000
AGPN40 KWNM 250929
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
229 AM PDT Wed Apr 25 2018

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

ASCAT-A data for 0555Z has come in but the B version of ASCAT is
not available. It returned a swath of northerly winds 20 to 25
kt across the PZ5 waters except light winds from SE Oregon waters
southward. Winds over the central California waters are
generally shown to be light and variable. Satellite imagery shows
a weak low center near 36N 137W co-located with an upper low, which
has been moving S. An altimeter pass from 0237Z indicates a
swath of seas 6 to 8 ft from central California coast SW through
outer southern waters.

For the most part the 00Z global models are in pretty good
agreement, with any differences most likely dealing with the
strength of the boundary layer winds over the far NE portion of
the Washington waters and across eastern portions of the
California waters from Sat night and beyond. The GFS is the
strongest of the models and shows that gales are possible later
in the period and for now appears the outlier, while the 00Z
ECMWF/UKMET/global GEM show winds to 25 to 30 kt. I will
maintain continuity and populate the wind grids using the
consistent 00Z ECMWF at 06Z Sun through the end of the period.
With better model agreement until then, populated the winds with
the 00Z GFS through Sat mostly using the 10 meter boundary layer
winds. While using the ECMWF, did boost the winds by 10 percent
as cold advection develops behind a passing cold front and high
pressure builds behind it.

Seas...both the 00Z ENP Wavewatch III and 00Z ECMWF WAM are
reasonable solutions through much of the forecast period. I will
populate the wave grids using the 00Z ENP through 00Z Sun when
the GFS is used for winds, then transition to the 00Z ECMWF WAM
for the remainder of the period, when ECMWF is the preferred
model for winds.

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

.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
None.

.PZ6 California Waters...
None.

$$

.Forecaster Bancroft. Ocean Prediction Center.