An offshore winter storm warning is in effect for Los Angeles County through Tuesday morning, according to the National Weather Service.
This cold Pacific storm could bring moderate to heavy rainfall as well as snow in the mountains, the agency reported.
"There will also be a slight chance of thunderstorms," the NWS reported. "This storm will hit Ventura and Los Angeles counties the hardest with heavy snow expected in the San Gabriel Mountains. There is a chance of snow in the Antelope Valley, especially the foothills Monday night into Tuesday morning."
Heavy snow is expected for elevations above 5,000 feet throughout Los Angeles County, with possible snow falling between 9 and 13 inches, the agency said.
Rainfall could reach between one quarter and three quarters of an inch throughout the mountains.
"The Monday morning and afternoon commute will likely be impacted by this storm so motorists should plan to allow extra time to reach their destination," the NWS reported.
Localized urban roadway flooding will be possible," according to the agency. "In addition, there could be potential drainage problems in the San Gabriel Valley, where tree debris remains on city streets."
Here are the temperatures for Montrose and La Crescenta:
Sunday: Low around 46 degrees, 50 percent chance of showers.
Monday: High near 55 degrees, low around 45 degrees, 80 percent chance of precipitation.
Tuesday: High near 53 degrees, low around 45 degrees, 50 percent chance of showers.
Wednesday: High near 56 degrees, low around 46 degrees.
Thursday:High near 55 degrees, low near 46 degrees with a slight chance of showers.
Foothill, San Gabriel Valley Communities on Flood Alert
"Residents of wind-damaged communities are urged to beware of the increased risk of localized street flooding during rainstorms and to not put debris out on their neighborhood roadways," according to Los Angeles County Department of Public Works.
The alert was issued in case of potential rainstorms headed on Monday, the agency reported.
The flood control system is prepared for the approaching rain, according to public works officials. Additional inspections were conducted in the windstorm impacted areas to determine if any channels need additional debris removal.
Despite the crew workers' efforts, it could be several weeks before streets and roadways are free of debris, said County Public Works spokesperson, Bob Spencer.
"The potential for localized street flooding could be serious if we get significant amounts of rainfall," Spencer said. "Residents of impacted communities need to stay alert to the possibility of such flooding."