An expansive upper low oriented in the NPAC will assist in driving an active period along the west coast through the medium term. Numerous moisture-laden systems are set to come onshore with both bouts of rain and elevation-dependent snow through this week and into part of the next before a change in the pattern is anticipated.

IR satellite view of the NE Pacific:

ir4-l

The Euro ensembles portray the expected upper pattern over the coming while.

00z EPS 500mb height anomalies, days 1-5:

ecmwf-ens_z500aMean_npac_1

Substantial precipitation totals are predicted with only fleeting breaks in the action between waves, though the specific track of each individual low could deviate to some extent.

A glance at high-resolution short-range guidance through the next 2 days.

00z HRDPS total precip (mm) @ hour 48:

hrdps_qpf_mm_britcol_49

Total snowfall (inch), same timeframe:

hrdps_snow_britcol_49

A look farther out from the GFS, total precip (inch) @ hour 120 / day 5:

gfs_tprecip_britcol_21

Total snowfall (inch), same timeframe:

gfs_6hr_snow_acc_britcol_21

WPC total precip for days 1-7:

p168i

A shift in the pattern is likely as the medium range period unfolds, with the offshore trough retrograding westward and allowing ridging to build back into the region. This incoming regime change could hold fairly steady through the 7-14 day period if the ensembles are correct.

More on that in my next post.

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