After one of the warmest Septembers on record for many areas get ready for a blast of arctic air in the Rockies on Wednesday and again on Friday/Saturday! Gladly we can report that snowfall will be piling up in North Central Montana especially near Billings and Missoula through Wednesday above 4,000 feet (4-8 inches) and slowly move South and East through the Dakotas. Areas near Yellowstone on the Montana border should also see snow. This system is carrying arctic air with low temperatures in the 20′s in many areas by Wednesday morning in the North!
On Friday, another cold front will sweep south through Wyoming bringing a dusting of snow to the Tetons and higher amounts along and North of I-80 towards the Eastern side of the divide (Laramie and East) Colorado could see snow on the Northeast border Friday night however most ski areas will not be impacted with the exception of perhaps some light snow near Steamboat.
Long Term? The models depict high pressure returning next week however it looks promising for some moisture under warmer air next weekend (October 12-14) for the Southern and Central Rockies. Snowfall might be possible at the highest elevations.