Atmospheric river to continue drenching rain, mountain snow over Northern California

By Alex Sosnowski, AccuWeather senior meteorologist
February 27, 2019, 3:16:59 PM EST

West Coast - atmospheric river 2.26

(Satellite loop/NOAA)

Northern California will remain in the swath of a brief atmospheric river with heavy rain and the risk of flooding, as well as heavy snow in the mountains, into Wednesday evening.

A series of storms with a plume of moisture will take aim from Northern California and part of Oregon to the interior western United States into midweek.

While the worst of the rain and mountain snow has already occurred, moisture will continue to stream in from the Pacific Ocean into Wednesday evening.

"As the storm track centers on Northern California through midweek, a general total 4-8 inches of rain will fall with locally higher amounts along the northern coast of California and lower west-facing slopes of the Sierra Nevada through Wednesday," said AccuWeather Senior Meteorologist Kristina Pydynowski.

This latest round has already caused trouble in terms of flash flooding and mudslides.

There were several reports of flooding around San Francisco and Santa Rosa on Tuesday morning as the storm began to ramp up. Reports continued through the night as motorists became trapped in flood waters and mudslides.

Cali 3 pm

A storm total of 1-3 inches of rain will fall elsewhere at lower elevations in Northern California. At the very least, enough rain will fall over parts of the Sacramento and upper San Joaquin valleys to lead to slick travel and delays on the highways.

"Motorists should expect delays due to poor visibility and excess water on the roads in San Francisco and Sacramento," Pydynowski said.

Part of US 101 in southern Oregon became impassable on Tuesday after the ground gave way under the highway. Motorists will need to use alternative routes.

us 101

Part of US 101 was closed near Brooking, Oregon, due to sunken grade. (Photo/Oregon DOT)

In the mountains, 5-10 feet of snow will fall on the high country of the central and northern Sierra Nevada with up to 2 feet of snow in store for the southern Cascades though Thursday, from the storm that began on Monday.

sierra snow 2/27

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Major travel disruptions are likely over the passes and summits during the storm siege along interstates 5, 80 and 84.

Due to the heavy rate of snow and extensive blowing and drifting, as well as avalanche danger," officials may be forced to shut down travel over the mountains for a time," according to Pydynowski.

Conditions are not likely to improve in the Cascades and Sierra Nevada until Thursday. Snow may continue to pester the northern and central Rockies through this weekend.

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Snow began falling in Eugene, Oregon, early Sunday evening and ended Monday afternoon. Eugene is located south of Portland, Oregon, at a mere few hundred feet above sea level.

A total of 12 inches was reported Monday afternoon at Eugene Sweet Field Airport, Oregon. The old 24-hour snowfall record for Eugene was 6.7 inches on Feb. 7, 2014.

The 24-hour snowfall record for any storm in Eugene is 22.9 inches set in January of 1969.

The most recent storm from late Tuesday to early Wednesday morning brought another 6 inches of snow to Eugene.

The storm train centered on Northern California will fluctuate enough to bring more snow to much of Oregon at midweek. Snow reached as far north as Washington, but marginal temperatures may limit accumulations along the coast with the current storm.

NW Snow through Wed

A break from the storms is likely during the latter part of the week.

However, while a storm slated to roll in from the Pacific this weekend may avoid Oregon, its farther south track is likely to bring rain and high-elevation snow to much of California, especially southern areas, as well as many inland locations in the Southwest.

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