What to Know
- A storm fueled by a river of moisture in the sky brought overnight rain and snow to Southern California.
- The rain will continue into Friday, when thunderstorms are possible.
- Downpours are possible, a major concern for SoCal’s recent wildfire burn zones.
A winter storm unlike any other this season drenched Southern California overnight and will continue to soak the region Friday.
What makes this storm different from previous storms this winter is that it’s fueled by an atmospheric river, a long plume of moisture in the sky over the Pacific. It can act likes a conveyor belt, delivering days of rain to California.
The weather phenomenon is associated with some of California’s most damaging storms and wettest winters.
Winter storm warnings were in effect for a widespread part of Southern California as the storm moved slowly down the coast. It is Southern California’s third storm in the last seven days after a mostly dry winter.
A flash flood watch in LA County expired, but watches remain in effect elsewhere.
Thunderstorms are possible Friday.
“Thankfully, the heaviest rain has passed,” said NBC4 forecaster Belen De Leon. “For tomorrow, out weather clears up and the sunshine returns.”
Overnight rainfall totals included 1.66 inches in Woodland Hills, 1.90 inches in Culver City, 2.87 inches in East Pasadena and 1.10 inches in Anaheim Hills.
In Riverside County, evacuation warnings were issued for the Apple and El Dorado burn scar areas, where residents were asked to be prepared for possible downpours that could trigger debris flows. A voluntary evacuation order was issued by the Orange County Sheriff’s Department for residents near the Bond Fire burn area.
The low-pressure system gathered strength off the Oregon coast, and remained mostly stationary through Thursday. The storm entered Los Angeles County and other parts of Southern California Thursday night with the heaviest rain expected Thursday night and into Friday.
The storm had already dropped nearly 14 inches of rain in some parts of San Luis Obispo County over 36 hours.
A winter storm warning went into effect at 3 p.m. Thursday and continues into Friday afternoon for most of SoCal. The warning also was in effect for Orange, Riverside and San Bernardino counties.
The region could see flood warnings as the storm moves closer, and residents in flood-prone areas will likely be urged to be prepared to evacuate at a moment’s notice.
“By Saturday, we could be seeing rain amounts of 1.5 to 3 inches,” said NBC4 forecaster Belen De Leon.
One to 3 feet of snow could accumulate at elevations above 6,000 feet.
Heavy snow was falling Thursday during a blizzard in the Sierra Nevada Mountains. Statewide snowpack is 41 percent of average. Last year at this time, California was a 73 percent of average.
“Things are about to change, and it’s all because of this atmospheric river storm,” De Leon said.
Winds will blow at 20 to 30 mph, with gusts ranging up to 50 mph. A wind advisory will take effect in the county’s mountains at 3 a.m. Wednesday and continue until 3 p.m. Thursday. Forecasters said the strongest winds are likely in the San Gabriel Peaks and the Grapevine area, making driving difficult, especially for high-profile vehicles.
Los Angeles County health officials have issued a cold weather alert through Thursday for the mountains and Antelope Valley, and through Tuesday for the Santa Monica Mountains and the Santa Clarita Valley.
Source: NBC Los Angeles