Freezing fog can be dangerous to drive in because it lowers visibility and can create a glaze on the roadways. Some parts of Northern Nevada and California sees fog more than others. Truckee is notorious for fog, especially in the winter and once there is enough moisture on the ground. A huge storm brought a good amount of rain and snow through northeast California in October, soaking the ground. Fog needs moisture as well as light winds to form. Another system moved through this past Monday, with clearing skies behind it. High pressure is building in and an inversion is setting up too. An inversion makes it easier for low clouds or fog to form. At night, the temperature falls, reaches the dewpoint, saturation occurs, and fog forms. The dewpoint is the point at which saturation occurs. If the dewpoint/temperature is below freezing when fog forms it freezes. A weather statement has been posted for portions of the Sierra because freezing fog could form Thursday night into Friday morning.
Fog/low level clouds developed in the Tahoe Basin Thursday morning and could develop over the next few mornings too. According to Chris Smallcomb from the National Weather Service, Truckee sees a lot of fog because of its geography. Truckee sits at a lower spot of the mountain valley allowing cold air to drain in. The Truckee River and some other wetlands aids fog development in this area by providing moisture. Light winds also helps. The Truckee Airport sees more fog than the rest of the town, because it sits at the lowest spot. Places like Loyalton, Hidden Valley, Mono Lake, and Bridgeport could also see fog Thursday night into Friday morning.
The fog will clear out by the early afternoon tomorrow allowing temperatures to warm. Highs will be in the upper 60’s through Monday with sunny skies in Reno. With a strong inversion, it could be a little hazy but overall the weather will be mild. Just expecting some patchy fog in our mountain valleys. Have a good weekend.
