Marine Interpretation Message
Issued by NWS

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000
AGPN40 KWNM 160326
MIMPAC

MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
826 PM PDT MON SEP 15 2014

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

THE SAT IMG HAS SOME CONV CLDS APPROACHING THE NRN WTRS WHILE THE
MOST OF THE SRN IS UNDER CLR OR THIN CLDS. SOME LIGHTNG IS EMBDD
IN A FEW AREAS W OF THE REGION WHILE MORE CONCNTRTD LGHTNG IS
INLAND OVR NV/OR BOARDER AREAS. THE RADAR SHOW NO TSTMS CELLS OVR
THE REGION. AT 16/0000Z A LARGE AREA OF LOW PRES XPANDS FROM 150W
ACRS THE NRN AND CTNRL REGION WATERS WITH A SERIES OF LOW PRES
CNTRS IN THE SAME AREA. A WEAK HGH PRES 1014 MB APPROX 120 NM NW
OF THE WA WTRS HAS A VERY WEAK RIDGE INTO THE NW PARTS OF THE WA
WTRS. INLAND LOW PRES OVR AZ XTNDS A TROF NW ACRS CA. THE PRES
GRDNT IS VERY SLACK AND THE MAX OBS WINDS ARE ONLY 15 KT FROM THE
NW OVR THE SRN WTRS AND MOSTLY VRB WINDS UP TO 10 KT OVR THE REST
OF THE REGION. THE LAST ASCAT PASS OVR THE REGION WAS AT 1928Z AND
HAD NO WINDS ABOVE 20 KT ACRS THE FCST REGION. THE SEAS ARE
EQUALLY MEDIOCORE RANGING BETWEEN 2 AND 5 FT OVER MOST OF THE
REGION EXCPT THE FAR SRN PARTS. HURCN ODILE HAS MOST OF ITS SWELLS
SHIELDED IN THE GULF OF CA AND SO SEAS ARE ONLY REACHING 7 FT
PEAKS OVR THE SRN WTRS. THE LAST JASON PASS AT 2316Z MISSED MOST
OF THE REGION BUT PASSED QUITE CLOSE TO THE WRN PARTS OF THE
FRCST WTRS AND HAD NO INDC OF SEAS ABOVE 5 FT OVR THE REGION. THE
NWW3 MULTI GRID FITS WELL WITH THE OBS SEAS PATTERN AND HAS BEEN
QUITE CONSSTNT IN THE PREVIOUS RUNS. THERE ARE JUST MEAGRE DIFFS
BTWN THE NWW3 AND THE ECMWFWAVE AND SO A BLEMD IS JUST AS FINE AND
SO WILL RETURN SEAS CLOSE TO THE PREVIOUSLY ISSUED SEAS. THE 18Z
RUN SHOW THAT GLBL MDLS HAV INITIALIZED WELL AND THEY DEPICT GUD
AGRMNT IN THE SHORT TERM. THE DIFS ARE VIVID WHEN A LOW PRES
APPROACHES THE CNTRL REGION FROM THE SW AS UKNMETHR BECOMES THE
ONLY ONE THAT DVLPS AN XTRS LOW OVR THE NRN WTRS. OTHERWISE WILL
GO WITH GFS. IN THE SHORT TERM LOW PRES AREA WILL PERSIST W OF THE
REGION BUT WILL BE WEAKENING AS HIGH PRES BUILD W OF THE LOW. THE
INLADN TROF WILL PERSIST BUT WITH NO COUNTERACTING FORCE THE PRES
GRDN WILL REMAIN FAIRLY SLACK AND WINSD WILL REMAIN BELOW GALE
FORCE THRU THE FCST PRD.

