000 AXNT20 KNHC 210552 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SAT AUG 21 2010 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 0545 UTC. ...SPECIAL FEATURES... A 1009 MB ELONGATED LOW IS CENTERED OVER THE TROPICAL EASTERN ATLC NEAR 11N27W THAT REMAINS THE FOCAL POINT OF A BROAD MONSOONAL TROUGH S OF 14N BETWEEN 20W-39W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION COVERS A BROAD AREA FROM 5N-15N BETWEEN THE WEST COAST OF AFRICA AND 40W. WHILE CONVECTION REMAINS GENERALLY UNORGANIZED...THE UPPER LEVEL ENVIRONMENT FOR TROPICAL CYCLONE DEVELOPMENT IS FAVORABLE FOR DEVELOPMENT AND A TROPICAL DEPRESSION COULD FORM DURING THE NEXT COUPLE OF DAYS. THERE IS A MEDIUM CHANCE OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT FEW DAYS AS IT MOVES SLOWLY WESTWARD. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 11N44W TO 11N42W MOVING W AT 10-15 KT. NIGHT VISIBLE SATELLITE INDICATES WEAK LOW-LEVEL CYCLONIC TURNING ALONG THE WAVE AXIS AND THIS WAS ALSO NOTED ON SATELLITE DERIVED WINDS. AN AREA OF MAXIMUM DEEP LAYER MOISTURE IS OBSERVED ON THE TPW IMAGERY EMBEDDED IN THE WAVE. HOWEVER..MUCH OF THIS MOISTURE IS POSITIONED BENEATH A STABLE SAHARAN AIR LAYER THAT COVERS MUCH OF THE CENTRAL A ND E ATLC. THEREFORE NO SIGNIFICANT DEEP ORGANIZED CONVECTION ACCOMPANIES THE WAVE... HOWEVER ISOLATED SHOWERS ARE WITHIN 20 NM OF THE AXIS N OF 20N AND S OF 14N. A TROPICAL WAVE EXTENDS FROM 25N67W TO 14N64W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH A MID/UPPER LEVEL LOW CENTERED NEAR 25N68W. MODERATE TOTAL PRECIPITABLE WATER VALUES ACCOMPANY THIS SYSTEM N OF 17N...AS THIS MOISTURE CONTINUES TO ADVECT NORTHWARD DUE TO A WEAKNESS IN THE SUBTROPICAL RIDGE BETWEEN 60W-70W. ISOLATED MODERATE CONVECTION AND WIDELY SCATTERED SHOWERS ARE OCCURRING FROM 17N-24N BETWEEN 62W-70W. NO DEEP CONVECTION IS OBSERVED AT THE MOMENT DUE TO THE LACK OF SUFFICIENT LOW-LEVEL MOISTURE. ONLY A FEW ISOLATED SHOWERS ARE NOTED WITHIN 30 NM IN THE VICINITY OF THE WAVE AXIS NORTH OF PUERTO RICO. TROPICAL WAVE IS OVER THE SW GULF OF MEXICO EXTENDING FROM 23N96W TO 13N92W MOVING W AT 5-10 KT. LOW-LEVEL CYCLONIC FLOW IS IN THE VICINITY OF THE WAVE...NOTED ON THE NIGHT VISIBLE SATELLITE IMAGERY. LOW-LEVEL SURFACE CONVERGENCE ALONG WITH PLENTY OF LOW-LEVEL MOISTURE IS GENERATING A LARGE AREA OF SCATTERED MODERATE AND ISOLATED STRONG CONVECTION OVER MUCH OF THE BAY OF CAMPECHE S OF 23N W OF 90W AND INLAND OVER SRN MEXICO. ...ITCZ... THE ITCZ AXIS IS BETTER DEFINED NE OF S AMERICA CENTERED ALONG 12N43W 10N51W 12N63W. EMBEDDED WITHIN THE MONSOONAL TROUGH MENTIONED IN THE SPECIAL FEATURES SECTION...A 1009 MB LOW IS CENTERED NEAR 