Storm Timeline: Pacific Northwest turns wet, windy, and snowy by Christmas night

PORTLAND, Ore. (KOIN) — A strong Pacific storm will arrive on Christmas Day, bringing back wet and windy conditions for much of the Oregon coastline and inland valleys. Snowy conditions will also return to the Cascades, bringing travel impacts through the end of the week.

Rain Impacts

Expect showers to begin around 9am on Christmas morning before conditions turn soggy by the evening for Portland and the Willamette Valley. A strong warm front, that's coupled by a moderate atmospheric river, will steadily increase rainfall throughout late Wednesday evening to early Thursday morning. Rain showers then continue Thursday afternoon with several more rounds of widespread rain throughout the weekend.

In general, your holiday week looks wet with forecast models showing between 3 to 4 inches of rainfall by the end of the weekend. With significant rain amounts in the forecast, small streams and creeks may run high with a chance for localized flooding in low lying areas. Drivers should be aware of ponded rain water on roadways here in the Willamette Valley.

Wind Impacts

Winds are expected to ramp up along the coastline Wednesday evening as the warm front passes. High-resolution models bring potential wind gusts up to 45 to 50 mph for the central coastline near Newport with peak wind gusts around 8pm to midnight. Isolated gusts up to 60 mph are also possible for some coastal communities and the higher elevations in the Coast Range.

Breezy south winds will first arrive in the central Willamette Valley throughout Wednesday afternoon with peak wind gusts around 40 to 45 mph late Wednesday night through early Thursday morning.

The Portland metro area will likely see peak wind gusts up to 30 mph in the evening and overnight hours.

Most impacts will be felt along the coastline, where these strong winds may cause downed trees and widespread power outages from Wednesday night to Thursday morning. A few isolated power outages are possible in the Central Valley. Few to no power outages are expected in the Portland metro area.

Mountain Snowfall Impacts

Snow levels will dip to 3,500 feet briefly on Tuesday before warming back above pass levels to around 7,000 feet on Wednesday. The passes will say mainly wet with little to no snow accumulations through Christmas Day until heavy snowfall picks up in the Cascades by Thursday morning.

With snow levels returning to 4,500 feet on Thursday, models are predicting up to 12 inches of wet and heavy snowfall down over the passes and roadways above 4,500 feet. Drivers should expect winter driving conditions with snow packed and/or slushy conditions throughout the day.

Two to three feet of new snowfall on Mt. Hood is possible through Friday night. The central Oregon Cascades could pick up three or more feet by the end of the week.

Stay with the KOIN 6 Weather Team for the latest on the forecast across the Pacific Northwest.