Heavy Rain Hits Lake Forest Last Week Of December, 2020

LAKE FOREST, CA —A winter storm slammed the Southland with rain, hail, wet roads, sporadic flooding, and mountain snow Monday. Forecasters said scattered showers would continue through Monday afternoon and into Tuesday morning. Thunder, lightning startled residents as the storm system moved rapidly through the area.

A High Surf Advisory was in place at Orange County beaches through Tuesday, the National Weather Service says. Waves at Orange County beaches were expected from 4 to 7 feet. The High Surf Advisory is in effect until 10 a.m. Wednesday, with it, dangerous swimming conditions are possible, and strong rip currents are highly likely.

A Beach Advisory is in place due to storm runoff, and unsafe water conditions due to bacteria from runoff. Ocean swimming is not recommended following a storm.

In Orange County, nearly an inch of rain fell in Yorba Linda, with half an inch recorded at the John Wayne Airport. Corona Del Mar and Lake Forest saw just under a half-inch of rain as of 10:30 a.m., Monday, while San Juan Capistrano saw just over a quarter-inch, while Laguna Beach saw just over a tenth of an inch.

According to the National Weather Service, erosion was expected in the burn-scarred areas of Bond and Modjeska Canyon. Orange County Sheriff's Department, the Orange County Fire Authority, and Public Works monitored conditions, cleaning up roadside storm drains in an effort to keep all roads open. Large tractors and backhoes were brought in to do the job of keeping roads clear of debris, a spokesperson for OC Public Works said over Twitter.

Canyon residents were given access to sandbags in advance of the storm that hammered the Orange County area through Monday.

To protect property from post-burn mudflows. Information for scheduling an appointment for sandbag pickup was available at myOCeServices.ocgov.com.

Although rain fell seemingly throughout the night in some parts of the basin, as of early Monday morning the National Weather Service indicated that most of Los Angeles County had received less than an inch of precipitation. But the isolated showers expected into Monday evening might change that.

The Hansen Dam area received just less than an inch as of 8 a.m., as did Culver City, La Verne, Alhambra, and mountain areas including the San Gabriel dam.

Portions of Santa Barbara and San Luis Obispo counties were hit harder, with some areas receiving more than an inch-and-a-half of rain. For those looking for a trip to the mountains, Mountain High received up to 10 inches of snow, while Pine Mountain had about 6 inches. Lower-elevation Frazier Park received about 4 inches.

There were reports of some flooding overnight, including on the San Bernardino (10) Freeway in El Monte. Forecasters also warned of a continued possible threat of debris slides in recent burn areas, saying some areas could get brief downpours that could trigger slides, particularly later in the day Monday.

"The threat for significant and damaging debris flows is small, but not zero," according to the NWS. Meanwhile, lifeguards reported the "rare sight" of slush and hail at some beaches, warning that stormwater being carried to the coast can lead to significant beach erosion while also carrying substantial pollutants to the ocean. That flow of pollutants prompted the Orange County Department of Public Health to issue a Beach Water Use Advisory, urging people to avoid entering the ocean for swimming, surfing, or other activities near discharging storm drains or creeks. The advisory will remain in effect until at least 7 a.m. Thursday.

According to the NWS, the storm system was moving southeast out of San Luis Obispo County.
"This will maintain showery conditions across the area through this afternoon at least," according to the NWS. "No lightning strikes have been detected in several hours but with the upper low coming through today providing some additional energy and cold air, there's a reasonable chance for at least a few more thunderstorms, especially over or near the coastal waters."

Forecasters said a risk of snow will linger throughout the day along the Grapevine in northern Los Angeles County.

Temperatures will remain relatively chilly, with most areas unlikely to reach the 60s.

The storm system should mostly move out of the region by Tuesday, and forecasters expect gusty winds Tuesday through Friday, bringing gusts of up to 50 mph to particularly wind-prone areas.

Humidity levels will also drop in some mountain and lower-elevation areas. But thanks to the rain, the region will likely avoid any red-flag warnings of severe fire danger, but "pockets of two to four hours of critical weather conditions are possible."

City News Service, Patch Editor Ashley Ludwig contributed to this report.