© Mammoth Times/Wendilyn GrasseschiExtreme conditions: A powerful storm has pelted California with heavy rain and snow - an incredible 13ft of snow has accumulated at Mammoth Mountain ski resort
California residents should brace themselves for the most severe of an ongoing series of storms to hit the state, forecasters have warned.
More than 12 inches of rain have fallen in parts of the Santa Monica Mountains in the south and up to 15.5ft of snow has accumulated at Mammoth Mountain ski resort over the last four days.
And the conditions are expected to worsen in the next few days, the National Weather Service has warned, with the possibility of thunderstorms, hail and even tornadoes and flash floods.
'The ground will be permeated with a lot of rain, and it was a very, slow consistent rain for the past five days,' said Stuart Seto, a specialist for the weather service in upstate Oxnard. 'This is going to be more of a thunderstorm-type rain. This thunderstorm activity is very dynamic and intense.'
Researchers have coined the ongoing influx of tropical moisture into the state as an 'atmospheric river'.
'The atmospheric river brings in the moisture,' said Lucy Jones of the U-S Geological Survey office in Pasadena. 'How much rain gets dropped out of it has a distribution, just like earthquakes.'
