000
AGPN40 KWNM 011422
MIMPAC

MARINE WEATHER DISCUSSION FOR N PACIFIC OCEAN
NWS OCEAN PREDICTION CENTER WASHINGTON DC
722 AM PDT TUE SEP 1 2015

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

STG LOPRES JUST W OF HAIDA GWAII WAS ANALYZED TO 995 MB ON THE
12Z OPC/NCEP PRELIM SFC ANALYSIS...ALONG WITH SIG WVHTS TO 17 FT
ON THE 12Z RP1 SEA STATE. THIS LOW WILL FILL QUICKLY AS IT DRIFTS
SE TWDS WRN BC...AND LTST 06Z GFS/NAM BOTH INDC WINDS WL ABATE
QUICKLY OVR THE NXT 24 HRS AS THE LOW WKNS. PREV FCST HAD WINDS TO
30 KT ACRS THE NRN PZ5 WTRS THIS EVE/TNGT AS THE LOW PASSES N OF
THE WTRS...HWVR BASED THIS NEW GUID AND 00Z ECMWF/UKMET...WILL
CAP WINDS TO 25 KT IN THE UPCOMING UPDATE ACRS THE NRN WASH AREAS.

OTWR...NO SIG CHANGES IN STORE FOR THE MORN UPDATE TO THE ONGOING
FCST PKG THAT IS ALREADY IN PLACE. WILL AWAIT 12Z MODEL CYCLE
THIS AFTN AND RE- EVALUATE FCST THRUT.

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

THE SAT IMG INDC MSTLY CLR SKIES OVR THE SRN HALF BUT CLDY OVR
THE NRN WTRS WITH NO LIGHTNG STRIKES. THE RADAR HAS NO INDC OF
TSTMS CELLS OVR THE ENTIRE REGION. AT 06Z WEAK INLAND LOW PRES
1000 MB OVR CANADA JUST N OF WA STATE HAS A CLD FRNT STRTCHNG SW
ACRS WA THEN INTO THE NRN WTRS HENCE THE CLDY NRN WTRS. HGH PRES
1030 MB NR 42N155W HAS ITS RIDGE RIDGE XTNDG SE ACRS THE SRN WTRS
WITH ITS RIDGE AXIS PASSING JUST W OF THE SRN WTRS. INLAND LOW
PRES TROF STRETCHES FROM SRN CA INTO SRN NV. THERE IS ANOTHER LOW
PRES 992 MB OVR THE ERN PARTS OF THE GULF OF AK THAT HAS A TROF
STRCHNG SE ALONG THE CANADA COAST. THE PRES GRDNT IS JUST TIGHT
OVR THE NRN WTRS ESPCLY WITHIN THE VCNTY OF THE CLD FRNT. THE MAX
OBSVD WINDS ARE 25 KT OVR THE NRN WTRS AND THEY RANGE BTWN 10 AND
20 KT ELSEWHERE. THE LATST ASCAT PASS OVR THE REGION AT 0624Z HAD
WINDS TO 20 KT OVR THE ERN PARTS OF THE CNTRL REGION. THE ASCAT
HAD GALE FORCE WINDS IN AREA BEYOND 240 NM NW OF THE REGION.

