By Jill Connelly and Rich McKay WRIGHTWOOD, California, Dec 26 (Reuters) - Three days of heavy downpours that spawned flash flooding and mudslides across Southern California subsided on Friday, as residents of homes in the hard-hit mountain resort of Wrightwood began digging out mud and assessing damage.

Another wave of rain was hitting the Los Angeles area on Friday, adding to the record-setting precipitation over Christmas.

Much of California is still digging out after days of torrential rain, floods and mudslides. NBC News’ Dana Griffin is in hard-hit Wrightwood, where cleanup is just beginning.

More than 41 million Americans across California, Nevada and Arizona are under flood watches on Wednesday amid a rare, high risk for excessive rainfall and flooding.

A final round of heavy rain is drenching California Friday and threatening to bring more flooding and debris flows after a days-long deadly siege of storms.

A sweeping flood watch stretching more than 800 miles along California’s coast and interior plains is in effect this week atmospheric rivers move through.

A powerful Christmas storm is dumping rain across Southern California, putting at-risk communities on alert and prompting evacuation warnings.