Marine Interpretation Message
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000
AGPN40 KWNM 240834
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
134 AM PDT Thu Aug 24 2017

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

The 06Z OPC surface analysis shows a cold front across the
northern PZ6 waters early this morning. Meanwhile, a surface
ridge axis extends over the PZ5 waters. An ASCAT-A pass just
after 05Z missed the strongest winds along the northern California
coast, but still showed 15 to 20 kt northerly winds across most
of our outer offshore zones.

The 00Z GFS winds remain the preferred model choice for this
forecast package. Overall, the global guidance remains in great
agreement for the next few days. Still do not have any gales over
the offshore waters through this forecast period. However, the GFS
and ECMWF continue to support gales over the coastal waters west
of Point Saint George on Friday evening as high pressure expands
eastward and a thermal trough strengthens inland. The surface
high that develops west of the northern PZ6 waters on Saturday
will lift northward into early next week, maintaining a surface
ridge west of the offshore waters through Monday night.

It is worth noting that there is still significant model spread on
Monday and Monday night with low pressure moving into the Gulf
of Alaska. Fortunately, the impacts to the offshore waters are
minimal as the ridge is expected to hold west of the area. The
00Z ECMWF appears too progressive with the ridge moving into the
outer PZ5 waters by 12Z Tuesday. Will continue to favor the GFS
and UKMET solutions that maintain the ridge west of the area with
slightly stronger northerly flow persisting offshore.


.SEAS...The 06Z sea state analysis revealed that both the NWW3
ENP and ECMWF WAM initialized too low over the northern PZ5
waters. Buoy 46005 reported 9.5 ft seas just west of the area at
06Z, and a Cryosat altimeter pass around 01Z detected seas to at
least 10 ft in PZZ900. Elsewhere, a 0245Z AltiKa altimeter pass
showed seas to 9 ft over the northern California coastal waters,
which was reflected by the 00Z WAM. So, the WAM was used as a
starting point for today with hand edits required to reflect the
discrepancies referenced above. Otherwise, the 00Z ENP seas were
favored tonight through Monday night.


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


.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
     None.

.PZ6 California Waters...
     None.

$$

.Forecaster Reinhart. Ocean Prediction Center.



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