000 AXNT20 KNHC 171720 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST TUE NOV 17 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 1645 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 9N11W 7N25W 5N34W 5N44W 4N55W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 6N-11N BETWEEN 8N-19N. ISOLATED MODERATE CONVECTION IS WITHIN 90 NM N...AND 120 NM S OF THE AXIS BETWEEN 19W-26W. A SURFACE TROUGH IS ANALYZED WITHIN THE ITCZ FROM 12N51W TO 4N46W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 7N-8N BETWEEN 46W-49W. ...DISCUSSION... GULF OF MEXICO... AS OF 1500 UTC...A COLD FRONT EXTENDS ACROSS THE FLORIDA PANHANDLE ENTERING THE GULF OF MEXICO NEAR 30N86W JUST W OF PANAMA CITY CONTINUING ALONG 25N88W 22N92W TO THE MEXICO COAST NEAR 18N94W EXTENDING AS A STATIONARY FRONT ALONG 18N96W 21N99W. A LINE OF SHOWERS IS ALONG THE FRONT AXIS WITH ISOLATED SHOWERS POSSIBLE WITHIN 100 NM BEHIND THE FRONT N OF 24N...AND WITHIN 150 NM BEHIND THE FRONT S OF 24N. NW TO N SURFACE WINDS OF 20 TO 25 KTS ARE BEHIND THE FRONT...REACHING 30 KT N OF 25N BETWEEN 90W-91W. GALE FORCE WINDS ARE ALSO NOTED IN THE SW GULF S OF 21N W OF 95W. THE FRONT IS SUPPORTED BY AN UPPER LEVEL TROUGH DIGGING ACROSS THE CENTRAL CONUS INTO THE NRN GULF CENTERED OVER MISSOURI. AN UPPER LEVEL RIDGE IS ACROSS THE SRN GULF EXTENDING FROM THE WRN CARIBBEAN ACROSS S FLORIDA AND INTO THE WRN ATLC. DRY AIR AND CLEAR SKIES BUILD BEHIND THE FRONT ACROSS THE NW GULF. MODERATELY DRY AIR AND FAIR WEATHER IS ALSO AHEAD OF THE FRONT ACROSS THE SE GULF AND S FLORIDA. EXPECT THE FRONT TO CONTINUE PUSHING E-SE THROUGH WED EVENING BEFORE STALLING AND WEAKENING OVER N FLORIDA. EXPECT GALE FORCE WINDS TO CONTINUE IN THE SW GULF OF MEXICO FOR THE NEXT SEVERAL HOURS. CARIBBEAN SEA... MUCH OF THE CARIBBEAN IS EXPERIENCING GENERALLY FAIR WEATHER UNDER THE INFLUENCE OF DRY AIR AND SUBSIDENCE ASSOCIATED WITH AN UPPER LEVEL RIDGE COVERING THE WRN CARIBBEAN EXTENDING FROM THE YUCATAN PENINSULA AND WRN CARIBBEAN ACROSS S FLORIDA TO THE WRN ATLC. ISOLATED SHOWERS/THUNDERSTORMS ARE IN THE SW CARIBBEAN AFFECTING PORTIONS OF COSTA RICA/PANAMA S OF 11N BETWEEN 77W-84W DUE TO SURFACE CONVERGENCE NEAR THE E PACIFIC ITCZ. ISOLATED SHOWERS/THUNDERSTORMS ARE ACROSS THE NE CARIBBEAN AFFECTING PUERTO RICO AND THE NW LEEWARD ISLANDS N OF 16N BETWEEN 60W-67W ASSOCIATED WITH SURFACE CONVERGENCE NEAR A SURFACE TROUGH EXTENDING FROM THE ATLC TO E OF PUERTO RICO NEAR 18N65W. AN UPPER LEVEL TROUGH EXTENDING FROM THE ATLC SWD ACROSS THE LESSER ANTILLES SUPPORTS THE SURFACE TROUGH AND PROVIDES AN UPPER DIFFLUENT ZONE TO ENHANCE THE SHOWER ACTIVITY. MODERATE TO FRESH TRADE WINDS ARE ACROSS MUCH OF THE BASIN. EXPECT SHOWERS/THUNDERSTORMS TO CONTINUE OVER THE FAR NE CARIBBEAN AS THE SURFACE TROUGH REMAINS MAINLY STATIONARY. ATLANTIC OCEAN... LOW PRESSURE REMAINS ACROSS THE WRN ATLC CENTERED AT A 1008 MB LOW NEAR 26N65W. A SURFACE TROUGH EXTENDS FROM THE LOW CENTER ALONG 22N65W 19N68W. A SECOND SURFACE TROUGH EXTENDS TO THE E ALONG 27N63W 23N63W TO E OF PUERTO RICO NEAR 18N65W. SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 250 NM E OF THIS TROUGH AXIS. THIS LARGE AREA OF CONVECTIVE ACTIVITY IS ENHANCED BY DIFFLUENT FLOW ALOFT BETWEEN AN UPPER LEVEL TROUGH CENTERED NEAR 27N65W...SUPPORTING THE LOW/TROUGHS...AND AN UPPER LEVEL RIDGE TO THE E WITH AXIS ALONG 48W. ACROSS THE ERN ATLC...A BROAD SURFACE RIDGE EXTENDS S FROM A 1026 MB HIGH NEAR 33N32W. A SURFACE TROUGH EXTENDS AROUND THE RIDGE PARALLELING THE ISOBARS ALONG 31N11W 20N27W 19N36W 22N47W 30N52W...DEPICTING A LINE OF CONVERGENT WIND SPEEDS...NOT WIND DIRECTION...WITH STRONGER WINDS TO THE N OF THE AXIS. A LONGWAVE UPPER LEVEL TROUGH EXTENDING FROM THE NE ATLC ALONG 46N9W TO THE CANARY ISLANDS NEAR 29N17W ACROSS THE CAPE VERDE ISLANDS NEAR 17N25W TO 12N35W SUPPORTS THE SURFACE TROUGH. UPPER LEVEL DIFFLUENCE AND STRONG SHEAR TO THE NE-E BETWEEN AROUND THE BASE OF THIS UPPER TROUGH IS ENHANCING CONVECTION IN THE ERN TROPICAL ATLC AND NEAR THE ITCZ. BESIDES THE CONVECTION DISCUSSED IN THE ITCZ SECTION...SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN A 200 NM SWATH FROM 10N42W 12N30W 17N17W. $$ WALTON