December 6, 2019 – The winter storm expected to impact the area today has slowed a bit slightly delaying the onset of precipitation in northern California. Rain will spread to the northern mountains and Valley late morning, with precipitation overspreading the Valley and Sierra Nevada by the late afternoon and evening. Heavy rain and mountain snow are expected overnight tonight with heavy rain continuing through Saturday and the heavy mountain snow through Sunday morning.

On top of the precipitation, gusty winds are expected late tonight continuing through Saturday night with gusts up to 50 mph possible in the Valley and foothill areas. The most likely time for thunderstorms will be Saturday afternoon and evening, although an isolated storm or two cannot be ruled out Sunday afternoon as well as this system moves out of the area.

Precipitation will become lighter Sunday morning, with the system moving out of the area by Sunday night. Dry weather is still expected early next week.

Impacts

  • Major mountain travel delays, chain controls & possible highway closures for mountain travel
  • Low visibility due to a combination of wind & heavy snow
  • Difficult driving conditions down to the Valley for high profile vehicles from gusty winds
  • Gusty winds may cause downed tree branches and weakened trees
  • Slick roads and minor roadway flooding 

Forecast Confidence

  • High for snow amounts & snow levels today through Sunday’s winter storm
  • Medium for strength of winds tonight through Saturday
  • Medium for thunderstorm chances

Timing

  • Today – Sunday
    • Rain begins in coastal and northern mountains late morning
    • Valley/foothill rain and mountain snow begins late this afternoon, becoming heavy overnight
    • Significant mountain travel impacts possible with 1-3 feet of snow possible, locally higher
      • Snow levels 6500 feet falling to around 5500 feet by Saturday night into Sunday morning
    • Moderate to heavy rainfall in the Valley, Delta, and Foothills, especially on Saturday
    • Gusty winds tonight – Saturday night, gusts to 40-50 mph
    • Isolated thunderstorms possible Saturday and Sunday afternoons in the Valley & foothills
    • Precipitation expected to end by Sunday night