The National Weather Service's (NWS) Sacramento office said "potentially historic rain" rain has fallen in parts of Northern California after a bomb cyclone accompanied an atmospheric river that unleashed massive amounts of moisture pulled in from the Pacific Ocean.

Northern California bore the brunt late Saturday/Sunday, with record rainfall in some areas. NWS Bay Area said, "We just passed the Gold Rush year of 1849 for 7th wettest October on record for Downtown SF. 1876 (3.36) here we come..(Current value is 3.14 which ties 1849)." 

Evacuations were ordered for parts of Northern California that have been drought-stricken and left barren by wildfires. Areas that have been burnt are prone to dangerous flooding called "debris flows." 

"If you are in the vicinity of a recent burn scar and haven't already, prepare now for likely debris flows," the Sacramento weather service tweeted. "If you are told to evacuate by local officials, or you feel threatened, do not hesitate to do so. If it is too late to evacuate, get to higher ground."

Flooded streets were reported across the Bay Area, closing some in Berkeley and Oakland's Bay Bridge toll plaza. Just north of San Francisco, a whopping 6 inches of rain has fallen this weekend. Rainfall estimates for the Bay Area show at least 3 inches have fallen, trouncing any other storm in years. 

"Some of our higher elevation locations could see 6, 7, 8 inches of rain before we're all said and done," Sean Miller, a meteorologist for the NWS in Monterey. 

The convergence of storms brings Northern California a huge relief amid devastating droughts and wildfires this past summer.

As we've previously mentioned, La Niña conditions have been declared by NWS, which means wetter than average conditions for Northern California and the Pacific Northwest. In contrast, drier than average conditions are expected for Southern and Central California.