000 AXPZ20 KNHC 050951 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC WED SEP 05 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0900 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH AXIS FROM 09N84W TO 10N94W TO 07N105W TO 09N111W TO 09N127W THEN ITCZ AXIS TO 09N140W. ISOLATED MODERATE CONVECTION WITHIN 180 NM S OF AXIS FROM 93W TO 95W AND WITHIN 90 NM OF AXIS FROM 103W TO 112W. ...DISCUSSION... UPPER LEVEL CYCLONE AT 36N132W WITH TROUGH EXTENDING S TO 32N133W TO 20N137W AND ILL-DEFINED ANTICYCLONE NEAR 16N133W COMBINE TO MAINTAIN VERY DRY AIR MASS OVER E PAC W OF 126W. ANTICYCLONE ALOFT OVER N BAJA CALIFORNIA BRINGS ABUNDANT MOISTURE INTO BASIN N OF 20N E OF 120W...BUT 1008 MB LOW PRES ...REMNANTS OF JOHN AT 25N119W...LACKS UPLIFT TO PRODUCE DEEP CONVECTION. STRONG EASTERLY SHEAR ALOFT AND COOL SEA SURFACE TEMPERATURES OBLITERATE ITS CHANCES OF SURVIVAL. SECOND BROAD ANTICYCLONE OVER ISTHMUS OF TEHUANTEPEC ADVECTS PLENTY OF TROPICAL MOISTURE INTO E PAC S OF 20N E OF 110W AVAILABLE FOR MORE CONVECTION BUT SURFACE PRESSURES REMAIN TOO HIGH AND CONVECTION REMAINS LIMITED TO ISOLATED MODERATE TSTMS ALONG AND S OF MONSOON TROUGH. ...ELSEWHERE AT THE LOW LEVELS... HIGH PRES CENTER 1036 MB NW OF BASIN HAS RIDGE EXTEND SE TO 23N126W...JUST NW OF REMNANTS OF JOHN. ALTHOUGH DEVOID OF CONVECTION...JOHN STILL MAINTAINS FAIRLY TIGHT CLOSED CIRCULATION AND FRESH TO STRONG BREEZE ARE EXPECTED JUST NE OF JOHN DUE TO THIS TIGHT PRES GRADIENT THROUGH LATE WED THEN DIMINISH AS JOHN BECOMES DIFFUSE. SECOND LOW PRES CENTER 1010 MB...REMNANTS OF ILEANA...AT 19N130W ALSO EXPECTED TO PRODUCE SOME FRESH TO STRONG BREEZE MAINLY IN NW QUADRANT AS PRES GRADIENT TIGHTENS AGAINST HIGH PRES RIDGE... BUT EXPECTED TO DIMINISH WED. $$ WALLY BARNES