The second part in an unseasonably cold storm's one-two punch lurked offshore for hours Friday morning, before finally making landfall at about 8 a.m.
The storm was expected to add to Thursday's rainfall totals and blow fierce winds that could create dangerous driving conditions in the San Gabriel Mountains and the Antelope Valley, forecasters said.
Mud and debris flows in recent burn areas constituted the main threat from the storm, according to the National Weather Service, while more thunderstorms like those seen Thursday were possible.
— Crystal Egger (@crystalNBCLA) May 15, 2015
Steady rain linked to a weakening cold front moved into San Luis Obispo and Santa Barbara counties Thursday morning, bringing some light showers and drizzle to parts of Ventura and Los Angeles counties.
But a cold and unstable air mass began sliding into the Southland by midday, bringing rain to areas such as Malibu and Catalina before the system brought light precipitation into the West Los Angeles and other areas.
Temecula was the hardest hit, receiveing 1.18 inches of rain. South Gate and Long Beach each received nearly half and inch of rain, while a more modest 0.22 inches fell on downtown LA.
But the rain caused traffic nightmares, injured a person and even threatened Dodgers record.
Rain caused a roof to collapse at a Food 4 Less store in South Los Angeles. Firefighters were also called out to rescue a man from the rushing water of the rain-swollen Wilbur Wash in Northridge.
The victim was reported to be in the wash, clinging to the wall of the channel west of the intersection of Wilbur Avenue and Parthenia Street, about 7:25 p.m., Robert Hinojosa of the Los Angeles Fire Department said.
The approximately 30-year-old man was in stable condition when taken to a hospital for treatment, Hinojosa said.
The firefighter who went into the water to fish him out was also taken to a hospital to be examined as a precaution, Hinojosa said.
Mike Ryan told NBC4 that his wife spotted the man in the river against a wall, waving his arms.
She called 911.
Before paramedics arrived, he said, good Samaritans tried to help.
Rain caused a one-hour, 25-minute delay in Thursday night's Los Angeles Dodgers-Colorado Rockies game at Dodger Stadium.
Play was halted at 8:58 p.m. with the game in the top of the sixth inning and the Dodgers leading, 4-1. Play resumed at 10:23 p.m.
The rain delay was the second of the season at Dodger Stadium. The start of the Dodgers' April 7 game against San Diego was delayed 30 minutes by rain, but the game was played without interruption.
Because at least five innings were played tonight, the game extended the team-record streak of games without a rainout to 1,231 games. The most recent of the 17 rainouts since Dodger Stadium opened in 1962 occurred on April 17, 2000.
Despite the rain, water officials stressed that the short-lived storm will not resolve the state's extensive drought and urged people to take advantage of the precipitation by turning off their irrigation systems for the next few days.
Rain fell at .15 an hour or less, except for up a half-inch in the heaviest showers. By 6:30 p.m., radar was showing scattered showers over portions of Los Angeles County, mainly the far western portion and valleys and mountains, according to the National Weather Service.
Radar detected some showers with heavy rain in Malibu and the western Santa Monica Mountains. The most rain fell on Opids Camp, traditionally the wettest place on record in Los Angeles County.
Through 6 p.m., 1.25 inches had fallen in the previous 24 hours on the school camp in the Angeles National Forest, 3,600 feet above Pasadena. Other rainfall leaders included the West Fork Heliport (.83 of a inch), Mount Baldy (.70), Crystal Lake (.66), Santa Anita Dam (.63), Pasadena (.57), and San Gabriel Dam and Inspiration Point (.55 each).
Rainfall records for this date were set at downtown Los Angeles (.16 of an inch, breaking the previous record of .03 set in 1902) and Los Angeles International Airport (.17, breaking the previous record of .06 set in 1962). The National Weather Service forecasts the second wave of rain starting early Friday morning in Southern Los Angeles County, continuing until the afternoon, except in the mountains, where it will extend until the early evening.
The potential for heavy showers resulting from a thunderstorm creates the possibility of minor debris and mud flows over slopes previously denuded by wildfire, the NWS said, describing a threat to communities below the foothills of the San Gabriel Mountains. In Glendora, local officials raised the alert status to "yellow" for residents living below the Colby Fire burn area.
The yellow status requires residents to remove vehicles, trash containers and other obstacles from streets to protect against damage from possible flooding or mud flows and to ensure emergency crews can access the area. In the San Gabriels, the snow level will drop to around 6,000 Thursday, then to around 5,500 feet Thursday night and Friday, the NWS forecast, adding that between three and six inches of snow is expected to accumulate between 6,000 and 7,000 feet.
Also expected are strong gusty winds, which will churn up blowing snow and make driving in the mountains hazardous, forecasters said.
A winter weather advisory, which is issued to herald dangerous driving conditions, will be in effect in the San Gabriels until 8 p.m. Friday.
The winds are also expected to lash the Antelope Valley, where a wind advisory will be in force until 10 p.m. Forecasters said the Antelope Valley will experience southwest winds blowing at sustained speeds of between 20 and 30 mph and gusting at 45 mph, and at as much as 55 mph in foothill areas such as Poppy Park and Lake Palmdale.
Crosswinds and blowing sand and dust may affect road travel in the Antelope Valley, restricting visibility, especially on the Antelope Valley (14) Freeway and Pearblossom Highway (state Route 138), they said.