Torrential rains struck southern California on Thursday triggering flash floods and mudslides. Several roads to the north of Los Angeles were badly affected as cars were swamped, forcing drivers to abandon their vehicles.

A deep area of low pressure system produced the heavy rain and even some hail in drought-stricken Southern California. A flash flood warning remains in effect for parts of Los Angeles county.

The Lake Hughes and Elizabeth Lake areas were particularly hard hit, with mudslides covering long stretches of road and submerging cars. Hundreds of vehicles were stranded as the major north-south highway was quickly covered in water, mud and rocks.

Firefighters were called in to help clear the debris and to rescue a number of drivers who were trapped in their cars. California transportation officials say it could take up to a day to clear almost two metres of mud on Interstate 5, north of Los Angeles.

This short burst of heavy rain will not be enough to break the on-going 4-year drought, but it could be a sign of things to come over the next few months.

Mike Halpert, deputy director of the National Oceanic and Atmospheric Administration’s (NOAA) Climate Prediction Centre said: “A strong El Nino is in place and should exert a strong influence over our weather this winter.”

Unusually heavy winter rain is possible across much of the southern US and moisture-laden storms are expected to reach not only California’s coast, as previously predicted, but inland mountain ranges, with the potential to replenish depleted snow reserves that are key to the state’s water supply.

NOAA predicts that this winter’s weather could partially mitigate the drought, if not resolve it entirely. Halpert added that “one season of above-average rain and snow is unlikely to remove four years of drought”.

The strong El Nino system in the winter of 1997-98 caused not only record rainfall but thousands of deaths and billions of dollars in damage worldwide.