Storm onslaught to bombard California with flooding rain, mountains of snow through Thursday

By Kristina Pydynowski, AccuWeather senior meteorologist
January 15, 2019, 5:56:35 AM EST

The threat for flooding and mudslides is expected to ramp up across California as the train of storms with heavy rain, mountain snow and gusty winds persists this week.

There will be no day through at least Thursday when a significant part of California is not being affected by a storm rolling in from the Pacific Ocean.

Each storm will bring an increasing risk of flooding and mudslides as snow further buries the mountains, making travel increasingly difficult.

(KGET-TV via AP)

In this photo provided by KGET-TV, a line of big rigs are stalled on Interstate 5 where it has been closed due to snow at Tejon Pass, an area known as the Grapevine, at Gorman in the Tehachapi Mountains of Southern California Monday, Jan. 14, 2019.


Interstate 5 at Grapevine in California.


Stuck on Interstate 5 at Grapevine in California.


Interstate 5 at Grapevine in California.

(CalTrans via AP)

This photo provided by the California Department of Transportation (CalTrans) shows a skiploader clearing a river of mud that has flowed onto Pacific Coast Highway in Malibu, Calif., Monday, Jan. 14, 2019.


All lanes were close in both directions on Interstate 5 in the Gorman and Lebec area due to heavy snow, accidents and vehicles stopped.

(CalTrans via AP)

This photo provided by the California Department of Transportation shows traffic stopped on Interstate 5 where it has been closed due to snow at Tejon Pass, an area known as the Grapevine, at Gorman in the Tehachapi Mountains of Southern California, Monday, Jan. 14, 2019.


Stuck on Interstate 5 at Grapevine in California.

Burn scar areas will be most susceptible to devastating debris flows, and residents living in these areas should heed all evacuation orders by officials. Flooding and mudslides may not be limited to these communities.

The Santa Barbara County Sheriff’s Office has issued an evacuation order for residents below the Thomas Fire and Sherpa and Whittier Fire burn areas.

Rainfall totals of all the storms from the weekend through this week can range from 4-8 inches along the western foothills of the Sierra Nevada and the northern Coast Ranges, as well as the south- and southwest-facing slopes of the mountains surrounding Los Angeles and Santa Barbara.

CA storms Jan 13

In the hardest-hit areas, there can be an AccuWeather Local StormMax™ of 15 inches.

"San Diego will likely receive between 1 and 3 inches of rain this week," according to AccuWeather Meteorologist Brian Thompson. "The city averages 1.98 inches for the entire month of January."

"In the mountains, there can be at least a couple yards of snow in the high country of the central and southern Sierra counting the storms during the seven-day-period ending late Thursday," according to AccuWeather Senior Meteorologist Alex Sosnowski.

Southern California will bear the brunt of the latest storm in the series into Monday night. Downpours and corresponding travel delays are expected from Santa Barbara to Los Angeles and San Diego.

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California Department of Transportation warned motorists that the Pacific Coast Highway (Route 1) may be shut down at anytime due to the risk of flooding and mudslides around the Woolsey Fire burn area in Ventura and Los Angeles counties.

Mandatory evacuation orders were issued near the burn scar areas of the Holy Fire in Riverside County early Monday.

Even in the absence of flooding and mudslides, commuters should prepare for slow travel, reduced visibility and a heightened risk of hydroplaning on interstates 5, 10, 15 and other area highways.

Static Cali Monday Night

Snow in the mountains north of Los Angeles can total up to a foot above 5,000 feet with this storm. While that will be a boon for the ski resorts, increasingly gusty winds can make mountain travel extremely difficult to impossible.

Snow caused travel disruptions along the Grapevine corridor of I-5 near Tejon Pass, causing the highway to be closed in both directions for a time on Monday.

The storm is expected to be a mostly rain event for the Grapevine corridor of I-5, but a burst of snow coating the summit of Tejon Pass cannot be ruled out.

Motorists driving through the Grapevine may also face strong southeasterly winds, which began on Sunday night.


Vehicles driving on Interstate 5 near the Grapevine on Monday amid heavy snow and freezing conditions. (Photo/Caltrans District 7)

As this storm pivots inland, it is forecast to spread a period of locally heavy rain to the desert areas from Palm Springs and Needles, California, to Las Vegas and to Kingman, Arizona, into Monday night. Some rain can reach Phoenix on Tuesday as snow returns to Flagstaff.

On the heels of this storm, another storm with more rain and mountain snow can push into California from Tuesday into Tuesday night.

If this next storm develops to its full potential, there can be heavy rain along the slopes of the mountains around Los Angeles and Santa Barbara.

Most of the state may be affected by the third storm of this week set to slam onshore from Wednesday to Thursday.

New Cali Storm static

"That Wednesday to Thursday storm has the potential to drop several inches of rain in the foothills east of the Sacramento Valley," Thompson said. "That includes the area devastated by the Camp Fire, which will enhance the risk for flooding and mudslides."

It is during this storm when the most difficult travel conditions are anticipated along I-80’s Donner Summit due to heavy and wind-driven snow. Motorists should anticipate potential restrictions and closures.

The storm onslaught on California is anticipated to wane next weekend with a turn toward drier weather for the final week of January.

Download the free AccuWeather app for more precise details of how each storm targeting California will affect your community.

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