Small stream flooding started in Montrose-La Crescenta Friday.
Montrose Avenue, toward Verdugo Road and Honolulu Avenue experienced areas of flooding from northbound streets.
Heaviest rains are expected to hit around 2 p.m. bringing about one half inch to three quarters of an inch, according to the National Weather Service.
"Excessive runoff from heavy rainfall will cause elevated levels on small creeks and streams and ponding of water in urban areas, highways, streets and underpasses as well as other poor drainage areas and low lying spots," the NWS reported.
Flashes of lightning and thunder are rumbling through the foothills, and the Los Angeles River is torrential, as it usually is in weather like this. The river is almost four feet from the top, which is high.
Gusty winds were whipping across the Los Angeles County ahead of what forecasters say is a cold Pacific storm that will start dousing the Southland Friday in time for the morning commute and make traveling difficult on Interstate 5 in the area of the Grapevine.
The storm is the second this week and expected to be stronger than the one on Wednesday.
Emergency crews were kept busy as the cold, windy Pacific storm swept across Southern California today. Between 6 a.m. and 11 a.m., 249 accidents were reported on Los Angeles County freeways, compared with 68 reports during the same five-hour period last Friday, when conditions were dry, said California Highway Patrol Officer Ed Jacobs.
Elsewhere, the wet weather appeared to be responsible for malfunction traffic signals at four intersections near Pacific Coast Highway and Second Street in Long Beach, the Long Beach Police Department reported.
The storm rolled through Santa Barbara and Ventura counties early today before reaching Los Angeles County, according to the National Weather Service. The Antelope Valley was the first area in the county to report rain this morning.
"Rain and snow will likely be heavy at times, especially late this morning through the afternoon hours," according to an NWS advisory. "Steady rain and snow will turn to showers tonight."
The storm is expected to produce thunderstorms with small hail in Los Angeles County, as it has been doing to the north, said NWS meteorologist Kurt Kaplan.
He said the storm will generate between three-quarters and an inch of rain in coastal and valley areas and between one and three inches in the mountains before dry weather returns Saturday. In local mountains, between eight and 14 inches of snow is expected to accumulate above 5,500 feet today, less at lower levels,
The snow level will fall to 5,000 feet this morning, then to 3,500 feet by tonight, according to an NWS advisory.
"Accumulating snow and blowing snow will likely affect Interstate 5 over The Grapevine during the busy evening commute," it said. "Snow may create travel hazards across the Interstate 5 Corridor this evening."
Along with the snow, south-to-southwest winds of between 25 and 35 miles per hour will howl across mountain areas later today, gusting to 55 mph, NWS forecasters said. Then, the wind is expected to start blowing from the northwest, gusting to 45 mph.
"The gusty winds will create blowing and drifting snow, which will reduce visibility to near zero at times in the mountains," according to an NWS advisory. "Driving conditions may become treacherous."
A winter storm warning indicating an expectation of heavy snow and hazardous conditions will be in effect in the Los Angeles and Ventura county portions of the San Gabriel mountains until 3 a.m. Saturday.
Forecasters said the storm, the second this week, also would churn up high winds at lower elevations. A wind advisory went into effect at 10 this morning, and will continue until 2 p.m. Saturday in coastal and metropolitan Los Angeles, Santa Catalina Island and the Antelope Valley, and from 11 a.m. until 11 p.m. in Orange County.
Temperature highs largely will be in the high 50s today, climbing to the low 60s Saturday. Because of the weather, the in the Angeles National Forest about 11:30 p.m. Thursday:
-- Angeles Forest Highway from Aliso Canyon Road to Upper Big Tujunga Canyon Road; and
-- Upper Big Tujunga Canyon Road from Angeles Forest Highway to Angeles Crest Highway, also known as state Route 2.
Access will be maintained for emergency vehicles only, officials said.