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330
AGPN40 KWNM 172236 CCA
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
158 PM PST Wed Jan 17 2018

.FORECAST DISCUSSION...Major features/winds/seas/significant
.weather for the North Pacific N of 30N and E of 150W.

18Z NCEP surface analysis places strong low pressure with 965 mb
center west of the Washington waters near 47N 138W with warm
front lifted just N of the waters followed by a strong cold front
crossing the offshore waters from northern PZ6 waters northward.
Latest ASCAT passes from near 18Z confirm at least strong gales
ahead of the cold front from northern PZ6 area northward with
some coastal buoys after 18Z showing gusts reaching storm force.
West of the front buoy 46005 in the more unstable flow post-
frontal reports gusts to 54 kt at 20Z. Farther SW around the
south semicircle of the storm center the ASCAT-A data showed a
swath of 50 to 55 kt. With the latest models and satellite loop
showing ststem moving NE before stalling just NW of the waters
later tonight and Thu, have continued above average confidence
that storm force south to southwest winds will develop over
outer portions of the Washington waters tonight into Thu before
the system weakens. Otherwise widespread gales are expected
northern PZ6 waters northward but will likely end by early
tonight in inner northern PZ6 waters but likely continue in
adjacent coastal waters.

The 12Z models have come into better agreement in the developing
synoptic pattern over the next 5 days with the first three days
doinated by stalled low pressure just north of the PZ5 waters and
west of Vancouver Island which eventually lifts north and
dissipates by Sat morning as the next low pressure system and
front approach from the west. The timing and strength of the
front moving through the waters Sat night into Sun night with the
front weakening into the central PZ6 waters by Sun night. We will
still carry gales with the front with above average confidence
affecting waters from northwern PZ6 waters northward. Front then
weakens Sun night as high pressure spreads over the area from the
W Sun night into Mon night.

For the new grids used the representative 12Z GFS throughout,
modified using a 10m/30m stability smart tool which places
higher first sigma winds in unstable areas and 10 meter winds in
stable areas.

.SEAS...The 12Z Wavewatch seas initialize 3-4 feet too high in
the waters from northern PZ6 northward. Initially for wave grids
used the 12Z ECMWF WAM until 06Z this evening and then for the
period through 00Z Fri used a 2:1 blend of the 12Z ECMWF WAM and
12Z WW3, respectively, and then after that an even blend of the
two models is preferred.

.EXTRATROPICAL STORM SURGE GUIDANCE...Storm surge around 1.0-
1.5 is forecast by the 12Z ESTOFS around Vancouver Island just
north of the waters through tonight, then reaching a peak up to
0.5-1.0 ft on Thu along the Washington and Oregon coasts.

.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
.PZZ800...Inner Waters from Cape Flattery to Cape Shoalwater...
     Gale tonight into Thursday night.
     Gale Possible Saturday night.
.PZZ900...Outer Waters from Cape Flattery to Cape Shoalwater...
     Storm tonight into Thursday.
     Gale Thursday night into Friday.
     Gale Possible Friday night into Saturday night.
.PZZ805...Inner Waters from Cape Shoalwater to Cape Lookout...
     Gale tonight into Thursday night.
     Gale Possible Saturday night into Sunday.
.PZZ905...Outer Waters from Cape Shoalwater to Cape Lookout...
     Storm tonight into Thursday.
     Gale Thursday night into Friday.
     Gale Possible Saturday night.
.PZZ810...Inner Waters from Cape Lookout to Florence OR...
     Gale tonight into Thursday.
     Gale Possible Saturday night into Sunday.
.PZZ910...Outer Waters from Cape Lookout to Florence OR...
     Storm tonight.
     Gale Thursday.
     Gale Possible Saturday night.
.PZZ815...Inner Waters from Florence OR to Point St. George...
     Gale tonight into Thursday.
     Gale Possible Saturday night into Sunday.
.PZZ915...Outer Waters from Florence OR to Point St. George...
     Gale tonight into Thursday.
     Gale Possible Saturday night.

.PZ6 California Waters...
.PZZ820...Inner Waters from Point St. George to Point Arena...
     Gale Possible Sunday.
.PZZ920...Outer Waters from Point St. George to Point Arena...
     Gale tonight.
     Gale Possible Saturday night into Sunday.

$$

.Forecaster Bancroft. Ocean Prediction Center.



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