A cold Pacific storm out of the Gulf of Alaska took aim at the Southland Wednesday, threatening a wet afternoon commute, sharply colder temperatures, snow as low as 3,500 feet, gusty winds, and whiteout conditions on mountain roads, National Weather Service forecasters said.
The storm will produce steady rain starting this afternoon or tonight, followed by widespread showers tonight and Thursday, when there also will be a slight chance of thunderstorms, some of which could produce small hail, according to an NWS advisory.
Rainfall totals resulting from the storm are expected to be up to a half- inch in coastal, valley and desert areas and up to an inch in the foothills and mountains, according to the NWS.
The storm will cause the snow level to fall to its lowest point so far this season, according to the advisory. It will start at 5,000 feet this afternoon and drop to between 4,000 and 3,500 feet by Thursday morning, likely leaving snow on roadways, including Interstate 5 through The Grapevine.
Between three and six inches of snow is expected above 5,000 feet, although between six and eight inches is possible, according to the advisory.
"Light accumulations are expected down to near 4,000 feet, including the Tejon Pass," it said. "The combination of wet snow and low temperatures in the mountains could create a dangerous situation for campers and outdoor enthusiasts who are not prepared ..."
Wednesday's forecast called for winds of between 15 and 25 miles per hour in mountain areas, gusting to 45 mph. A winter weather advisory warning of difficult travel conditions, caused in part by blowing snow and a resulting loss in visibility, will be in effect in the San Gabriel Mountains for 24 hours starting at 4 this afternoon.
Temperatures, meanwhile, will fall substantially and not rise above the low 60s Wednesday or Thursday, when they will be 10 to 20 degrees below normal, according to the NWS.
The NWS forecast high Wednesday of 40 on Mount Wilson; 58 in Saugus, Lancaster and Palmdale; 60 in Pasadena, San Gabriel, Burbank, Woodland Hills and Avalon; 61 at LAX; 62 in Long Beach; 62 in downtown L.A; 63 in Anaheim; and 64 in Newport Beach. Temperatures will remain roughly at that level for several days.
Following Thursday's showers, no precipitation is expected until a new bout of rainfall Sunday.