Residents of Los Angeles spent the day before Christmas under rain showers and winds of around 40 mph, while the New England area braces for heavy snow later in the week.

The Christmas rain storm expected to washout California over the next few days is already rearing it’s ugly head — as a debris flow ripped through the mountain town of Wrightwood in San Bernardino County early Wednesday.

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.

The California Highway Patrol reported a seemingly weather-related crash south of Sacramento in which a Sacramento sheriff’s deputy died. James Caravallo, who was with the agency for 19 years, was apparently traveling at an unsafe speed, lost control on a wet road and crashed into a power pole, CHP Officer Michael Harper said via email.

A major storm is gearing up to deliver months’ worth of rain and powerful winds to Southern California — the most potent in a slew of atmospheric river-fueled storms aiming for the region this week.

Torrential rain is drenching the west and snarling travel for people still trying to get out. Some communities are urging people to shelter in place, while others are scrambling to respond to reported water rescues.