In Santa Monica, the westbound lanes of Pacific Coast Highway were closed due to a landslide, and at the intersection of Malibu Canyon Road and Piuma Road in Agoura Hills, large boulders blocked both lanes of traffic. Flooding also briefly shut down the HOV and second lanes of Interstate 5 in Burbank late Monday morning.
The worst-hit area appears to be between Los Angeles and San Luis Obispo. Montecito reported 8.84 inches of rain, and a few miles to the northeast, in the mountains near Toro Canyon Creek, reported 9.71 inches. Most of Ventura County's mountains received at least 6 inches of rain, with 5 inches just north of Malibu and 4.36 inches at Pepperdine University. Downtown Los Angeles has seen a significant drop in rainfall, but more rain is on the way. 11.64 inches of rain has already fallen this month, the fifth-most on record. Two more inches would make it the wettest February on record.
Southern California is at risk of isolated tornadoes and water fountains after multiple tornado warnings were issued in the Sacramento Valley on Monday. At least one of the storms that triggered a tornado warning entered the mountains, bringing snow.
High winds toppled trees and power lines in the central and northern parts of the state. Although the strongest winds had subsided, more than 10,000 customers remained without power Tuesday.
Atmospheric river effects are expected to finally subside by Wednesday evening, but active weather is likely to return over the weekend.
Where are the atmospheric rivers now?
An atmospheric river, a thread of deep tropical moisture from near Hawaii, is being swirled ashore by a stationary low pressure system off the coast of Oregon. It has moved south down the coast and is now headed for Southern California. San Diego and Los Angeles are targeted by the moisture plume and will be affected for much of Tuesday.
Behind it, a pocket of frigid air moves overhead in relation to an upper-level low-pressure center. As a result, scattered heavy rain and a few thunderstorms are possible across much of California into Wednesday evening.
Some of those thunderstorms can produce small hail, isolated funnel clouds, and even rogue tornadoes.
The risk of flash flooding and excessive rainfall reaches a level 3 out of 4, which includes the Los Angeles metropolitan area. The National Weather Service says that “individual showers and associated storms will move very quickly,” but that “training will continue.” In other words, heavy rain will continuously move over the same area, like a train on a track.
Mountain areas north of Los Angeles could see an additional 2 to 4 inches of rain, while downtown could see nearly an inch or more if it really rains heavily.
The problem with this storm is not the total rainfall. This amount of rain will be significantly less than the previous storm, which dumped more than 7 inches over two days.Rather, what is of concern is the amount of rainfall. Rise by 0.5 inch per hour. This would rapidly inundate the soil and already saturated ground, causing further flooding.
Meanwhile, in central and northern California, the rain has largely stopped, with only scattered showers expected over the next 36 hours.
heavy snow and strong winds
Snowfall in the Sierra Nevada will drop from 7,000 feet to about 6,000 feet, with higher elevations receiving even more snow. The resort level will likely see a few more inches of snow above 6,000 feet, while the High Sierras could see an additional 2 to 4 feet of snow.
By Monday, many areas of the Sierra Nevada had seen double-digit damage totals, including Northstar, Bear Valley, June Lake, Kirkwood and Mammoth Mountain.
Wind gusts exceeding 40 mph are also possible along the Sierra Ridge, but the strong winds have largely subsided elsewhere. At the Central Sierra Snow Laboratory in Donner Pass, managed by the University of California, Berkeley, Power outage due to strong winds on Monday. Numerous wind gusts exceeded 90 mph in the Sierra Nevada Mountains, with gusts as high as 99 mph near Mammoth Mountain.
The National Weather Service predicted 10 to 20 inches of fresh snow would fall in Southern California's mountains, with snow levels dropping from 7,500 feet to 6,000 feet.
By Thursday, the parent upper atmosphere disturbance behind this atmospheric river is expected to end. After that, calm weather is expected until the next atmospheric river arrives late Sunday.
Jason Samenow contributed to this report.
