

777 

AGPN40 KWNM 071407

MIMPAC



MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

707 AM PDT SUN AUG 7 2016



.FORECAST DISCUSSION: MAJOR FEATURES/WINDS/SEAS/SIGNIFICANT

.WEATHER FOR THE NORTH PACIFIC N OF 30N AND E OF 150W.



UPDATE...06Z NCEP SFC ANALYSIS SHOWS A DISSIPATING COLD FRONT

DRIFTING E ACROSS THE PZ5 AND NRN PZ6 WTRS...WITH RIDGING

ASSOCIATED WITH A STRONG EPAC HI BUILDING E TOWARDS A BROAD AREA

OF LOW PRES OVER WRN CONUS. LATEST AVAIL ASCAT AND ASCAT HI-RES

PASSES FROM LAST NITE SHOW AREAS OF WINDS TO 20 KT IN NW FLOW OVER

THE OFSHR WTRS...MAINLY ACROSS THE CENTRAL AND SRN CALIFORINIA

WTRS. 



MAIN WEATHER FEATURES...A LOW PRES TROF WILL DISSIPATE NEAR THE

WASHINGTON COAST TONITE. ANOTHER TROF WILL PERSIST OVER CALIFORNIA

THRU THE FCST PERIOD. THE HI PRES RIDGE WILL BUILD E OVER THE

OFSHR WTRS TOWARDS THE COAST THRU TUE NITE...THEN RECEDE BACK TO

THE W WED THRU THU NITE. THE PRES GRADIENT BETWEEN THE RIDGE AND

THE TROF IS EXPECTED TO BECOME STRONG ENUF TO PRODUCE MARGINAL

GALES OVER THE NRN AND CENTRAL CALIFORNIA INNER OFSHR ZONES ON

TUE.



MODELS...THE MED RNG MDLS ARE IN VERY GUD AGREEMNT ACROSS THE

OFSHR WTRS THRU THE ENTIRE FCST PRD. THE GFS LOOKS REPRESENTATIVE

ENUF TO BE USED THRU THU NITE...WITH A 50/50 BLEND OF THE GFS

10M/30M SOLNS PREFERRED FOR TUE TO CAPTURE THE TIGHT PRES

GRADIENT. AM NOT PLANNING TO MAKE ANY SIGNIF CHANGES TO THE

CURRENT FCST TREND.



SEAS...THE ENP WAVEWATCH III AND ECMWF WAM BOTH INITIALIZED

REASONABLY WELL OVER THE OFSHR WTRS. THE MDLS ARE IN GUD OVERALL

AGREEMNT OVER THE OFSHR WTRS...WITH ONLY A FEW MINOR DIFFS SEEN

DURING THE FCST PERIOD. WILL BE USING A 50/50 BLEND OF ENP

WAVEWATCH III/ECMWF WAM THRU THU NITE IN ORDER TO SMOOTH OUT THE

DIFFERENCES. 



EXTRATROPICAL STORM SURGE GUIDANCE...N/A.



-----------------------------------------------------------------

PREVIOUS DISCUSSION...



GOES15 WV SAT IMAGERY REVEALS A MID/UPR LVL LOW ENTERING NE PZ5

WTRS WHILE A SHORTWAVE TROF IS MOVING INTO NRN AND CENTRAL CA. THE

UPR LOW DROPPING INTO THE WATERS HAS WEAKENED THE RIDGE ALOFT AND

CONTRIBUTED TO A RELAXING OF THE PRES GRADIENT ALONG THE W COAST.

