A storm expected to reach the Southland by Friday could cause ponding on roadways, flash flooding, and debris flows down slopes previously denuded by wildfire, the National Weather Service said Tuesday.
Less than an inch of rain is generally expected in Los Angeles and Ventura counties, but there could be higher amounts in mountain areas and wherever thunderstorms develop, the NWS said in a statement.
The weather service said an upper-level low-pressure system now over the eastern Pacific Ocean is expected to move into Central California by Friday. The cold front behind it is expected to generate moderate to heavy rainfall, with thunderstorms possible, it said.
The approaching storm is expected to be wetter than the one that hit the region late Sunday and early Monday. It likely will produce gusty south-to- southwest winds and may lead to ponding on roadways, flash flooding and debris flows, the NWS said.
With the San Gabriel Valley foothills around Duarte, Bradbury and Azusa weakened from years of drought plus occasional brush fires, the area is prone to debris flows when rain comes down in short, heavy bursts, NWS meteorologist Kathy Hoxsie told the Los Angeles Times.
This week’s storms are the first of the fall rains in Southern California. Temperatures, meanwhile, will remain moderate.
The NWS forecast partly cloudy skies Tuesday and highs of 70 at LAX; 71 in Avalon and on Mount Wilson; 73 in Long Beach; 74 in downtown L.A; 76 in San Gabriel and Burbank; 77 in Saugus and Palmdale; 78 in Pasadena and Lancaster; and 81 in Woodland Hills.
Sunny skies were forecast in Orange County, along with highs of 70 in San Clemente and Newport Beach; 72 in Laguna Beach; 75 in Anaheim, Irvine and Mission Viejo; 76 in Fullerton; and 77 in Yorba Linda.
Temperatures will rise by a few degrees Wednesday and by a few more Thursday — hitting highs of 80 in downtown L.A., 84 in Woodland Hills and 81 in Yorba Linda — before retreating to the low to mid 70s on Friday, when rain is in the forecast.
