AGPN40 KWNM 091539 MIMPAC MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN NWS OCEAN PREDICTION CENTER WASHINGTON DC 830 AM PDT SAT 9 MAY 2009 .FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT .WEATHER FOR THE NORTH PACIFIC N OF 30N AND E OF 150W. 12Z OBS SHOW GALES OFF NRN CA CST DOWN TO PT ARENA AREA. EARLIER QUIKSCAT DATA FM LAST EVENING SHOWED GALES FARTHER S OFF SRN CA AND SHIP NR 37N124W AT 10Z RPTD MRGL GALE BUT SAME SHIP RPTD WNDS DOWN TO 25 KT AT 12Z. GIVEN DOWNWARD TREND IN OBS AND MDLS PLAN TO LEAVE WNDS BLO GALE FORCE AS CURRENTLY FCST IN SRN CA WTRS. SINCE ECMWF 1000 MB WNDS APPR TO MOST CLOSELY MATCH OBSVD CONDS AND THAT MDL MAINTAINS CLOSED 35 KT CONTOUR INTO THIS AFTN PLAN TO MAINTAIN GALE WARNG INTO THIS AFTN NRN CA AND NE PART OF CNTRL CA WTRS. BY COMPARISON 06Z GFS SHOWS LTL CHG IN GRADIENT OFF CA THRU THIS AFTN LENDING SPRT TO ECMWF. OTHER PROBLEM AREA IS PZ5 WTRS WITH GFS CONTG TO FCST A DVLPG GALE APCG FM SW SUN AND MOVG INTO OREGON WTRS SUN NIGHT WHILE NAM IN AGRMT WITH OTHER GLOBAL MDLS FCSTG A WEAKER LOW PASSING ACRS WA WTRS OR A BIT TO NW IN CASE OF CMC GLOBAL. GOING WITH MDL CONSENSUS WITH 06Z NAM/00Z ECMWF BLEND TAKING WKNG LOW ACRS SRN WA WTRS AND TAKING A STRONGER LOW COMING FM NW TO N OF WTRS MON. WILL MAKE ONLY MINOR CHANGES TO CURRENT FCST FOR SUN-SUN NGT PRD WITH WNDS INCRG TO 25 OR 30 KT LATE SUN INTO SUN NIGHT HIGHEST OREGON WTRS AND AS IN CURRENT FCST LEAVE WNDS AT 30 KT FM W TO NW OVR WA WTRS MON. PLAN TO LEAVE WNDS AT 30 KT FOR NOW AT DAY 5 IN NRN WTRS FOR STABLE SLY FLOW AHD OF A FNT AND HOLD OFF ON ISSUING GALE FCST BY GFS...ALSO GIVING CONSIDERATION TO TIME OF YR. SEAS...RECEIVED REPORT OF 17 FT OFF CAPE MENDICINO FM A SHIP WHICH IS ABT 5 FT HIGHER THAN WAVE WATCH III AT 12Z. HAVE ACCEPTED THIS RPT AS RELIABLE AND IT GOES ALG WITH FCST BY WW3 SPRDG SEAS 12 FT OR HIGHER N INTO NRN CA WTRS BY THAT TIME. PLAB TO ADD 3 TO 5 FT TO WW3 SEAS IN CA OFSHR AREAS FOR FIRST PRD...HIGHEST OFF PT ARENA AND TAPER ADJUSTMENT DOWN TO CLOSER TO MDL TONIGHT AND SUN AS THE APCH OF LOW PRES FM SW DMSHS GRADIENT ESPCLY IN NRN CA WTRS. PREVIOUS DISCUSSION... --------------------------------------------- NO SIGNIFICANT CHANGES WILL BE MADE TO THIS FORECAST PACKAGE. GALES WILL CONTINUE INTO EARLY TODAY FOR THE SE NRN CA AND NE CNTRL CA WATERS AS A COASTAL TROUGH INTERACTS WITH A HIGH PRES RIDGE W OF THE OFFSHORE REGION. THIS GRADIENT WILL RELAX LATER TODAY AS THE RIDGE BREAKS DOWN AHEAD OF A LOW PRES CENTER APPROACHING FROM THE SW. THERE IS SOME MODEL DISCREPANCY WITH REGARD TO THE TRACK AND INTENSITY OF THIS LOW. THE GEM GLOBAL IS THE FARTHEST NW...TAKING IT THROUGH THE FAR NW WA WATERS SUN NIGHT. THE OTHER 00Z MODELS TAKE THE LOW THROUGH THE PZ5 WATERS DURING THE SAME TIME FRAME BUT FOLLOW A MORE S TRACK. THE GFS IS THE DEEPEST WITH THE LOW...AND THE ONLY MODEL TO SHOW GALES. WILL FAVOR A MORE S TRACK IN LINE WITH THE CONSENSUS...BUT KEEP MAX WINDS SUB-GALE. THE NEXT UPSTREAM LOW WILL AFFECT THE FORECAST WED. THE GFS...GEM GLOBAL...AND ECMWF ALL INDICATE GALES FOR THE PZ5 WATERS AS A VIGOROUS FRONT ASSOCIATED WITH THE LOW PUSHES THROUGH. IT REMAINS TO BE SEEN WHETHER AN AREA OF HIGH PRES SE OF THE FRONT WILL BE STRONG ENOUGH TO SUPPORT GALES. FOR NOW...GIVEN THE FACT THAT THIS IS DAY 5...WILL WAIT FOR SUBSEQUENT MODEL GUIDANCE BEFORE MAKING ANY ADJUSTMENTS TO THE FORECAST. THE WW3 SEEMS REASONABLE COMPARED TO THE 06Z OBS. WILL GENERALLY FOLLOW ITS OUTPUT...BUT LOWER SEAS OVER THE PZ5 WATERS SUN INTO MON TO CORRESPOND WITH WINDS LIGHTER THAN FORECAST BY 00Z GFS. .WARNINGS/FORECAST CONFIDENCE...WARNINGS ARE PRELIMINARY AND ARE SUBJECT TO CHANGE. ANY CHANGES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .PZ5 WASHINGTON/OREGON WATERS... .CAPE FLATTERY TO CAPE LOOKOUT...NONE. .CAPE LOOKOUT TO POINT ST GEORGE...NONE. .PZ6 CALIFORNIA WATERS... .PT ST GEORGE TO PT ARENA...GALE TODAY...MOD CONFDC. .PT ARENA TO PT CONCEPTION...GALE TODAY...MOD CONFDC. .PT CONCEPTION TO GUADALUPE ISLAND...NONE. .FORECASTER BANCROFT. OCEAN FORECAST BRANCH.