Marine Interpretation Message
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AGPN40 KWNM 210325
MIMPAC

MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
825 PM PDT SUN APR 20 2014

.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT
.WEATHER FOR THE NORTH PACIFIC N OF 30N AND E OF 150W.

THE SAT IMG INDCT MOST OF THE CONV CLDS ASSCTD WITH A FRNTL BNDRY
OVR THE NRN WTRS. THE RADAR SHOW VERY ISOL TSTMS JUST OVR THE
N-ERN PORTION OF THE WASH WTRS. AT 21/0000Z HGH PRES 1025 MB ALONG
130W JUST W OF THE SRN WTRS HAS A RIDGE XTNDG NE INTO THE CNTRL
REGION WITH ANOTHER RIDGE XTNDG SE PASSING JUST W OF THE SRN WTRS.
LOW PRES 998 MB ABOUT 360 NM NW OF THE REGION HAS A FRNT STRTCHNG
SE THAT CONTINUES SE AS A WRM FRNT AND SW AS A CLD FRNT PASSING
ACRS THE NRN WTRS AND LINKS UP WITH A WRM FRNT FROM LOW PRES 1020
MB ABOUT 360 NM W OF THE CNTRL REGION. INLAND TROF FROM LOW PRES
1009 MB OVR AZ STRETCHES NW ALONG THE CA COAST. THE PRES GRDNT IS
WEAK OVR MOST OF THE REGION XCPT THE FAR NRN WTRS WHERE THE MAX
OBS WINDS ARE 25 KT. THE HGHST SEAS ARE ALSO CONFINED TO THE NRN
WTRS WITH 20 FT PEAKS OVR THE NW PARTS. THE LAST JASON PASS AT
2008Z HAD 17 FT SEAS OVR THE NRN WTRS. THE NWW3 MULTI GRID WV MDL
FITS FAIRLY WELL WITH THE SEAS PATTERN XCEPT THAT IT IS UNDERDONE
BY UP TO 2 FT IN SOME AREAS. NWW3 IS ALSO CLOSE TO THE ECMWFWAVE
AND HAS BEEN QUITE CONSSTNT WITH THE FCST AND SO WILL STAY WITH IT
FOR THIS UPDATE. THE GLB MDLS HAVE ONLY A FEW SYNOP FEATURES TO
AGREE ON OVR THE FCST WTRS AND THEY HAVE INITILAIZED FAIRLY WELL.
IN THE SHORT TERM THE HGH PRES WILL DRIFT E AS IT DSIPTS WHILE THE
LOW PRES WILL ZOOM NE ACRS THE CNTRL REGION AS THE CLD FRNT MOVES
E ACRS THE NRN WTRS WITH ITS ACCTD LOW PRES TO THE NW MOVING N
THEN NW INTO THE GULF OF AK. ANOTHER LOW PRES WILL MOVE FROM THE
NW TWD THE NRN WTRS. THE PRES GRDNT WILL REMAIN FAILY SLACK BUT AS
HGH PRES BUILDS FROM THE W AND THE INLAND LOW PRES TROF DEEPENS
THAT WILL FORCE ISOBARS TO PACK UP OVR THE ERN PARTS OF THE SRN
WTRS MID WEEK. THE ENERGY CURR IN THE GULF OF AK WILL BE
TRANSFERED SE AND THAT SUPPORTS THE DEEPENING OF THE TROF. ALL THE
MDLS HV INDCTD ENHANCED WINDS OVR THE ERN PARTS OF THE SRN WTRS.
BOTH THE UKMETHR AND ECMWFHR HV WINDS INCREASING TO 30 KT WHILE
THE GFS/CMC/NOGAPS AND JMA HV WINDS IN THE GALE FORCE RANGE. SO
WILL REINTRODUCE THE GALES OVR THE SRN WTRS IN THE XTNDD PRD.

-----------------------------------------------------------------
PREVIOUS DISCUSSION...

18Z OPC SFC ANALYSIS SHOWS A DISSIPATING WARM FRONT OVER THE NRN
PZ5 WATERS W/A COLD FRONT ENTERING THE NW WATERS. A HIGH PRES
RIDGE IS PRESENT OVER THE REST OF THE PZ6 WATERS.

THROUGH WED NIGHT NOT MANY CHANGES AS THE 12Z GUIDANCE REMAINS IN
DECENT AGREEMENT SO FAVORED 12Z GFS THROUGH DAY 3. COLD FRONT
PUSHES THROUGH THE PZ5 WATERS TONIGHT AND NRN HALF OF THE PZ6
WATERS MON. A HIGH PRES RIDGE REBUILDS OVER THE NRN PZ6 WATERS
LATE MON INTO TUE...WHILE A WEAK LOW SLIDES SE ACROSS THE PZ5
WATERS TUE INTO WED. MODELS BEGIN TO DIVERGE A BIT LATE WED INTO
THURS AS THE NEXT LOW PRES/FRONTAL SYSTEM APPROACH THE PZ5 WATERS.
WHILE IN GENERAL TIMING AMONGST THE GUIDANCE IS OKAY DIFFERENCES
ARISE CONCERNING THE STRENGTH OF THE LOW...W/THE 12Z GFS/CMC
SUGGESTING GALES IN THE NRN PZ5 WATERS LATE WED. W/THIS PACKAGE
DECIDED TO LEAN MORE TOWARDS A 12Z GFS/ECMWF BLEND WHICH STILL
FEATURES THE LOW BUT WILL KEEP WINDS BELOW GALE FORCE WED NIGHT IN
THE NRN PZ5 WATERS WHICH IS A CHANGE FROM THE PRIOR FORECAST.
BEYOND THAT THE LOW MOVES N OF THE WATERS THURS WHILE WEAKENING
AND ANOTHER FRONTAL BOUNDARY APPROACHES FROM THE W FRI.

OVER THE PZ6 WATERS DECIDED TO CONTINUE W/GALES LATE TUE IN THE
NE SRN CA WATERS AS THE LOW PRES TROUGH STRENGTHENS ALONG THE
COAST BUT CONFDC IS LOW TO MDT AT THE MOMENT.

.SEAS...FAVORED 12Z NWW3 WHERE 12Z GFS WINDS WERE FAVORED W/BLEND
OF 12Z NWW3/ECMWF WAVE MODEL WERE A 12Z GFS/ECMWF BLEND WAS USED.

.EXTRATROPICAL STORM SURGE GUIDANCE...N/A.



.WARNINGS...PRELIMINARY. ANY CHANGES WILL BE COORDINATED THROUGH
AWIPS 12 PLANET CHAT OR BY TELEPHONE:

.PZ5 WASHINGTON/OREGON WATERS...
     NONE.

.PZ6 CALIFORNIA WATERS...
.PZZ840...INNER WATERS FROM SANTA CRUZ ISLAND, CA TO SAN CLEMENTE ISLAND, CA...
     GALE TUE.
     GALE POSSIBLE TUE NIGHT.

$$

.FORECASTER MUSONDA/HOLLEY. OCEAN PREDICTION CENTER.



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