000 AXNT20 KNHC 162345 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED SEP 16 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 22W S OF 22N MOVING W NEAR 15 KT. UPPER AIR TIME SECTION ANALYSES FROM DAKAR SENEGAL INDICATE THAT A SHALLOW LAYERED WAVE PASSED AROUND 15/0000 UTC. ALSO...HOVMOLLER DIAGRAM ANALYSIS OF METEOSAT-9 IMAGERY OVER THE PAST FEW DAYS SHOWS THE WAVE EMERGING OFF THE W AFRICA COAST. THE WAVE ALIGNS ITSELF ON THE LEADING EDGE OF A MAXIMUM IN DEEP LAYER MOISTURE AS NOTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 11N-17N BETWEEN 19W-24W. TROPICAL WAVE IS ALONG 79W S OF 14N MOVING W NEAR 12 KT. THIS WAVE REMAINS LOW AMPLITUDE AND COINCIDES WITH A BROAD AREA OF DEEP LAYER MOISTURE ACROSS THE SW CARIBBEAN AS OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. WIDELY SCATTERED MODERATE CONVECTION IS FROM 8N-13N BETWEEN 74W-81W. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 12N16W 11N21W 10N24W 7N35W 12N60W 11N66W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 6N-12N BETWEEN 24W-35W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM OF THE AXIS BETWEEN 46W-62W. ...DISCUSSION... GULF OF MEXICO... AS OF 2100 UTC...A SURFACE TROUGH EXTENDS FROM ERN LOUISIANA NEAR 29N91W TO 25N94W. THE BOUNDARY IS SUPPORTED BY AN UPPER LEVEL LOW OVER NW LOUISIANA AND UPPER LEVEL TROUGHING THAT DIPS SWD OVER MUCH OF TEXAS...LOUISIANA AND THE NW GULF. WHILE THE SURFACE TROUGH DENOTES A WIND SHIFT AT THE SURFACE...MOIST SWLY WINDS ALOFT SWEEP ACROSS MUCH OF THE GULF FROM E/CENTRAL MEXICO NE TO NRN FLORIDA AND THE SE CONUS. MOISTURE IS BEING DRAWN NEWD FROM SRN MEXICO AND COUPLED WITH THE UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE SW GULF S OF 24N BETWEEN 90W-95W...INCLUDING THE BAY OF CAMPECHE ALONG WITH A LARGE AREA OF SIMILAR CONVECTION N OF 24N E OF 90W OVER THE NE GULF. A 1014 MB SURFACE HIGH IS CENTERED OVER THE SE GULF NEAR 24N84W AND IS SUPPORTED ALOFT BY AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER WRN CUBA NEAR 22N84W. DRY AIR IS NOTED ON WATER VAPOR IMAGERY S OF 24N E OF 90W AND IT KEEPING GENERALLY FAIR SKIES OVER THE SE GULF AND STRAITS OF FLORIDA. CARIBBEAN SEA... THE NW CARIBBEAN AND YUCATAN PENINSULA REMAINS FAIRLY CALM UNDER THE INFLUENCE OF DRY AIR AND SUBSIDENCE ALOFT ASSOCIATED WITH AN UPPER LEVEL HIGH OVER WRN CUBA NEAR 22N84W. HOWEVER...A FEW SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING DUE TO DAYTIME HEATING AND INSTABILITY OVER MUCH OF CUBA AND THE CARIBBEAN WATERS N OF 17N BETWEEN 76W-84W. FARTHER S...A TROPICAL WAVE ALONG 79W IS SUPPORTING ISOLATED SHOWERS IN THE SW CARIBBEAN 8N-13N BETWEEN 74W-81W...SEE ABOVE. THIS ACTIVITY IS BEING ENHANCED BY SURFACE CONVERGENCE NEAR THE ITCZ AXIS ACROSS PANAMA ALONG 9N. AN UPPER LEVEL LOW NEAR 15N70W IS SUPPORTING A LARGE AREA OF DISTURBED WEATHER ACROSS THE ERN CARIBBEAN. MOIST SWLY FLOW ALOFT COUPLED WITH UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED SHOWERS AND TSTMS E OF A LINE FROM CENTRAL HISPANIOLA TO THE N/CENTRAL COAST OF VENEZUELA NEAR 10N66W. SCATTERED SHOWERS EXTEND FROM OVER PUERTO RICO...THE US/UK VIRGIN ISLANDS AND MOST OF THE LESSER ANTILLES. ATLANTIC OCEAN... A SURFACE TROUGH EXTENDS FROM A 1011 MB SURFACE LOW NEAR 33N71W TO THE NW BAHAMAS NEAR 26N75W. SCATTERED SHOWERS AND TSTMS ARE WITHIN 200 NM E OF THE SURFACE TROUGH BOUNDARY. THIS ACTIVITY IS BEING ENHANCED BY UPPER LEVEL DIFFLUENCE BETWEEN A BROAD UPPER LEVEL TROUGH OVER THE W ATLC AND AN UPPER LEVEL RIDGE THAT EXTENDS FROM WRN CUBA TO BERMUDA. THE UPPER LEVEL LOW OVER THE ERN CARIBBEAN NEAR 15N70W IS SPREADING A FEW ISOLATED SHOWERS OVER THE FAR SW NORTH ATLC AND PORTIONS OF THE TROPICAL N ATLC S OF 21N BETWEEN 62W-70W. ACROSS THE CENTRAL ATLC...A SURFACE TROUGH IS ANALYZED FROM 18N53W TO 25N55W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN 200 NM EITHER SIDE OF THE SURFACE TROUGH AND ARE BEING ENHANCED BY THE NRN PERIPHERY OF AN UPPER LEVEL LOW CENTERED NEAR 19N52W. A 1011 MB SURFACE LOW IS CENTERED NEAR 15N32W AND CONTINUES TO SURROUND ITSELF WITH DISORGANIZED SHOWERS FROM 13N-18N BETWEEN 30W-36W. FARTHER TO THE N...AN UPPER LEVEL TROUGH IS DIGGING SWD ACROSS THE NE ATLC WITH AN UPPER LEVEL LOW CENTERED NEAR 28N28W. A SURFACE TROUGH IS ANALYZED FROM 25N29W TO 30N28W WITH ASSOCIATED SCATTERED SHOWERS AND POSSIBLE ISOLATED TSTMS FROM 27N-30N BETWEEN 26W-30W. ACROSS THE ERN TROPICAL ATLC...AN UPPER LEVEL RIDGE DOMINATES S OF 20N E OF 43W AND CONTINUES TO ENHANCE THE CONVECTION ALONG THE ITCZ. $$ HUFFMAN