Thunderstorms rumbled across Southern California on Wednesday evening, hammering central Los Angeles and surrounding communities with torrential downpours that flooded roads and buildings while lightning strikes blacked out vast areas.
A powerful cell from the storm system stalled for more than an hour over the heart of the city east of Los Angeles International Airport, dumping rain and hail that accumulated at a rate of more than two inches an hour. Air traffic in and out of the airport was halted temporarily by limited visibility and erratic winds gusting as high as 30 mph.
Especially hard hit were Watts, Compton, Lynwood and South Gate, where as much as five inches of rain fell. At least 50,000 customers lost power for various lengths of time as hundreds of lightning strikes lighted up the sky.
"This is an extremely rare event," said Stuart Seto, a weather specialist with the National Weather Service in Oxnard. "To get five inches of rain in two hours is something you usually see only in a hurricane."
Thousands of evening commuters were stranded by flooded roads and blacked-out traffic signals. Surging runoff from the continuing rain invaded dozens of homes and businesses.
The Los Angeles Police Department called a modified tactical alert, requiring all officers in the southern half of the city to stay on duty until the emergency was over.
Fire rigs were dispatched throughout the flooded areas to help drivers stranded in waist-high water .
At King/Drew Medical Center in Willowbrook just south of Watts, about 100 visitors and employees huddled in the lobby, stranded by floodwaters that lapped around the buildings and seeped across the floor of the Augustus Hawkins Medical Clinic.
Ambulances that had bogged down in flooded intersections were hauled in by tow trucks. A bolt of lightning knocked out the electricity at 5:40 p.m., but emergency generators kicked in and the power was restored within seconds. Water was several feet deep in some rooms at the adjacent King Drew Medical Magnet School, which will remain closed today.
At least 15 cars stalled in a pond at the intersection of 120th Street and Success Avenue in Willowbrook.
"We probably pulled 30 people out of their cars," said county Fire Capt. Brown Lie, who stood hip-deep in the swirling runoff, directing the traffic that could still move around the stranded vehicles. In all, the Fire Department pulled 50 to 100 people out of marooned vehicles, said a department spokesman.
At the intersection of 119th Street and Willowbrook Avenue, Gerald Dotson, his wife and his two teenage sons fled their flooded house.
"The water came in under the door," said Dotson, 55. "The kitchen is full of water, the bathroom is full of water ... and it was going into the bedroom. We said, 'We'd better get out of here before we get trapped.' "
In Lynwood, the rain and hail started falling at 3:30 p.m.
"The whole street turned white with the hail, plenty big, like marbles," said Ramon Flores, 33, who works at Thee Sound Shop, a consumer electronics store in the 1800 block of Long Beach Boulevard. "It took a break for about half an hour, but another hour later, the ice started again."
Pedro Munoz, 33, another employee at the store, said workers had hefted merchandise from the floor onto counters as water "came in through the front door and went out through the back."
At Nino's Pizza in Lynwood, a lightning-laced downpour hit hard about 5 p.m. The lights went out, and runoff began pouring in the back door. The owner, Tony Garcia, 44, said he soon found himself standing in about three inches of water.
"We had orders for delivery, but what were we going to do?" he said. "We ask them, 'Can you pick it up?' They say, 'No.' Well, I ain't going to deliver them. There's too much water."
Curt Kaplan, a meteorologist with the National Weather Service office in Oxnard, said 5.31 inches of rain fell at 96th Street and Central Avenue in Watts.
"It just dumped and dumped and dumped," he said.
The most rain ever recorded in a 24-hour period in Los Angeles occurred on Dec. 31, 1933 to Jan. 1, 1934, and that was 7.33 inches downtown, Kaplan said. On Wednesday, downtown got 1.25 inches.
At LAX, spokeswoman Nancy Castles said 25 planes had been diverted to airports in Ontario and San Diego, starting about 5 p.m. Normal arrivals and departures resumed at LAX several hours later.
At least one plane from London had to remain on the tarmac in Ontario for hours because there were no Customs agents at that airport.
Forecasters said the scattered but powerful thunderstorms should be over by this morning, with no more rain expected into next week, at the earliest.
The thunderstorms came from a "cutoff low," an area of low pressure that lurked off the coast for several days, picking up subtropical moisture, before invading Southern California, the National Weather Service said.
Most storms at this time of year travel down the coast from the Gulf of Alaska, moving into the Los Angeles Basin from the northwest.
This one did just the opposite. Rotating counterclockwise around the center of low pressure, storm cells swept inland across northern Mexico before circling back, entering Southern California from the southeast.
In Walnut, accumulated rainwater collapsed part of the roof of a 1,000-square-foot business building, but no one was injured, the Los Angeles County Fire Department said. Three people were in U.S. First American Mortgage when the roof fell in.
Other storm cells dumped heavy rain in the San Gabriel Valley, Orange County and the San Bernardino and Riverside areas.
There were no reports of major mudslides in the wildfire areas in San Bernardino, Riverside and San Diego counties, but rains earlier in the day caused a small rockslide on Highway 18 near Rimforest in the San Bernardino Mountains.
Federal, state and county emergency service personnel went house to house in communities below fire-denuded slopes, warning residents of the possibility of slides.
Snow fell in the San Gabriel and San Bernardino mountains as low as 5,000 feet, with as much as half a foot expected by this morning.
Times staff writers Jose Cardenas, Allison Hoffman, Jia-Rui Chong and Wendy Thermos contributed to this report.