Marine Interpretation Message
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000
AGPN40 KWNM 251459
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
759 AM PDT Tue Apr 25 2017

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

At this time I don`t plan on making any changes to the current
grids or associated text forecast. An altimeter pass from 13Z
indcates seas near 14 ft across the far SE portion of the
California waters. A large swath of ASCAT data is missing from
the area around 120W, the area of expected highest winds
currently over the offshore waters. When taking a look at the
most recent 30M GFS forecast for the region and the surround
observations there is enought evidence to maintain gale warnings
for the region, especially in area around the Channel islands,
extending into the inner offshore waters.

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PREVIOUS DISCUSSION...

There was an ASCATB pass at 06Z with a swath across the offshore
waters W of 126W. Strongest winds were associated with a warm
front evident just W of the WA/OR waters with winds to 20 kt and
also over the srn CA over the far wrn waters. Elsewhere E of the
satellite data over the srn CA waters there were surface
observations showing winds to 25 kt and just E of the offshore
waters winds were to 35 kt.

At 06Z latest 06Z OPC surface analysis had high pressure just W
of the central and srn CA waters. To the W of the WA waters low
pressure was moving towards the NE and will move near the
Canadian coast by tonight. An associated warm front will lift NE
into the WA/OR waters today and be followed by a cold front that
will move into the nrn CA waters late this afternoon into
tonight. Will have winds to 30 kt in advance of the cold front
today over the WA/OR waters. Elsewhere over the inner waters of
the srn CA waters from Santa Cruz Island to San Clemente Island
will continue with winds to 35 kt today through about Fri.
Coastal trof along srn CA should develop and expand N through Fri
night. Will use the instability fields of the GFS 10m/30m winds
for today through early Wed, then use the ECMWF for late Wed
through end of the forecast period. Will boost the ECMWF winds
with strongest winds being along the central and srn areas
initially, then expanding over the nrn areas of the CA
waters. By late Sat and Sat night a cold front weakens while
moving E over the WA/OR waters.

Seas...Will use a 50/50 blend of the WWIII and ECMWF wam through
the forecast period with models with few adjustments.

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


.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
     None.

.PZ6 California Waters...
.PZZ840...Inner Waters from Santa Cruz Island, CA to San Clemente Island, CA...
     Gale today into Wednesday night.
     Gale Possible Thursday into Friday.
.PZZ940...Outer Waters from Santa Cruz Island, CA to 120W...
     Gale Possible Thursday into Thursday night.
.PZZ945...Outer Waters from 120W to San Clemente Island, CA...
     Gale Wednesday night.
     Gale Possible Thursday into Friday.

$$

.Forecaster Shaw/Rowland. Ocean Prediction Center.


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