North Pacific Marine Weather Discussion

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AGPN40 KWNM 042019
MIMPAC

Marine Weather Discussion for N Pacific Ocean
NWS Ocean Prediction Center Washington DC
119 PM PDT Sat Jul 4 2020

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

.At 20Z,latest available satellite imagery, marine and land
surface observations and analysis detect near 1030 mb center of 
an anticyclone out near 45N 150W. An 1025 mb attendant ridge axis
extends ESEwards from this center and reaches into the Northern 
and Central PZ6 waters. Well east of that, a well entrenched 
trough is analyzed from NNW-SSE across Interior CA. As such an 
available 17Z ASCAT pass caught near 25 knotters across Inner
Regional PZ6 waters of PZZ825-830. 

For tonight through Tuesday, 12Z runs of both the 
GFS and ECMWF are maintaining the aforementioned anticyclone 
between 1030-1035 mb thru this period, with an attendant WNW to 
ENE oriented near 1025 mb ridge located across waters just 
upstream of Northern and Central PZ6 tonight thru Tue night. This
will allow for the coastal trough to spread more down the CA 
coast tonight through Sunday, then strengthening in place Sun 
night. As a result, subgale winds between 20 and 30 knots will 
increase in areal coverage across the Inner PZ6 waters tonight 
and Sunday, then spread into portions of the Outer waters for 
Sunday night thru Tuesday. Will continue to use a 50/50 blend of
the 12Z NCEP models which are similar in magnitude and location 
of this type of synoptic scale ridging. Confidence is above 
average.

Extended, (For Tue night thru Thursday). The Eastern Pacific 
anticyclone remains strong and averages 1030-1035 mb out near 45N
150W, yet the attendant ridging west of PZ6 begins break down 
Tuesday night and broadens out Wed thru Thu. As such the Ca 
coastal trough weakens markedly Tue night, with only spotty areas
of 20 to 25 knots in the Inner PZ6 waters. Thereafter these 
winds remain confined to the immediate nearshore coastal waters 
of CA for Wed thru Thu (out to 60 nm). 

For Thu night thru Saturday the attendant ridging west of 
Northern PZ6 waters strengthens again, as the main anticyclone 
over the Eastern Pacific builds back to 1035 mb plus (aoa 47N 
along 150W) As a result subgales return into the Inner PZ6 zones
Fri through Saturday. For the extended period will continue to 
stay the course with the 50/50 blend given similarities in 
magnitude and aerial extent of the stronger winds. Confidence is 
average. 

.Seas...The 18Z waveheight analysis initialized better this 
afternoon with the updated am grids. The PZ5 waveheights were 
very well matched but portions of the PZ6 CA Regional Inner 
waters appear to be within 1-2 feet lower then he grids. Hence 
will continue to use a blend of the latest 12Z WWW3 and the ECMWF
wave. Nevertheless, winds will increase and seas will build 
tonight with the increasing areas of subgales expected. 

.EXTRATROPICAL STORM SURGE GUIDANCE...N/A

.WARNINGS...Preliminary.

.PZ5 Washington/Oregon Waters...
     None.

.PZ6 California Waters...
     None.

$$

.Forecaster Futterman. Ocean Prediction Center.