Travel disruptions will mount across the western United States as rain, snow and ice push inland into Saturday.
Waves of moisture will crash onto the West Coast as a storm swirls offshore.
After an initial wave of soaking rain expands inland across northern and central California on Thursday, a second wave will follow on Friday and continue into Saturday.
The second burst of moisture will progress farther northward into western Oregon and Washington.
The saturated nature of the soil will enhance the threat of localized flash flooding, especially across northern California.
“Localized flooding is anticipated to be most disruptive from Eureka to San Francisco, California, as well as at the foot of the higher terrain to the north and east of the San Joaquin Valley,” AccuWeather Meteorologist Faith Eherts said.
After the abundance of rain in January across California, any additional rainfall could cause high streams and reservoirs to spill over onto neighboring lands.
“As with other storms over the previous weeks, road closures and power outages will be possible as the threat of flash flooding, landslides and toppled trees returns,” Eherts said.
Motorists should prepare for slower-than-normal commute times and the potential for the necessity for an alternate route.
Little, if any, rain will reach as far south as Los Angeles and San Diego from the storm.
In addition to disruptions on the roads, airline delays are possible from San Francisco to Seattle due to a low cloud ceiling and rainy spells.
In some areas of the Pacific Northwest, moisture will clash with stubborn cold air and cause a period of ice.
“As cold air remains trapped at the surface, the stage will be set for a prolonged period of freezing rain in Portland, Oregon, from Thursday night through Friday afternoon,” AccuWeather Meteorologist Kyle Elliott said.
The area of freezing rain can extend as far south as Eugene, Oregon, and as far north as Seattle.
Roads and sidewalks that appear wet can have a thin layer of ice on the surface.
“For those who must travel, be sure to reduce speeds on roadways as even the slightest bit of freezing rain on roadways greatly increases the risk for spin-outs and multi-vehicle accidents,” Elliott said.
Temperatures along this corridor are expected to rise above freezing by Friday night, when most areas will change over to rain.
Snow will pile up in feet from the Sierra Nevada northward to the Oregon and Washington Cascades and eastward to the Bitterroot and Teton mountains.
“Ski resorts in the northern Rockies and California have enjoyed plentiful snowfall already this season, with many places already seeing double their average seasonal snowfall,” Elliott said. “The additional snow will only add to the abundant snowpack already in place.”
Travel over the mountain passes will be dangerous, if not impossible, for a time. Some may be forced to close due to the intensity of the snow.
There may be another opportunity for flooding rain and heavy snow along the West Coast late Sunday into Monday as another storm pushes ashore.