After a dry autumn, California faces an extreme weather shift as a powerful atmospheric river brings heavy rain and potential flooding to the region. The storm, fueled by a bomb cyclone forming over the Pacific, will deliver substantial rainfall to the Bay Area, North Coast, Sacramento Valley, and northern Sierra Nevada between Tuesday night and Saturday morning. Rainfall totals may reach 15 inches in some areas, with the North Coast seeing the heaviest downpours first.
The bomb cyclone, forming off Vancouver Island, will steer subtropical moisture from near Hawaii toward Northern California. Its stationary position, coupled with smaller cyclones, could cause the atmospheric river to stall, intensifying flooding risks. Historical precedent, like San Francisco’s 5.5-inch rainfall on Dec. 31, 2022, underscores the danger.
Rainfall projections vary with stalling uncertainty, ranging from 2-3 inches in San Francisco to over 10 inches in Redwood National Park. The heaviest rain begins Tuesday night in the North Coast, moving to the Bay Area by midday Wednesday. Monday and Tuesday will be colder, with highs in the upper 50s and lows dropping to near freezing in some regions.
