A Pacific storm system will approach the West Coast Friday morning, bringing increasing precipitation chances to California and the Pacific Northwest.
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Moderate to locally heavy rainfall is likely for much of California Friday, focusing along the northern and central coast and along the higher terrain of the coastal ranges.
Snow levels will start rather high as a plume of warm, moist air moves in from the Pacific, keeping snowfall limited to higher mountain peaks.
Areal average rainfall totals of 1-3" may lead to some isolated flooding concerns.
Some gusty winds are also expected.
Precipitation totals will come down some Saturday as the system weakens, but spread a bit further inland, with a light wintry mix for western portions of the Great Basin.
Also, as snow levels come down with cooler air moving in, some heavier snowfall totals between 8-12" will be possible for the Sierra, locally as high as 1-2 feet.
Most of the precipitation should come to an end by later Saturday night, early Sunday morning.
To the east, a frontal system dropping southward from Canada into the Interior Northeast/New England will bring a wintry mix Friday, starting out as rain for many locations before transitioning to snow by Friday night into Saturday.
Any snow accumulations should remain limited.
However, one exception will be in interior Maine where freezing rain accretions of 0.1-0.2" and snowfall of 1-2" may be a bit more disruptive to any travel this holiday weekend.
A very light wintry mix will also likely continue to linger Friday further south and west into the Ohio, Tennessee, and Middle Mississippi Valleys as well as the central and southern Appalachians under the influence of a deep upper low.
Some light, spotty showers will also be possible in the Mid-Atlantic and northeastward through coastal New England.
Precipitation chances Saturday should remain light and be limited to the Appalachians and New England.
Elsewhere, a clipper system passing through the Upper Midwest/Great Lakes Saturday may bring a few light snow showers.
The rest of the country looks to remain dry.
Most of the country will see high temperatures running above average Friday and Saturday.
Conditions will be most anomalous Friday from the Northern Plains into the Upper Midwest/Great Lakes where highs in the 30s and 40s are 15-20 degrees above average.
Temperatures will drop into the 20s and 30s Saturday.
Elsewhere, forecast highs range from the 30s and 40s in New England, the 40s and 50s for the Mid-Atlantic, the 40s and 50s for the Central Plains, and the 50s and 60s for the Southern Plains/Texas.
In the West, 30s and 40s are expected for the Rockies/Great Basin, with 50s and 60s for the Pacific Northwest and California and some 70s into the Desert Southwest.
One area where temperatures will be running below average is from the Lower Mississippi Valley into the Southeast, as conditions will be slower to moderate following a cold front passage and a deep upper low passes overhead.
Forecast highs are mainly in the 40s and 50s, with some chilly morning lows dropping to at/near freezing along the central/northern Gulf Coast. ■