Below is the temperature trend this December shown in navy blue. The red shading represent record highs, the green shading is the average temperature range for each day, and the blue shading is the record cold temperature. Many days this month has been over 10 degrees above average! Some of our daily low temperatures were as warm as our average high. These warm temperatures mean the inversion we typically see this time of year isn't very strong. Two things have helped keep the inversion away. First, we don't have snow on the ground. Snow reflects the sun's radiation back to space and prevents day time heating. And second, we haven't had a mass of Canadian air come down and fill our valleys with their painfully cold air. Just because it hasn't happened yet doesn't mean it wont. We still have January and February to get through and weather can change quickly.
Below is the current PM 2.5 trend from the last few days. We're still below the"toxic" level of 35 ug/m3. With snow on the ground the inversion would be much stronger and we would definitely be in the orange and red.
This Sunday the ski resorts could get dumped on :) We'll see if this plays out. Other models keep this storm a little drier, but we can hope this will play out.
You can check out utahskiweather.com for the latest forecasts of your favorite ski resorts.