California is about to get its first major atmospheric flood of the season. Here’s where it goes

The strongest atmospheric river to hit California in months is expected to dump rain and snow across the northern half of the state this week — also bringing strong winds and possible flooding — before eventually making its way south, forecasters say.

“This is going to be the first big storm of the season,” said Dial Hoang, a meteorologist with the National Weather Service in Monterey. The low-pressure system off the Pacific Northwest coast that is driving this storm will begin to rapidly intensify Tuesday — reaching the threshold of a bomb cyclone – which will increase its moisture and strength drastically.

Parts of northwestern California will be under flood and strong wind watches start Tuesday, when persistent rain is expected to begin, falling 4 to 8 inches over several days. Some ridgetops could see wind gusts up to 75 mph.

“A powerful storm system will bring heavy mountain snowfall, rain and strong winds to the Pacific Northwest and northern California through midweek,” National Weather Service Weather forecast center warned. “Numerous flooding, hazardous travel, power outages and tree damage can be expected as the storm reaches maximum intensity” Wednesday.

But after its initial peak, the system is expected to linger into the weekend, with a second wave of precipitation extending further south over most of the San Francisco Bay Area, down into the Central Coast and possibly reaching parts of Southern California.

The North Bay is expected to see 3 to 7 inches of rain Wednesday through Sunday, with some areas getting up to 11 inches, according to the National Weather Service’s forecast discussion. Officials hope the region will see only minor flooding as few areas have seen any real rainfall this season, so the soil should be able to absorb significant rainfall.

But some areas of the North Bay “are likely to become saturated very quickly,” Dalton Behringer, a National Weather Service meteorologist, wrote in the daily outlook. “Even if we don’t see too much flooding on Wednesday, I wouldn’t be surprised if flooding gets worse on Friday with the second wave, although less rain is expected during that time.”

Some light rain may reach Southern California this weekend, but it likely won’t be enough to eliminate any wildfire threat by the end of the year.

“It’s not going to be what Northern California is going to be, but something helps,” said Bryan Lewis, a National Weather Service meteorologist in Oxnard. “It’s probably not enough to get us completely out of the way yet (for fire reasons).”

ONE winter storm watch has been issued for the northern Sierra Nevada and other northern California mountains above 3,500 feet, where 4 to 15 inches of snow is possible Tuesday and Wednesday.

This storm kicks off what appears to be a stretch of wet weather across the state, with above-average rainfall expected through at least Thanksgiving, according to National Weather Service’s Climate Prediction Center.

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This story originally appeared in Los Angeles Times.