Another atmospheric river to bring a hefty dose of rain and snow to California

AccuWeather meteorologists say another atmospheric river is imminent across California by early week, causing residents to brace for an additional round of flooding rainfall, high-elevation snow and strong winds.

Many eyes are on the main powerhouse of energy that will drive into the West Coast through Tuesday. Still, even in the days leading up to this event, conditions will be anything but dry in parts of California.

Bursts of energy into Monday will produce rounds of heavy snow across the Klamath Mountains, southern Cascades and the Sierra Nevada. The heaviest snow is expected to impact areas above 6,500 feet. Forecasters say that above this elevation, snowfall amounts can range on the order of several feet, resulting in road closures and enhancing the risk of avalanches in the area.

Strong southerly winds will spread across Northern California into Monday, with gusts up to 45 mph possible across the terrain. In locations where blowing winds and steady snowfall overlap, meteorologists warn that visibility can be drastically reduced and travel impacted.

"Frequent showers will track into Northern and Central California through Monday, thunderstorms prowling around the central valleys and foothills on Saturday," explained AccuWeather Meteorologist Brandon Buckingham.

Forecasters say that the flooding concerns around San Fransisco will ramp up Monday night into Tuesday; however, given the threshold for flooding can be low from previous rounds of rain and showers early this weekend as the next atmospheric river event arrives. Residents may take advantage of any lighter showers or breaks in the rain between Saturday and Monday to prepare for additional steady rainfall.

Rainfall amounts around San Francisco can range in the neighborhood of 2 inches from late Monday into Tuesday evening before the rain tapers off in the Bay Area later Tuesday night.

As this surge of moisture tracks into California from Monday to Wednesday, the resulting impacts will range from road washouts and extended road closures to heavy snow above 7,500 feet and the danger of avalanches. In residential locations across higher elevations, heavy snow can inundate buildings and homes, elevating the risk of roof collapse.

In zones across the state where rainfall totals are the highest and in locations that have a low water threshold from previous storms, the risks to lives and property will range from moderate to high. The risk to lives and property will also be high for areas across the higher elevations forecast to receive hefty snowfall accumulations early this week that faced plentiful snowfall last week and early this weekend.


From Monday to Wednesday, rainfall amounts can total 2-4 inches across areas north of San Francisco from Santa Rosa and Redding, California, to portions of coastal southwest Oregon. In the western foothills of the Klamath Mountains and the Sierra Nevada, rainfall totals can climb to 4-8 inches during this time with the AccuWeather Local StormMax™ of 12 inches.

The heaviest rain is expected to make its way into California by late Monday night and Tuesday when the heart of the storm will shift onshore.

In the mountains, snow levels will gradually rise by Monday to above 7,500-8,000 feet. Forecasters point out that the upcoming atmospheric river is following on the heels of a hefty mid-elevation snowpack that accumulated from previous events, which can spell trouble as temperatures climb.

"Since snow levels are rising much higher than what has occurred in recent storms, a major flooding risk will quickly arise as rain falls at these elevations," explained Buckingham.

The heaviest round of snow can fall above 8,000 feet early Tuesday morning through Tuesday night, mainly across the Sierra Nevada.

In the aftermath of this potent storm, a brief stretch of dry weather will likely arrive and give Californians a reprieve from the active pattern. Many locations across the Golden State will note this break from Wednesday night to midday Thursday, with intervals of sunshine possible Thursday morning across interior areas.

The stormy pattern will ease some by late week and the upcoming weekend. However, a front can shift into parts of Northern California, Oregon and Washington by late Thursday and Friday. This front can bring a swath of light rain or showers to locations such as Redding, California; Eugene, Oregon; and Seattle by late week.

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