11N27W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 5N-15N BETWEEN THE WEST COAST OF AFRICA AND 40W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE COVERS MOST OF THE GULF OF MEXICO. WATER VAPOR IMAGERY SHOWS A MID/UPPER LEVEL DRY AIRMASS MOVING WESTWARD ACROSS MUCH OF THE BASIN TONIGHT...PROVIDING STABLE CONDITIONS ACROSS THE AREA. THIS UPPER LEVEL RIDGE SUPPORTS A 1016 MB HIGH CENTERED OVER THE NE BASIN NEAR 27N86W. HOWEVER...A FEW SHOWERS AND THUNDERSTORMS STILL REMAIN OVER THE FAR E AND SE GULF AFFECTING THE W COASTAL WATERS OF THE FLORIDA PENINSULA INCLUDING THE FLORIDA KEYS...FROM A WEAK SURFACE TROUGH ALIGNED OVER THE W FLORIDA COASTLINE FROM 25N TO 29N. THE SW GULF IS UNDER THE INFLUENCE OF A TROPICAL WAVE ALONG 95W IMPACTING THE BAY OF CAMPECHE S OF 23N W OF 90W WITH SCATTERED SHOWERS AND TSTMS. CARIBBEAN SEA... ABUNDANT MOISTURE AND INSTABILITY IS NOTED ACROSS THE INTERIOR CENTRAL AMERICA AND SURROUNDING WATERS COVERING THE SW CARIBBEAN GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS W OF 74W S OF 17N. SATELLITE IMAGERY DENOTES THE STRONGEST ACTIVITY LIES WITHIN 100 NM OFFSHORE OF WESTERN PANAMA...COSTA RICA... NICARAGUA...AND HONDURAS. FARTHER EAST...WATER VAPOR IMAGERY SHOWS A MID/UPPER LEVEL DRY AIRMASS ACROSS MUCH OF THE BASIN E OF 74W...PROVIDING STABLE CONDITIONS ACROSS THE AREA. HOWEVER...IN THIS REGION OF DRY AND STABLE AIR...A TROPICAL WAVE IS ANALYZED MOVING OVER PUERTO RICO ALONG 66W WITH NO ASSOCIATED DEEP CONVECTION DUE TO THE LACK OF LOW-LEVEL MOISTURE. ONLY A FEW ISOLATED SHOWERS ARE NOTED WITHIN 30 NM IN THE VICINITY OF THE WAVE AXIS NORTH OF PUERTO RICO. ATLANTIC OCEAN... A WEAK 1015 MB HIGH IS CENTERED OVER THE NW BAHAMAS NEAR 26N76W THAT RESIDES ON THE SE PERIPHERY OF AN ANTICYCLONIC CIRCULATION CENTERED OVER THE SE CONUS. WITH A FRONTAL BOUNDARY DRAPED NEAR THE NORTHERN EDGE OF THE DISCUSSION AREA ALONG 31N...WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING OVER THE W ATLC N OF 29N W OF W OF 71W. SE OF THE UPPER LEVEL ANTICYCLONE ...AN MID/UPPER LEVEL LOW IS CENTERED NEAR 25N68W AND EXTENDS UPPER LEVEL TROUGHING TO 30N BETWEEN 60W-70W AND SOUTHWARD INTO THE NE CARIBBEAN SEA. A TROPICAL WAVE IS ALONG 66W WITH NO ASSOCIATED DEEP CONVECTION DUE TO THE LACK OF LOW-LEVEL MOISTURE. ONLY A FEW ISOLATED SHOWERS ARE NOTED WITHIN 30 NM IN THE VICINITY OF THE WAVE AXIS. ELSEWHERE ACROSS THE REMAINDER OF THE CENTRAL AND EASTERN ATLC...SURFACE RIDGING DOMINATES N OF 25N ANCHORED BY A 1022 MB HIGH CENTERED NEAR 32N27W MAINTAINING GENERALLY FAIR WEATHER. THE RIDGE AXIS EXTENDS FROM THE HIGH CENTER TO THE W ATLC NEAR 26N65W. 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