NWS San Diego provided IDSS before and after record snowfall in Southern California

In late February 2023, two polar cold fronts and atmospheric rivers combined to bring unprecedented snowfall and damaging winds to southern California. This resulted in major snow removal emergency response efforts that lasted for just over 1 month, ending in early April.

NWS San Diego issued its first-ever blizzard warning for the San Bernardino and San Gabriel mountains prior to the storm cycle, forecasting up to 100 inches of snow in 7 days. The storm systems brought snow down to the coast, record snowfall in the mountains, and damaging winds from the coasts across mountains and into the deserts. In the hardest hit communities, a historic 100 to 150 inches of snow fell in 7 days (7 to 12 inches of water) and record 36 to 42 inches twice in a 24 hour period, trapping nearly 50,000 residents in the mountains during the first 2 weeks. The community of Crestline was the epicenter of the response where the only grocery store suffered a complete roof collapse. Many residents were unable to leave their own driveways and required rescues by snowcats.

From February 28 through April 3, 2023 the San Bernardino County Office of Emergency Services operated an Incident Management Team and activated their Emergency Operation Center (EOC). Incident Commanders facilitated twice daily video conference calls supporting agency partners including Red Cross, SoCal Gas, Southern California Edison, Public Works, Highway Patrol, State and County transportation, hospitals, and school districts. NWS San Diego provided detailed event specific daily weather briefings during the entire period of impact and recovery and also participated in the Public Information Officer calls to further collaborate messaging to the public.

Prior to the snowfall NWS provided already established specific snowfall briefings to emergency management that evolved during the unprecedented event. NWS San Diego expanded daily support for a specific email briefing for partners and twice daily virtual EOC briefings for a 4 week period to support the extensive recovery efforts, which. At the impacts peak the Incident Management Team coordinated 1000 firefighters, law enforcement, California National Guard, first responders, volunteer groups such as CalDART helicopter services (37 flights), and mutual aid assistance crews working in the mountains. Over a three week period following the crippling snowfall, the additional NWS forecasts aided in managing over 350 rescues of stranded residents, response to 12 home fires due to buried damage gas lines leaking, emergency shelter establishments, the removal of 12 million cubic yards of snow, towing of dozens of abandoned vehicles, the exhausting 1 to 3 week process of reopening of 8 state highways and numerous secondary and private roads, the restoration of gas and power to 2000 homes, and the distribution of emergency food and medical supplies to those in need. Emergency managers reported the existing snowfall forecasts along with live webinar briefings and then the expanded weather briefings for recovery efforts were instrumental in managing the incident for resources and life safety.