California Live Updates: Evacuations, Warnings Issued Because of Debris Flow and Flood Threat | The Weather Channel – Articles from The Weather Channel

Date: 2021-10-24 17:52:10

In an aerial view, trees cast shadows in an area burned by the Dixie Fire on Sept. 24, 2021 in Greenville, California. Burn scars left by the fire are at risk for dangerous flash flooding and debris flows.

(Justin Sullivan/Getty Images)

  • Residents in an Alisal Fire burn scar are under an evacuation order.
  • In some areas, it might be too late to leave, the NWS warns.
  • Tens of thousands are without electricity.

Evacuations were ordered in at least one area and others are being told it might be too late to leave Sunday as a powerful storm moves across parts of California bringing the threat of potentially deadly landslides and flash flooding.

The threat is especially high in terrain left barren by wildfires, which is vulnerable to flooding and an especially dangerous and fast-moving type of landslide that scientists call “debris flows.”

Watches and warnings for flooding and debris flow were issued ahead of the storm for areas including the Dixie and Alisal burn scar areas.

(FORECAST: Powerhouse Atmospheric River Storm Arrives in California)

The weather is bringing relief amid a historic drought and tamping down the threat of fall wildfires. But it remains to be seen how the region’s wet season will play out.

Here are the latest updates.

Evacuations Ordered in Alisal Burn Scar Area

An evacuation order is in effect starting at noon PDT for some residents in the Alisal Fire burn scar area, including areas west of Las Flores Canyon, east of Mariposa Reina, south of West Camino Cielo, and down to the ocean. A warning was issued on Saturday.

The Alisal Fire started earlier this month and burned more than 26 square miles in Santa Barbara County.

It May be Too Late For Some to Leave, NWS Warns

The National Weather Service in Sacramento said debris flows were already occurring early Sunday morning. In a tweet, the agency warned residents that it may too late for some to leave.

“If you are near a burn scar, it may be too late to evacuate,” the agency said in a tweet. “Do not attempt to cross a debris flow. Take shelter in the highest floor of your home.”

Warning signs of an impending debris flow including rushing water and mud as well as unusual sounds including cracking, breaking, roaring or the sound of a freight train.

Tens of Thousands Without Power

More than 80,000 power outages are being reported in California as of about 10 a.m. PDT, according to Most of those were centered in the northern part of the state, including Sonoma, Marin, San Mateo and Butte counties.

What’s Causing This Weather?

The rain is from a powerhouse storm tapping into a strong atmospheric river that moved into California Sunday.

Soaking rain from this latest storm to hit the West Coast is ongoing right now from Northern California into the Pacific Northwest.

Heavy snow is also possible in some areas.

Click here for the full forecast.

What are Debris Flows and Why are They so Dangerous?

Terrain left barren by wildfires is most vulnerable to an especially dangerous and fast-moving type of landslide that scientists call “debris flows.” Known less formally as mudslides, these flows are typically triggered by short, intense rainstorms and can send a wall of water, soil, ash, vegetation, rocks and other debris careening downhill, sweeping away or burying everything in its path.

“A debris flow is kind of a flood on steroids,” Jason Kean, a debris flow expert with the U.S. Geological Survey, told in an interview. “It’s all bulked up with rocks, mud, even boulders – and boulders can be the size of cars.”

Besides destroying vegetation that would normally hold soil and debris in place, wildfires change certain characteristics of the soil itself. It becomes less likely to absorb water, which creates conditions ripe for flash flooding and debris flows

Click here to learn more.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.

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