A powerful storm slowly made its way into the Southland Wednesday, with potentially heavy downpours again raising fears of flooding and debris flows in recent burn areas.
Light rain fell across most of the area Wednesday morning, making for a wet but tolerable commute. But as the storm moves closer, rain will slowly begin to intensify, beginning with rates of one-tenth to a quarter-inch per hour in some areas, according to the National Weather Service. By Wednesday afternoon and night, however, rain will keep getting heavier, with downpours continuing into Thursday and reaching one inch per hour in some locations. The “peak intensity” of the storm is expected to be Thursday morning.
NWS forecasters said 2 to 4 inches of rain could fall across most of the area, with some mountain areas receiving 4 to 8 inches before the storm moves out.
“These rates and amounts could cause significant flash flooding or debris flows across the region in and outside of recent burn scars with significant small stream and urban flooding possible,” according to the NWS.
In anticipation of the rain, many cities were offering residents free sandbags to help protect their properties from flooding.
At 8 a.m. Wednesday, the Los Angeles Department of Transportation closed Laurel Canyon Boulevard between Hollywood Boulevard and Mulholland Drive, a move that was taken “in preparation for heavy rain.” The closure was expected to remain in place until noon, allowing crews “to secure roads in advance of inclement weather,” according to the LADOT.
Crews were installing concrete k-rail barriers in the area to help control anticipated storm runoff.
Meanwhile, Caltrans officials cautioned motorists statewide to stay off the roads if possible.
“Caltrans districts statewide are coordinating with local & state officials to assist with this latest storm system. TRAVEL IS NOT RECOMMENDED,” the agency tweeted Tuesday.
Caltrans officials also said they cleared a section of the Angeles Crest (2) Highway in the Angeles National Forest below state Route 39, but drivers were advised to check Quickmap.dot.ca.gov for chain requirements.
The NWS issued a flood watch that will be in effect Wednesday evening through Thursday afternoon over the bulk of the Southland. In Orange County, the flood watch will be in effect Thursday morning through Thursday afternoon.
A high surf advisory was in effect from 6 a.m. Thursday to 10 a.m. Friday.
A winter storm warning will be in effect from 6 p.m. Wednesday to 10 p.m. Thursday for the Los Angeles County Mountains including the cities of Acton and Mount Wilson.
Forecasters said 1 to 2 feet of snow could accumulate at elevations above 7,500 feet, with 4 to 8 inches possible between 6,500 and 7,500 feet. Mountain winds could also gust up to 60 mph, according to the NWS.
The wintry weather could lead to “slippery road conditions” on some of the higher roadways in the mountains, such as Angeles Crest and Big Pines highways in Los Angeles County, forecasters warned.
The rain will be accompanied by gusting winds in the Southland. Wind advisories will be in effect for the bulk of the area from 6 p.m. Wednesday until 10 a.m. Thursday, with winds of 15 to 25 mph expected, along with gusts of up to 40 mph. Winds could hit 50 mph in the Antelope Valley, according to the NWS. In Orange County, a wind advisory will be in effect from 2 a.m. to 4 p.m. Thursday, with winds of 15 to 25 mph possible, including gusts of up to 40 mph, according to the NWS.
“There will be many potential problems associated with this storm system including urban and small stream flooding, rocks and debris on roads, downed trees and numerous power outages, and mud and debris flows out of recent burn areas,” according to the NWS.
Conditions are expected to dry out by Thursday night, continuing into Friday. A series of “weak disturbances” are anticipated over the weekend, but “there will likely be drier and less cloudy intervals in between the clouds and rain,” forecasters said.
Temperatures, meanwhile, will remain about six degrees cooler than normal through the weekend.
With rain falling, Los Angeles County health officials issued their standard warning for people to avoid entering ocean water near discharging storm drains, creeks and rivers. An ocean water quality rain advisory will be in effect until at least 7 a.m. Friday.
Health officials noted that stormwater runoff that reaches the ocean can carry bacteria, chemicals, debris trash and other health hazards. People who come in contact with impacted water in the ocean could become ill, health officials said.
More rain was in the forecast early next week, with a chance of showers Sunday through Tuesday, according to the NWS.