000 AXNT20 KNHC 302352 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN AUG 30 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. ...SPECIAL FEATURES... AN ACTIVE TROPICAL WAVE EXTENDS FROM 18N45W TO 8N49W WITH AN ASSOCIATED 1007 MB SURFACE LOW CENTER NEAR 11N48W. THE WAVE IS MOVING W NEAR 15 KT. SATELLITE IMAGERY INDICATES ELONGATED CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS CONCENTRATED AROUND THE LOW CENTER. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS MAINLY TO THE NW OF THE WAVE AXIS FROM 14N-18N BETWEEN 47W-49W..AND TO THE W OF LOW CENTER FROM 8N-14N BETWEEN 48W-54W. THIS SYSTEM HAS A HIGH CHANCE...GREATER THAN 50 PERCENT...OF BECOMING A TROPICAL CYCLONE IN THE NEXT 48 HRS. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 24W S OF 16N SLOWLY DRIFTING W. LOW/MID-LEVEL CYCLONIC FLOW IS NOTED IN CURRENT SATELLITE IMAGERY AND SATELLITE DERIVED WINDS. THE CYCLONIC FLOW HAS REMAINED NEARLY STATIONARY FOR THE PAST 24 HRS CENTERED OVER THE CAPE VERDE ISLANDS. THE WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. HOWEVER...DRY AIR AND SUBSIDENCE TO THE W OF THE WAVE AXIS IS INHIBITING DEEP CONVECTION. A TROPICAL WAVE IS ALONG 72W/73W S OF 17N MOVING W NEAR 15 KT. THE WAVE TRAILS AN AREA OF RELATIVELY INCREASED MOISTURE OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. HOWEVER...THE WAVE IS CURRENTLY EMBEDDED WITHIN AN AREA OF DRY STABLE AIR INHIBITING ANY DEEP CONVECTION. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 11N15W 9N27W 16N40W 8N51W 8N61W. A LARGE CLUSTER OF NUMEROUS STRONG CONVECTION IS ALONG THE AFRICA COAST FROM 10N-14N BETWEEN 12W-17W. ...DISCUSSION... GULF OF MEXICO... A COLD FRONT CLIPS THE NW GULF EXTENDING FROM A 1013 MB LOW OVER SRN MISSISSIPPI NEAR 31N89W CONTINUING ALONG 30N93W 28N98W. A PRE-FRONTAL SURFACE TROUGH EXTENDS AHEAD OF THE FRONT ALONG 28N92W 25N95W CONTINUING S INTO THE BAY OF CAMPECHE TO NEAR 19N95W. SURFACE CONVERGENCE NEAR THE FRONT AND PRE-FRONTAL TROUGH IS SUPPORTING SCATTERED SHOWERS THUNDERSTORMS ACROSS THE WRN GULF WITHIN 300 NM NW OF A LINE ALONG 20N94W 26N89W 31N84. THIS SHOWER ACTIVITY IS ENHANCED BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL TROUGH ACROSS THE CENTRAL AND ERN CONUS AND AN UPPER LEVEL RIDGE ACROSS THE WRN GULF CENTERED OVER MEXICO NEAR 19N100W. THE REMAINDER OF THE GULF IS EXPERIENCING GENERALLY FAIR WEATHER BESIDES A FEW ISOLATED SHOWERS/THUNDERSTORMS DUE TO MOIST SWLY FLOW ALOFT AROUND THE UPPER LEVEL TROUGH ACROSS THE ERN CONUS. EXPECT THE COLD FRONT IN THE FAR NW GULF TO MOVE FARTHER INTO THE AREA AND CONTINUE TO THE FLORIDA PANHANDLE ON MONDAY...WEAKENING TO A TROUGH BY WED. CARIBBEAN SEA... AN UPPER LEVEL TROUGH IS OVER THE W CARIBBEAN WITH AXIS ALONG 85W. UPPER LEVEL DIFFLUENCE BETWEEN THIS UPPER TROUGH AND AN UPPER LEVEL RIDGE OVER THE CENTRAL CARIBBEAN CENTERED S OF HAITI NEAR 17N75W...ALONG WITH MOIST SLY FLOW ALOFT ARE SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS ACROSS THE SW CARIBBEAN S OF 16N BETWEEN 75W-84W. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO ACROSS JAMAICA...CUBA AND THE ADJACENT COASTAL WATERS. THE ERN CARIBBEAN REMAINS FAIRLY CALM DESPITE THE PRESENCE OF A TROPICAL WAVE ALONG 72W/73W DUE TO DRY AIR AND SUBSIDENCE ALOFT. A FEW SHOWERS/THUNDERSTORMS ARE ACROSS HISPANIOLA AND PUERTO RICO DUE TO UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL HIGH S OF HAITI AND AN UPPER LEVEL LOW N OF PUERTO RICO NEAR 21N65W. FRESH TO STRONG TRADE WINDS ARE ACROSS MUCH OF THE BASIN. EXPECT THE TROPICAL WAVE IN THE CENTRAL CARIBBEAN TO CONTINUE WWD. INTERESTS IN THE LESSER ANTILLES SHOULD MONITOR THE ACTIVE TROPICAL WAVE EXTENDING FROM 18N45W TO 8N49W WHICH MAY AFFECT THE ISLANDS IN THE NEXT COUPLE DAYS...SEE SPECIAL FEATURES ABOVE. ATLANTIC OCEAN... ISOLATED SHOWERS/THUNDERSTORMS ARE ACROSS THE WRN ATLC WITHIN 200 NM NW OF A LINE ALONG 23N79W 27N74W 32N69W INCLUDING PORTIONS OF CUBA...THE BAHAMAS...AND S FLORIDA. THIS ACTIVITY IS ENHANCED BY MOIST SWLY FLOW ALOFT AND UPPER LEVEL DIFFLUENCE E OF THE UPPER LEVEL TROUGH OVER THE ERN CONUS. ISOLATED SHOWERS ARE N OF PUERTO RICO FROM 19N-26N BETWEEN 59W-69W IN ASSOCIATED WITH AN UPPER LEVEL TROUGH EXTENDING THROUGH A PAIR OF UPPER LEVEL LOWS NEAR 21N65W AND 28N51W. ELSEWHERE ACROSS THE ATLC...A BROAD SURFACE RIDGE DOMINATES ANCHORED BY A 1030 MB HIGH WELL N OF THE DISCUSSION AREA NEAR 42N45W. IN THE UPPER LEVELS...A BROAD UPPER LEVEL RIDGE IS E OF THE PAIR OF UPPER LOWS CENTERED NEAR 17N35W. AN UPPER LEVEL TROUGH DOMINATES THE FAR E ATLC WITH AXIS ALONG 24N. THIS UPPER TROUGH MAY BE INFLUENCING THE LACK OF FASTER WWD MOVEMENT OF THE TROPICAL WAVE ALONG 24N. $$ WALTON