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000
AGPN40 KWNM 270306
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
806 PM PDT Mon Jun 26 2017

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

Model agreement is very good and very consistent with the current
forecast. Will likely adjust very little throughout the forecast
with only a few minor changes to match observations in the very
near term. As stated in the previous forecast, there is a chance
for some gales reaching into the northern Washington waters
through Tuesday night; however, the chances still appear to be
low so will leave current warnings as- is and will closely watch
this area through the night.

Hurricane Dora is located well to the south and southeast of the
offshore waters this afternoon, or near 18.4N 108.3W at 03Z. It
is forecast to move mainly off to the west and weaken over the
next few days with no major impact on conditions over the
offshore waters. For additional information on Dora please see
the latest advisory issued by the National Hurricane Center.

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PREVIOUS DISCUSSION...

The preliminary 18Z OPC-NCEP surface analysis shows a
dissipating cold front moving into northern Oregon offshore
waters, and a low pressure trough extending southward from a
position just west of the northern and central California waters.
A large 1031 MB high pressure area was centered near 44N 146W,
and it is moving eastward at 10 to 15 kt. A low pressure trough
is still forecast to strength near Vancouver Island tonight, and
persist into Wednesday before weakening. Gale force winds are
likely north of the offshore waters, off the coast of Vancouver
Island over the next few days. There is a slight chance for these
gales reaching into northern Washington waters overnight into
Tuesday night, but chances appear to be too low to add to the
offshore forecast at this time. The latest satellite imagery and
lightning data indicates that most of the thunderstorm activity
has moved into southwestern Washington state this afternoon,
with a diminishing threat over the far eastern PZ5 waters.

Hurricane Dora is located well to the south and southeast of the
offshore waters this afternoon, or near 17.8N 107.3W at 21Z. It
is forecast to move mainly off to the west and weaken over the
next few days with no major impact on conditions over the
offshore waters. For additional information on Dora please see
the latest advisory issued by the National Hurricane Center.

The main weather features impacting the offshore waters over the
next several days will be high pressure building west of the
waters, and a developing California coastal trough. The 12Z
global models remain in very good agreement over the region
right into the upcoming weekend. We will remain close to the 12Z
GFS 10 meter winds for the afternoon forecast package tonight
into Friday night, and then transition toward the 12Z ECMWF
thereafter as it appears to handle a weakening cold front moving
into PZ5 waters a little better, and more consistently than the
GFS guidance. At this time, it appears that any gales that
develop over the region during the next several days will remain
over the coastal waters during mid and late week. There are some
indications that the gales may spread and develop into the
offshore waters from far southeastern offshore Oregon waters
south and southeast to the eastern central California offshore
waters next weekend. For now, we will cap winds at 30 kt and
continue to monitor this potential.

Seas...Both the 12Z ENP Wavewatch and ECMWF WAM have initialized
well across the offshore waters this afternoon. For the
afternoon package we will use a 50/50 blend of these two wave
models into Friday night, and then to accompany the wind
forecast transition toward using mostly the WAM for sea heights
at that time.

Extratropical Storm Surge Guidance: n/a.



.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
     None.

.PZ6 California Waters...
     None.

$$

.Forecaster Sommerville/Mills. Ocean Prediction Center.


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