marine weather discussion for N Pacific Ocean
NWS ocean prediction center Washington DC
715 am PDT Thu 21 Aug 2008
Forecast discussion: major features/winds/seas/significant
weather for the North Pacific N of 30n and E of 150w.
Mrng update...prev fcst looks on track with no major changes
planned. 06z GFS/NAM show similar timing as prev runs with frntl
sys this weekend. GFS showing stronger wnds ahead of the fnt on
Sat but will not pull the trigger on a gale wnrg yet. After the
fnt passes thru the N pz6 wtrs sun a high pres ridge will build
over the pz5 wtrs. 06z GFS is an outlier in showing a deep low
over the g of AK late Mon.
Seas...06z run of ww3 is within 1-2 ft of ltst sfc obs across
the offshr and cwf. NW swell over the nrn areas is moving just
slightly faster than gdnc...but nothing major.
Prev discussion follows:
Ltst Quikscat showing area of 20 to 25 kt winds acrs the WA
offshr waters as well as in the NW portion of the or offshr
waters. 06z sfc analysis showing a 1000 mb low nr 50n129w. Low
exptd to continue to weaken as it moves ewrd today...and winds
slowly diminish.
Models in good agrmt with the timing and strength of the cold
front to affect the nrn waters this weekend. Front progged move
into the pz5 waters Sat. Still exptng Max winds of 30 kt in the
sly flow ahead of the front in the WA waters. GFS continues to
show a wave developing along the front and moving it NE across
the pz5 waters sun. Other glbl models do not show this feature
and will be ignored for this fcst cycle. Front exptd to dsipt as
it moves into the nrn pz6 waters Mon.
Some model differences noted for Mon. GFS is bringing in a
second low pres area towards the pz5 waters late in the period
Mon...with gales dvlpg acrs the WA and NW or waters by 12z Tue.
Other glbl models...the ECMWF and UKMET in particular...are
showing a high pres ridge bldg acrs the waters during this time
period. Since this is the first run in which the GFS has shown
this low dvlpmnt...will trend towards model consensus...which is
also similar to the prev fcst.
As this high builds in from the W Mon...both the ECMWF and UKMET
are showing tightening of the gradient along the nrn and cntrl
calif coast. Will incr winds in the nrn calif waters a bit to 25
kt for the next pacakge. If the ECMWF and UKMET are
correct...gales may be a psblty for late Mon. But due to the
uncertainty...do not want to put them in just yet.
Seas...ww3 handling the swell in the nrn waters a bit better
than in prev run...but is still a bit overdone when compared to
ltst sfc obs. Will make necessary adjustments to the fcst to
reflect initial conditions. Otw...will trend towards model
guidance for this pacakge...with the exception of Mon where will
not be going as high as the model in the nrn waters due to
discounting the low the GFS brings into the region.
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...none.
.Cape Lookout to point St George...None.
.Pz6 California waters...
.Pt St George to pt Arena...none.
.Pt Arena to pt Conception...None.
.Pt Conception to Guadalupe island...None.
Weather
