SFC HIGH. AN EARLIER ASCAT PASS SHOWED WIND SPEEDS OF 15 TO 20 KT. A NARROW BAND OF LOW-LEVEL CLOUDS WITH POSSIBLE ISOLATED SHOWERS...REMNANTS OF A FRONTAL BOUNDARY...REMAINS ACROSS THE CENTRAL AND SE GULF. ALOFT...A RIDGE CENTERED OVER BELIZE AND NORTHERN GUATEMALA ENVELOPS THE ENTIRE GULF. SWLY AND THEN WLY FLOW AROUND THE WESTERN PERIPHERY OF THIS UPPER FEATURE IS TRANSPORTING UPPER-LEVEL MOISTURE FROM THE EPAC THROUGH CENTRAL MEXICO INTO THE GULF. THESE WINDS ARE ALSO HELPING TO INDUCE SCATTERED SHOWERS AND TSTMS OVER PARTS OF CENTRAL MEXICO. HIGH PRES OVER THE SE CONUS WILL MOVE INTO THE W ATLC TONIGHT THROUGH WED. THE NEXT COLD FRONT IS FORECAST TO MOVE OFF THE TEXAS COAST LATE THU. CARIBBEAN SEA... A SFC HIGH PRESSURE CENTERED IN THE E ATLC EXTENDS A RIDGE SW TO OVER THE EASTERN CARIBBEAN PROVIDING FAIR WEATHER AND PATCHY CLOUDS ACROSS THE REGION. LIGHT TO MODERATE TRADE WINDS CONTINUE TO DOMINATE THE BASIN WITH THE STRONGEST WINDS...AS USUAL JUST OFFSHORE THE COLOMBIAN COAST. A COLD FRONT FROM THE WESTERN ATLC CROSSES THE CENTRAL BAHAMAS AND THE N COAST OF WEST AND CENTRAL CUBA WHERE IT IS DISSIPATING. CONVECTION HAS DEVELOPED OVER CAMAGUEY AHEAD OF THE FRONT WITH LIGHTNING DATA SHOWING SCATTERED TSTMS. WIND SPEED CONVERGENCE IN THE SW CARIBBEAN IS GENERATING A LINE OF SHOWERS FROM THE COAST OF NICARAGUA NEAR 12N84W TO THE PANAMA CANAL. THIS CONVECTION IS BEING ENHANCED BY A DIFFLUENT PATTERN ALOFT BETWEEN THE BASE OF AN UPPER TROUGH AND THE SOUTHERN PERIPHERY OF THE UPPER HIGH SITUATED OVER BELIZE AND N GUATEMALA. MODERATE TO STRONG SUBSIDENCE ALOFT CONTINUES TO INHIBIT THE DEVELOPMENT OF ANY SIGNIFICANT CONVECTION. AS A RESULT...ONLY SMALL PATCHES OF SHALLOW MOISTURE ARE SEEN ACROSS THE BASIN. EXPECT SOME INCREASE IN MOISTURE OVER THE SRN WINDWARD ISLANDS OVER THE NEXT 24 TO 48 HOURS AS THE TROPICAL NOW ALONG 57W/58W CONTINUES TO MOVE WWD. ATLANTIC OCEAN... A STRONG DEEP-LAYERED LOW PRESSURE SYSTEM IS CENTERED OFFSHORE THE MID-ATLANTIC STATES NEAR 37N64W. THE ASSOCIATED COLD FRONT ENTERS THE FORECAST AREA NEAR 31N60W THEN CONTINUES SW ACROSS THE CENTRAL BAHAMAS AND THE N COAST OF WEST-CENTRAL CUBA. A 120-140 NM WIDE BAND OF SHOWERS WITH EMBEDDED TSTMS IS JUST AHEAD OF THE FRONTAL SYSTEM N OF 23N. COLD AIR STRATOCUMULUS CLOUDS AND NW WINDS OF 20 TO 25 KT ARE FOUND BEHIND THE COLD FRONT WHILE SWLY WINDS WITH SIMILAR SPEED ARE ALSO SEEN AHEAD OF THE FRONT AFFECTING THE AREA N OF 26N BETWEEN 50W AND 60W. A BROAD SFC RIDGE COVERS THE CENTRAL AND EAST ATLC ANCHORED BY A 1024 MB SFC HIGH PRESSURE NEAR 29N36W. FRAGMENTS OF MAINLY LOW LEVEL CLOUDS AND MODERATE TRADE WINDS ARE OBSERVED OVER THE TROPICAL ATLC UNDER THE INFLUENCE OF THIS FEATURE. AN ELONGATED UPPER-LEVEL RIDGE IS S OF 18N BETWEEN AFRICA AND THE LESSER ANTILLES ENHANCING CONVECTION ALONG THE ITCZ. $$ GR