Although the popular song insists "It never rains in Southern California," winter storms have raised the rainfall total in Los Angeles to nearly four times the seasonal norm--and more is sure to come.
As any CHP officer will tell you, a downpour in Los Angeles triggers events far more complex than a thunderstorm in, say, Ames, Iowa. There, people often describe rains as "good," and think in terms of whether or not the moisture is needed for the winter wheat crop.
Angelenos, on the other hand, tend to think of rain as an adversary standing between them and a speedy, uneventful drive home.
Urban animals that we are, we want to know whether or not the parking lot is washed out, which freeways are tied up and how bad is it? We want to know if the lights are going to go off and how waterlogged is the slope in back of the house? We want to know what's going to happen.
According to Weather Bureau spokesmen, CHP and public works officers, it is possible to do a little predicting about the consequences of varying amounts of rain in Los Angeles.
It doesn't take much, for example, before drivers, particularly freeway commuters, are sliding around and into each other on rain-slicked streets and highways.
According to Jill Angel, California Highway Patrol public affairs officer, the first day of the first big winter storm usually produces more accidents than any other day of the year. That's because during the dry summer, motorists forget how to drive in the rain and need a refresher.
"(On the first day) they drive too fast for conditions," Angel said. "The most important thing (to prevent accidents) is to allow even more distance between your car and the car in front of you than would normally be safe, and they don't."
Special problems also develop during the first rain because oil dripped from cars during the dry summer rises to street surfaces and makes pavement unusually slick. The same goes for the early stages of any downpour: Oil dripped since the last rain greases the pavement until it is washed away.
"It's even tough to walk on it. It's like driving on black ice until you've had several rains and it washes off," said Lt. Richard Dyer, officer in charge of the traffic coordination section of the Los Angeles Police Department.
As the rain progresses, not all the news is bad, though. Experts say that only a quarter inch of rain is enough to clear the Los Angeles air of pollutants, allowing residents the next day to enjoy sparkling air and bright, blue skies.
On an average day in the Los Angeles basin, more than 9,700 tons of pollutants--including 6,500 tons of carbon monoxide--are emitted into the atmosphere, according to Art Davidson, public adviser for the Air Pollution Control District.
The rain, he said, creates atmospheric conditions which allow this discharge to rise so high that it is diluted and rendered insignificant for air pollution concentrations.
As rain continues and the storm level mounts, however, other changes occur which increase danger levels and make blue skies seem even more attractive.
The level of automobile accidents rises as cars begin to stall and low visibility and slick pavement causes still more drivers to come together in fender-benders and worse. As rainfall amounts rise into the one-half to one-inch range, waterlogged trees begin to fall, causing power outages.
Automobile accidents were particularly fearsome during the afternoon of Thursday, Oct. 22, the first day of the recent storms which lasted intermittently for two weeks. At 3 p.m. that day the California Highway Patrol had received reports of 45 traffic accidents in Los Angeles County and 33 in Orange County, compared to a typical total of about 30 in Los Angeles and 15 in Orange County during the entire rush hour.
CHP officer Angel said accidents also forced the ordering of seven SigAlerts, which are issued when traffic on a highway will be tied up for 30 minutes or more. The alerts are named after former KMPC general manager Lloyd Sigmon, who invented them.
In any heavy rain, Angel said, the number of accidents in Los Angeles increases by about 33%.
For one thing, there are more multi-vehicle collisions in rain. "In dry weather, one car will hit another and everybody will brake in time. In rain, people will hit and start sliding and now you've got more than the original two cars because people haven't allowed (enough) stopping distance."
Many drivers also hydroplane, leaving the road and riding across the surface of the water into accidents.
If accidents weren't enough of a problem, mud slides cause even more dilemmas, backing up traffic for hours. "A typical accident, a fender bender, can occur and the scene can be cleared in 30 minutes," Angel said. "A mud slide . . . can involve closure of an entire freeway for 24 hours."
Mud slides commonly become a problem after three or four inches of rain, said Pat Howard, director of the bureau of street maintenance for the city Department of Public Works.