000 AXPZ20 KNHC 200354 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC THU SEP 20 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 0300 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM 09N84W TO 1009 MB LOW PRES AT 12N98W TO 10N124W. ITCZ AXIS EXTENDS FROM 07N130W TO BEYOND 06N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 120 NM OF AXIS FROM 124W TO 132W. SCATTERED MODERATE CONVECTION WITHIN 90 NM S OF AXIS FROM 100W TO 105W. ...DISCUSSION... BROAD UPPER LEVEL ANTICYCLONE AT 16N127W DOMINATES DRY AIR MASS N OF 11N W OF 122W...CONTINUING STRONG SW WIND SHEAR OVER REMNANTS OF TROPICAL CYCLONE LANE. WEAK DEEP LAYER CYCLONE AT 19N119W EXTENDS DRY SLOT FURTHER E TO 111W. MOISTURE REMAINS CONFINED TO S OF 20N E OF 111W. SECOND ANTICYCLONE ALOFT JUST W OF GULF OF TEHUANTEPEC ENHANCES MOISTURE FLOW INTO MONSOON TROUGH AND BRINGS LIGHT SHEAR TO REGION THAT ALLOWS WEAK SURFACE CIRCULATION TO LOWER PRES IN AREA AND POSSIBLY INTENSIFY IN THE NEXT 24-48 HRS. ELSEWHERE IN THE LOWER LEVELS... LOW PRES CENTER...REMNANTS OF TROPICAL CYCLONE LANE 1012 MB AT 21N132W...HAVE BECOME COMPLETELY DEVOID OF DEEP CONVECTION AND NO LONGER CONSIDERED POTENTIAL TROPICAL THREAT AND EXPECTED TO DISSIPATE BY LATE FRI UNDER SUCH A DRY AND STABLE ATMOSPHERE. HIGH PRES CENTER 1025 MB AT 34N136W KEEP TIGHT GRADIENT AGAINST REMNANTS OF LANE WITH STRONG GUSTY NE WINDS IN NW QUADRANT OF LANE AND SUBSIDING LINGERING SEAS TO 13 FT. GAP WINDS...BUILDING HIGH PRES BEHIND GULF OF MEXICO STATIONARY FRONT ACROSS BAY OF CAMPECHE FORCE STRONG N BREEZE ACROSS CHIVELAS PASS INTO GULF OF TEHUANTEPEC. LATE NIGHT DRAINAGE WINDS MAY ENHANCE GUSTS TO NEAR GALE FORCE IN EARLY MORNINGS THROUGH FORECAST PERIOD. $$ WALLY BARNES