Ocean Water Quality Rain Advisory In Effect For Manhattan Beach

MANHATTAN BEACH, CA — An ocean water quality rain advisory is in effect for Los Angeles County beaches through Thursday, County of Los Angeles Public Health officials said Monday night.

A rain advisory is issued when significant rainfall can cause bacteria levels in the ocean to increase, officials said.

Bacteria levels can rise significantly during and after rainstorms, as contaminants within the runoff enter the ocean. Bacteria levels may remain elevated for up to three days depending on rain intensity or volume of runoff, especially near storm drains, creeks and rivers.

The bacteria advisory will be in effect through 10 a.m. Thursday.

"Elevated bacteria levels in ocean water may cause illness, especially in children and the elderly," officials said.

Southland Storm

After a week of generally above-average temperatures, rain fell on much of the Southland Monday, making for wet morning and afternoon drives and prompting concerns of possible flooding in Orange County hillsides.

The flooding fears initially prompted Orange County to issue a mandatory evacuation order for the Silverado, Modjeska and Williams canyon areas that took effect at noon. But by 4 p.m., the order was downgraded to an evacuation warning.

The National Weather Service issued a flash flood watch for the Bond, Apple and El Dorado fire burn areas, which includes the Silverado, Modjeska and Williams canyons. Forecasters said heavy rain is possible in the mountain areas, and residents nearby "should prepare for potential flooding impacts."

"Heavy rainfall could trigger flash flooding of low-lying areas, urbanized street flooding and debris flows in and near recent wildfire burn scars," according to the NWS.

The flash flood watch is expected to remain in effect until late Monday night.

Forecasters said the storm will linger over the region until early Tuesday morning, "bringing widespread rain, high elevation snow, and gusty winds. There will also be a chance of thunderstorms capable of producing heavy downpours and small hail later this morning through this evening."

Light rain fell in coastal areas early Monday, gradually increasing in intensity through the morning rush hour and spreading eastward. Forecasters said rainfall rates were generally below an inch-per-hour in most areas in Los Angeles County.

Wind advisories will be in effect until 10 p.m. in the Antelope Valley, Santa Monica Mountains Recreational Area and the Santa Clarita Valley. Forecasters said the areas could see winds gusting up to 50 mph, possibly making driving difficult for high-profile vehicles, and potentially leading to downed tree limbs or power outages.

A winter storm warning will be in effect for the Los Angeles County Mountains, excluding the Santa Monica range, until 6 a.m. Tuesday.

According to the NWS, 6 to 12 inches of snow could accumulate in mountains above 6,000 feet, with 18 inches possible at 7,500 feet and higher -- along with winds of up to 60 mph.

The bulk of the weather system is expected to move out of the area by early Tuesday morning, "but there could be some lingering (mountain) showers persisting in the morning."

Drier conditions are expected by later Tuesday and Wednesday, with a "slight" chance of some more rain on Thursday, following by warming conditions on Friday and Saturday.

Here is the forecast for Manhattan Beach:

Monday Night: Showers and possibly a thunderstorm before 11 p.m., then showers likely. Low around 54. West southwest wind 5 to 15 mph, with gusts as high as 20 mph. Chance of precipitation is 90%.

Tuesday: Sunny, with a high near 64. Northwest wind 5 to 10 mph becoming west southwest 10 to 15 mph in the afternoon. Winds could gust as high as 25 mph.

Tuesday Night: Patchy fog after 11 p.m. Otherwise, increasing clouds, with a low around 54. West wind 5 to 15 mph becoming east in the evening. Winds could gust as high as 20 mph.

Wednesday: Patchy fog before 11 a.m. Otherwise, cloudy through mid-morning, then gradual clearing, with a high near 64. East southeast wind 5 to 15 mph becoming west southwest in the afternoon.

Wednesday Night: Patchy fog after 11 p.m. Otherwise, mostly cloudy, with a low around 54. West southwest wind 5 to 15 mph becoming east southeast after midnight. Winds could gust as high as 20 mph.

Thursday: Patchy fog before 11 a.m. Otherwise, mostly cloudy, with a high near 64.

Thursday Night: Patchy fog after 11 p.m. Otherwise, mostly cloudy, with a low around 54.

Friday: Patchy fog before 11 a.m. Otherwise, partly sunny, with a high near 66.

Friday Night: Patchy fog after 11 p.m. Otherwise, mostly cloudy, with a low around 53.

Saturday: Patchy fog before 11 a.m. Otherwise, partly sunny, with a high near 66.

Saturday Night: Patchy fog. Otherwise, mostly cloudy, with a low around 54.

Sunday: Patchy fog. Otherwise, partly sunny, with a high near 65.

Sunday Night: Patchy fog. Otherwise, mostly cloudy, with a low around 53.

Monday: Patchy fog. Otherwise, mostly sunny, with a high near 68.

- City News Service and Patch Editor Nicole Charky contributed to this report.