000 AXPZ20 KNHC 300332 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC THU AUG 30 2012 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0315 UTC. ...SPECIAL FEATURE... HURRICANE ILEANA IS CENTERED AT 19.1N 113.1W AT 30/0300 UTC. ILEANA IS MOVING NW OR 320 DEG AT 08 KT AROUND THE W PERIPHERY OF AN UPPER RIDGE THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 987 MB. MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH GUSTS TO 80 KT. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS WITHIN 150M OF CENTER WITH THE HEAVIEST ACTIVITY OBSERVED OVER THE SE QUADRANT. ISOLATED MODERATE AND STRONG CONVECTION IS NOTED ELSEWHERE WITHIN 270 NM OF CENTER...WITH OUTER BANDING INDICATED OVER THE SE SEMICIRCLE. THE CYCLONE WILL BEGIN TO MOVE OVER COOLER SEAS SURFACE WATERS LATE THU AND IS FORECAST TO BEGIN TO WEAKEN THU NIGHT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM NW COLOMBIA WNW ACROSS THE CARIBBEAN TO THE PACIFIC COAST OF NORTHERN COSTA RICA AND CONTINUING W ALONG 11N TO 11N98W WHERE THE TROUGH LOSES IDENTITY IN THE BROAD CYCLONIC CIRCULATION ASSOCIATED WITH TROPICAL CYCLONE ILEANA. THE MONSOON TROUGH BECOMES ESTABLISHED AGAIN SW OF ILEANA NEAR 14N116W AND CONTINUES SW TO 10N125W THEN WESTWARD TO BEYOND 11N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION VERIFIED BY LIGHTNING DATA IS OBSERVED WITHIN 180 NM EITHER SIDE OF A LINE FROM 07N79W TO 08N93W TO 14N105W. ...DISCUSSION... AN UPPER LEVEL TROUGH IS MOVING OVER THE NW COAST OF THE CONUS AND CONTINUES SW INTO AN UPPER CYCLONE AT 34N133W WITH THE TROUGH CONTINUING S INTO THE DISCUSSION AREA TO A BASE AT 27N137W WITH CLOUD MOTION WINDS DETECTING A WESTERLY UPPER JET AT 50 TO 85 KT TO THE W OF THE TROUGH AXIS. A MID LEVEL CYCLONE IS OBSERVED AT 30N139W EMBEDDED WITHIN THE BROADER LOW LEVEL RIDGE THAT DOMINATES THE AREA N OF 15N W OF 120W. NORTHEASTERLY SURFACE WINDS ARE EXPECTED TO CONTINUE FOR A COUPLE OF DAYS AT 15 TO 20 KT SW OF THE RIDGE...IN THE AREA FROM 12N TO 16N W OF 135W...WITH SEAS 7 TO 9 FT IN NE SWELL. AN UPPER LEVEL ANTICYCLONE IS OVER COLORADO WITH AN UPPER RIDGE EXTENDING SW INTO THE DISCUSSION AREA TO 31N119W. ANOTHER UPPER ANTICYCLONE IS CENTERED NEAR 17N136W WITH A RIDGE NE TO 26N128W...AND A RIDGE ALSO EXTENDS SW TO A CREST AT 14N145W. UPPER DEBRIS MOISTURE IS ADVECTED NE AROUND THE SW RIDGE ACROSS THE TROPICS FROM 16N TO 22N BETWEEN 135W AND 145W. AN ILL-DEFINED UPPER CYCLONE IS OBSERVED AT 30N120W WITH AN UPPER TROUGH EXTENDING S THROUGH 20N122W INTO A SMALL UPPER CYCLONE AT 14N125W. MOST OF THE DEBRIS MOISTURE FROM ILEANA IS ADVECTED SW TO ALONG 08N BETWEEN 111W AND 124W...BUT SOME MOISTURE IS ALSO FANNING OUT IN THE UPPER ANTICYCLONIC FLOW N OF ILEANA ACROSS THE SOUTHERN BAJA PENINSULA AND GULF OF CALIFORNIA. OTHERWISE...THE UPPER LEVELS APPEAR VERY DRY TO THE W OF A LINE EXTENDING FROM THE BAJA PENINSULA AT 25N111W TO THE EQUATOR AT 130W. AN UPPER CYCLONE IS QUASI STATIONARY OVER THE NW CARIBBEAN AT 19N80W WITH AN UPPER TROUGH EXTENDING S ACROSS EASTERN PANAMA TO BASE OVER COLOMBIA AT 07N76W. AN UPPER ANTICYCLONE...ASSOCIATED WITH ATLANTIC TROPICAL CYCLONE ISSAC...IS OVER THE N CENTRAL GULF OF MEXICO WITH AN UPPER RIDGE EXTENDING SW ACROSS OLD MEXICO TO A BROAD CREST OVER THE TROPICAL PACIFIC NEAR 13N100W. THE UPPER DIFFLUENCE BETWEEN THE CARIBBEAN UPPER CYCLONE AND THIS UPPER RIDGE IS SUPPORTING CONVECTION OVER CENTRAL AMERICA AND THE TROPICAL PACIFIC AS PREVIOUSLY DESCRIBED. THE RESULTANT DENSE UPPER DEBRIS MOISTURE IS ADVECTED SW TO ALONG 02N BETWEEN 82W AND 108W. ELSEWHERE AT THE LOW LEVELS...SOUTHWESTERLY MONSOONAL FLOW AT 20 TO 25 KT WINDS WITH SEAS 8 TO 11 FT ARE OBSERVED FROM 12N TO 19N BETWEEN 106W AND 117W...MERGING WITH THE SOUTHERLY WINDS OVER THE S SEMICIRCLE OF TROPICAL STORM ILEANA. GLOBAL MODELS SUGGEST THAT A SURFACE LOW WILL FORM ALONG THE MONSOON TROUGH NEAR 10N95W ON THU AND MOVE NW WITH CYCLONIC WINDS OF 20 TO 25 KT GRADUALLY EXPANDING OUT TO ABOUT 180 NM ON FRI MIXING WITH LONG PERIOD CROSS EQUATORIAL SOUTHWESTERLY SWELL AT 15 TO 18 SECONDS...THAT WILL PROPAGATE N TO ALONG 15N BETWEEN 88W AND 100W. $$ NELSON