Marine Interpretation Message
Issued by NWS

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AGPN40 KWNM 181540
MIMPAC

MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
740 AM PST THU DEC 18 2014

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

OCCLUDING FNTL SYSTEM ASCD WITH THE STG LOW OUT AT 50N150W IS
APCHG PZ5 WTRS AT 12Z. STRONGEST WNDS EXPECTED FAR N WATERS OF UP
TO 45 KT AS FNT ENTERS THE WTRS WITH HI CONFDC GALES N OF
FLORENCE OR MAINLY OUTER WTRS EARLY THEN EXPANDING S ALG INNER
WTRS AS INCREASED CHANNELING DVLPS AS FNT MOVS TWD CST. GFS BL
WNDS UP TO 60 KT AND UKMET 10M WNDS UP TO 45 KT N OF AREA IN BC
WTRS SPRT STORM CONDS WITH INCREASED CHANNELED FLOW IN THAT AREA.
CONT TO FAVOR HIGHER GFS 30M WNDS WITH THIS FNT. 15Z RPT FM 46005
INDC FNT HAS PASSED. IR STLT IMAGERY SHOWS EXTENSIVE COLD TOPPED
CNVTN HEADING TWD OFFSHORE WTRS BHND FNT ON S SIDE OF STORM CNTR
ALG WITH SOME LTG STRIKES APPRNG IN LTG DATA. HENCE WILL CONT TO
MENTION SCT TSTMS IN SOME OF OUTER PZ5 ZONES MAINLY TONIGHT. NEXT
FNT DUE SAT INTO SAT NIGHT DOES NOT LOOK QUITE AS STG IN MDLS BUT
MAY STILL SPRT STORM WNDS VANCOUVER ISL WTRS NWD IN MORE FAVORABLE
CHANNELED FLOW THERE. OTRW THERE IS GOOD SPRT FOR GALES IN PZ5
WTRS WITH THE HIGHEST WNDS ASCD WITH THE STRONGER WRMFNT IMMEDLY
PRECEDING THE CDFNT. GENL SW FLOW SETS UP WITH CDFNT AND ANOTHER
CDFNT FOLLOWING CLOSE BHND AS LOWS CONT TO TRACK INTO GLF OF AK.
SOME CHANGE IN PTRN EXPECTED LATE SUN INTO MON NIGHT AS UPR RDG
AND ASCD SFC HIGH BUILDS OVR WTRS.

MDLS...PREFER GFS 30M WNDS INTO SAT NIGHT THEN MORE CONSERVATIVE
10M WNDS IN SW FLOW OR DVLPG HI PRES SUN AND BYND. ONE WRINKLE IS
00Z ECMWF/UKMET DVLPG A STG LOW CLOSE TO WA WTRS LATER SAT NOT
SPRTD BY GFS/GEM OR 00Z GFS/EC ENSEMBLE MEANS. WITH 06Z GFS
CONSISTENT WITH PREVIOUS RUN WILL USE EXISTING WND GRIDS BASED ON
00Z GFS WITH MINOR EDITS.

SEAS...PRESENT GRIDS BASED ON 00Z ENP WW3 LOOK RSNBL AND WILL STAY
WITH 00Z/06Z GUIDANCE. 00Z ECMWF WAM LOOKS TOO HIGH SAT INTO SUN
DUE TO PRESENCE OF STG LOW PASSING NR WA WTRS...AND PREFER
FLATTER WW3 PATTERN. THE TWO MDLS OTRW SHOW SML DIFFERENCES. ENP
WW3 DOES BRING IN SWELL 2-3 FT HIGHER THAN ECMWF ASCD WITH STG LOW
W OF AREA...BUT SO FAR HAVE NO DATA AROUND S AND SE SIDES OF THAT
LOW.
-----------------------------------------------------------------
PREVIOUS DISCUSSION...

