The first in what is expected to be a series of three storms walloped parts of the Southland Thursday, bringing not only soaking rain, but also prompting flooding that blocked a stretch of Pacific Coast Highway and lighting that sent people scrambling from beaches.
The rain began falling northwest of Los Angeles early Thursday, but by mid-morning, the storm had moved into the Malibu area, through Santa Monica and into West Los Angeles and beyond, with driving rain, widespread lightning and ominous thunderclaps.
Pacific Coast Highway quickly became inundated with water and mud, forcing a closure of the roadway between Broad Beach Road in Malibu past the Ventura County line to Las Posas. Only Malibu residents with ID were being permitted north of Broad Beach Road.
Lightning strikes were visible across the region, prompting beach closures in Malibu and Santa Monica. Los Angeles County lifeguards warned anyone venturing toward the coast to avoid the beaches if lightning is spotted in the area. Seal Beach in Orange County was also closed due to lightning strikes.
National Weather Service forecasters initially said they expected between a quarter-inch and three-quarters of an inch of rain in Friday’s storm, with up to an inch possible in some mountain and foothill areas. By late morning, however, some areas in Santa Barbara County had already reported more than 2 inches of rain, and some parts of Ventura County were nearing that mark.
A flood advisory in Los Angeles County had been expected to expire at noon, but the NWS extended it until 2 p.m., warning that roads and low-lying areas will be vulnerable to flooding, particularly in recent burn areas.
A flash flood watch was in effect in the Santa Ana mountains and foothills, where voluntary evacuation orders were in place for the Trabuco Creek, Rose Canyon, Mystic Oaks and El Cariso areas near the recent Holy Fire burn scar.
No evacuation orders were issued for the Woolsey Fire burn area in Malibu, where a flash flood watch will be in effect through 3 p.m., although county officials warned residents to have an escape plan and be prepared to leave if so ordered.
Forecasters said the storm is expected to continue moving to the southeast, with the rain dissipating Thursday night.
The area should get a break from the rain on Friday, but another more powerful storm is expected to arrive late Friday night. According to the NWS, the system will again move eastward at a slow pace, with the brunt of it first hitting the Central Coast early Saturday and more intense rain coming through Los Angeles County late Saturday morning and afternoon, accompanied by gusting southeastly winds.
Rainfall rates of 0.5- to 0.8-inch per hour are expected Saturday, although some localized downpours could bring rain rates of an inch per hour, again creating the risk of mudflows in burn areas. Rainfall totals of 1.5 to 3 inches are expected in the storm, with up to 4 inches possible in south-facing slopes, according to the NWS.
According to the NWS, the rain will again taper off Saturday night, with the third storm expected to move in late Sunday into Monday. Forecasters said the third system appears to be much weaker, with the best chance of rain coming Monday.
Clear weather is expected beginning Tuesday, but there is a chance of another storm system moving in by the following weekend.