An exceptionally rare tornado warning shook Northern California this week as a relentless atmospheric river-driven storm system caused historic flooding, record snowfall, and infrastructure damage across the state. The temporary alert for rotating thunderstorms near Sacramento – lifted by Friday evening – underscored the extreme instability of what meteorologists call one of California's most volatile December weather events in decades.
Since December 24, downtown Los Angeles recorded 6.6 centimeters of rain – its wettest Christmas period in 54 years – while Sierra Nevada's snowpack grew by 60 centimeters within 24 hours. The storm's ferocity was exemplified at San Jose's Lick Observatory, where 160 km/h winds ripped part of a 19th-century telescope dome from its mountaintop perch.
Emergency crews remain on high alert for flash floods and mudslides, particularly in Southern California's fire-scarred hillsides. Over 5,500 Pacific Gas & Electric workers continue restoration efforts amid widespread outages, while coastal communities brace for 7.6-meter waves persisting through weekend high tides.
Climate scientists note this storm sequence aligns with projections of more extreme precipitation patterns in the American West. With the state's reservoirs now at 115% of historical averages, water managers face balancing flood control with drought preparedness for 2026.
