Marine Interpretation Message
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480
AGPN40 KWNM 212114
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
114 PM PST Tue Feb 21 2017

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

A large swath of ASCAT data is missing across the offshore waters
on the latest pass...between 130w and 135w the winds are light
5-15 kt. The most recent satellite picture indicates a short-
wave west of the California waters moving east...expected to turn
southeast while remaining w of the region over the next 36 hrs.

The 12z global models are in very good agreement during the next
72 hours...then begin diverge days 4-7. There will be two main
problem areas over the next 7 days. The first chance of gale
conditions will occur over the favored area near the channel
islands across the southern California waters Thursday into
Thursday night. Both the GFS and ECMWF are indicating the gales
are possible...with GFS 30M winds forecasting max winds near 35
kt. The ECMWF is also showing a small area of 30 kt winds. At
this time I will maintain continuity and keep gales out of the
offshore waters...while also matching with the southern coastal
zones. The biggest forecast problem will occur later in the
period...Saturday into Sunday night. The GFS and ECMWF have
essentially switched solutions since yesterday at this time.
Yesterday the GFS was the outlier model...while all of the other
global models were in decent agreement. The GFS switched
solutions with the 00z last night to a stronger...ECMWF
solution...therefore gales were issued. The 12z GFS run from
today is consistent with the previous run...indicating that the
southern stream will phase with the northern stream bringing a
strong area of low pres across the California waters...although
about 12 hours slower than previous runs. The 12z ECMWF did not
phase the two systems however and therefore forecasts a much
weaker system eventually moving into the California waters. I
will try and keep as much continuity as possible from the last
couple of forecasts and populate the wind grids using the GFS
throughout the period..and the 30M winds during periods of
instability. I will also cap the max winds at 40 kt for late in
the week.

Seas...Both the ENP and WAM initialized well across the waters.
During the first couple of days the WAM indicates higher waves
possible in the southern waters in areas of higher winds...the
ENP is likely too weak in that region. I will populate the wave
grids using a 50/50 blend of the two models through 00z
Saturday...then transition to 100 percent ENP thereafter.

.EXTRATROPICAL STORM SURGE GUIDANCE...N/A.

.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
     None.

.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 night.
.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 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 into Sunday night.

$$

.Forecaster Shaw. Ocean Prediction Center.



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