A mild atmospheric river will pass through the North Bay today, bringing as much as 4 inches of rain and the possibility of flash floods in areas scarred by the recent wildfires, according to the National Weather Service.
“We have some models that are predicting as much as an inch per hour,” said Rick Canepa, a meteorologist for the weather service in Monterey.
A flash flood watch has been issued for all of the North Bay from 4 p.m. today until 3 a.m. Thursday. The weather service noted that hilly areas — such as Fountaingrove and Atlas Peak in Napa County — that were torched by the recent wildfires could be potentially susceptible to flooding and trigger mudslides with burned debris.
“It means that there are conditions that could potentially develop and lead to flash flooding,” Canepa said of the flood watch.
An area from Sea Ranch down toward Santa Rosa will bear the brunt of the rainfall.
The system also will bring high winds from 15 to 30 mph, though some areas at higher elevations could have gusts as much as 50 mph, he said.
“There is definitely some wind damage that could be associated with it,” Canepa said.
There will be periods of precipitation starting after midnight Tuesday with heavier rainfall predicted for today.
“There is brief window of time that is maybe three to four hours long,” Canepa for the biggest downpour.
The fast-moving system is expected to move through the area quickly and leave the region by Thursday. The weather service predicts only a 30 percent chance of showers by Thursday night.
“It may help things that it will move through a little bit faster,” Canepa said of the storm.