CALIFORNIA — A powerful stretch of winter storms is developing across the West as several atmospheric rivers prepare to repeatedly hit California and the Desert Southwest through the end of December. Forecasters warn that this multi-week pattern will bring heavy rainfall, flooding risks, mudslides, debris flows, and multiple feet of mountain snow, especially at higher elevations. The first surge will target Northern and Central California before conditions shift south toward Southern California and interior desert regions by Christmas week.
Heavy Rainfall Expected Across Northern and Central California
Meteorologists say the first atmospheric river will ride the Pacific jet stream and make direct landfall along the California coastline, delivering widespread and potentially hazardous rainfall. Key projected amounts include:
Northern & Central California Rainfall Projections
- San Francisco: 7–8 inches
- Santa Cruz: 7–8 inches
- Sacramento: 6–7 inches
- Coastal California (general): 3–6 inches
These rainfall totals will quickly saturate soils, raising the risk of flash flooding, mudslides, rapid runoff, and debris flows, especially in areas scarred by recent wildfires.
Southern California and the Desert Southwest to See Increasing Impacts by Christmas Week
As later atmospheric rivers shift southward, Southern California and nearby desert regions will experience widespread, soaking rainfall that could last several days.
Southern California Rainfall Projections
- Los Angeles: 4–5 inches
- Santa Barbara: 5–6 inches
- San Diego: 2–3 inches
- Bakersfield: 1.5–2.5 inches
SoCal Mountains Liquid Water Totals
- 7–14 inches of liquid water, significantly increasing the risk of mudslides and slope failures
Communities in canyon areas and foothill regions should remain alert for rapidly changing conditions.
Sierra Nevada Faces Multiple Feet of Heavy Snow
Some of the greatest impacts will be felt in the Sierra Nevada, where forecasters expect exceptional snowfall at higher elevations.
Sierra Nevada Snowfall Outlook
- 1–2 feet of liquid water, supporting several feet of heavy, wet snow
- Potential for whiteout travel conditions
- Elevated avalanche risks as snowfall rapidly accumulates
Travel through mountain passes may become extremely dangerous or impossible during peak snowfall periods.
Moisture Pushes Inland Into Nevada, Arizona and Utah
The influence of the atmospheric rivers will extend beyond California and into desert and interior regions of the Southwest.
Projected Inland Rainfall Totals
- Reno: 0.75–1.25 inches
- Las Vegas: 0.75–1.25 inches
- St. George: 0.75–1.25 inches
- Phoenix: 0.25–0.75 inch
- Flagstaff: 1.5–2.5 inches
- Tucson: 0.10–0.25 inch
Even smaller rainfall totals can cause urban flooding in desert cities where water drainage is limited.
What Residents Should Know
With multiple atmospheric rivers forecast to arrive one after another, residents across the West should prepare for a prolonged period of disruptive weather. Emergency managers advise the public to keep:
- Regular monitoring of weather alerts and forecasts
- Emergency kits stocked and ready
- Caution when traveling near mountain passes or flood-prone roadways
- Awareness that power outages, road closures, mudslides, and flooding may occur across impacted regions
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