Yesterday at NCAR in Boulder, temperatures shot up 15 degrees in a matter of a few minutes. This was due to the arrival of Chinook winds. When the wind blows out of the west, the air compresses as it falls down the Front Range of the Rockies, and heats at the adiabatic lapse rate of 10C per kilometer. This is independent of the amount of GHG (water vapor) in the atmosphere on that day.
There really is not an easy way to explain chinook winds without getting into some pretty technical meteorology, but no discussion of Black Hills weather would be complete without mentioning the chinook. The reason is that the Black Hills of South Dakota are home to the world’s fastest recorded rise in temperature, a record that has held for nearly six decades.
On January 22, 1943, the northern and eastern slopes of the Black Hills were at the western edge of an Arctic airmass and under a temperature inversion. A layer of shallow Arctic air hugged the ground from Spearfish to Rapid City. At about 7:30am MST, the temperature in Spearfish was -4 degrees Fahrenheit. The chinook kicked in, and two minutes later the temperature was 45 degrees above zero. The 49 degree rise in two minutes set a world record that is still on the books. By 9:00am, the temperature had risen to 54 degrees. Suddenly, the chinook died down and the temperature tumbled back to -4 degrees. The 58 degree drop took only 27 minutes.