Great Western Freeze of 1990

[Chinook]

This western freeze of 12/18-12/24 1990 was fairly similar to what we just went though. The surface and 850mb temperatures were 12-15C below normal in Montana over this time period (up to 27F below normal) according to NCEP reanalysis. I plotted surface temp on the NARR to show just how much of an area was 0F to -30F. Many of the colors plotted represent 0 to -30F.  I also plotted the 500mb plot for 12/20 because this looked particularly nasty for Colorado.