

518 

AGPN40 KWNM 010226

MIMPAC



MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

726 PM PDT SUN JUL 31 2016



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

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



THE LTST NCEP SFC ANALYS INDC A STG PREG GRAD ACRS THE NRN CAL

OFSHR WTRS...AS A WKNG HIGH PRES RDG ACRS PZ5 INTERACTS WITH A

LOW PRES TROF OVR CENTRAL CAL. THE 19Z ASCAT PASS LARGELY MISSED

THE AREA WITH THE STGST WINDS...BUT INDC A LARGE AREA OF 30 KT OVR

THE NRN CAL ZONES. HOWEVER...CRNT SFC RRPTS STILL INDC UP TO 35 KT

IN PZ6...AND SINCE IT WAS IN PREV FCST AND NR THE DIURNAL

MAX...PLANNING ON STARTING OFF WITH GALE. THE 18Z GFS INDC THE

WINDS WL SLOWLY WKN OVRNGT...AS THE STGST WINDS BCM CONFINED TO

THE COASTAL WATERS BY MON MRNG. THE PREV FCST ENDED THE GALES

LATE TNGT IN THE OFSHR WTRS...WHICH AGREES WELL WITH THE 12Z/18Z

GFS AND THE REST OF THE 12Z GUID...AND CONFDC IS STILL HIGH WITH

THEM...SO PLANNING ON MAINTAINING PREV WRNGS IN UPDATE PKG.



OTRW...THE MDLS INDC A BF BREAK IN THE GALES MON INTO TUE...AS A

PAIR OF WK CDFNTS MOV INTO THE E PAC AND DSIPT OVR PZ5. THE WK CD

SURGE BEHIND THESE FRNTS SHUD BE ENUF TO LOWER STATIC

STABILITY...AND ALLOW STRONGER WINDS ALOFT TO MIX DN TWD THE SFC.

THE 12Z/18Z MDLS AGREE WELL ON THE OVERALL SYNOP PTTN...AND INDC

HIGH PRES WL BUILD W OF THE AREA AND INTERACT AGAIN WITH THE TROF

OVR THE CAL INTERIOR. THE ENHANCEMENT FROM THE LOWER STABILITIES

OVER THE STRENGTHENING PRES GRAD SHUD BE ENUF TO INCRS THE WINDS

TO GALES FRC NR PT ST GEORGE TUE NGT INTO THU NGT. THE 12Z MDLS

ALL INDC GALE OR NR GALE FRC WINDS AT THE SFC...SO CONFDC REMAINS

MDT TO HIGH. THE PREV FCST HAD WINDS IN THE GALE

RANGE...CONSISTENT WITH THE GFS...SO NOT PLANNING ON MAKING ANY

MAJOR ADJUSTMENTS. OTRW WL CONT WITH THE GFS FOR THE REMAINDER OF

THE UPDATE PKG.



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

PREVIOUS DISCUSSION...



THE CURRENT SAT IR IMAGERY SHOW A RIDGE ACROSS THE FORECAST

WATERS WITH AN UPPPER LOW IN THE GULF OF AK. THE 18Z NCEP MAP HAS

HIGH PRES 1034 MB TO THE W OF THE FORECAST REGION NEAR 45N 152W

THAT HAS ITS NE RIDGE INTO THE NRN AND SE RIDGE INTO THE SRN

WATERS. INLAND LOW PRES OVER SRN CA EXTENDS A TROF NW NEAR THE

COASTAL AREAS OF CA WHILE THE TROF OVER SRN OR IS NOW WEAKENING.

PRES GRADIENT IS STILL FAIRLY TIGHT OVER THE ERN PARTS OF THE NRN

CA WATERS. ALL THE OBSERVATIONS INCLUDING AN ASCAT PASS OVER THE

SRN WATERS NOW INDICATE HIGHER WINDS ONLY OVER THE NRN CA WATERS.