THE CRNT GOES WV IMGRY INDC AN UPR RDG OVR THE COAST...AND A TROF
JUST W OF THE OFSHR WTRS WITH A FAIRLY PRGRSV FLAT PTTN IN THE C
AND W PACIFIC. THE IR IMGRY AND LTST NCEP SFC ANALYS INDC A WKNG
LOW PRES SYS OVR THE NRN CAL OFSHR WTRS ATTM...AND 0447 UTC ASCAT
WND RETRIVALS INDC WINDS UP TO 30 IN THE CHANNELING FLOW BTWN A
FRNTL BNDRY AND THE COAST. EARLIER RAPIDSCAT WINDS FROM 2257 UTC
INDC WINDS IN THE 25 TO 30 KT RANGE...WITH A FEW RAIN-FLAGGED GALE
BARBS ALNG THE COAST NEAR CAPE MENDOCINO. THE TIME DIFF AND DIFF
IN WIND INTSTY BTWN THE 2 SCATTEROMETERS SUGGESTS THE BNDRY IS
WKNG...AND THIS CORROBORATED BY THE TREND OF SFC RPRTS OVR THE
PAST FEW HOURS SHOWING A DCRS IN THE WIND ITNNSTY. THE 00Z GFS
WINDS INDC UP TO 25 KT AT 06Z...WITH THE FRNT DSIPTG BY AROUND
12Z. THE REST OF THE 00Z MDLS INDC A VRY SIMILAR TREND...SO WL
CONT ALNG WITH THAT IDEA IN THE NEXT FCST PKG.

THE 00Z MDLS ALL INDC THE MID-LVL TROF W OF THE AREA WILL PASS
THRU THE AREA TDA INTO FRI...AS THE ASSOC STG FRNTL SYS PASSES
THRU THE OFSHR WTRS. THE GFS HAS BEEN THE STGST WITH THE WNDS ON
THIS SYS...ESP NEAR VANCVR ISLE WHERE STG CHANNELING FLOW BTWN THE
FRNT AND THE COAST IS XPCTD TO CAUSE AN ACCELERATION IN THE WNDS.
THE GFS INDC 55 TO 60 KT NEAR JUST W OF VANCVR ISLE TDA...AND ONLY
THE 00Z NAM INDC STORM FRC. THE 00Z ECWMF/UKMET/GEM ARE CAP WINDS
AT 45 KT...THO THE ECMWF TRENDED SLGTLY STGR TWD THE GFS SOLN WITH
THE 00Z RUN. HOWEVER...THE GFS HAS BEEN PERFORMING BETTER OVER
THE PAST FEW WEEKS WITH NEARLY SAME SCENARIO OCCURRING ON SEVL
OCCASIONS....SO ATTM PREFERRING THE STGR GFS WNDS...THO KEEPING
STRM FRC N OF THE OFSHR WTRS. ALSO PLAN ON USING THE 30M BL GFS
WINDS WHICH BETTER REPRESENTS THE XPCTD MIXG. FURTHERMORE...THE
GFS INDC A STG NEG ANOMOLY IN THE H5 TEMP FIELD ON TOP OF THE CAA
AFTER THE FROPA. THE MDLS ARE HINTING AT A FEW TSTMS OVR THE NRN
OFSHR WTRS IN THE UNSTABLE ENVRMT...WHICH SEEMS PSBL WITH THE
XPCTD UNSTABLE LAPSE RATE...SO WL PUT IN A MENTION OF TSTMS IN A
FEW OF THE PZ5 ZONES.

