LOS ANGELES (CNS) - Following a day of high heat records, Southland temperatures will dip sharply today as a storm out of the Pacific Northwest bears down on the region, poised to unleash rainfall as early as tonight, forecasters said.
National Weather Service forecasters said they expect brief, heavy downpours late tonight into Wednesday, along with a slight chance of thunderstorms.
Between a quarter-inch and three quarters of an inch of rain are expected in L.A. County as a result of the weather event.
The storm will also trigger snowfall, with six inches expected in the San Gabriel Mountains above 5,500 feet, causing roads to become dangerously slick and threatening some flooding, which could prompt road closures, forecasters said, adding that the issuance of a winter storm advisory is a distinct possibility.
“A low-pressure trough approaching the California coast will bring significantly cooler conditions, and periods of rain as well as mountain snow Wednesday and Thursday,” according to a National Weather Service statement. “Drier and warmer conditions will return going into the weekend.”
As of this morning, forecasters do not expect the Southland's first rain of the season to trigger mud slides or debris flows in Southern California areas previously denuded by wildfire, unless a thunderstorm produces an inordinate volume of rain, said Oxnard-based NWS meteorologist Rich Thompson.
“We don't yet see any significant issues,” he said, adding that the lion's share of the storm system would strike San Diego County.
The offshore flow that kept the region warm Monday began to weaken Monday night, giving way to an onshore flow that will generate “a significant cooling trend” today, with high temperatures 10 to 20 degrees cooler than Monday across coastal and valley areas.
Going into effect tonight is a high surf advisory scheduled to be in force from 9 p.m. until noon Thursday. The surf will build to between 4 and 7 feet tonight, continuing through Thursday morning.
“There is an increased risk for ocean drowning,” warned an NWS statement. “Rip currents can pull swimmers and surfers out to sea. Large breaking waves can cause injury, wash people off beaches and rocks and capsize small boats near shore.
“...Swim near a lifeguard. If caught in a rip current, relax and float. Don't swim against the current. If able, swim in a direction following the shoreline. If unable to escape, face the shore and call or wave for help.”
Record highs for a November 18 were set in several parts of L.A. County Monday -- 93 degrees at LAX, topping the record of 88 set in 1989; 92 in Downtown L.A, topping the 91 recorded in 2008; 92 at Long Beach Airport, beating the record of 90 set in 1989; 92 at UCLA, beating the 89 set in 2008; 92 in Woodland Hills, tying the record set in 2008; 89 at Bob Hope Airport, beating the 88 recorded in 2006; and 76 at Sandberg, tying a record set in 1995.
Partly cloudy skies were forecast in L.A. County today, along with highs of 65 degrees on Mount Wilson; 72 in Avalon; 75 in Palmdale, Lancaster Long Beach and at LAX; 77 in Downtown L.A., San Gabriel, Saugus and Burbank; 78 in Pasadena; and 79 in Woodland Hills. Wednesday's highs will be up to 15 degrees lower amid showers, with a warmup expected on Saturday.
The NWS forecast partly cloudy skies in Orange County today, along with temperatures of 64 on Santiago Peak; 70 in San Clemente; 71 in Laguna Beach; 72 in Newport Beach and on Ortega Highway at 2,600 feet; 76 in Fremont Canyon; 77 in Yorba Linda, Fullerton and Trabuco Canyon; 78 in Irvine and Mission Viejo; and 79 in Anaheim. Amid showers, Wednesday's highs will be up to 18 degrees cooler.
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