LOS ANGELES (CNS)—A wet and potentially damaging storm is expected to hit the Southland Jan. 28, bringing what forecasters are calling an “atmospheric river” of moisture that will persist into Jan. 29.
Rain was already falling Jan. 2 over San Luis Obispo County, where the system remained largely stalled.
“The front sags southward into Ventura and Los Angeles counties by Thursday afternoon into Friday,” according to the National Weather Service.
“Heaviest rainfall across the southern counties will occur Thursday night into Friday morning. Several inches of rain are expected with flooding concerns including recent burn areas. Several feet of high elevation mountain snow is also expected, along with moderate to strong winds.”
The National Weather Service initially issued a winter storm watch for the Los Angeles County mountains, excluding the Santa Monica range, from Jan. 28 afternoon through Jan. 29 afternoon, but the agency later upgraded it to a winter storm warning.
Winds in mountain areas will blow at 20 to 30 miles per hour (mph), with gusts ranging up to 50 mph. A wind advisory will be in effect for Los Angeles County mountains until 3 p.m. Jan. 28.
Forecasters said the strongest winds are likely in the San Gabriel Peaks and the Grapevine area, making “driving difficult, especially for high-profile vehicles.”
A flood watch will be in effect for most of Orange County from Jan. 28 afternoon through Jan. 29 afternoon. Forecasters said the heaviest rain there is anticipated to begin before midnight Jan. 28, continuing through Jan. 29 morning, including a chance of thunderstorms and rain rates topping a half-inch per hour.
According to the NWS, the low-pressure system was gathering strength off the Oregon coast, and will likely remain mostly stationary through Jan. 28.
“This will create a steady and nearly persistent stream of moist southwest flow, known as an atmospheric river, focused over San Luis Obispo and Santa Barbara counties ... lasting through at least Thursday with two to three days of nearly constant rain,” according to the weather service.
Forecasters said Los Angeles County could see 1.5 to 3.5 inches of rain, with 2 to 5 inches possible in the foothills and mountains, although the largest rainfall totals are likely to occur in Ventura County.
Whenever persistent rain is in the forecast, fears are raised about possible mudslides.
“With the potential of this event, the area may approach critical thresholds for mud and debris flows in and around the recent burn areas,” according to the NWS.