Atmospheric River Brings Severe Weather to Northern California

Overview

A powerful atmospheric river is moving through Northern California, bringing heavy precipitation, strong winds, and significant snowfall at higher elevations. This weather system is expected to create challenging conditions across multiple regions, with impacts lasting through Wednesday.

Timeline of Weather System

Monday Evening

• Continuous rain returns after sunset
• Precipitation intensifies overnight

Tuesday (Peak Impact)

• Heaviest rainfall and strongest winds expected
• Cold front may stall over Bay Area
• High risk of excessive rainfall and flooding

Wednesday

• Conditions improve by afternoon
• Return to dry weather

Regional Impact Analysis

Bay Area

• Rainfall: 1-4 inches expected
• Wind Gusts:
  • Up to 50 mph near water and hills
  • 25-40 mph in valleys
• High-Impact Areas: San Francisco, Richmond, Berkeley, Oakland
• Moderate flood risk in urban areas

Valley and Foothills

• Valley Rainfall: 1.5-2 inches
• Foothill Rainfall: 2-4 inches
• Wind Gusts: 40-45 mph
• Risks: Localized flooding, standing water on poorly drained roads

Sierra Nevada

• Heavy snowfall above 6,000 feet
• Snow Accumulation:
  • 12-18 inches at Donner Pass
  • 1-2 feet above 7,000 feet
• Travel strongly discouraged on Tuesday

Coastal and Surrounding Areas

• Pacific Coast/Peninsula: Gusts exceeding 50 mph, heavy overnight rain
• North Bay: Light to moderate rain, up to 4 inches in mountains
• East Bay: Increasing rain and wind, particularly in Berkeley/Oakland hills
• South Bay/Santa Cruz: Enhanced precipitation in Santa Cruz mountains

Primary Hazards

• Flooding: Urban and low-lying areas at risk
• Transportation: Severely impacted by rain, snow, and wind
• Power: Potential outages due to strong winds
• Infrastructure: Possible tree damage

Extended Forecast

• Dry conditions return Wednesday afternoon
• Another storm system possible by week’s end
• Additional strong winds anticipated with next system

This atmospheric river event requires careful monitoring, particularly in flood-prone areas and higher elevations where snow accumulation could create hazardous conditions.

Northern California atmospheric river forecast: Heavy rain, snow return Monday night