Storms continue to hound California with flooding rain, mountain snow

The end of winter will not bring relief from a historically stormy cold season in California. AccuWeather meteorologists warn that a potent storm can deliver another round of significant precipitation during the middle of this week.

The state's brief lull in the stormy pattern ended Saturday evening when a relatively weak storm arrived. The storm from Sunday with its round of drenching rain and Sierra Nevada heavy snow were not classified as an atmospheric river, like some previous events. However, any rainfall will continue to help improve the lingering drought in the region.


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The city of Santa Rosa, California, has officially received more than triple its historical average rainfall for the month of March in the wake of Sunday's storm. The city stands at a staggering 9.34 inches of rainfall as of March 20 when by this point in the month it typically picks up just under 3 inches.

Last week's report from the United States Drought Monitor placed roughly 36% of the state in drought, a value sharply lower from the 98% coverage that was reported in early October.

Following a brief reprieve with rain and mountain snow for California on Monday, a second and stronger storm arrived late Monday night. This robust round of rain and mountain snow from Tuesday to Wednesday will include a greater risk of dangerous flooding to Southern California.

Unlike with the storm from Sunday, a majority of the most robust tropical moisture from this event is likely to focus on Southern California, according to AccuWeather Meteorologist Mary Gilbert, adding that ample availability of moisture could send rainfall amounts skyrocketing and lead to flooding issues.

Heavy rain is expected to affect the Los Angeles metropolitan area on Tuesday, with widespread flooding possible on streets and in poor drainage areas. As of March 18, downtown Los Angeles has picked up 24.49 inches of rain since November, a whopping 208% of their historical average rainfall tally of 11.78 inches, and the upcoming rain will further boost area reservoir levels.

A bit farther west along the coast, Santa Barbara is in a similar position, having received 24.14 inches of rain since November, nearly double its typical total of 14.04 inches. This total includes the remarkable 4.22 inches of rain that fell on Jan. 9, causing numerous downed trees and power lines, landslides and washed-out roadways around Santa Barbara County in a previous atmospheric river event.

This rainfall surplus has even led to the relaxation of water restrictions in Southern California earlier this month, with this week's rainfall serving to further reduce the strain on the area's water supplies.

"Given recent rains and saturated ground, the threshold for additional rainfall that can produce a significant risk for flooding is reduced. Creeks, streams and dry washes, especially in the higher elevations, can rise rapidly resulting in quickly escalating life-threatening flash flooding in some areas. Mudslides, rock slides and road closures may occur once again," AccuWeather Chief Meteorologist Jonathan Porter said.

Widespread rainfall amounts of 1-2 inches are expected across California, factoring in the rain from Sunday to Wednesday. Several inches of rain will fall on the lower west- and south-facing slopes of the Coast Ranges and Sierra Nevada. Some of the higher elevations in Southern California could end up with over 4 inches of rainfall through Wednesday, with an AccuWeather Local StormMax™ of 10 inches.

Snow will once again pile up over the Sierra Nevada, although this system may not bring quite the excessive amounts from prior storms this winter from Tuesday to Wednesday. Snow will also fall over the ridges and peaks in Southern California.

"It looks like the storm will deposit another several feet over the high country of the Sierra Nevada, but with lower snow levels when compared to the storms from earlier in March, difficult travel and road closures are likely over the passes," AccuWeather Senior Meteorologist Alex Sosnowski said. "Snow levels will dip down to the passes in Southern California for a time with enough for slippery conditions with 2-4 feet of snow possible in high-elevation communities such as Big Bear Lake and Wrightwood."

Rain and snow will not be the only hazards with this more powerful second storm, AccuWeather meteorologists say. Strong onshore winds will also accompany this potent disturbance on Tuesday, with gusts as high as 80 mph possible right along the coast from south of San Francisco to near the U.S/Mexico border.

Much stronger winds will occur over the mountains and through the passes, with an AccuWeather Local StormMax™ of 100 mph.

"Over the intermediate and high elevations, winds are likely to be strong enough to knock over many trees, which can not only block roads but also trigger widespread power outages," Sosnowski said. "The saturated soil will play a major role in the number of downed trees."

This storm's precipitation is expected to taper off through Wednesday, with less coverage of precipitation Wednesday night before yet another storm Thursday into Friday offers an additional opportunity for rain and snow. However, gusty winds may continue to cause power disruptions through Wednesday.

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