I heard about this a few days ago. Snow has been known to fall in the coastal foothills here in SoCal, but snow levels near the coast don't usually drop below 3500 ft. Once in a while you'll get snow to fall as low as 1500 ft., but it melts as soon as it hits the ground. Last year was an anomaly as several foothill communities above 500 ft. actually woke up to a light dusting.
This situation setting up sounds like one of those 'once every 30 years' occurrences.