CA weather: How will Sacramento storm compare historically?

Date: 2021-10-23 10:23:53

Forecasters now predict Sacramento could get 4 to 5 inches of rain between Saturday night and Tuesday, when the brunt of a “bomb cyclone” pressure system is expected to unload on Northern California.

How much is that, exactly?

If it reaches the high end, the coming storm would be the wettest to hit the capital region in almost five years.

The last time Sacramento got at least 5 inches of rain in a four-day stretch was early 2017, when 5.4 inches fell from Jan. 7 to Jan. 10, according to National Weather Service records. That deluge was the same storm that kicked off a historically wet winter, a major factor in the Oroville Dam spillway crisis that began February 2017.

Since then, the only storm to drop more than 4 inches on Sacramento within four days came in February 2019.

For this weekend’s storm, more rain is expected in the foothills: the weather service predicts as much as 10 inches could fall near Grass Valley. Feet of snow are also anticipated in the Sierra Nevada foothills.

The storm will be especially extreme for this time of year. Sacramento has averaged less than an inch of rain in October over the past three decades and has only recorded more than 5 inches of rain for the entire calendar month once, in 1962 (7.51 inches), according to weather service records dating back to 1942.

Serious flash flooding risk near burn scars

The primary concern is for areas recently stricken by wildfires, weather and emergency officials say.

Burn scars — including for the Dixie and Caldor fires from 2021 along with the North Complex, Carr Fire and numerous others large blazes from the past few years — can be susceptible to flash flooding, debris flows and mudslides.

“If you live next to, or downstream from, any burned area affected by recent wildfires, you must be vigilant as heavy rainfall increases the potential for flash flooding, deadly debris flow and increased mudslides that feed directly into streams and watershed,” El Dorado County wrote in a social media post Friday.

The Caldor Fire destroyed hundreds of homes this summer in El Dorado County and prompted the evacuation of South Lake Tahoe for nearly a week. All evacuations have been lifted, and the blaze was declared 100% contained this week. But authorities warn that residents living near burned areas should, once again, be ready to leave at a moment’s notice.

The weather service has flash flood watches in place over the next few days in numerous counties near many burn scars, including but not limited to the Caldor Fire, Dixie Fire, River Fire, CZU Lightning Complex, Creek Fire, French Fire, SQF Complex, KNP Complex, Windy Fire, McCash Fire and multiple burns in the North Bay Area.

If the weather service upgrades a flash flood watch to a flash flood warning, it means flash flooding is imminent in that area, and that residents should immediately evacuate to higher ground.

“Soils in most places still have substantial capacity to absorb water, & rivers are low,” UCLA climate scientist Daniel Swain tweeted Thursday. “Urban/small stream flooding possible, but widespread serious flooding not expected. However…

“A major exception may be near wildfire burn areas … There will be high risk of flash flooding and debris flows in recently burned areas. Considerable damage/disruption could occur near/along the Hwy 50 and Hwy 70 corridors, though other recent (2020/2021) burn areas will also be at elevated risk.”

This story was originally published October 22, 2021 1:27 PM.

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Michael McGough anchors The Sacramento Bee’s breaking news reporting team, covering public safety and other local stories. A Sacramento native and lifelong capital resident, he interned at The Bee while attending Sacramento State, where he earned a degree in journalism.




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