 

THE 500 MB RELATIVE VORTICITY HAS ELEVATED VALUES ASSOCIATED WITH

LOW PRES IN THE GULF OF AK AND THAT ENERGY WILL SHIFT SE INTO THE

NRN WATERS. LOWER REALTIVE VORTICITTY VALUES ASSOCIATED WITH THE

HIGH PRES TO THE W OF THE REGION WILL PERSIST AND THAT WILL ASSIST

TO RETAIN THE HIGH PRES TO THE W OF THE REGION. AS THE ERNEGY

PASSES E OVER THE NRN WATERS...THERE WILL BE SOME ENERGY THAT WILL

SPREAD INTO THE CENTRAL REGION AND THAT WILL HELP TO KEEP THE

INLAND TROF STRONGER RESULTING IN PERSISTENT GALE FORCE WINDS OVER

THE CENTRAL REGION. AT 925 MB HIGHER WINDS TO 45 KT ARE STILL

DEPICTED OVER THE NRN CA WATERS AND THAT WILL PERSIST INTO FRI.

THERE WILL BE AN INCREASE ALSO OVER THE NRN WATERS TWD THE END OF

FORECAST PERIOD. THE STABILTY INDEX SHOW PERSISTENTLY HIGHER

VALUES OVER THE REGION AS SUCH THERE IS A MOD TO HIGHER CONFDNC TO

KEEP STRONGER WINDS OVER THE WATERS.

 

THE GLOBAL MODELS HAVE CONTINUED TO INITIALIZE FAIRLY WELL WITH

STILL JUST MINOR DIFFERENCES AND MAINLY IN THE CENTRAL PRES VALUE

FOR THE HIGH WITHIN 1 MB. THE MODELS ALSO AGREE ON THE INLAND LOW

PRES THAT WILL FORM NEAR THE CENTRAL CA COAST. THERE IS STILL SOME

DIFFERENCE IN THE WIND SPEED IN WHICH CMC CONTINUES TO HAVE THE

HIGHEST VALUE AT 45 KT AND UKMETHR HAS ALSO REMAINED TO BE THE

WEAKEST. MEANWHILE THE ECMWFHR AND GFS ARE FAIRLY CLOSE AND ARE

WITHIN RANGE. SO FOR THIS PACKAGE THE GFS 10M WINDS WILL STLL BE

USED THROUGHOUT THE FORECAST PERIOD SINCE THE REST OF THE MODELS

CONTINUE TO SOMEHOW SUPPORT THE GFS. THE GFS HAS ALSO CONTINUED TO

BE QUITE CONSITENT. WILL MAKE JUST MINOR CHANGES TO THE PREVIOUS

FORECAST AND ALL THE WARNINGS WILL BE RETAINED. IN THE SHORT TERM

WILL DIMINISH WINDS OVER THE NRN WATERS AND CONTINUE GALE WARNINGS

ONLY OVER THE NRN CA WATERS. HIGH PRES TO THE W WILL START TO MOVE

E AND STILL DOMINATE THE WEATHER OVER THE REGION AND THIS SENARIO

WILL PERSIST INTO THE EXTENDED PERIOD.



.SEAS...THE SEAS HAVE PEAKED AT 15 FT IN THE AREA WITH GALE FORCE WINDS. 

WAVEWATCH-III AND ECMWF WAM MODELS ARE STILL VERY CLOSE TO THE

OBSERVED SEAS PATTERN BUT THEY ARE STILL UP TO 2 FT NOW LOWER ON

THE PEAK VALUE. BOTHE WAVE MODELS AGREE WELL THROUGH MOST OF THE

FORECAST PERIOD AND SO WILL CONTINUE TO USE NWW3 FOR THE SEAS BUT

LIKE BEFORE EDIT THE SEAS OVER THE AREA WITH HIGHER WINDS TO MATCH

THE INITIAL SEAS AND ALSO ACCOUNT FOR FORECAST HIGHER WINDS.



.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 TONIGHT.

     GALE POSSIBLE TUE NIGHT INTO THU NIGHT. 



$$



.FORECASTER KELLS/MUSONDA. OCEAN PREDICTION CENTER.