THE SHRTWV HAS CONTRIBUTED TO SHRT TERM DPNG OF THE INLAND

THERMAL TROF OVR CA. HI RES ASCAT-B PASSES AT 0426Z/0605Z REVEALED

A SWATH OF 15-25 KT NLY WINDS OVER THE CA OFFSHORE OUTER WTRS BIT

MISSES THE INNER AND CSTL WTRS. WINDS ARE MOSTLY LIGHT OVER MUCH

OF THE PZ5 WTRS...GENERALLY 15 KT OR LESS...AS THE UPR LOW HAS

MAINTAINED A WK SFC REFLECTION IN FORM OF A TROF OR WK LW. A 1033 MB

SFC HIGH REMAINS WELL OFFSHORE NEAR 45N144W AS PER 06Z OPC SFC

ANALYSIS.



THE 00Z GFS/ECMWF/UKMET REMAIN IN VERY GOOD AGREEMENT THRU THE

FCST PERIOD. AS THE UPR LOW NEAR VANCOUVER ISLAND TURNS MORE EWD

AND INLAND OVER WA LATER TODAY THRU MON...THE UPR RIDGE EXPANDS

EASTWARD AND THE SFC HIGH PRES MOVES SE TO AROUND 42N142W. A SFC

RIDGE AXIS WILL DROP SE ACROSS THE PZ5 WTRS ON MON...ACCOMPANIED

BY A NLY SURGE ACROSS THE OUTER PZ5 WTRS WITH WINDS INCREASING TO

15-25 KT. THE SFC GRADIENT TIGHTENS OFF THE CA COAST MON INTO TUE

AS A THERMAL TROF SHARPENS OVER CA. BY 12Z TUE...COULD POTENTIALLY

SEE GALES DEVELOP OVER THE NRN CA COASTAL AND INNER OFFSHORE WTRS.

THE PAST FEW GFS RUNS HAVE CONSISTENTLY GENERATED GALES OVER THE

COASTAL WTRS RIGHT UP TO THE INTERFACE OF OUR OFFSHORE ZONES...AND

EVEN THE 00Z ECMWF/UKMET SHOW A SWATH OF 30 KT IN THIS AREA.

THEREFORE...FEEL COMFORTABLE MAINTAINING A SMALL AREA OF GALES

OVER INNER PORTIONS OF PZZ820 AND PZZ825 ON TUE. THEN SFC HIGH

PRES SHIFTS NW AWAY FROM THE WTRS BY MID WEEK...ALLOWING THE

GRADIENT TO RELAX AGAIN WED THRU THU NIGHT.



THE 00Z GFS 10M WINDS WERE THE PREFERRED MODEL CHOICE FOR THE

EARLY MORNING FCST ISSUANCE...EXCEPT TRANSITIONED MON NIGHT TO A

50/50 30M/10M BLEND DURONG THE PERIOD OF TIGHTEST GRADIENTS BETWEN

TROF AND RIDGE ON TUE...WHICH KEEPS GALES OVER THE INNER NRN CA

WTRS.



.SEAS...BASED ON THE 06Z SEA STATE ANALYSIS...THE 00Z ECMWF WAM

SEEMS TO HAVE INITIALIZED BETTER THAN THE 00Z NWW3. THEREFORE

USED THE ECMWF WAM FOR THE FIRST PERIOD OR TODAY...THEN

TRANSITIONED TO THE 00Z NWW3 SUN NIGHT THRU THU NIGHT. THE NWW3

WAS PREFERRED LATER IN THE FCST PERIOD AS IT GENERATED HIGHER SEAS

ON TUE WITH THE ANTICIPATED GALES OFF NRN CA.



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



.WARNINGS...PRELIMINARY.



.PZ5 WASHINGTON/OREGON WATERS...

     NONE.



.PZ6 CALIFORNIA WATERS...

.PZZ820...INNER WATERS FROM POINT ST. GEORGE TO POINT ARENA...

     GALE POSSIBLE TUE INTO TUE NIGHT. 

.PZZ825...INNER WATERS FROM POINT ARENA TO PIGEON POINT...

     GALE MON NIGHT.

     GALE POSSIBLE TUE INTO TUE NIGHT. 



$$



.FORECASTER SCOVIL/BANCROFT. OCEAN PREDICTION CENTER.

