000 AXNT20 KNHC 221053 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT TUE SEP 22 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0945 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 15N35W TO 6N37W MOVING W NEAR 15 KT. SATELLITE IMAGERY AND SATELLITE DERIVED WINDS INDICATE BROAD LOW LEVEL CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS. A LARGE AREA OF SAHARAN DUST TRAILS THE WAVE MAINLY E OF 33W INHIBITING MOST DEEP CONVECTION NEAR THE WAVE. HOWEVER...A FEW CLUSTERS OF ISOLATED MODERATE CONVECTION ARE N OF THE WAVE AXIS FROM 15N-17N BETWEEN 35W-38W...E OF THE WAVE AXIS FROM 7N-8N BETWEEN 34W-36W...AND W OF THE WAVE AXIS FROM 7N-10N BETWEEN 41W-42W. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 12N16W 9N25W 11N34W 7N45W 6N56W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 11N-18N BETWEEN 11W-18W. ISOLATED MODERATE CONVECTION IS WITHIN 100 NM S OF THE AXIS BETWEEN 23W-28W. ...DISCUSSION... GULF OF MEXICO... THE GULF OF MEXICO REMAINS FAIRLY CALM THIS MORNING AS A WEAK SURFACE RIDGE BUILDS FROM THE E ALONG 30N. AN UPPER LEVEL RIDGE COVERS THE MAJORITY OF THE BASIN CENTERED OVER MEXICO NEAR 20N103W. A FEW ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS ARE NOTED ACROSS THE SRN PORTIONS OF THE GULF DUE TO UPPER LEVEL DIFFLUENT FLOW BETWEEN THE UPPER RIDGE AND A SHORTWAVE UPPER TROUGH THAT DIGS ACROSS THE NW BAHAMAS TO THE STRAITS OF FLORIDA CONTINUING TO THE NRN YUCATAN PENINSULA. MODERATE SURFACE WINDS ARE ACROSS MUCH OF THE BASIN FLOWING ANTI-CYCLONICALLY AROUND THE SURFACE RIDGE ACROSS THE FAR N GULF. EXPECT THE RIDGE TO LIFT N OF THE AREA AS A COLD FRONT MOVES OFF THE COAST OF TEXAS LATER THIS EVENING. CARIBBEAN SEA... AN UPPER LEVEL RIDGE COVERS THE W CARIBBEAN W OF 70W WHILE AN UPPER LEVEL TROUGH COVERS THE REMAINDER OF THE BASIN EXTENDING FROM THE ATLC. UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER RIDGE...THE UPPER TROUGH...AND THE AFOREMENTIONED SHORTWAVE UPPER TROUGH EXTENDING FROM THE NE BAHAMAS ACROSS THE STRAITS OF FLORIDA TO THE NRN YUCATAN PENINSULA IS SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS ACROSS THE NRN CARIBBEAN N OF 17N W OF 66W. NUMEROUS SHOWERS/THUNDERSTORMS ARE ACROSS THE SW CARIBBEAN S OF 10N W OF 76W DUE TO SURFACE CONVERGENCE NEAR THE E PACIFIC ITCZ AND A 1007 MB LOW OVER COLOMBIA NEAR 8N74W. THE REMAINDER OF THE ERN CARIBBEAN REMAINS FAIRLY TRANQUIL. FRESH TRADE WINDS ARE ACROSS MUCH OF THE S CENTRAL CARIBBEAN WITH STRONGER WINDS NEAR THE COAST OF COLOMBIA AND ACROSS THE ERN CARIBBEAN. ATLANTIC OCEAN... A WEAKENING 1018 MB SURFACE LOW IS IN THE WRN ATLC NEAR 31N76W WITH A SURFACE TROUGH EXTENDING FROM THE LOW TO 24N79W. SURFACE CONVERGENCE NEAR THE LOW AND TROUGH IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM 26N-31N BETWEEN 73W-77W. THE SHOWER ACTIVITY IS ALSO ENHANCED BY DIFFLUENT FLOW ALOFT BETWEEN A SHORTWAVE UPPER LEVEL TROUGH ACROSS THE NW BAHAMAS AND AN UPPER LEVEL RIDGE CENTERED NEAR 34N77W. A SURFACE TROUGH EXTENDS FROM 31N60W TO 27N61W. SURFACE CONVERGENCE NEAR THE TROUGH IS SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS N OF 28N BETWEEN 60W-63W. ANOTHER SURFACE TROUGH EXTENDS FROM 23N59W TO 21N62W. THIS SURFACE TROUGH IS SUPPORTED BY AN UPPER LEVEL TROUGH WITH AXIS ALONG 58W. ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS ARE FROM 18N-21N BETWEEN 61W-64W. THE UPPER LEVEL TROUGH IS ALSO SUPPORTING ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS FROM 19N-20N BETWEEN 51W-59W. A 1011 MB LOW IS CENTERED NEAR 14N48W. THE TROPICAL WAVE THAT WAS PREVIOUSLY JUST E OF THE LOW IS NOW ANALYZED A SURFACE TROUGH THAT EXTENDS THROUGH THE LOW CENTER FROM 21N44W TO 11N49W. SURFACE CONVERGENCE NEAR THE TROUGH AND LOW IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM 17N-22N BETWEEN 41W-46W...AND ISOLATED SHOWERS FROM 13N-17N BETWEEN 44W-47W. THE REMAINDER OF THE ATLC REMAINS FAIRLY CALM UNDER THE INFLUENCE OF A WEAK SURFACE RIDGE ACROSS THE BASIN. IN THE UPPER LEVELS...AN UPPER LEVEL RIDGE DOMINATES THE CENTRAL ATLC BETWEEN 30W-50W. AN UPPER LEVEL LOW CENTERED NEAR 31N25W COVERS THE ERN ATLC SUPPORTING ISOLATED SHOWERS N OF 27N BETWEEN 18W-25W. A BROAD UPPER LEVEL RIDGE COVERS THE TROPICAL ATLC E OF 50W CENTERED NEAR 17N28W ENHANCING CONVECTION NEAR THE SURFACE LOW NEAR 14N48W. $$ WALTON