Thursday, December 3, 2020
After the storm on Opening Day, a cold and dry air mass has settled over the Steamboat Springs area, bringing cold nights and sunny days. There won’t be much change to our weather for the upcoming week, though we can look forward to warming daytime highs closer to our average of 31 F. There is hope, however, that our area will see snow chances return in about a week.
That Opening Day storm was far more productive than advertised, with 6” reported at mid-mountain on Wednesday morning and 11” shown on the Steamboat Powdercam at the top of Sunshine Peak behind Patrol Headquarters, most of which fell during the day Tuesday. Snow density was very low thanks to the cold temperatures which encouraged the formation of dendrites, which are the classic and familiar branch-shaped snow crystal. The branches of the dendrites allow lots of space to separate each fallen crystal which inflates the depth of accumulated snowfall.
With clear sunny days and cool nights, the most interesting aspect of our upcoming week’s weather will be the temperatures, specifically the formation of night time temperature inversions. These occur when cold air pools at the lower elevations, becoming colder than the air aloft, which is the opposite of the normal atmospheric temperature profile which cools with height. For example, the low temperature this morning was -2 F at the Bob Adams airport, -6 F at my house near the base of the mountain (lower in elevation than the airport) and 4 F at the top of Mt. Werner. The conditions that support the formation of temperature inversions, mainly snow cover (the fresher the better), clear night skies, light winds and low sun angle will persist this upcoming week so expect the cold starts to the morning with warmer temperatures found higher on the mountain to continue.
A pattern change may be in the offing though, as a storm traveling across the Gulf of Alaska makes landfall in the Pacific Northwest mid-weekend and forms an eddy cut off from the jet stream. This eddy is forecast to dive through the western Great Basin early next work week, taking up residence near Baja and southern California, before another Gulf of Alaska storm makes landfall, again in the Pacific Northwest, around midweek.
Eventually, these storms will interact, with the southern storm possibly transporting subtropical moisture northward that can be incorporated into the northern storm or perhaps being ejected out ahead of the northern storm. As might be expected this far out, there is a lot of uncertainty as to how these storm will interact, though longer-term weather forecast models agree that a ridge of high pressure builds in the Gulf of Alaska behind that second northern storm. This may allow favorable and moist northwest flow to set up over our area around the next weekend, though it is unclear for how long that may persist
Enjoy what will likely be a gorgeous upcoming week of weather, and I should know more about this pattern change in my next regularly scheduled weather narrative on Sunday afternoon.