As a storm moves through Northern California, the real work is just beginning for atmospheric river researchers.

A strong atmospheric river is bringing impacts across California, including flooding rain to Los Angeles later this week.

With an atmospheric river set to arrive in Southern California, precautionary evacuation warnings have been issued in recent wildfire burn areas.

A Pacific storm could help California crews battle the dangerous Pack Fire in Mono County, but it could also wreak havoc on fire-charred communities further south.

For the West Slope Northern Sierra Nevada, including Blue Canyon, a winter weather advisory is also in effect to 10 a.m. Friday. Snow totals are expected to reach three to six inches south of Highway 50, with 12 to 18 inches at the highest peaks. Gusty winds up to 50 mph are also expected.

The storm could trigger dangerous flash floods and mudslides, but it may also extinguish California’s wildfire season.

"Rain is going to be the primary concern," a National Weather Service meteorologist told the Sentinel. "This looks to be our wettest system of the (rain) year so far."

A colder-than-expected Pacific system will bring up to two feet of snow to higher elevations and a fast burst of rain and wind across the Bay Area by Thursday.