Well, the latest GFS runs are instead calling for it to be even colder. The latest GFS 700-mb temperature forecast for 15Z Wednesday is -25.3C. Trevor has examined the KSLC RAOBS for 1956-2010 and has found that the coldest November 700-mb temperature observed in that period is -22.6C. Further, there have only been 14 soundings (out of 40,246) with a 700-mb temperature below -25C during the entire record. The last day we were below -25C was on 30 December 1990 when the 700-mb temperature was -27.2C.
Let's convert to American units to put this into perspective. -25.3C = -13.5F. That is a seriously cold day of skiing in the mountains. Well mixed, that's 17F in the valley. Cold. Bloody cold.