The National Weather Service today issued a flash flood watch for Northern California’s wildfire-scarred areas, including the Butte County mountainsides denuded in the past two weeks by the Camp Fire.
The alert is in effect from Wednesday through Friday when the first rain and snowstorm of the season is expected to hit the north state.
Although rain amounts are forecast to be moderate, weather service officials said scorched hillsides in wildfire areas are susceptible to failure, causing ash and debris flows into ravines, as well as boulder and mudslides that could tumble onto roads.
Officials particularly warned residents and travelers in the areas burned this summer and fall by:
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- The Camp Fire in the mountains above the Feather River in Butte and Plumas counties, and along Skyway and Highway 70.
- The Carr Fire in Redding and areas west, including along Highway 299.
- The Delta and Hirz fires along Interstate 5 between Shasta City and Redding.
- The Mendocino Complex fire in the hills northwest of Clear Lake.
The initial storm, expected to hit the foothills Wednesday afternoon, should bring moderate to heavy rain, the weather service forecasts. That will ease into showers that could last into the weekend. Another set of storms is expected next week.
“This first (storm) is not what we’d call a gully washer, but we are apprehensive and we are watching it closely,” said Dan Keeton, a meteorologist with the National Weather Service. “It remains to be seen how (soil) is going to react.”
Keeton said officials see a potential for some debris flows or slides in canyons that feed tributaries into the Feather River. That could also cause problems for Highway 70 in the mountains.
Officials are asking residents of fire areas to stay tuned to weather reports and be prepared to evacuate their homes.
In Butte County, where the Camp Fire ravaged the towns of Paradise, Magalia and Concow, emergency services officials said they are monitoring the storm and expect to issue advice to residents late Monday afternoon.
“We’re watching the weather,” Camp Fire incident spokesman Brian Ramsey said. ”We’ll put out alerts if needed.”
Cal Fire and weather service officials said the soil just below the surface gets packed by intense wildfire heat and can become impermeable to water, causing an almost instant wash off of debris, ash and loose dirt during extremely heavy rainstorms.
For most Northern Californians, though, this week’s expected rain is desperately welcome. Firefighters say it will help their efforts to finally put out the Camp Fire.
The rain should clear up some of the extremely unhealthy air Northern Californians have had to deal with for the past 10 days.
The biggest benefit will come from the winds that accompany the storm, Michelle Meade of the National Weather Service said. Those winds, flowing from the south and west, will push the particulate-laden smoke up and to the east. The rain, she said, will knock down larger particulates, returning healthy air to the north state for the first time in two weeks.