

600 

AGPN40 KWNM 190315

MIMPAC



MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN

NWS OCEAN PREDICTION CENTER WASHINGTON DC

815 PM PDT THU AUG 18 2016



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

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



ATTM I DONT PLAN ON MAKING ANY CHANGES TO THE CURRENT GRIDS OR

ASSOCIATED TEXT FCST. ASCAT PASS FROM 19Z INDICATES LARGE SWATH OF

30 KT WINDS ACROSS THE WA WATERS...COULD BE SOME 35 KT MIXED IN.

MAX SEA NR 12 FT ACROSS THE OFFSHORE WATERS.



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PREVIOUS DISCUSSION...



THE SAT IMG STILL INDC STRONG HIGH PRES TO THE W OF THE NRN

WATERS. ALL THE OBSERVATIONS INCLUDING THE ASCAT PASSES AT 1704Z

AND 1842Z SHOW MAX WINDS OVER THE NRN WATERS. THE WINDS HAVE

DIMINISHED TO BELOW GALE FORCE OVER THE CENTRAL WATERS BUT REMAIN

IN THE GALE FORCE THRESHOLD JUST N OF THE REGION. AT 18Z THE NCEP

MAP STILL HAS HIGH PRES 1036 MB TO THE W OF THE REGION NEAR

45N140W WITH ITS RIDGE EXTENSION INTO THE WATERS. INLAND LOW PRES

1008 MB OVER CA HAS CONTINUED TO MAINTAIN A TROF EXENDING NW INTO

THE OR WATERS AND ANOTHER SE ACROSS CA. ANOTHER TROF EXTENDS NW

ACROS WA STATE. THE PRES GRADIENT HAS CONTINUED TO RELAX OVER THE

CENTRAL WATERS BUT REMAINS TIGHT JUST N OF THE REGION.



AN UPPERLEVEL HIGH PRES JUST W OF THE WATERS EXTENDS A RIDGE INTO

THE GULF OF AK AND THAT HAS KEPT MOST OF THE ENRGY EMBEDDED IN AN

UPPERLEVEL CUT OFF LOW AROUND THE ALEUTIAN ISLANDS. SOME OF THE

LOCALLY INDUCED ENERGY INLAND EXTENDS INTO THE CENTRAL FORECAST

WATERS. THE MODELS INDC THAT THE UPPERLEVEL HIGH WILL SHIFT

FARTHER SW AND THAT WILL ALLOW MORE ENERGY INLAND TO REMAIN OVER

THE CENTRAL WATERS AND ALSO LET THE ENERGY IN THE GULF OF AK TO

SHIFT SE AND PASS NEAR THE NRN WATERS. 



THE GLOBAL MODELS HAVE CONTINUED TO INITILAIZE WELL THE PRES

FIELDS BUT STILL HAVE SOME MINOR DIFFERENCES IN THE WIND SPEED AND

DIRECTION. THE GFS AND UKMETHR MATCH THE OBSERVED WIND SPEED BUT

ECMWFHR IS 5 KT BELOW THE OBS OVER THE NRN AND CENTRAL WATERS

WHILE THE CMC IS 5 KT ABOVE THE OBS. SINCE THE ECMWFHR IS

CONSISTENTLY BELOW THE OBSERVED WIND SPEED AND THE CMC IS

GENERALLY ABOVE...WILL USE GFS AND MAKE SOME MODIFICATIONS TO THE

WINDS OVER THE NRN WATERS. IN THE SHORT TERM THE HIGH PRES WILL

PERSIST TO THE W OF THE REGION WHILE THE INLAND TROF WEAKENS. THE

PRES GRDIENT WILL REMAIN RELAXED OVER THE REGION EXCEPT TO THE N

AND SO WILL BRIEFLY KEEP GALES IN THE FAR NRN WATERS FOR JUST ONE

PERIOD BUT MAINTAIN THEM JUST N OF THE REGION. THE PRES GRADIENT

WILL REMAIN RELAXED IN THE EXTENDED PERIOD AND SO WITH MOD CONFDNC

WILL KEEP WATRES FREE OF WARNINGS IN THE EXTENDED PERIOD. JUST

BEFROE END OF PREIOD AS MORE INALND ENERGY MOVES INTO THE WATERS

THE PRES GRADIENT WILL BECOME TIGHT OVER THE CENTRAL WATERS AND

WINDS ESPECIALLY OVER THE ERN PORTIONS WILL BE ELEVATED TO JUST

BELOW GALE FORCE THRESHOLD.



.SEAS...THE SEAS PEAK AT 11 FT OVER THE CENTRAL WATERS AND THEY

RANGE BETWEEN 6 AND 9 FT ELSEWHERE. THE NWW3 MULTI GRID WAVE MODEL

IS VERY CLOSE TO THE OBSERVED SEAS PATTERN BUT JUST UNDERDONE BY A

FOOT OVER THE NRN AND CENTRAL WATERS. OTHERWISE NWW3 AND THE

ECMWFWAVE AGREE WELL IN THE SHORT TERM WITH JUST MINOR DIFFERENCES

WITHIN 1 FOOT IN THE EXTENDED PERIOD. THE SEAS WILL SUBSIDE TO

BELOW 8 FT BY MON AND WILL REMAIN THAT WAY THRU TUE NIGHT.





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





.WARNINGS...PRELIMINARY.



.PZ5 WASHINGTON/OREGON WATERS...

     NONE.



.PZ6 CALIFORNIA WATERS...

     NONE.



$$



.FORECASTER SHAW/MUSONDA. OCEAN PREDICTION CENTER.

