Marine Interpretation Message
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000
AGPN40 KWNM 230206
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
606 PM PST Wed Feb 22 2017

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

The 00z surface analysis indicated weak low pressure just west of
the southern California waters, with a stronger low over the Gulf
of Alaska. The 18z GFS was very similar to the previous 12z GFS,
and continues to be in very good agreement with the other 12z
models during the short term period. The main concern continues
to be from later Saturday through Sunday evening. The 18z GFS,
similar to the previous 12z run continues to indicate a weaker
low affecting the northern and central California waters with
winds below gale. This is also very similar to 12z ECMWF. At
this time, plan to stay with the current wind grids. However, if
00z GFS continues this trend and especially if UKMET follows will
need to make some changes to decrease winds. The 00z sea state
analysis indicated that for the most part observed seas were
within a foot of the MWW3 forecast values, and do not plan on
making drastic changes to wave grids.

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

At 18z a high pressure ridge was across the offshore waters with
a 1021 mb low just north of the WA offshore waters and a 1027 mb
low just west of the central CA waters. 1851z ASCAT high
resolution revealed 10-20 kt winds over the inner PZ5 waters with
15-25 kt over the outer PZ5 waters. 10-20 kt winds were noted
over the northern and central CA waters and over the southern CA
waters east of roughly 120W.

Through about Sat 12z...the 12z model guidance was in fairly good
agreement...hence favored 12z GFS 30m winds through that point.
Guidance still diverges later Sat into late Sun in terms of
whether or not a significant low pressure system will develop
over the central CA waters Sat night before shifting eastward
into inland CA Sun. 12z GFS has now come into alignment with the
12z ECMWF...as well as the 12z NOGAPS...in terms of not showing
any significant low over the central CA waters Sat night. It now
shows the weak low expected to move south and out of the WA/OR
waters Sat...continuing to move southeastwards while weakening to
an open wave before moving inland Sat night. Which is a drastic
change from its prior 00z/06z runs which absorb this low into a
stronger low moving in from the west. That said the 12z UKMET/CMC
continue to show this scenario in terms of the southward moving
low from the north being absorbed into a stronger low west of the
waters by Sat night...with the low then tracking east across the
central CA waters...then inland. With such differences noted felt
making drastic changes from late Sat into late Sun for now wasnt
needed as would like to see a few more model cycles to see
whether guidance can come to a consensus. So as a result left in
prior grids...the 00z GFS 30m winds for late Sat into late
Sun...however backed off on winds a bit and capped them at 40 kt.
From overnight Sun on favored 50/50 blend of the 12z GFS 30m
winds/12z ECMWF.

.SEAS...Through Sat used 50/50 blend of the 15z NWW3/ECMWF
WAM...then kept prior 50/50 blend of 00z NWW3/ECMWF from Sat 18z
through Mon 00z given choice to continue with existening winds
grids from overnight...then transitioned back to a 50/50 blend
of the 12z NWW3/ECMWF WAM from Mon 06z through the end of the 5
day period.

.EXTRATROPICAL STORM SURGE GUIDANCE...n/a.

.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
.PZZ815...Inner Waters from Florence OR to Point St. George...
     Gale Possible Sunday night.

.PZ6 California Waters...
.PZZ820...Inner Waters from Point St. George to Point Arena...
     Gale Possible Saturday night into Sunday night.
.PZZ920...Outer Waters from Point St. George to Point Arena...
     Gale Possible Saturday night into Sunday night.
.PZZ825...Inner Waters from Point Arena to Pigeon Point...
     Gale Possible Saturday night into Sunday.
.PZZ925...Outer Waters from Point Arena to Pigeon Point...
     Gale Possible Saturday night into Sunday night.
.PZZ830...Inner Waters from Pigeon Point to Point Piedras Blancas...
     Gale Possible Saturday night into Sunday night.
.PZZ930...Outer Waters from Pigeon Point to Point Piedras Blancas...
     Gale Possible Saturday night into Sunday night.
.PZZ835...Inner Waters from Point Piedras Blancas to Santa Cruz Island, CA...
     Gale Possible Saturday night into Sunday night.
.PZZ935...Outer Waters from Point Piedras Blancas to Santa Cruz Island, CA...
     Gale Possible Saturday night into Sunday night.
.PZZ940...Outer Waters from Santa Cruz Island, CA to 120W...
     Gale Possible Sunday night.

$$

.Forecaster Kosier/Holley. Ocean Prediction Center.


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