Scattered showers moved into Southern California early Wednesday as the region prepares for a powerful winter storm that will bring heavy rain and raise the threat of debris flows in wildfire burn areas and widespread flooding.
Pockets of moderate rain developed early Wednesday and will continue through mid-day before the storm delivers a wallop overnight and into Thursday.
“We have increasing chances of rain as we head into the afternoon,” said NBC4 forecaster Stephanie Olmo. “They’ll continue to go up later this evening.”
Here’s what to know about the storm, weather alerts, travel conditions and more.
When will the heaviest rain arrive in Southern California?
The heaviest rain will be overnight into Thursday morning after scattered showers Wednesday.
Rainfall will range from one-tenth to a quarter-inch per hour in some areas early Wednesday. The rain will increase steadily, with downpours continuing into Thursday and reaching an inch per hour in some locations.
The storm’s peak intensity is expected to deliver the heaviest rain Thursday morning. Two to 4 inches of rain could fall across most of the area, with some mountain areas receiving 4 to 8 inches.
Downpours could result in flash flooding and debris flows.
In the San Gabriel Valley, K-rails were installed on streets in a foothill neighborhood in Duarte, where the storm raises the risk of destructive mud and debris flows.
Flood Watches and Other Weather Advisories
A flood watch will be in effect Wednesday evening through Thursday afternoon for most of the region. That’s just one of the weather alerts to know about.
- In Orange County, the flood watch will be in effect Thursday morning through Thursday afternoon.
- A high surf advisory was in effect from 6 am Thursday to 10 am Friday.
- A winter storm warning was in effect from noon Wednesday to 3 am Friday for the Los Angeles County Mountains including the cities of Acton and Mount Wilson.
- A wind advisory will be in effect in Orange County from 2 am to 4 pm Thursday, with winds of 15 to 25 mph possible, including gusts of up to 40 mph
- Wind watches could be issued in Los Angeles County mountains and deserts.
- A wind advisory was in place for San Bernardino and Riverside county valleys.
Travel Warning Ahead of California Storm
Caltrans warned drivers statewide to stay off the roads if possible during the storm.
“Caltrans districts statewide are coordinating with local & state officials to assist with this latest storm system. TRAVEL IS NOT RECOMMENDED,” the agency tweeted Tuesday.
Caltrans also cleared a section of Angeles Crest Highway in the Angeles National Forest below State Route 39, but drivers were advised to check for chain requirements.
Heavy snow was expected above 6,000 feet initially, but levels will drop Thursday, potentially affecting some of the higher roadways in the mountains, such as Angeles Crest and Big Pines highways in Los Angeles County.
The storm threat also led to a planned closure of Laurel Canyon Boulevard. The Los Angeles Department of Transportation announced that the canyon road will be closed between Hollywood Boulevard and Mulholland Drive from 8 am to noon Wednesday.
“There will be many potential problems associated with this storm system including urban and small stream flooding, rocks and debris on roads, downed trees and numerous power outages, and mud and debris flows out of recent burn areas,” the National Weather Service said.
When will the storm move out?
Rainfall will decrease by Thursday night and into Friday.
More rain is possible over the weekend, but nothing to match the severity of Thursday’s conditions. More rain was in the forecast early next week, with a chance of
showers Sunday through Tuesday.
Temperatures will remain about six degrees cooler than normal through the weekend.
California Drought Update