000 AXPZ20 KNHC 281553 AAA TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC FRI SEP 28 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC. ...SPECIAL FEATURE... TROPICAL STORM NORMAN LOCATED NEAR 22.8N 108.6W AT 1500 UTC MOVING N AT 14 KT, MAXIMUM SUSTAINED WINDS 40 KT GUSTS TO 50 KT WITH MINIMUM PRESSURE 1000 MB. MULTIPLE SHIP OBSERVATIONS THIS MORNING CONFIRMED TROPICAL STORM FORCE WINDS...PROMPTING THE FIRST TROPICAL CYCLONE ADVISORY. NORMAN WILL MOVE NORTHWARD INTO THE SOUTHERN GULF OF CALIFORNIA WITH LITTLE CHANGE IN INTENSITY OVER THE NEXT 12 HOURS THEN WEAKEN RAPIDLY AS IT MOVES INLAND OVER WESTERN MEXICO ON SAT. LOCALLY HEAVY RAINS AND GUSTY WINDS ARE EXPECTED ALONG PORTIONS OF THE WEST COAST OF MEXICO AND THE SOUTHERN BAJA PENINSULA THROUGH SAT NIGHT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... DISCONTINUOUS MONSOON TROUGH EXTENDS FROM 10N86W TO 12N102W... THEN RESUMES FROM 15N120W TO 10N127W TO 10N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION FROM 11N TO 15N BETWEEN 91W AND 111W. SCATTERED MODERATE CONVECTION WITHIN 45 NM S OF TROUGH BETWEEN 121W AND 133W. ...DISCUSSION... POST-TROPICAL REMNANT LOW MIRIAM CONTINUES TO LINGER NEAR 21.5N 116W AND SLOWLY WEAKEN OVER COLD WATER WITHOUT DEEP CONVECTION. THE LOW WILL DRIFT SLOWLY SOUTHWARD THROUGH SUN AND EVENTUALLY DEGENERATE INTO AN OPEN TROUGH BY TUE. A WEAKENING COLD FRONT EXTENDING FROM 40N134W TO 33N150W BISECTS THE SUBTROPICAL HIGH NW OF THE AREA INTO TWO HIGH PRES CELLS... CENTERED NEAR 38N150W AND 31N150W. NW SWELL ASSOCIATED WITH THE WEAK FRONT WILL SWEEP INTO THE NW PORTION OF THE DISCUSSION AREA LATE TONIGHT...BUILDING SEAS TO 9 FT NW OF A LINE FROM 30N131W TO 26N140W BY SAT MORNING. THE SUBTROPICAL HIGH WILL STRENGTHEN SAT AND SHIFT WELL N OF THE AREA W OF OREGON NEAR 43N133W SUN. THIS WEAK RIDGE PATTERN WILL SUPPORT MODERATE N-NE TRADE WINDS OVER MOST OF THE REGION N OF 16N W OF 120W THROUGH THE WEEKEND. GFS MODEL GUIDANCE SHOWS SW WINDS ASSOCIATED WITH THE MONSOON TROUGH GRADUALLY DIMINISHING THROUGH SAT NIGHT. EXPECT THE TROUGH TO REMAIN CONVECTIVELY ACTIVE FOR THE NEXT COUPLE OF DAYS PARTICULARLY BETWEEN 115W AND 135W WITH MULTIPLE WEAK VORTICES EMBEDDED WITHIN THE CONVERGENCE ZONE. SEAS GENERATED BY FRESH SW WINDS BETWEEN 105W-125W WILL SUBSIDE BELOW 8 FT BY SAT AFTERNOON. $$ MUNDELL