A Winter Storm Watch is in effect for the Sierra Nevada above 6,000 feet, from Wednesday afternoon through Friday morning.
According to the National Weather Service, the first of a series of storms is set to arrive tonight and will bring moderate to heavy snow to the mountains from Wednesday afternoon through Thursday morning.
Total snow accumulations from Wednesday afternoon through Thanksgiving morning will range from four inches to twenty inches above the 6,000 foot elevation.
There will be significant reductions in visibility with wind gusts up to fifty mph over the higher terrain.
After a brief lull, the next storm is expected late Thanksgiving Thursday into Thursday night, with one last system pushing through on (Black) Friday.
Total snow accumulations from Thursday afternoon through Friday morning will range from four to fifteen inches above the 6,000 foot elevation.
The snow levels are expected to rise to around 7,000 feet by Friday afternoon.
Travel in the high Sierra could be very difficult to impossible. Holiday travelers should be prepared for long delays and possible road closures. Damage to trees and power lines is possible. Tree branches could fall. If traveling at this elevation, consider alternate plans and remember to carry tire chains, extra food, water and clothing.
The accumulation of dirt and oils on the roadways in the Mother Lode and the Northern San Joaquin Valley will produce very slick conditions, especially early on in this wet period tonight and Wednesday. The Wednesday evening commute and Thanksgiving travel period will likely see increased traffic accidents due to the slick roadways and motorists should use extra caution.
As rainfall accumulates over the holiday weekend, ponding water will be possible where storm drains have been clogged by leaves and other debris. Debris flows over any of the recent fires will also become a major concern.
Downed tree limbs, blowing objects and difficult driving will also be a concern during this late Thursday through Friday time period. Use extra care while traveling this holiday weekend as many weather related hazards will be present that have not been a concern for the last several months.
Conditions will begin to improve on Sunday with a return to drier weather expected early next week.
Meanwhile, the Air Quality Alert remains in effect today for Tuolumne and Mariposa counties, due to smoke impacts from surrounding wildfires.
Exposure to particle pollution can cause serious health problems, aggravate lung disease, cause asthma attacks and acute bronchitis and increase the risk of respiratory infections.
Residents are advised to use caution as conditions warrant. People with heart or lung diseases should follow their doctor`s advice for dealing with episodes of unhealthy air quality.
Additionally, older adults and children should avoid prolonged exposure, strenuous activities or heavy exertion, as conditions dictate.
A Winter Storm Watch means there is potential for significant snow, sleet or ice accumulations that may impact travel.