marine weather discussion for N Pacific Ocean

NWS ocean prediction center Washington DC

630 PM PST sun 12 Feb 2012

.Forecast discussion: major features/winds/seas/significant

.Weather for the North Pacific N of 30n and E of 150w.

As an elongated area of low pres and its ascd front drift E acrs

the nrn/cntrl ofshr wtrs blv postfrontal nwly gales are likely

present acrs the ofshr wtrs N of pt Arena attm. Max ascd seas

over these wtrs are in the low teens which are being handled

slightly better by the 12z ECMWF wam vs the 18z wavewatch iii.

Over the short term...smlr to what was noted earlier below the

latest mdls are in rsnbly good agrmt that the sfc low wl mov

inld tonite flwd by a high pres ridge bldg in FM the W Mon with

the gale force nnwly gradient in btwn shifting swd into the

cntrl nt2 wtrs by late Mon...then bcmg subgale thrut Mon nite.

Plan on using a blended 12z/18z GFS and 12z UKMET/ECMWF solution

for this gradient and as a result do not plan on making any sig

timing and/or areal coverage chngs to the prevly fcstd gale

wrngs and wl just make minor tweaks to the ascd conds.

Then late in the short term...Tue...the 18z GFS now just fcsts a

cold fropa afctg the pz5 wtrs with no attendant sfc low which is

gnrly sprtd by the 18z gefs and 18z 4km NAM. Wl wait to see the

00z mdls later...so for now wl maintain the prev fcst continuity

and favor the stronger 12z UKMET/ECMWF solution for this feature.

In the long range...again as noted below...the latest global

mdls cont to hv sig fcst differences. Vs its prev 12z run...the

18z GFS now fcsts a stronger sfc low to pass NE of the pz5 wtrs

Wed nite/early Thu with gale force ascd bl winds movg into the

cp flattery to cp lookout wtrs. The 18z gefs indicates that the

18z GFS sfc low is too strong. Therefore plan on favoring a

solution closer to the weaker 18z gefs mean and 12z ECMWF for

Wed nite/Thu.

Then on Fri...vs its prev 12z run...the 18z GFS now fcsts a

stronger closed upr low to aprch FM the W with a stronger sfc

low aprchg the pz5 wtrs late Fri with gale force ascd bl

winds... which is in line with the 12z ECMWF. The 18z gefs

indicates tho that the 18z GFS is too strong. The 12z

GFS/Gem/UKMET also fcst weaker solutions. Therefore for now wl

go with a compromise btwn these two mdl camps and hold off on

fcstg any psbl gales smlr to the prev ofshr fcst package and wl

revisit this system later when the 00z mdls come in.

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Previous discussion...

The 18z opc sfc analysis indicated an occluded front over the WA

and Oregon waters...with cold front trailing SW and W along 36n.

An oscat pass from around 0740z indicated predominantly light

winds over most of the offshore waters ranging from 17 to 23 kt

or less. There was a small area of winds near 30 kt over the S

CA waters in the vicinity of The Channel islands.

The 12z models were in decent agreement through the short term

period beginning tonight through about 12z Thu. From 12z Thu

through the end of the period...model agreement decreases

considerably with low fcst confdc overall beyond 12z Thu. For

the short term period however...models have maintained good

continuity indicating h5 low closing off over N CA Mon...then

moving se and eventually E across the Great Basin. At the

sfc...the models also on the same Page with several lows to

impact the waters the next few days. The first low ovet the or

waters will track se through 36 hours pulling a cold front se

across the area. The gales for all but the S CA waters still

look good through Mon. Another low is fcst to move into the

WA/OR waters early Tue then move se before dissipating over the

or waters late Tue night. The GFS and UKMET are very close with

the track of the low...with the ECMWF only being a shade slower.

Will include gales for both the WA and or waters for Tue as both

the ECMWF/UKMET indicate 35 kt or close. The GFS only indicates

35 kt over the WA waters...however the ECMWF/UKMET have shown

better consistency with this system over the past few days. For

Wed...low to pass NW of the pz5 waters with a weaker front

passing across the WA/OR waters. Winds will remain below gale

however with this system. For Thu and Fri...as mentioned quite a

variety of solutions to chose from. While most of the models

indicate a strong low to approach the pz5 waters...there is

considerable differences with intensity and track of low. The

UKMET is the furthest N and weakest moving the low across the WA

waters. The GFS is furthest S and slightly stronger than the

UKMET...while the ECMWF is in between the UKMET/GFS tracks but

is about 8 to 12 mb deeper. The CMC is closer to the UKMET in

strength and track. Looking at the ensemble members off the

GFS...most are clustered over the SW Oregon waters. Given the

large model spread and since the gales are not indicated until

very late in day 5 will opt to keep gales out for now and keep

winds at 30 kt for the or and N CA waters. Will favor track

close to ECMWF...but will keep winds/seas lower.

Seas...the 18z sea state analysis indicated that the ww3 was

initalized well with observed seas within a ft or two of the

model. Plan to go close to the ww3 through the period.

Extratropical storm surge guidance...N/A.

.Warnings/forecast confidence...Preliminary. Any changes will be

coordinated through AWIPS 12 planet chat or by telephone:

.Pz5 Washington/Oregon waters...

.Cape Flattery to Cape Lookout...gale tonight into Mon...high

confdc. Gale Tue...low to mod confdc.

.Cape Lookout to point St George...Gale tonight into Mon...high

confdc.

.Pz6 California waters...

.Pt St George to pt Arena...gale tonight into Mon...high confdc.

.Pt Arena to pt Conception...Gale tonight into Mon...high confdc

.Pt Conception to Guadalupe island...None.

.Forecaster vukits/kosier. Ocean forecast branch.