High pressure is causing a temperature inversion and dense fog for parts of Idaho, particularly in the Treasure Valley and extending to Mountain Home. Fog will linger into the afternoon leading to cooler daytime high temperatures on Tuesday. Tomorrow, the fog will be less widespread but will still impact mountain valleys.
A coastal low pressure dives southeast brushing southeastern Oregon and southwest Idaho with snowfall overnight into Wednesday morning. A quick dusting to an inch is possible for the lower Treasure Valley and the Magic Valley, while 1-4" will fall for southeastern Oregon, Owyhee county, and southern Twin Falls county. The central mountains will receive an inch or two of snowfall. Light rain and snow showers are possible on Wednesday, although most of the precipitation will avoid the valleys. Temperatures will remain cool, with afternoon highs reaching the lower 40s and overnight lows dipping into the 20s.
On Friday, a quick-moving disturbance will cross Idaho, bringing widespread light snowfall down to the valley floors. This could potentially impact the Friday evening commute. On Saturday, a stronger system will arrive, bringing cold temperatures, snow, and gusty winds. The valleys can expect 1-4" of snowfall, while areas above 5000 feet may see 6-15" of snowfall from Friday to Sunday. Next week, there will be a more active weather pattern with below normal temperatures and several chances for snowfall.
