Don’t be fooled by the weekend’s warm temperatures — you’ll need your raincoat again soon with forecasters predicting a pair of cold storms that could drench Southern California this week and threaten the recent burn areas.
The first of the storms will arrive in the Southland on Monday evening with a 70% chance of light showers on Tuesday, and areas of gusty winds south of Point Conception, according to the National Weather Service.
Then a powerful atmospheric river is expected to arrive early Wednesday, bringing heavy rain along the coast through Thursday, with significant impacts to the mountains as it moves east through the week.
“It’s unlikely any area is going to be spared from the moderate to heavy rain,” said Robbie Munroe, a meteorologist with the National Weather Service in Oxnard. “We’ll probably have some convective or heavier showers that could be a little more isolated and only hit certain areas.”
It could rain 1 to 2 inches in the valleys and 2 to 4 inches in the higher elevations, the weather service said. Officials said they expect to issue a flood watch alert from 6 p.m. Wednesday to 6 p.m. Thursday.
There is a possibility of heavier showers and thunderstorms hitting the southwest-facing mountains and foothills, areas that are prone to such storm patterns, but Munroe said, “Everyone is going to get a piece of this” storm.
Mountains and foothills could see flooded roads while areas near burn scars could experience flash flooding, debris flows and mudslides.
County officials say they’re prepared.
“We’re feeling comfortable about the amount of debris that we’ve taken and our capacity to capture debris flows based on the rainfall prediction,” said Mark Pestrella, director of the Los Angeles County Public Works and chief engineer of the Los Angeles County Flood Control District.
The department is also in communication with the sheriff’s and fire departments to coordinate potential evacuations in areas where the county doesn’t have debris basins to capture what flows off the hillsides, Pestrella said. The rains forecast for Wednesday night are particularly concerning, Pestrella said, so the county has communicated with vulnerable residents in Pacific Palisades, Altadena and Malibu about what to do.
Here’s how the atmospheric river will affect the coastal, valley and mountain areas of Southern California.
Coastal and valley communities
The coastal and valley communities can expect 1 to 2 inches of rainfall between Wednesday and Thursday.
During this time, there’s a 10% to 20% chance of thunderstorms with brief, heavy downpours that could cause significant roadway flooding or debris flows in recent burn scars.
There is also a potential for peak wind gusts of 30 to 50 mph, possibly causing downed tree branches and power outages.
If you experience a power outage:
- Stay home. Streetlights may be out, and debris may be flying around.
- Avoid opening the fridge or freezer. Food can be safe for up to four hours even without power.
- Don’t light candles. It’s a fire hazard; use a battery-powered flashlight instead.
- Unplug electronics and appliances that aren’t plugged into a surge protector.
- Avoid using your phone and laptop if possible to conserve the batteries for emergencies.
Mountain and desert areas
Residents in mountain areas can expect 2 to 4 inches of rainfall, and desert areas may see an inch, as well as heavy snow in some locations.
The mountains have a higher chance of rainfall, meaning an elevated chance of significant flooding or debris flows near recent burn scars. Those that could be at risk include areas that burned in the Palisades, Hurst, Kenneth, Sunset and Eaton fires.
According to the National Weather Service, travel may become delayed or hazardous in certain areas because of rain, mountain snow and gusty winds.
If you have to drive in the rain, officials from the Los Angeles Emergency Management Department advise the following:
- Slow down. Leave plenty of distance between your car and other cars on the road.
- Avoid driving through areas prone to flooding, and never bypass street barriers.
- Never attempt to drive through a flooded roadway or flowing stream.
Snow levels
Forecasters predict snow in mountain areas at elevations of 3,000 to 4,000 feet Wednesday, possibly dropping down to 2,500 feet Thursday.
The San Bernardino and Riverside County mountains could see snow at around 6,000 feet. In the San Diego County mountains, snow may fall at 6,500 feet.
Heavy snow and strong winds, gusting from 40 to 60 mph, are expected across the Sierra Nevada and Northern California.
Some highways may be impacted by snow Wednesday night through Friday morning, but especially Wednesday night into Thursday morning. They include:
- The 5 Freeway near Tejon Pass
- Highway 14 through the Antelope Valley foothills and near Acton
- Highway 33 north of Ojai
- Upper portions of Highway 154 in Santa Barbara County
If you have to drive in the snow, Caltrans recommends you prepare:
- Check the roadway conditions including chain controls and road closures before you leave your residence or work site. You can do so by checking the Caltrans Quick Map online.
- Be sure you have a full tank of gas; it may be necessary to change your route or turn back during a bad storm.
- Build in some extra time to reach your destination. If there are storms or icy conditions, travel time can take longer.