MOST OF THE ERNGY IS CONFINED TO THE N OF THE REGION IN AN
UPPRLVL TROF THAT HAS ITS SHALLOW TROF AXIS XTNDG TO JUST W OF THE
SRN WTRS. AN UPPRVL RIDGE IS FARTHER W OVR THE CNTRL PAC. THE
ENRGY TO THE N WILL SLOWLY SHIFT SE AND ENTER THE NRN HALF OF THE
REGION. THIS SENARIO SHUD BE ABLE TO STRENGTHEN THE SFC FEATURES
AND EVEN TIGHTEN THE PRES GRDNT. HOWEVER THE PAC HAS TO BALANCE
ITS ENRGY WITH OTHER SYS TO THE S AND ALSO THE INLAND RIDGE WILL
BE WEAK. THIS COMBINATION WILL STILL MAINATIN A TROF ACRS THE WTRS
BUT RELATIVELY DRY AND NOT TIGHT ENOUGH TO GENERATE GALE FORCE
WINDS. UPPRLVL RIDGE WILL START TO SHIFT E AS THE TROF MOVES
INLAND IN THE XTNDD PRD AND THAT WILL RELAX THE PRES GRDNT AND
WINDS WILL SLIGTHLY DIMINSH. A MDL CHOICE SHUD THERFORE BE ONE
THAT WILL NOT HV GALE FORCE WINDS IN THE FRCST AND MUST SHOW
ENHANCED WINDS IN THE SHORT TERM BUT DIMINISHING IN THE XTNDD PRD.

THE GLBL MDLS HV INITIALIZED FAIRLY WELL AND THEY ARE IN GENERAL
AGRMNT IN THE SHORT ERM WITH JUST MNR DIFFS MAINLY OVR THE TRACK
OF THE LOW IN THE GULF OF AK AS IT APPROACHES THE NRN WTRS. ONLY
UKMET KEEPS THE LOW STILL OVR THE WTRS WED. ANOTHER MNR DIFFS IS
THAT MOST OF THE MDLS JUST MAINTAIN A TROF ALONG THE CANADA COAST
WHILE GFS SLIGHTLY DEEPENS TO TRY AND HAVE CLOSED LOW WHICH ALLOWS
ENHANCED WINDS. THE CMC WEAKENS ITS HGH PRES TO THE W WHICH
IMPLIES WEAKER WINDS. ALL THE MDLS JOIN GFS AND AGREE ON CLOSED
LOW BY THU. OTHERWISE THERE ARE REALLY MNR DIFFS IN THE MAIN SYNOP
PIC AND SO WILL USE THE LEADING MDL GFS WITH MNR ADJ IN THE GRIDS.
IN THE SHORT TERM THE HGH PRES OVR THE CNTRL PAC WILL REMAIN IN TE
SMAE VCNTY AND ABOUT THE SAME STRENGTH AND WILL MAINTAIN ITS SE
RIDGE IMPCAT OVR THE SRN AND CNTRL WTRS. THE CLD FRNT WILL SLOWLY
MOVE SE ACRS THE NRN WTRS AND THEN WEAKEN AND FINALLY DSIPT OVR
THE CNTRL WTRS. LOW PRES IN THE GULF OF AK WILL MOVE SE TO PASS
OVR THE ERN PARTS OF THE NRN WTRS THEN DSIPT IN THE XTNDD PRD. THE
WINDS WILL REMAIN BELOW GALE FORCE THRU THE FCST PRD.

.SEAS...THE SEAS ARE EQUALLY SMALL WITH 11 FT BEING HGHST OVR THE
FAR SRN WTRS MAINLY DUE TO LARGE PRD SWELL FROM THE TC SYSTEMS TO
THE SW. OTHERWISE SEAS RANGE BTWN 7 AND 10 FT ELSEWHERE. BOTH THE
NWW3 MULTI GRID AND THE ECMWFWV MDLS ARE VERY CLOSE TO THE OBSVD
SEAS PATTERN AND THEY HV BEEN QUITE CONSSTNT IN THE PREVIOUS RUNS.
EVEN A BLEDN OF 50/50 DOES NOT YIELD ANY VIVID CHNGS AND SO WILL
JUST STICK TO THE NWW3 MULTI GRID WV MDL THRU OUT THE FCST PRD.


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



.WARNINGS...PRELIMINARY.

.PZ5 WASHINGTON/OREGON WATERS...
NONE.

.PZ6 CALIFORNIA WATERS...
NONE.

$$

.FORECASTER SOMMERVILLE/MUSONDA. OCEAN PREDICTION CENTER.