Rain and snow will make a dramatic return to the Southland overnight, with precipitation expected to start after midnight and continue into Thursday, potentially dropping several inches of rain and bringing a few feet of snow to the mountains.
A winter storm warning took effect at 1 a.m. Wednesday and remain in place until 4 a.m. Friday in the Los Angeles County mountains, excluding the Santa Monica range. According to the National Weather Service, “heavy snow” is possible, with 1 to 3 feet accumulating above 5,000 feet, and “light snow” falling as low as 4,000 feet. The snow will be accompanied by winds of 35 to 40 mph, with higher-elevation gusts of up to 60 mph.
“Travel could be very difficult to impossible,” according to the NWS. The weather service said that some mountain roadways that could be affected by snowfall include Angeles Crest Highway, Mount Baldy Road and Highway 39.
Caltrans later said workers were clearing Angeles Crest Highway in the Angeles National Forest north of La Canada Flintridge, and chains were required.
“Storm Wednesday (12/29) is expected to bring heavy snow / possible closure. Check quickmap.dot.ca.gov for latest conditions. Watch out for Workers!” the agency tweeted.
Meanwhile, in Orange County, voluntary evacuation warnings will go into effect at 10 a.m. Wednesday for the Silverado, Williams and Modjeska canyon areas in the Bond Fire burn area due to fears of possible debris flows. The same areas were subjected to mandatory evacuations during last week’s storm.
The NWS issued a flash flood watch for Orange County coastal and inland areas and the Santa Ana Mountains, including the Bond Fire burn area. The watch will be in effect Wednesday morning through Thursday afternoon.
“Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations,” according to the NWS. “Flooding may occur in poor drainage and urban areas. Flash flooding and debris flows are possible, especially near recent burn scars.”
NWS forecasters for Orange County said the area could receive up to 2.5 inches of rain along the coast and as much as 6 inches in the mountains below 5,000 feet, with hourly rainfall amount of 0.6 to 0.7 inches possible.
Rainfall amounts in the Los Angeles area were still somewhat uncertain, with forecasters saying the storm is likely to “stall somewhere over the region, likely over or just east of Los Angeles County.”
“Storm rain totals of 2 to 6 inches are expected where this stall occurs, highest in the foothills, with snow totals of 1 to 3 feet above 5,000-foot elevations,” according to the NWS. “Recent burn areas would likely see limited and shallow debris flows, while rivers will likely have non-flooding but elevated flows. Elsewhere, more modest totals of 0.5 to 2 inches of rain and 6 to 12 inches of snow are expected. While thunderstorms are not favorable, they cannot be ruled out either.”
Temperatures will also remain “significantly below average” across the region, according to the NWS.
On Tuesday, Anaheim recorded its lowest daytime temperature for that date at 56 degrees, breaking the old record of 59 set in 2007.
The rainy weather is expected to continue through Thursday, with dry — but cool — conditions anticipated starting Friday and lasting through the holiday weekend.