marine weather discussion for N Pacific Ocean

NWS ocean prediction center Washington DC

635 PM PST Sat 21 Nov 2009

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

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

00z NCEP prelim surface analysis shows a 992 mb low N of the pz5

waters at 51n131w W/its warm front extending across the ern pz5

waters and its cold front across the NW WA waters. A 996 mb low

was just W of the SW WA waters at 46n132w with its cold front

approaching the wrn or waters.

As the 996 mb low strengthens and slides thru the pz5 waters

expect winds to increase with a brief period of storm force

winds in the or waters supported by the 18z GFS W/the 12z ECMWF

indicating 45 kt winds. B/c other globals Max out around 40 kt

so will leave confdc levels untouched for the storm force event.

See no reason to significantly adjust forecast Mon into Tue as

latest 18z GFS/NAM still maintains agreement with prior 12z

global models concerning timing and strength of pre-frontal

winds in the pz5 waters Mon...then again in the WA waters Tue

into Wed in association with the next frontal system. Will not

adjust forecast for day 5 given noted differences in the models

and we wait to evaluate the 00z package.

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Previous discussion...

Cold front currently moving into the pz5 waters as of 18z.

Latest Quikscat pass showing winds generally 20 to 30 kt across

the pz5 and NW portion of the nrn pz6 waters ahead of the cold

front...which was verified by a ship nr 42n130w rptng 30 kt at

18z...as well as buoy 46089 rptng 25 g 30 kt at 19z. Still

expecting min gale conditions to develop along the front across

the pz5 waters this afternoon. Still expect a brief lull later

this afternoon as the front passes to the E and the next low

pres nr 46n137w approaches from the W. Low expected to move

generally to the W towards Cape Lookout and inland during the

overnight hours. Models still hinting at psbly a brief period of

storm force winds developing across the or waters later this

evening and into the overnight hours...as GFS still showing 50

kt bl wind and the usually conservative ECMWF and UKMET showing

40 to 45 kt sfc winds. Thinking has not changed with atmosphere

fairly unstable...some storm force winds may mix down to the

sfc. So will continue with storm warnings for the or

waters...and keep winds just below storm force for the WA waters

tonight.

So changes with the next system to affect the nrn waters Sun

night into Mon. Global models in general agrmt with the timing

and strength of the front...with gales dvlpg in the sly flow

ahead of the front Sun night and continuing into Mon...before

front weakens Mon night as it encounters the ridge to the se.

Good agrmt with the global models on the system to affect the

nrn waters Tue and Wed...with all models in agrmt with gales

across the WA waters Tue and continuing into Wed as the front

moves across the area. Gales may creep into the far NW portion

of the or waters...but will keep winds below gale force for now.

Again...front quickly weakens as it approaches the nrn pz6

waters Wed as it encounters the strong ridge to the se.

Some minor differences noted in the models for Thu. GFS tries to

keep the front alive across the nrn calif waters...with a weak

low trying to develop along the front and approach the area. The

06z GFS was much stronger with this low...with the 12z GFS now

barely showing a 1020 low. Majority of global

models...ECMWF/UKMET/cndn...all showing front dissipated by Thu

with high pres building in from the W. ECMWF is much stronger

with the ridge...about 5 mb higher than the other global models.

Will trend toward the UKMET and cndn and just have nly flow

around 10 to 20 kt for Thu.

Seas...ww3 looks reasonable across the cstl/offshr waters when

compared to latest sfc obs. Will generally stay close to

guidance for this pacakge.

.Warnings/forecast confidence...Warnings are preliminary and are

subject to change. 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 sun...hi

confdc. Gale Sun night into Mon...MDT to hi confdc. Gale Tue

into Wed...MDT confdc.

.Cape Lookout to point St George...Storm tonight...MDT

confdc...with gale into sun...hi confdc. Gale Sun night into

Mon...MDT confdc.

.Pz6 California waters...

.Pt St George to pt Arena...none.

.Pt Arena to pt Conception...None.

.Pt Conception to Guadalupe island...None.

.Forecaster Holley/achorn. Ocean forecast branch.