000 AXNT20 KNHC 221156 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT THU OCT 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 1015 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 33W S OF 18N MOVING W NEAR 10 KT. THE WAVE COINCIDES WITH A MAXIMUM IN TOTAL PRECIPITABLE WATER AS WELL AS AN AREA OF MAXIMUM 850 MB RELATIVE VORTICITY IN GLOBAL MODEL FIELDS ALONG THE WAVE AXIS. CYCLONIC CURVATURE OF THE LOW LEVEL CLOUD FIELD IS NOTED ON SATELLITE IMAGERY WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 14N-18N BETWEEN 26W-32W. THE CONVECTION IS CONTINUING TO BE MARGINALLY ENHANCED BY AN UPPER LEVEL RIDGE OVER THE TROPICAL EASTERN ATLC WHILE AT THE SAME TIME BEING SHEARED TO THE EAST BY STRONG UPPER LEVEL WESTERLY FLOW. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 12N16W 9N31W 8N35W 9N50W 9N61W. CLUSTERS OF SCATTERED SHOWERS AND ISOLATED MODERATE CONVECTION ARE FROM 3N-9N BETWEEN 18W-34W. ...DISCUSSION... GULF OF MEXICO... THE EASTERN GULF IS CONTROLLED BY A SURFACE RIDGE ANCHORED IN THE W ATLC LOCATED 150 NM EAST OF THE NORTH CAROLINA COAST. S-SE RETURN FLOW ASSOCIATED WITH THE SURFACE RIDGE AND THE RESULTING INCREASED PRESSURE GRADIENT CONTINUES TO IMPACT THE GULF WITH WINDS UP TO 25 KT ACROSS MUCH OF THE GULF. LOW-LEVEL 3-+C ONVERGENCE AHEAD OF THE NEXT COLD FRONT CURRENTLY POSITIONED ACROSS CENTRAL TEXAS IS GENERATING ISOLATED SHOWERS OVER THE NORTHERN GULF WATERS N OF 25N W OF 87W. MOSAIC DOPPLER RADAR OVER THE NW GULF INDICATES A LINE OF SCATTERED SHOWERS AND TSTMS FROM HOUSTON TEXAS SOUTHWARD TO 25N96W. SIMILAR ISOLATED SHOWER ACTIVITY IS MOVING WESTWARD OVER THE SE GULF AND PORTIONS OF THE FLORIDA PENINSULA THIS MORNING. AN AMPLIFIED UPPER LEVEL RIDGE EXTENDS FROM SOUTHERN MEXICO OVER THE BAY OF CAMPECHE TO THE SE CONUS. THIS UPPER RIDGE IS ENHANCING MUCH OF THE CURRENT SHOWER AND TSTM ACTIVITY OBSERVED ALONG THE TEXAS AND LOUISIANA GULF COASTS AS WELL AS INTERIOR EASTERN TEXAS. AS THE SURFACE RIDGE SLIDES EASTWARD...THE COLD FRONT IS FORECAST TO ENTER THE NW GULF WATERS THIS AFTERNOON. CARIBBEAN SEA... A 1009 MB LOW IS IN THE SW CARIBBEAN OFF THE COAST OF NICARAGUA NEAR 12N83W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING OVER THE SW CARIBBEAN AND PORTIONS OF CENTRAL AMERICA FROM 10N-17N BETWEEN 77W-85W. THIS AREA IS UNDER THE INFLUENCE OF THE BASE OF A SHARP UPPER LEVEL TROUGH THAT DIPS SOUTHWARD FROM CUBA TO EASTERN HONDURAS. UPPER LEVEL DIFFLUENCE E OF THE TROUGH AXIS IS ENHANCING THE CONVECTION ASSOCIATED WITH THE SURFACE LOW. THE UPPER LEVEL TROUGH ALSO SUPPORTS A SURFACE TROUGH THAT LIES LARGELY IN THE SW NORTH ATLC OVER THE SE BAHAMAS AND EXTENDS SW THROUGH THE WINDWARD PASSAGE TO 19N74W. SCATTERED SHOWERS ARE OCCURRING FROM 17N-21N BETWEEN 73W-79W...INCLUDING JAMAICA. FARTHER EAST...AN UPPER LEVEL RIDGE IS ANCHORED OVER NW VENEZUELA WITH RIDGE AXIS ALONG 69W WHILE UPPER LEVEL TROUGHING COVERS THE FAR EASTERN CARIBBEAN E OF 63W PROVIDING A DRY STABLE ENVIRONMENT AND GIVING GENERALLY CLEAR SKIES E OF 66W THIS MORNING. A FEW ISOLATED LOW-LEVEL SHOWERS HOWEVER ARE PRIMARILY N OF 17N BETWEEN 66W-70W INCLUDING EASTERN PUERTO RICO AND THE MONA PASSAGE. ATLANTIC OCEAN... A BROAD UPPER LEVEL TROUGH COVERS THE WESTERN AND CENTRAL ATLC N OF 30N WITH A NARROW AMPLIFIED TROUGH AXIS EXTENDING S OVER THE SW NORTH ATLC THROUGH 32N70W 27N76W ACROSS CENTRAL CUBA AND INTO THE NW CARIBBEAN SEA. THIS AMPLIFIED UPPER LEVEL TROUGH IS PROVIDING STRONG SUBSIDENCE AND MOSTLY DRY STABLE AIR W OF 76W WITH ONLY A FEW ISOLATED SHOWERS MOVING WESTWARD OVER THE NW BAHAMAS AND FLORIDA PENINSULA. THE SHARP UPPER LEVEL TROUGH IS SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 24N72W TO THE WINDWARD PASSAGE NEAR 20N74W. LOW-LEVEL CONVERGENCE NEAR THE SURFACE TROUGH COUPLED WITH UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS FROM 18N-28N BETWEEN 64W-76W. ACROSS THE CENTRAL ATLC...THE BROAD UPPER LEVEL TROUGH IS SUPPORTING A SURFACE TROUGH ANALYZED FROM 31N49W TO 26N55W. WEST OF THE SURFACE TROUGH...A SURFACE RIDGE ANCHORED BY A 1022 MB HIGH OFF THE COAST OF NORTH CAROLINA CONTINUES TO PROVIDE NE TO ELY FLOW W OF 55W. EAST OF THE MAIN FRONTAL BOUNDARY IN THE CENTRAL ATLC...A SURFACE TROUGH EXTENDS FROM 31N41W TO 25N48W. LOW-LEVEL CONVERGENCE LOCATED TO THE EAST OF THE SURFACE TROUGH ALONG WITH A MID-LEVEL SHORTWAVE TROUGH WITH AXIS ALONG 42W N OF 20N IS SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 120 NM OF A LINE FROM 21N44W TO BEYOND 32N37W. A WEAK SURFACE RIDGE DOMINATES THE REMAINDER OF THE EASTERN ATLC ANCHORED BY A 1017 MB HIGH CENTERED NEAR 29N25W. IN THE TROPICAL ATLC...A 1009 MB LOW IS N OF THE ITCZ NEAR 14N42W WITH SCATTERED SHOWERS AND ISOLATED TSTMS E OF THE LOW FROM 11N-16N BETWEEN 35W-41W. THIS ACTIVITY OVER THE PAST 6 HOURS HAS CONTINUED TO BE INFLUENCED BY STRONG UPPER LEVEL WESTERLY SHEAR ACROSS A ZONE FROM 12N-18N E OF 45W. $$ HUFFMAN