Marine Interpretation Message
Issued by NWS

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AGPN40 KWNM 170255
MIMPAC

MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
755 PM PDT TUE 16 SEP 2014

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

18Z GFS AND 18Z/00Z NAM WERE GENERALLY CONSISTENT WITH THEIR
RESPECTIVE PREVIOUS RUNS OVER THE E PACIFIC FOR NEXT COUPLE
DAYS. GFS CONTINUES TO BE SLIGHTLY STRONGER THAN NAM/ECMWF/UKMET
WITH PRE FRONTAL WINDS MOVING INTO PZ6 WATERS TNGT INTO WED NGT.
SO THE PREVIOUSLY FAVORED GFS/ECMWF BLEND LOOKS GOOD WITH
INCREASING S TO SE WINDS TO 25 KT. MDLS ARE IN GOOD AGREEMENT
THAT SFC LOW SHOULD WEAKEN FAIRLY RAPIDLY OVER OFFSHORE WATERS
ALONG WITH ASSOCIATED N TO NW WINDS OVER W AND SW QUADS OF LOW.
THERE IS ABOVE AVG AGREEMENT BETWEEN MDLS AT DAYS 3-5 AS WELL.
WILL NOT BE MAKING SIGNIFICANT ADJUSTMENTS TO PREVIOUS PZ5/PZ6
FORECASTS/ GRIDS IN THIS EVENINGS UPDATES.

18Z MULTIGRID WAVEWATCH III HAS GOOD HANDLE ON E PACIFIC SIG WV
HGTS...AND OVER PAST SEVERAL RUNS THERE HAS BEEN GOOD AGREEMENT
BETWEEN MWW3 AND ECMWF WAVE MDL.

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

OVER THE SHORT TERM...THE NEW 12Z MDLS REMAIN RMRKBLY CONSISTENT
IN FCSTG AN UPR TROF TO APRCH THE OFSHR WTRS TONITE/WED...THEN
WEAKEN WED NITE INTO THU NITE AS IT MOVES TO THE COAST. AT THE
SFC THE 12Z MDLS OVERALL REMAIN IN EXCELLENT AGRMT IN REGARDS TO
THEIR FCST TRACKS OF AN ASCD SFC LOW MOVG INTO THE NRN PZ6 WTRS
LATE WED/WED NITE...THEN DSIPTG LATE THU. IN RGRDS TO THE FCST
GRADIENTS ASCD WITH THIS SYSTEM...A COMPROMISE BTWN THE SLIGHTLY
STRONGER 12Z GFS/GEM AND THE WEAKER 12Z NAM/UKMET/ECMWF LOOKS
RSNBL. THEREFORE TO ASSIMULATE THIS COMPROMISE PLAN ON
POPULATING OUR SHORT TERM WIND GRIDS WITH A 50/50 BLEND OF THE
12Z GFS 30M AND 12Z ECMWF BL WINDS THRU THU NITE. SO AS A RESULT
ANTICIPATED MAKING ONLY MINOR SHORT TERM CHNGS TO THE PREV OFSHR
FCSTS.

IN THE LONG RANGE...AFTER A DSIPTG COLD FRONT PUSHES INTO THE
PZ5 WTRS THU NITE THE 12Z MDLS GNRLY AGREE THAT A HIGH PRES
RIDGE WL BUILD SW TO NW ACRS THE PZ5 WTRS FRI INTO SAT WHILE A
CSTL TROF NR THE CALIFORNIA COAST STRENGTHENS. AS A RESULT TO
VARYING DEGREES THE MDLS ALL FCST A STRENGTHENING NNWLY GRADIENT
TO DVLP ACRS THE NRN PZ6 AND SE PZ5 WTRS. CONSISTENT VS THEIR
PREV RESPECTIVE RUNS THE 12Z GFS/GEM FCST A STRONGER NNW
GRADIENT (WITH THE 12Z GFS FCSTG SM 30M GALE FORCE BL WINDS NR
PT ST GEORGE FRI NITE) THAN THE 12Z NAVGEM/UKMET/ECMWF. AGAIN AS
A COMPROMISE PLAN ON POPULATING OUR WIND GRIDS FOR THIS GRADIENT
USING A 50/50 BLEND OF THE 12Z GFS 30M AND 12Z ECMWF BL WINDS
FRI INTO SAT. THEN BY LATE SAT/SAT NITE THE MDLS ALL FCST THE
RIDGE TO WEAKEN ALWG THE NNWLY GRADIENT TO WEAKEN WITH DMNSHG
WINDS. THEN SAT NITE THE 12Z GFS/ECMWF BOTH FCST A WEAK SFC LOW
TO DVLP ALONG THE CSTL TROF AND THEN MOV NW INTO THE PZ5 WTRS
SUN AND DSIPT WITH WEAK (PRIMARILY 10-15 KT) ASCD GRADIENTS.
THEN SINCE ITS IN SMWHT BETTER AGRMT WITH THE LATEST WPC MEDIUM
RANGE GUIDANCE WL FAVOR THE 12Z ECMWF FCST TIMING OF A WEAK COLD
FRONT APRCHG FM THE W SUN AND THEN MOVG INTO THE PZ5 WTRS SUN
NITE. THEREFORE SINCE ITS QUITE SMLR TO THE 12Z GFS...PLAN ON
TRANSITIONING TO POPULATING OUR FCST WIND GRIDS WITH ALL 12Z
ECMWF BL WINDS LATE SAT THRU SUN NITE.

.SEAS...WITH THE DIFFERENCES BTWN THE TWO MDLS NEVER EXCEEDING
1-2 FT...PLAN ON USING A 50/50 BLEND OF THE 12Z WAVEWATCH III
AND 12Z ECMWF WAM MDLS THRU SUN NITE.

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

.WARNINGS...PRELIMINARY.

.PZ5 WASHINGTON/OREGON WATERS...
     NONE.

.PZ6 CALIFORNIA WATERS...
     NONE.

$$

.FORECASTER CLARK/VUKITS. OCEAN PREDICTION CENTER.


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