000 AXNT20 KNHC 310556 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT MON AUG 31 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0345 UTC. ...SPECIAL FEATURES... BROAD AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE EXTENDS FROM 18N46W TO 7N51W AND A 1010 MB LOW ALONG THE WAVE NEAR 13N. SATELLITE IMAGERY INDICATES ELONGATED CYCLONIC FLOW ALONG THE WAVE AXIS CONCENTRATED AROUND THE LOW LEVEL CENTER. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION DOT THE AREA FROM 8N-19N BETWEEN 44W-55W BUT ARE NOT CONCENTRATED AROUND THE LOW. HOWEVER ENVIRONMENTAL CONDITIONS STILL APPEAR FAVORABLE FOR DEVELOPMENT AND THIS SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR SO AS IT MOVES WNW 10-15 KT. INTERESTS IN THE LESSER ANTILLES SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. ...TROPICAL WAVES... TROPICAL WAVE IS ANALYZED ALONG 24W S OF 17N DRIFTING W. WAVE IS ON THE E EDGE OF AN UPPER RIDGE WHICH IS MASKING THE SATELLITE SIGNATURE AND LIMITING ANY SHOWERS/CONVECTION EVEN THOUGH THE WAVE IS EMBEDDED WITHIN AN AREA OF MOISTURE AS INDICATED BY THE PRECIPITABLE WATER IMAGERY. TROPICAL WAVE IS ALONG 74W S OF 18N MOVING W NEAR 15 KT. THIS WAVE IS EMBEDDED WITHIN AN AREA OF LIGHT MOISTURE AS INDICATED BY THE PRECIPITABLE WATER IMAGERY AND UNDER UPPER LEVEL MOISTURE MASKING ANY SATELLITE SIGNATURE. NO ASSOCIATED SHOWERS/ CONVECTION. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 13N15W 9N25W 15N42W 8N53W 8N61W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS OFF THE COAST OF W AFRICA FROM 8N-12N BETWEEN 16W-20W. ...DISCUSSION... GULF OF MEXICO... THE FRONTAL BOUNDARY IS NEAR STATIONARY EXTENDING ACROSS THE SE U.S. TO ALONG THE COAST OF W LOUISIANA AND E TEXAS TO CORPUS CHRISTI WHERE IT CONTINUES W AWAY FROM THE COASTLINE. WEAK SURFACE TROUGHS ARE ANALYZED IN THE GULF WITH ONE EXTENDING FROM TALLAHASSEE FLORIDA TO 27N91W AND A SECOND FROM 25N94W S THROUGH THE BAY OF CAMPECHE TO S MEXICO NEAR 17N93W. A BROAD UPPER RIDGE ANCHORED IN THE E PACIFIC EXTENDS ACROSS MEXICO AND THE GULF OVER TUXPAN MEXICO TO NEAR 28N87W WITH A SHORTWAVE UPPER TROUGH OVER THE NE GULF EXTENDING FROM A BROAD UPPER TROUGH COVERING THE E HALF OF THE U.S. THROUGH SE ALABAMA TO THE FLORIDA KEYS. DIFFLUENCE ALOFT BETWEEN AN UPPER TROUGH AND AN UPPER RIDGE ARE GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS MAINLY OVER THE NW GULF N OF 23N W OF 87W. CARIBBEAN SEA... AN UPPER LEVEL TROUGH IS OVER THE FAR W CARIBBEAN WITH AXIS ALONG 87W FROM HONDURAS TO W CUBA GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS W OF 83W INCLUDING THE YUCATAN CHANNEL. AN UPPER LEVEL RIDGE COVERS THE CENTRAL CARIBBEAN EXTENDING FROM W COLOMBIA ALONG 14N78W TO OVER E CUBA NEAR 20N75W. DIFFLUENCE ALOFT IS GENERATING SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS WITHIN 120 NM ALONG THE COAST OF NICARAGUA FROM 11N-14N. AN UPPER TROUGH OVER THE CENTRAL ATLC DIPS S OVER THE GREATER ANTILLES BETWEEN THE WINDWARD PASSAGE AND THE VIRGIN ISLANDS N OF 15N AND IS PRODUCING SCATTERED SHOWERS AND POSSIBLE ISOLATED SHOWERS N OF 17N BETWEEN THE MONA PASSAGE AND WINDWARD PASSAGE. MODERATE/STRONG EASTERLY TRADE WINDS CONTINUE ACROSS THE AREA USHERING IN ISOLATED FAST MOVING LOW LEVEL SHOWERS MAINLY ACROSS THE FAR E CARIBBEAN E OF 65W TO OVER THE LESSER ANTILLES. THE TROPICAL WAVE/LOW MENTIONED IN THE SPECIAL FEATURES IS EXPECTED TO MOVE OVER THE LESSER ANTILLES LATE TUE/EARLY WED. ATLANTIC OCEAN... NARROW UPPER RIDGE IS OVER THE FAR W ATLC EXTENDING FROM E CUBA ACROSS THE N BAHAMA ISLANDS TO 32N73W AND PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 26N-31N W OF 76W WITH HIGHEST CONCENTRATION OF ACTIVITY WITHIN 75 NM ALONG THE COAST OF FLORIDA FROM PALM BEACH TO DAYTONA BEACH. AN UPPER TROUGH EXTENDS ACROSS THE ATLC BASIN FROM THE E ATLC THROUGH 33N23W AND A SERIES OF UPPER LOWS CENTERED NEAR 30N36W...28N52W...TO A THIRD NEAR 21N67W. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE IN THE VICINITY OF THE UPPER LOWS FROM 21N-25N BETWEEN 60W-70W AND FROM 26N-29N BETWEEN 51W-55W. OTHERWISE THE REMAINDER OF THE ATLC BASIN REMAINS TRANQUIL TONIGHT AS A SURFACE RIDGE DOMINATES THE BASIN ANCHORED BY A 1031 MB HIGH WELL N OF THE REGION NW OF THE AZORES. $$ WALLACE