One day after a strong storm brought heavy rain and caused flooding and road closures across the Southland, the area was preparing Friday for an even more powerful system that forecasters say could drop major amounts of precipitation over multiple days beginning Sunday, creating severe flood risks.
“People need to start preparing now for a major flooding event,” National Weather Service forecasters warned in a statement Friday.
According to the NWS, the multiple-day storm could drop 3 to 6 inches of rain in coastal and valley areas, and 6 to 12 inches in the mountains, with much of that downpour occurring in a 24- to 36-hour period between Sunday into Monday.
“Historically, rainfall of this magnitude creates major hydrologic problems in our area and there’s no reason to think this won’t happen with this event,” forecasters said.
Forecasters said the most recent models are suggesting a slight reduction in overall rain totals, but “we’re still talking about major amounts of rain falling across the area.” The heavy rain will be accompanied by strong winds in many areas, blowing at speeds of 30 to 50 mph in parts of L.A. County, and reaching up to 60 to 90 mph in higher mountain areas and the Golden State (5) Freeway corridor.
As the storm moves slowly toward the Southland from the north, Saturday should be mostly dry, except for a slight chance of rain late in the day in the far western reaches of Los Angeles County.
Rain will fall across most of the region Sunday, arriving in the L.A. area by Sunday night. The exact timing of the storm’s arrival locally was still uncertain, with forecasters saying there’s a chance much of the heaviest rain could remain over Santa Barbara and Ventura counties for most of Sunday
“At this point, it appears that the focus of the heavy rain will shift into Los Angeles County by Monday morning, possibly lingering there into the afternoon, while lighter rain continues across the remainder of the region,” forecasters said Friday afternoon.
A winter storm watch will be in effect in the eastern San Gabriel Mountains from Saturday night through Tuesday afternoon, with forecasters predicting as much as 2 to 4 feet of snow above 7,000 feet, as much as 20 inches as low as 6,000 feet, and 8 inches at 5,000 feet. Winds will also gust in that area at 80 mph.
A flood watch will be in effect from Sunday afternoon through Tuesday afternoon for most of L.A. County.
“The Los Angeles River will fill quickly and become a raging river and a very dangerous place to be,” according to the NWS. “Anyone in that basin should be removed well before the onset of rain. Creeks and streams may rise out of their banks. Flooding may occur in poor draining and urban areas. Low-water crossings may be flooded. Storm drains and ditches may become clogged with debris. Extensive street flooding and flooding of creeks and rivers are possible.”
The wet weather pattern will continue into Tuesday evening, with periods of rain anticipated to continue. Drier conditions are expected by Wednesday, but a chance of showers will still be lingering. Snow levels could fall as low as 3,500 feet by Thursday, forecasters said.