Don’t be fooled by the weekend’s warm temperatures, you’ll need your rain jacket again as forecasters are predicting an incoming cold front with moderate to heavy rains in Southern California. A storm is first expected to drench San Diego County on Monday night before an atmospheric river storm soaks the L.A. region midweek, posing a threat to burn scar areas.
Even though residents across the Los Angeles region should still have sunny skies Monday, there will be a 10-degree dip in temperatures to the low 60s and a 50% chance of showers Tuesday, according to the National Weather Service.
An atmospheric river is expected to arrive early Wednesday, bringing heavy precipitation along the coast of California through Thursday, with significant impacts to mountain areas as it moves east toward the end of the week.
Rain will first hit San Diego County on Monday night, potentially causing roadway ponding and leading to hazardous driving conditions and minor flooding in urban areas. Orange County and the Inland Empire are expected to receive less than an inch of rain from Monday night through Tuesday. Southern California deserts will also see some rain, likely less than a tenth of an inch, according to the National Weather Service. Forecasters say a second system, the atmospheric river, will follow, moving through the coastal basin and bringing about an inch of rain.
The heaviest downpour is expected to occur in mountain areas Wednesday afternoon into early Thursday, with a chance of roadway and flash flooding, mudslides and possible debris flows near recent burn scars.
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 an inch for desert areas, 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 due to the rainfall, 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 on Thursday.
The San Bernardino and Riverside County mountains could see snow at around 6,000 feet elevation and 6,500 feet in the San Diego County mountains.
Heavy snow and strong winds, gusting from 40 to 60 mph, will probably have substantial impacts 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.
