000 AXNT20 KNHC 170005 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT JUN 16 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 2315 UTC. ...TROPICAL WAVES... ATLC TROPICAL WAVE IS ALONG 40W S OF 16N MOVING W 15-20 KT. WAVE REMAINS FAIRLY EASY TO LOCATE WITH A BROAD INVERTED-V SIGNATURE. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 2N-10N BETWEEN 35W-45W. CARIBBEAN TROPICAL WAVE IS ALONG 71W S OF 14N MOVING W 10-15 KT. THE WAVE REMAINS DIFFICULT TO LOCATE WITH NO SATELLITE SIGNATURE NOTED. VERY DRY/STABLE MID TO UPPER AIR OVER THE AREA IS SUPPRESSING CONVECTION IN THE VICINITY. CARIBBEAN TROPICAL WAVE IS ALONG 81W S OF 15N MOVING W 10-15 KT. OVERALL THIS WAVE IS ALSO DIFFICULT TO LOCATE WITH ITS PSN BASED MAINLY ON CONTINUITY. THERE ARE SCATTERED SHOWERS/ISOLATED TSTMS OFF THE COAST OF NICARAGUA FROM 11N-16N BETWEEN 79W-84W...BUT THIS MAY BE ASSOCIATED WITH LOW LEVEL SPEED CONVERGENCE W OF THE STRONG TRADES IN THE CENTRAL CARIB. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 10N14W 6N30W 7N41W 5N55W. NO DEEP CONVECTION NOTED E OF 29W. SCATTERED MODERATE IS WITHIN 150 NM EITHER SIDE OF THE AXIS BETWEEN 28W-35W. LOOKING BACK AT SATELLITE HOVMOLLER DIAGRAMS...THIS MAY BE ASSOCIATED WITH A QUICK MOVING LOW AMPLITUDE TROPICAL WAVE OR SURGE OF CONVECTION THAT MOVED OFF AFRICA EARLY ON JUNE 15. HOWEVER...LITTLE EVIDENCE IN THIS WAS NOTED IN THE AVAILABLE SOUNDING DATA OVER AFRICA SO HAVE OPTED NOTE TO PLACE ANOTHER WAVE ON THE MAP AT THIS POINT. ELSEWHERE...SCATTERED SHOWERS/ISOLATED TSTMS NOTED WITHIN 220NM OF THE AXIS W OF 45W. ...DISCUSSION... GULF OF MEXICO... OVERALL THE SYNOPTIC PRES GRADIENT REMAINS LOOSE OVER THE GULF...WITH WEAK SFC RIDGING OVER THE NRN WATERS AND TROUGHING IN THE SE PORTION. THIS IS MOSTLY PRODUCING WINDS OF 15 KT OR BELOW AND SEAS LESS THAN 4 FT ACROSS THE BASIN...EXCEPT POSSIBLY HIGHER UNDER CONVECTION. THE HIGHLIGHT TONIGHT REMAINS THE SIGNIFICANT MOISTURE AND SHOWER ACTIVITY OVER THE SE GULF MAINLY SE OF THE TROUGH. AS OF 16/2100 UTC..THE ELONGATED SFC TROUGH EXTENDS ENE FROM THE YUCATAN TO FAR SRN FLORIDA ALONG 21N88W 25N80W. AN IMPRESSIVE PULSE OF SHOWER/TSTM ACTIVITY MOVED QUICKLY N FROM CUBA THROUGH THE FL KEYS OVER THE LAST COUPLE OF HOURS...PROMPTING A SPECIAL MARINE WARNING FROM WFO KEY WEST EARLIER THIS EVENING. THIS ACTIVITY ALSO BEING SUPPORTED BY UPPER DIFFLUENCE BETWEEN AN UPPER RIDGE EXTENDING E ALONG 22/23N AND TROUGHING NE OF THE AREA. SCATTERED SHOWERS/TSTMS ALSO NEAR THE E TEXAS/LOUISIANA COAST...MAINLY N OF 28N BETWEEN 93W-96W. THIS IS ASSOCIATED WITH INSTABILITY AHEAD OF THE UPPER LOW OVER TEXAS AND THE WARM/MOIST LOW LEVEL INFLOW FROM THE S. LOOK FOR SCATTERED SHOWERS/ISOLD TSTMS ASSOCIATED WITH THE SFC TROUGH TO PUSH N/NW THROUGH THE E AND MIDDLE GULF OVER THE NEXT DAY OR SO. CARIBBEAN SEA... SIGNIFICANT MOISTURE WITH SCATTERED SHOWERS/ISOLATED TSTMS ARE OVER THE NW CARIBBEAN AND CUBA...NOW MAINLY N OF 18N W OF 78W. THIS ACTIVITY IS ASSOCIATED THE TROUGH MENTIONED IN THE GULF SECTION. THE OTHER STORY...BESIDES FOR THE TROPICAL WAVES...IS THE CONTINUED STRONG TRADES ESPECIALLY BETWEEN 68W-80W. FRESH TO STRONG TRADES LOOK TO CONTINUE IN THIS VICINITY THROUGH SUN. A FEW SHOWERS AND TSTMS ARE NOTED N OF THE ABC ISLANDS FROM 13N-16N BETWEEN 66W-69W...LIKELY AIDED BY THE UPPER LOW OVER THE LESSER ANTILLES REGION. OTHERWISE...VERY DRY/STABLE MID TO UPPER AIR AND FAIR WEATHER RULE. ATLANTIC OCEAN... NUMEROUS SHOWERS/SCATTERED TSTMS ARE AFFECTING THE BAHAMAS...SOUTH FLORIDA...AND ADJACENT WATERS TONIGHT ASSOCIATED WITH THE AFOREMENTIONED ELONGATED TROUGH OF LOW PRESSURE EXTENDING ENE FROM THE YUCATAN PENINSULA. A 1015 MB LOW WAS ADDED TO THE 1800 UTC MAP NEAR THE NORTHWESTERN BAHAMAS PER THE CYCLONIC CIRCULATION NOTED IN BOTH SATELLITE IMAGERY AND SFC OBSERVATIONS. HOWEVER...UPPER-LEVEL WINDS ARE NOT FAVORABLE FOR THIS LOW TO DEVELOP INTO A TROPICAL CYCLONE AS IT MOVES EAST-NORTHEASTWARD INTO THE ATLANTIC. A PLUME OF TROPICAL MOISTURE WITH POSSIBLE SHOWERS IS BEING STRETCHED NE WITH UPPER SW FLOW...WITHIN 150NM EITHER SIDE OF A ELEUTHERA TO BERMUDA LINE. DISTINCT UPPER DIFFLUENCE NOTED OVER THIS REGION BETWEEN THE TROUGHING OVER THE EAST COAST AND RIDGING EXTENDING NE FROM ERN CUBA. OVERALL THE REMAINDER OF THE DISCUSSION AREA IS TRANQUIL...WITH A 1025 MB SFC HIGH NEAR 27N60W AND A 1024 MB CENTER NEAR 27N45W. A DISSIPATING COLD FRONT IS OVER THE FAR NE PORTION OF THE AREA ALONG 31N20W 28N30W...ASSOCIATED WITH A DEEP LAYER LOW W OF NRN PORTUGAL. NO SIGNIFICANT CONVECTION IS IN THIS VICINITY. $$ WILLIS