Marine Interpretation Message
Issued by NWS
AGPN40 KWNM 030334
Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
734 PM PST FRI DEC 2 2016
.FORECAST DISCUSSION...Major features/winds/seas/significant
.weather for the North Pacific N of 30N and E of 150W.
Cyclonic vortices in the gulf of AK and just NW of the Aleutian
Islands are clearly depicted on the latest IR satellite picture
with clouds associated with a warm sector now passing across the
norhern waters. The satellie picture also shows anticyclonic
circulation that is associated with almost clear skies over the
southern waters. The lightning density map has sporadic lightning
in the gulf of AK and almost nothing over the forecast waters. The
SREF model has PROB 0 for severe TSTMS across the region and will
remain that way through the short term. The latest observations
including earlier scatterometer pass at 1850Z show higher winds
over the southern and far northern waters with maximum 30 kt. At
00Z the NCEP map has low pressure 975 mb in the gulf of AK that
has an occludded front stretching SE inland near the coast and
then enters the northern waters as a cold front while its
associated warm front continues south just east of the northern
waters. High pressure 1033 mb about 360 NM west of the southern
waters has its ridge extending SE into the southern waters.
Inland trough stretches along the entire CA coast. The presssure
gradient is relaxed over most parts but just tight over the
central waters and not even enough to generate winds at gale
force threshold. The seas over the southern waters peak at 15 ft
while another peak is over the northern waters at 22 ft near the
northwest edge of the WA waters due to norhwest large period swell.
NWW3 wave model fits very well with the observed seas pattern
especially over the forecast waters. The ECMWFWAVE model also
mirrors NNW3 at 00Z and they both agree well in the rest of the
short term. So will not deviate from the afternnoon solution and
will stay with NWW3 initially and then use ECMWFWAVE to account
for movemnet of the synoptic systems in the extended period.
The models GFC/CMC/ECMWFHR/UKMETHR/NOGAPS have initially agreed
well with the 00Z surface map with minor differences within 2 mb
over the high pressure to the west of the region. The models are
also in a decent agreement in the short term on keeping the high
pressure to the west of the southern waters and also maintaining
a relaxed pressure gradient over the region through the short
term. For this update will continue with GFS in the short term
and then retain current winds in the extended period. Gales
warnings will be retained in the northern waters for next week.
The latest model guidance indicates that the low pressure trof
along the California coast continues to combine with a high
pressure ridge west of the pz6 waters to produce north to
northwest winds up to 30 knots off the coast of central and
southern California with the strongest conditions west of Point
Reyes. Conditions will slowly diminish through Saturday. Farther
north...one front will move through the pz5 waters today followed
by another front Saturday night. Low pressure will then move
southeast towards the Washington coast by late Monday. The latest
runs of the gfs and ecmwf look to be in reasonable agreement
through early Tuesday. By Tuesday and Wednesday the gfs is faster
than the ecmwf with the front forecast to move towards the pz5
waters. At this time will lean more towards the slower ecmwf
solution as it is supported by the ukmet. For wind grids will use
the gfs 10m winds through 96 hours...then transition to the ecmwf
winds. Current warnings look reasonable and few changes should be
needed on the next offshore waters forecast.
For wave grids will also use the ww3 through 96 hours...then
transition to the ecmwf wam after 96 hours.
Extratropical storm surge guidance...n/a.
.PZ5 Washington/Oregon Waters...
.PZZ900...Outer Waters from Cape Flattery to Cape Shoalwater...
Gale Possible Monday night.
Gale Possible Wednesday night.
.PZZ905...Outer Waters from Cape Shoalwater to Cape Lookout...
Gale Possible Wednesday night.
.PZ6 California Waters...
.Forecaster Musonda/Nolt. Ocean Prediction Center.