OTRW...THE 00Z GFS AGREES FAIRLY WELL WITH THE 00Z ECMWF ON THE
SYNOP PTTN...AND INDC ANTHR STG FRNTL BNDRY THRU THE PZ5 WTRS ON
SAT. THE MDLS HAVE BEEN CONSISTENTLY INDCG GALES OVR THE OFSHR
WTRS FRI NGT INTO SAT...AND AGAIN INDC STGR WNDS AHD OF THE FRNT
AS IT PINCES AGAINST THE COAST OF VANCVR ISLE. HOWEVER...THIS SYS
DOES NOT APPEAR TO BE QUITE AS STG...AND GFS WINDS RMN IN THE 40
TO 45 KT RNG. THE ECMWF IS ALSO INDC A WK H5 VORT WL MOV IN BEHIND
THE FRNT...AND DVLP A SFC LOW. THE REST OF THE GUID IS EVENLY
SPLIT ON IT...AND THE ECWMF HAS BACKED OFF SOME WITH THE STRENGTH
OF THE LOW FM THE 12Z RUN...SO CONFDC IS LOW ON IT. THE GFS HAS
BEEN A LTL MORE CONSISTENT ON IT...SO WL STAY NR IT WITH THIS SYS.

IN THE EXTENDED...THE 00Z MODELS ALL SLOWLY BUILD AN UPR RDG OVR
THE E PAC AFTER SAT...WHICH PUSHES ALL SUBSEQUENT WK SHRTWVS
PRGRSVLY N. WITH NOT MUCH SIG DIFF BTWN SOLNS...WL CONT WITH THE
00Z GFS THRU THE END OF THE PD...THO WL FAVOR 10M WNDS AFTER SAT.

SEAS...00Z NWW3 AND ECMWF WAM ARE INIT OK AND ARE IN GUD AGRMT IN
THE SHORT TERM. MDL START DIFFERING ON SUN IN PZ5...WITH ECWMF WAM
BUILDING SEAS HIGHER IN WAS WTRS DUE TO AFOREMENTIONED SHRTWV
ENGERY THAT DVLPS LOW AND ULTIMATELY STGR SFC WINDS THAN GFS. ATTM
PREFERRING THE GFS SOLN WITH THIS NEXT FCST...SO WL USE NWW3 MDL
FOR SEAS...TO REMAIN CONSISTENT WITH PREFERRED WX MDL.

GRIDS...00Z GFS WITH 30M BL WNDS TDA THROUGH 09Z SUN...THEN 00Z
GFS 10M WINDS TO END OF FCST. 00Z NWW3 MDL USED FOR SEAS.

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

.WARNINGS...PRELIMINARY.

.PZ5 WASHINGTON/OREGON WATERS...
.PZZ800...INNER WATERS FROM CAPE FLATTERY TO CAPE SHOALWATER...
     GALE TODAY.
     GALE FRI NIGHT.
     GALE POSSIBLE SAT.
.PZZ900...OUTER WATERS FROM CAPE FLATTERY TO CAPE SHOALWATER...
     GALE TODAY.
     GALE FRI NIGHT.
.PZZ805...INNER WATERS FROM CAPE SHOALWATER TO CAPE LOOKOUT...
     GALE TODAY.
     GALE FRI NIGHT.
     GALE POSSIBLE SAT.
.PZZ905...OUTER WATERS FROM CAPE SHOALWATER TO CAPE LOOKOUT...
     GALE TODAY.
     GALE FRI NIGHT.
.PZZ810...INNER WATERS FROM CAPE LOOKOUT TO FLORENCE OR...
     GALE TODAY.
     GALE FRI NIGHT.
     GALE POSSIBLE SAT.
.PZZ910...OUTER WATERS FROM CAPE LOOKOUT TO FLORENCE OR...
     GALE TODAY.
     GALE FRI NIGHT.
.PZZ815...INNER WATERS FROM FLORENCE OR TO POINT ST. GEORGE...
     GALE TODAY.
     GALE FRI NIGHT.
     GALE POSSIBLE SAT.
.PZZ915...OUTER WATERS FROM FLORENCE OR TO POINT ST. GEORGE...
     GALE FRI NIGHT.

.PZ6 CALIFORNIA WATERS...
.PZZ820...INNER WATERS FROM POINT ST. GEORGE TO POINT ARENA...
     GALE TODAY.

$$

.FORECASTER BANCROFT/KELLS. OCEAN PREDICTION CENTER.


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