000 AXNT20 KNHC 212354 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON SEP 21 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 34W S OF 14N MOVING W 15-20 KT. WAVE IS EMBEDDED WITHIN THE ITCZ WITH SATELLITE IMAGERY SHOWING CYCLONIC CURVATURE IN THE LOW LEVEL CLOUD FIELD ALONG THE WAVE AXIS. A LARGE AREA OF SAHARAN DUST FOLLOWS THE WAVE MAINLY E OF 30W. AN ISOLATED SHOWER IS N OF THE WAVE AXIS WITHIN A 30/45 NM RADIUS OF 16N34W. TROPICAL WAVE IS TILTED FROM 22N42W TO 15N45W MOVING NWW 10-15 KT. WAVE IS BEING GUIDED WNW AROUND A 1010 MB LOW THAT IS CENTERED NEAR 15N48W. THE ENTIRE AREA SURROUNDING THE WAVE AND LOW COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE AS OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. BROAD LOW LEVEL CYCLONIC CURVATURE IS OBSERVED ON SATELLITE IMAGERY EXTENDING FROM THE LOW NE ALONG THE WAVE AXIS. THIS LOW LEVEL CURVATURE AND SURFACE CONVERGENCE IS GENERATING SCATTERED MODERATE/STRONG CONVECTION FROM 15N-17N BETWEEN 45W-48W AND SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 16N-20N BETWEEN 40W-45W. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 11N15W 8N22W 9N36W 8N40W 9N48W 10N62W. SMALL CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 7N-12N BETWEEN 36W-39W. ...DISCUSSION... GULF OF MEXICO... AN UPPER RIDGE EXTENDS FROM S/CENTRAL MEXICO INTO THE GULF NEAR TAMPICO NE TO NEAR 28N87W WITH A SECOND UPPER RIDGE COVERING THE E GULF W OF 87W AND ANCHORED IN THE W ATLC. SCATTERED SHOWERS/ THUNDERSTORMS ARE INLAND AND WITHIN 45 NM ALONG THE COAST OF FLORIDA FROM THE FLORIDA KEYS TO TAMPA. DIFFLUENCE ALOFT IS GENERATING ISOLATED SHOWERS/THUNDERSTORMS DOTTING THE REMAINDER OF THE GULF. A WEAK COLD FRONT WILL MOVE OFF THE TEXAS COAST LATE TUE/EARLY WED THEN STALL OVER THE W GULF THU AND FRI. CARIBBEAN SEA... AN UPPER LEVEL RIDGE COVERS THE W CARIBBEAN EXTENDING FROM COSTA RICA TO W CUBA COVERING THE AREA W OF 80W WITH A WEAK UPPER TROUGH EXTENDING FROM THE CENTRAL ATLC ACROSS THE VIRGIN/LEEWARD ISLANDS TO NEAR 13N76W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE INLAND AND WITHIN 60 NM ALONG THE COAST OF PUERTO RICO TO CUBA INCLUDING JAMAICA AND N OF 20N W OF 82W TO OVER THE YUCATAN PENINSULA. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE FROM 11N-16N W OF 81W TO INLAND OVER NICARAGUA AND HONDURAS. THE ITCZ IS S OF PANAMA IN THE E PACIFIC REGION GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER PANAMA AND COSTA RICA MOVING INTO THE SW CARIBBEAN WITHIN 60 NM ALONG THE COAST. THE REMAINDER OF THE CARIBBEAN REMAINS TRANQUIL THIS EVENING. ATLANTIC OCEAN... A WEAKENING SURFACE TROUGH IS IN THE FAR W ATLC EXTENDING FROM 31N79W TO INLAND OVER FLORIDA NEAR DAYTONA BEACH WITH A WEAK 1017 MB LOW NEAR 30N75W. AN UPPER RIDGE COVERS THE W ATLC ANCHORED NEAR 28N77W ENHANCING SCATTERED SHOWERS/THUNDERSTORMS WITHIN 75 NM RADIUS OF 28.5N73.5W. AN UPPER TROUGH DIPS S INTO THE W ATLC N OF 26N BETWEEN 62W-71W SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 31N63W TO 26N67W AND GENERATING SCATTERED SHOWERS WITH POSSIBLE ISOLATED THUNDERSTORMS WITHIN 120 NM OF THE SURFACE TROUGH. AN UPPER TROUGH COVERS THE CENTRAL ATLC INTO THE CARIBBEAN FROM AN UPPER LOW NEAR 21N61W ACROSS THE VIRGIN/LEEWARD ISLANDS COVERING THE AREA FROM 16N-27N BETWEEN 55W-70W WITH A SURFACE TROUGH EXTENDING ALONG 59W FROM 17N-22N AND GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 19N-23N BETWEEN 49W-62W. A WEAK SURFACE RIDGE DOMINATES THE ATLC WITH WEAKNESSES IN THE IMMEDIATE VICINITY OF THE SURFACE TROUGHS. $$ WALLACE