Marine Interpretation Message
Issued by NWS

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AGPN40 KWNM 161417
MIMPAC

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

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

AS PREVLY EXPECTED GNRLY WEAK GRADIENTS PERSIST THRUT MUCH OF THE
CSTL/OFSHR WTRS AT THE MOMENT. HIGHEST WINDS (UP TO 20-25 KT) ARE
OFF THE SRN CALIFORNIA IN NNWLY GRADIENT IN CONJUNCTION WITH THE
INLAND SFC TROF. MAX SEAS THRUT THE CSTL/OFSHR WTRS ARE IN THE 6-8
FT RANGE ACRS THE SRN PZ6 WTRS WHICH ARE BEING AIDED BY LONG
PERIOD SSWLY SWELL AND ARE BEING HANLDED SMWHT BETTER BY THE 00Z
ECMWF WAM VS THE 06Z WAVEWATCH III.

OVER THE SHORT TERM...THE LATEST MDLS ARE IN EXCELLENT AGRMT IN
REGARDS TO THEIR FCST TRACKS OF A SFC LOW MOVG INTO THE NRN PZ6
WTRS LATE WED/WED NITE...THEN DSIPTG LATE THU. IN RGRDS TO THE
FCST STRENGTH OF THE GRADIENTS ASCD WITH THIS SYSTEM A COMPROMISE
BTWN THE STRONGER 00Z/06Z GFS AND SMWHT WEAKER 00Z ECMWF/UKMET
LOOKS RSNBL. THEREFORE PER THIS COMPROMISE WL TWEAK THE PREVLY
POPULATED WIND GRIDS TO KEEP THE MAX ASCD WINDS IN THE 20-25 KT
RANGE IN THE NEXT OFSHR FCST PACKAGE.

IN THE LONG RANGE...THE LATEST MDLS AGREE THAT THE MOST PROMINENT
FEATURE WL BCM A STRENGTHENING NNWLY GRADIENT DVLPG LATE FRI INTO
SAT BTWN A HIGH PRES RIDGE ACRS THE PZ5 WTRS AND A STRENGTHENING
SFC TROF NR THE CALIFORNIA COAST...WHICH WL THEN WEAKEN LATE
SAT/SAT NITE. FOR THIS NNWLY GRADIENT ACRS THE NRN PZ6 AND SE PZ5
WTRS A COMPROMISE BTWN THE STRONGER 00Z/06Z GFS 30M BL AND WEAKER
00Z ECMWF BL WINDS LOOKS RSNBL. SO PER THIS BLEND PLAN ON MAKING
SM MINOR LONG RANGE CHNGS TO THE PREV OFSHR FCSTS.




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

THE SAT IMG STILL HAS SOME CONV CLDS APPROACHING THE NRN WTRS
WHILE THE MOST OF THE SRN IS STILL UNDER CLR OR THIN CLDS. LGHTNG
IS EMBDD IN A FEW AREAS W OF THE REGION WHILE MORE CONCNTRTD
LGHTNG IS INLAND OVR NV/OR BOARDER AREAS. THE RADAR CONTINUES TO
SHOW NO TSTMS CELLS OVR THE REGION. AT 16/0600Z 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 240 NM NW OF THE WA WTRS HAS A VERY WEAK RIDGE INTO THE NW
PARTS OF THE WA WTRS. INLAND LOW PRES OVR AZ STILL 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 LATST ASCAT PASS OVR THE
REGION AT 0510Z HAD NO WINDS ABOVE 20 KT ACRS THE FCST REGION.

THERE IS SOME LOCALLY INDUCED ENERGY APPROACHING THE NRN AND
PARTS OF CNTRL WTRS THAT WILL FORCE MORE PRES FALLS OVR THE REGION
AS TROF ALOFT MOVES ACRS THE NRN WTRS. MOST OF THE ENRGY WILL
SLIDE DOWN TO THE SRN CA AND AZ AREA. THAT WILL BE FOLLOWED BY AN
UPPER LEVEL RIDGE WHICH WILL BLOCK ANY FARTHER ENERGY TO REINFORCE
THE SYS OVR THE REGION. THIS SENARIO WILL LIKELY FORCE DVLPMNT OF
LOW PRES OVR THE CNTRL REGION AT THE SFC.

THE 00Z 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 UKMETHR BECOMES
THE ONLY ONE THAT DVLPS AN XTRA LOW OVR THE NRN WTRS. THE DVLPMNT
OF LOW PRES OVR THE REGION IS STRNGLY SUPPORTED BY SYNOP FEATURES
ALOFT AND SO WILL GO WITH A MDL THAT SUPPORTS THAT AND BOTH THE
ECMWFHR AND GFS ARE IN DECENT AGRNT ON THAT. AS SUCH WILL RETURN
MOST OF THE WINDS AS BEFORE WITH 50-50 BLEND OF GFS AND THE
ECMWFHR. IN THE SHORT TERM LOW PRES AREA WILL DVLP W OF THE REGION
AND MOVE E INTO THE REGION AS IT WEAKENS AS HIGH PRES BUILDS IN
JUST BEHIND THE LOW. THE INLAND TROF WILL PERSIST BUT WITH NO
COUNTERACTING FORCE THE PRES GRDN WILL NOT TIGHTEN ENOUGHT TO
FORCE WINDS TO GALE FORCE THRESHOLD.THRU THE FCST PRD.

.SEAS...ARE EQUALLY MEDIOCORE RANGING BETWEEN 2 AND 5 FT OVER MOST
OF THE REGION EXCPT THE FAR SRN PARTS. TROP STRM 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 LATST 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 BLEND IS
JUST AS FINE AND SO WILL RETURN SEAS CLOSE TO THE PREVIOUSLY
ISSUED SEAS.

.EXTRATROPICAL STORM SURGE GUIDANCE...ETOFS SHOW A POSITIVE SURGE
TO 2/10 FEET OVR THE FAR SRN CA TNGHT.


.WARNINGS...PRELIMINARY.

.PZ5 WASHINGTON/OREGON WATERS...
     NONE.

.PZ6 CALIFORNIA WATERS...
     NONE.

$$

.FORECASTER VUKITS/MUSONDA. OCEAN PREDICTION CENTER.


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