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

OVER THE SHORT TERM...THE NEW 12Z MDLS GNRLY AGREE THAT IN
RESPONSE TO A CLOSED UPR LVL LOW APRCHG THE NRN PZ5 WTRS TUE
NITE/WED...THEN TRANSITIONING INTO AN OPEN TROF WED NITE/THU... AS
ASCD NRLY VERTICALLY STACKED SFC LOW WL APRCH THE NRN PZ5 WTRS TUE
NITE...THEN MOVE INTO THE NRN PZ5 WTRS LATE WED/WED NITE AND DSIPT
LATE THU. FOR THE FCST TRACK OF THIS SYSTEM THE 12Z GFS/ECMWF FCST
NRLY IDENTICAL TRACKS WHICH ARE SPRTD BY THE 12Z GEFS MEAN. IN
RGRDS TO THE ASCD FCST GRADIENTS...A COMPROMISE BTWN THE SLIGHTLY
STRONGER 12Z GFS AND SLIGHTLY WEAKER 12Z ECMWF LOOKS RSNBL.
THEREFORE PLAN ON POPULATING OUR SHORT TERM WIND GRIDS THRU THU
WITH A 50/50 BLEND OF THE 12Z GFS 10M AND 12Z ECMWF BL WINDS WHICH
WL RESULT IN MAX WINDS UP TO 20-25 KT INVOF THE SFC LOW ACRS THE
NRN PZ6 AND SRN PZ5 WTRS. SO AS A RESULT EXPECT TO MAKE MINIMAL
SHORT TERM CHNGS TO THE PREV OFSHR FCSTS.

IN THE LONG RANGE...BY LATE THU/THU NITE THE 12Z MDLS AGREE THAT
THE NEXT FEATURE WL BE A DSIPTG FRONT MOVG INTO THE PZ5 WTRS WITH
WEAK (15-20 KT) ASCD GRADIENTS. WITH THEIR SOLUTIONS RMNG SMLR FOR
THIS FROPA WL CONT TO POPULATE OUR WIND GRIDS WITH A 50/50 BLEND
OF THE 12Z GFS 10M AND 12Z ECMWF BL WINDS THU/THU NITE. THEN BY
LATE FRI INTO SAT ALL OF THE 12Z MDLS FCST A HIGH PRES RIDGE TO
BUILD INTO THE PZ5 WTRS WHILE A LOW PRES TROF NR THE CALIFORNIA
COAST STRENGTHENS...RESULTING IN A STRENGTHENING NNWLY GRADIENT
DVLPG IN BTWN ACRS THE NRN PZ6 AND SE PZ5 WTRS...WHICH THEN
WEAKENS SAT NITE AS THE RIDGE IS FCST TO WKN. FOR THIS NNWLY
GRADIENT BLV THE 12Z GFS LOOKS A LTL TOO STRONG (IN FACT THE 12Z
GFS FCSTS GALE FORCE 30M BL WINDS DVLPG OFF PT ST GEORGE FRI NITE)
WHL THE 12Z ECMWF LOOKS A LTL TOO WEAK. THEREFORE AS A COMPROMISE
FOR THIS GRADIENT WL USE A 50/50 BLEND OF THE 12Z GFS 30M AND 12Z
ECMWF BL WINDS ON FRI THRU SAT NITE.

.SEAS...WITH HURCN ODILE NOW TRACKING NNW ACRS THE BAJA PENINSULA
THE BULK OF ITS HIGHEST ASCD SWELL ARE NOW CONFINED TO THE GULF
OF CALIFORNIA...THO SM MINIMAL SSE SWELL WL LIKELY AFFECT THE SRN
PZ6 WTRS TONITE INTO TUE AS THE SYSTEM WKNS. SEE THE LATEST NHC
ADVSRY ON ODILE. OTHERWISE WITH THE DIFFERENCES BTWN THE 12Z
WAVEWATCH III AND 12Z ECMWF WAM NOT EXCEEDING 1-2 FT...SMLR TO HOW
THEIR ASCD GLOBAL MDL FCST WINDS WL BE BLENDED...PLAN ON
POPULATING OUR FCST WAVE GRIDS WITH A 50/50 BLEND OF THE TWO MDLS
THRU SAT NITE.

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


.WARNINGS...PRELIMINARY.

.PZ5 WASHINGTON/OREGON WATERS...
     NONE.

.PZ6 CALIFORNIA WATERS...
     NONE.

$$

.FORECASTER MUSONDA/VUKITS. OCEAN PREDICTION CENTER.


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