000 AXNT20 KNHC 100013 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON JUL 09 2007 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 2330 UTC. ...TROPICAL WAVES... A NEW TROPICAL WAVE IS INTRODUCED IN THE EASTERN ATLC ALONG 20W SOUTH OF 14N MOVING W AT 15 KT. THE WAVE SHOWS UP PROMINENTLY IN SATELLITE IMAGERY AS WELL AS ANIMATED SSMI PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE CONVECTION IS EVIDENT WHERE THE WAVE INTERSECTS THE ITCZ FROM 8N TO 10N BETWEEN 18W AND 21W. THIS TROPICAL WAVE WILL BE ADDED ON THE 00Z SURFACE ANALYSIS MAP. AN ATLANTIC OCEAN TROPICAL WAVE PREVIOUSLY ALONG 41W WILL BE RELOCATED A LITTLE FURTHER W TO 44W/45W ON THE 00Z SURFACE ANALYSIS MAP. THIS ADJUSTMENT IS BASED ON ANIMATED SSMI PRECIPITABLE WATER IMAGERY AND HOVMOLLER ANALYSIS...AS WELL AS SATELLITE IMAGERY SHOWING A SURGE OF LOW LEVEL CLOUDINESS ROUGHLY E OF 45W. THE WAVE IS MOVING WEST AT 15 KT. THIS REMAINS A LOW AMPLITUDE WAVE WITH NO SIGNIFICANT CONVECTION OUTSIDE THE ITCZ. TROPICAL WAVE IS ALONG 57W SOUTH OF 15N MOVING WEST 10 TO 15 KT. THIS IS A LOW AMPLITUDE WAVE WITH SCATTERED MODERATE CONVECTION WITHIN 60 NM OF AXIS FROM 7N TO 9N. AN CARIBBEAN SEA TROPICAL WAVE IS ALONG 70W SOUTH OF 17N MOVING WEST 15 KT. THE WAVE IS DIFFICULT TO DETECT IN SATELLITE IMAGERY AND PLACEMENT IS BASED ON CONTINUITY. NO SIGNIFICANT CONVECTION IS NOTED WITH THIS WAVE. A WESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 87W SOUTH OF 19N...FROM WESTERN HONDURAS N TO JUST OFF THE BELIZE COAST...MOVING WEST AT 10 TO 15 KT. NO SIGNIFICANT CONVECTION IS ASSOCIATED WITH THIS WAVE. THIS IS DUE IN PART TO DRY SUBSIDENT NLY FLOW ALOFT OVER THE WAVE POSITION...BETWEEN AN UPPER LEVEL LOW CENTERED JUST TO E...AND AN UPPER LEVEL ANTICYCLONE TO THE W. ...THE ITCZ... FROM 11N15W AT THE AFRICA COAST TO 7N22W 5N32W 4N41W TO 4N51W NEAR THE BORDER OF FRENCH CAYENNE AND BRAZIL. SCATTERED MODERATE CONVECTION WITHIN 90 NM N OF AXIS BETWEEN 18W AND 28W. ...DISCUSSION... THE GULF OF MEXICO... LARGE MID/UPPER SHORT WAVE TROUGH IS PUSHING THROUGH THE LOWER MISSISSIPPI VALLEY. THIS WILL MOVE OVER THE NRN GULF OF MEXICO TONIGHT. AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER THE FLORIDA PENINSULA...BLUNTING THE SWD APPROACH OF THE UPPER TROUGH AS IT LIFTS OUT TO THE MID ATLC STATES. THE SWLY FLOW ALOFT BETWEEN THE TWO FEATURES IS DRAWING DEEP LAYER MOISTURE FROM THE BAY OF CAMPECHE THROUGH THE NE GULF. ISOLATED SHOWERS AND THUNDERSTORMS ARE MOVING INTO THE NW GULF WATERS OFF TEXAS AND LOUISIANA IN RESPONSE TO THE APPROACHING SHORT WAVE...BUT WILL DIMINISH THROUGH TONIGHT AS THE TROUGH LIFTS OUT. OTHERWISE...LIGHT TO MODERATE SLY FLOW IS NOTED AT THE SURFACE ON THE WRN EDGE OF HIGH PRES CENTERED OVER THE WRN ATLC. THE CARIBBEAN SEA... AN UPPER LEVEL TROUGH IS ORIENTED E-W ACROSS THE CARIBBEAN BASIN ALONG 17N...WITH MAIN CYCLONIC ROTATION CENTERED NEAR 17N85W AND 18N67W. SUBSIDENT DRY AIR ASSOCIATED WITH THIS TROUGH IS SUPPRESSING CONVECTION AND GENERAL CLOUD DEVELOPMENT OVER THE NRN CARIBBEAN N OF 16N. THE ONLY EXCEPTION IS MINOR CONVECTION OVER PUERTO RICO AND HISPANIOLA...ENHANCED IN PART DUE TO SOME DESTABILIZATION DELIVERED BY COLD CORE CENTER OF UPPER LOW. FURTHER S...A BROAD UPPER ANTICYCLONE IS CENTERED OVER VENEZUELA. UPPER LEVEL WLY SHEAR DOMINATES BETWEEN THE UPPER TROUGH AND THE ANTICYCLONE ACROSS THE CARIBBEAN S OF 17N. DIVERGENCE ALOFT ALONG WITH STRONG LOW LEVEL ELY CONVERGENCE IS PROMOTING LARGE CLUSTER OF CONVECTION OVER THE SW CARIBBEAN...FROM 10N TO 13N W OF 80W. SURFACE HIGH PRES N OF THE AREA IS MAINTAINING MODERATE TO FRESH ELY FLOW AT THE SURFACE ACROSS THE CENTRAL CARIBBEAN. THE ATLANTIC OCEAN... UPPER LEVEL TROUGH EXTENDS FROM CYCLONIC CIRCULATION ALOFT NEAR 20N41W...SW TO UPPER TROUGH OVER CARIBBEAN...N OF OF AN UPPER ANTICYCLONE CENTERED OFF THE GUIANA COAST NEAR 12N48W. DRY MID AND UPPER LEVELS DUE TO THE SUBSIDENCE ASSOCIATED WITH THE UPPER TROUGH IS SUPPRESSING CONVECTION OVER THE WRN ATLC N OF 15N. DIVERGENCE ALOFT ON THE W SIDE OF UPPER ANTICYCLONE IS ENHANCING CONVECTION E OF TRINIDAD NEAR THE TROPICAL WAVE IN THE AREA. HOWEVER NLY FLOW ALOFT ON THE E SIDE OF THE UPPER ANTICYCLONE IS SUPPRESSING CONVECTION ACROSS THE CENTRAL TROP ATLC. FURTHER E...A BROAD UPPER ANTICYCLONE IS CENTERED OVER THE CAPE VERDE ISLAND AREA NEAR 17N21W. DIVERGENCE ALOFT ALONG THE PERIPHERY OF THIS UPPER ANTICYCLONE IS ENHANCING CONVECTION ALONG THE ITCZ IN THE SLIGHTLY MORE MOIST EASTERN TROP ATLC. MEANWHILE...FRESH ELY FLOW PERSISTS S OF 20N ACROSS THE ATLC BETWEEN MID ATLC SURFACE RIDGE TO THE N AND TROP WAVE PROGRESSION TO THE S. $$ CHRISTENSEN