Marine Interpretation Message
Issued by NWS

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AGPN40 KWNM 030251
MIMPAC

MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
751 PM PDT SUN AUG 2 2015

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

HGH PRES 1027 MB TO THE W HAS ITS RIDGE INTO THE NRN WTRS. LOW
PRES 1014 MB OVR NRN CA HAS TROF XTNDG SW. INLAND LOW PRES 1008
MB OVR NRN CA STATE HAS ITS TROF STRCTHNG SE INTO AZ. THE PRES
GRDNT IS FAIRLY WEAK AND THE MAX OBSVD WINDS ARE GENERALLY 20 KT.
THE LAST R-SCAT PASS AT 1846Z HAD NO WINDS ABOVE 20 KT ACRS THE
REGION. THE SEAS RANGE BTWN 3 AND 6 FT ACRS THE WTRS.

MDLS HV INITIALIZED WELL AND ARE IN GUD AGRMNT ON THE FEW SYNOP
FEATURES IMPACTING THE WX OVR THE REGION. WILL STAY WITH GFS. IN
THE SHORT TERM HGH PRES WILL REMAIN TO THE W AND THE LOW PRES OVR
NRN CA WTRS WILL DSIPT. HGH PRES RIDGE WILL CVR MOST OF THE
REGION. THE INLAND TROF WILL STENGTHEN TOWD THE END OF PRD AND
ALLOW WINDS TO INCREASE. SO WILL RETAIN THE WRNGS IN THE XTND PRD
OVR THE CNTRL WTRS.

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

SUMMARY...THE LATEST SATELLITE IMGRY AND THE EXPERIMENTAL
LIGHTNING STRIKE DENSITY DATA INDICATES A FEW TSTMS OVR THE INNER
OFF WTRS OFF THE OREGON COAST EARLY THIS AFTN. FOR THE AFTN FCST
PACKAGE WE WILL KEEP TSTM CHANCES FOR MAINLY INNER OREG OFF WTRS
INTO THE SRN WASH OFF WTRS...OR OFF ZONES PZZ805-810-815. LOCALLY
BRIEF GUSTY WINDS AND ROUGH SEAS CAN OCCUR IN OR NR ANY TSTMS
INTO TONITE. OVERALL...NO MAJOR CHANGES WILL BE MADE TO THE PREV
FEW OPC FCSTS FOR THE AFTN PACKAGE... WITH HIGH PRES STILL FCST
TO BUILD TO THE W OF THE OFF WTRS THROUGH THE MIDDLE OF THE WEEK
ALLOWING N WINDS TO INCREASE ESPEC OVR THE OREG AND NOCAL OFF
WTRS. THE HIGH WILL SLOWLY WEAKEN FRI AFTN AND NIGHT ALLOWING FOR
WINDS TO SLOWLY DIMINISH. IT STILL APPEARS THAT GALES WILL DVLP
OVR THE ERN NOCAL OFF WTRS LTR THU INTO FRI...AND FOR THE AFTN
PACKAGE WE WILL GO AHEAD AND ADD IN THE SE OREG OFF WTRS AS
WELL...OR OFF ZONE PZZ815. CONFDC LVLS REMAIN NEAR AVERAGE FOR
THESE GALES BY LTR THU INTO FRI.

MODELS...THE 12Z GLBL MDLS ARE ONCE AGAIN IN GOOD AGREEMENT OVR
THE OFF WTRS RIGHT THRU FRI NITE. WE WILL STAY CLOSE TO THE 12Z
GFS...WHICH WAS QUITE SIMILAR ITS PREV FEW MDL CYCLES...AND ALSO
IN VRY GOOD AGREEMENT WITH THE 12Z ECMWF MDL OUTPUT. FOR THE AFTN
PACKAGE WE WILL RELY ON THE 30M WINDS FROM THE GFS AS THEY APPEAR
TO BE VERIFYING CURRENTLY BASED ON THE LATEST OBS...ASCAT...AND
RSCAT DATA FROM THE REGION.

.SEAS...PER THE LATEST OBS...ALTIMETER DATA...RP1 OPC SEA STATE
ANALYSIS SEA HTS RANGE FROM 4 TO 7 FT OVR THE OFF WTRS. THESE SEA
HTS ARE WITHIN A FT OR SO OF THE 12Z ENP WV WATCH III MDL OUTPUT.
THE 12Z ECMWF MDL GUID IS ALSO QUITE SIMILAR TO THE WV WATCH III
MDL OUTPUT OVR THE AREA INITIALLY. THERE ARE SOME MINOR
DIFFERENCES IN THEIR OUTPUT TOWARD THE MIDDLE AND LATER PART OF
THE WK...BUT OVERALL NO MAJOR DIFFERENCES ARE NOTED. FOR THE AFTN
PACKAGE WE WILL USE A 50-50 BLEND OF THE ENP WW3 AND ECWMF WAM
MDL. THIS BLEND WILL ALLOW US TO MAINTAIN CONTINUITY FROM THE
PREV FEW OPC FCSTS...AND LKLY HELP TO LIMIT ERRORS BY USING JUST
A SINGLE MDL SOLUTION.

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


.WARNINGS...PRELIMINARY.

.PZ5 WASHINGTON/OREGON WATERS...
.PZZ815...INNER WATERS FROM FLORENCE OR TO POINT ST. GEORGE...
     GALE POSSIBLE THU NIGHT.

.PZ6 CALIFORNIA WATERS...
.PZZ820...INNER WATERS FROM POINT ST. GEORGE TO POINT ARENA...
     GALE POSSIBLE THU NIGHT.

$$

.FORECASTER MUSONDA/MILLS. OCEAN PREDICTION CENTER.


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