000 AXNT20 KNHC 121751 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT MON OCT 12 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 16N43W TO 7N48W MOVING WNW NEAR 15 KT. THE WAVE REMAINS EMBEDDED WITHIN AN AREA OF MAXIMUM TOTAL PRECIPITABLE WATER ACROSS THE CENTRAL TROPICAL ATLC WITH MOISTURE BEING DRAWN N-NE AS THE NRN PORTION OF THE WAVE MOVES BENEATH THE INFLUENCE OF A MARGINALLY SHEARED ENVIRONMENT DUE TO AN UPPER LEVEL TROUGH ACROSS THE ERN ATLC. WITH THE UPPER LEVEL SHEAR IN PLACE...NO ORGANIZED DEEP CONVECTION ACCOMPANIES THE WAVE...HOWEVER...ISOLATED SHOWERS ARE POSSIBLE WITHIN 200 NM EITHER SIDE OF THE WAVE AXIS. TROPICAL WAVE IS ALONG 83W S OF 15N MOVING W NEAR 15 KT. WAVE REMAINS EMBEDDED WITHIN A DEEP LAYER MOISTURE MAXIMUM IN TOTAL PRECIPITABLE WATER IMAGERY. WIDELY SCATTERED MODERATE CONVECTION IS OCCURRING ACROSS THE SW CARIBBEAN FROM 10N-15N BETWEEN 80W-85W. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 10N14W 8N25W 10N44W 10N55W 10N62W. SCATTERED MODERATE CONVECTION IS FROM 4N-9N BETWEEN 14W-25W. SIMILAR CONVECTION IS FROM 9N-12N BETWEEN 30W-39W. ALSO EMBEDDED WITHIN THE ITCZ...A SURFACE TROUGH IS ANALYZED FROM 13N51W TO 9N53W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 8N-12N BETWEEN 50W-56W. ...DISCUSSION... GULF OF MEXICO... AT 1500 UTC...A STATIONARY FRONT REMAINS DRAPED ACROSS THE SE CONUS AND INTO THE NW GULF ALONG THE TEXAS COAST NEAR MATAGORDA BAY TO INLAND NEAR BROWNSVILLE. A SURFACE TROUGH EXTENDS FROM BROWNSVILLE ALONG 24N97W TO 20N95W. LOW-LEVEL CONVERGENCE NEAR THE BOUNDARIES ACROSS THE WRN GULF ARE GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS N OF 21N W OF 92W. MOST OF THIS ACTIVITY IS ENHANCED ALOFT BY DIFFLUENCE DUE TO A BROAD UPPER LEVEL RIDGE CENTERED OVER THE ERN GULF NEAR 26N83W THAT EXTENDS UPPER LEVEL RIDGING WSW THROUGH 24N90W TO 23N100W. THE REMAINDER OF THE GULF E OF 92W...WHILE BENEATH THE UPPER LEVEL HIGH...HAS GENERALLY FAIR WEATHER ON STRONG SUBSIDENCE AND MOSTLY SOUTH-SOUTHEASTERLY SURFACE WINDS OF UP TO 15 KT. CARIBBEAN SEA... A WEAK SURFACE TROUGH EXTENDS FROM THE BAHAMA ISLANDS NEAR 22N75W ACROSS ERN CUBA TO ERN JAMAICA NEAR 18N76W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM 16N-19N BETWEEN 75W-83W W OF THE BOUNDARY. FARTHER TO THE E...A SECOND SURFACE TROUGH EXTENDS FROM THE US/UK VIRGIN ISLANDS ALONG 17N67W TO 16N73W. SCATTERED SHOWERS AND TSTMS ARE OBSERVED WITHIN 75 NM EITHER SIDE OF THE SURFACE TROUGH. THE CONVECTIVE ACTIVITY ACROSS THE N/CENTRAL AND NE CARIBBEAN IS LARGELY ENHANCED BY UPPER LEVEL NELY DIVERGENT FLOW ON THE SRN PERIPHERY OF A BROAD UPPER LEVEL RIDGE THAT COVERS MOST OF THE CARIBBEAN BASIN. S OF 15N E OF 80W...DRY AIR AND STRONG SUBSIDENCE IS NOTED ON WATER VAPOR IMAGERY. THIS IS PROVIDING FOR GENERALLY CLEAR SKIES WITH MODERATE TO FRESH TRADES THIS AFTERNOON. ATLANTIC OCEAN... A CENTRAL ATLC LONGWAVE TROUGH DIPS TO 29N BETWEEN 40W-57W AND SUPPORTS A COLD FRONT WHICH ENTERS THE DISCUSSION AREA NEAR 32N45W AND CONTINUES ALONG 30N50W 32N62W 31N70W WHERE IT CONTINUES WWD AS A STATIONARY FRONT TO THE NE FLORIDA COAST NEAR JACKSONVILLE. ISOLATED SHOWERS ARE MOSTLY CONFINED TO N OF 30N W OF 70W AS A SURFACE RIDGE BRIDGES THE FRONTAL BOUNDARY ACROSS THE W ATLC WATERS. A 1022 MB SURFACE HIGH IS CENTERED S OF THE FRONT NEAR 30N68W. THIS SURFACE RIDGE IS DUE LARGELY TO A BROAD UPPER LEVEL ANTICYCLONIC CIRCULATION THAT ENCOMPASSES A MAJORITY OF THE WRN ATLC E OF 57W. DRY AIR AND STRONG SUBSIDENCE IS NOTED ON WATER VAPOR IMAGERY S OF 30N...INCLUDING THE BAHAMAS... CUBA...AND HISPANIOLA. A 1010 MB LOW IS CENTERED NEAR 33N39W AND EXTENDS A SURFACE TROUGH ALONG 30N40W 29N50W. ISOLATED SHOWERS ARE WITHIN 90 NM EITHER SIDE OF THE SURFACE TROUGH. ACROSS THE ERN ATLC...A SHARP UPPER TROUGH DIGS SWD NEAR 32N28W S TO 15N32W. THIS TROUGH IS SUPPORTING A STATIONARY FRONT THAT ENTERS THE REGION NEAR 32N27W CONTINUING SW ALONG 28N30W TO 24N40W. THE BOUNDARY CONTINUES SW AND BECOMES MORE DIFFUSE AS A SURFACE TROUGH ALONG 20N44W TO 17N57W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM 23N-32N BETWEEN 25W-34W IN ASSOCIATION WITH THE STATIONARY BOUNDARY...WHILE ISOLATED SHOWERS ARE FOUND WITHIN 90 NM EITHER SIDE OF THE SURFACE TROUGH. $$ HUFFMAN