Scientist concerned California storm will exhibit "windshield-wiper" effect (2024)

The firehose of intense rainfall that’s been battering Southern California since Sunday couldrecedeand then target the region yet again, according toclimatescientist Daniel Swain — in a concerning pattern he called the “windshield-wiper” effect.

If that happens, areas that have already been inundated by record-breaking rainfall will get thrashed again by torrential downpours “without much of a break in between.”

The storm has already dumped nearly 10 inches of rain on parts of Los Angeles County and in the Santa Monica Mountains.

Swain warned theflooding“may get worse and more widespread as the day goes on,” especially as afternoon heating could lead to some thunderstorm activity.

Six homes were damaged and one was "threatened" due to “debris flow” in a Los Angeles neighborhood Monday morning as the region continues to face a powerful winter storm,according to the Los Angeles Fire Department.

The flow caused “significant damage”to the homesin the Beverly Crest area of Los Angeles, the fire department said in an alert on its website.

There were no reports of people trapped or injuries.Firefighters helped six adults and nine children who were left stranded as a result, according to the fire department.

The Los Angeles Department of Building and Safety responded to the area to assess any structures that might have been seriously compromised, according to the alert.

Rain has fallen nonstop across the Los Angeles metro since Sunday morning, creating jaw-dropping rainfall totals that continue to climb.

As of 11 a.m. PT ( 2 p.m. ET) Monday, 6.35 inches of rain has fallen in downtown Los Angeles since Sunday morning. This is the fifth-wettest two-day stretch ever recorded there.

The wettest two-day stretch ever for downtown Los Angeles occurred more than 90 years ago when 7.98 inches of rain fell from December 31, 1933, to January 1, 1934.

This storm will continue to climb in the history book as more rain falls Monday. Rain is forecast to persist across the city through Tuesday before tapering off to a few showers Wednesday.

Strong winds roared across California Sunday and Sunday night as the atmospheric river-fueled storm reached its full strength. Wind gusts of 30 to 50 mph were common along the state’s coast while valley areas saw 20 to 40 mph wind gusts.

But the strongest winds centered on high-elevation areas where some gusts reached triple digits.

Winds were screaming Sunday night in the Sierra Nevada. Wind gusts eclipsed 140 mph for two weather reporting stations located at about 8,700 feet in elevation in the greater Lake Tahoe area.

One of these stations, located on Ward Peak in Placer County, recorded a 162 mph wind gust just after midnight Monday.Stronger winds are more common at higher elevations, but these winds are still exceptional for mountainous terrain.

Wind gusts this strong are more often associated with powerful storms like Category 4 or 5 hurricanes.

Here are some other notable wind gusts:

The strongest winds with the ongoing storm subsided early Monday. Gusty conditions are still possible Monday — especially at higher elevations —but nowhere near the extreme level that unfolded overnight.

A powerful storm has lashed Southern California with torrential rain that has triggered dangerous flooding, mudslides and debris flows. On Monday, photos showed downed trees, debris in the streets and rising rivers.

Speaking on CNN's Newsroom Monday morning, San Diego mayor Todd Gloria said the city is working to prepare for the impact of the storm as it moves south over the course of the day.

The mayor added that he had issued a second evacuation warning to low-lying and flood-prone parts of the city.

"We've seen areas that have not traditionally flooded flood because of the volume of rain in a very short amount of time," he said. "These atmospheric rivers are something that probably many of us never even grew up with knowing about, but now they're sort of ever-present in our lives. And it means an extraordinary amount of water can be dumped on a community, a very finite, small part of our city, in a very short amount of time."

He added that city officials are "doing absolutely everything we can" to prepare for the storm, including distributing over 150,000 sandbags.

Still, "we could use a break from mother nature, that's for sure," he said.

The city is under flood watch from 4 p.m. local time (7 p.m. ET) Monday until 10 a.m. local time (1 p.m. ET) Wednesday 1 p.m. Peak rainfall is expected to begin around 7 p.m. local time tonight (10 p.m. ET) and last until 3 a.m. local time Wednesday morning (6 a.m. ET).

While rain pounds Southern California, heavy snow is burying some of the state's mountains. Winter storm alerts are in effect through Tuesday afternoon for portions of the Sierra Nevada and Southern California’s mountain ranges.

Parts of the Sierras have already recorded more than two feet of snow this week with several more inches to come into Tuesday.

In Southern California, the heaviest snow will target the highest elevations of the San Gabriel, Ventura County and San Bernardino mountains through Tuesday. Several feet of snow may bury these ranges by the storm’s end, mainly above pass level.

Heavy, wet snow will still reach pass level for some travelers and pose “very difficult-to-impossible” conditions, according to the National Weather Service.

The snow is necessary for California’s snowpack, which has been beleaguered by warmth and storms that have brought more rain than snow.This winter’s snowpackwas just 52% of average for this time of year as of Tuesday, according to the latest survey conducted by the state’s Department of Water Resources.

Snowpack is a vital water source, and the survey helps California to forecast how much water will be available for the rest of the year.

Adeluge of rain from a long-lasting atmospheric riverhas caused “significant” flooding on canyon roads in Malibu resulting in road closures, MayorSteve Uhring said in an email to CNN, adding the city is also bracing itselffor "significant" beach erosion.

"Rain in Malibu all day. All north south Canyon routes from Malibu are closed or listed as hazardous," he wrote.

Malibu has been identified as a high-risk flash flood zone, according to Uhring, and residents are being advised to "stay home and avoid the hazardous roads – rock and mud slides, flooding and dark traffic signals."

All Malibu schools were closed on Monday due to the road closures in place and the inability for some staff to get to school. Pepperdine University in Malibu also canceledin-person classesand events Monday, they announced on X.

This post has been updated with Pepperdine's cancelations.

A powerful atmospheric river-fueled storm is moving at an agonizingly slow pace across Southern California, directing a firehose of moisture at deluged cities for hours at a time.

Downtown Los Angeles has picked up 5.96 inches of rain since Sunday — well above what it typically receives in the entire month of February.

The worst of the storm’s rainfall will slowly shift south throughout the day. Los Angeles will bear the brunt of the storm early Monday, but the threat will shift to the San Diego area by the evening.

Here's what to know: