The Great Blue Norther of November 11, 1911 was a cold snap that affected the central United States on Saturday, November 11, 1911. Many cities broke record highs, going into the 70s and 80s early that afternoon. By nightfall, cities were dealing with temperatures in the teens and single-digits on the Fahrenheit scale. This is the only day in many midwest cities' weather bureau jurisdictions where the record highs and lows were broken for the same day. Some cities experienced tornadoes on Saturday and a blizzard on Sunday. A blizzard even occurred within one hour after an F4 tornado hit Rock County, Wisconsin. The main cause of such a dramatic cold snap was an extremely strong storm system separating warm, humid air from frigid, arctic air. Dramatic cold snaps tend to occur mostly in the month of November, though they can also come in February or March. These arrivals of Continental Polar or Arctic air masses are generally called northers, and the one in question was marked by a mass of steel blue clouds in the vicinity of the surface front, hence the name. Although temperature drops of this extent have happened on other occasions, as recently as February 2009, the fact that the 1911 cold front passage was during the autumn and came after such warm weather contributed to the properties mentioned in this article.
Temperatures in Kansas City had reached a record high of 76° F by late morning before the front moved through. As the cold front approached, the winds increased turning from southeast to northwest. By midnight, the temperature had dropped to 11° F, a 65Fahrenheit degree difference in 14 hours.
In Springfield, the temperature difference was even more extreme. Springfield was at at about 3:45 PM, before the cold front moved through. Fifteen minutes later, the temperature was at 40 °F with winds blasting out of the northwest at. By 7:00 P.M. Central Standard Time the temperature had dropped a further 20 °F, and by midnight, a record low of 13 °F was established. It was the first time since records had been kept for Springfield when the record high and record low were broken in the same day. The freak temperature difference was also a record breaker: 67 °F in 10 hours.
Record highs and lows were established on the same day in Oklahoma City as well with a high of and low of ; temperature difference: 66 °F. Both records still hold.
Alongside the dramatic temperature swings, the cold front brought a destructive tornado outbreak to parts of the Midwest. At least nine tornadoes touched down across five states as the system moved through, resulting in 13 fatalities. Hundreds of structures were destroyed by the storms and many areas had to conduct search and rescue missions amidst blizzard conditions. According to Thomas P. Grazulis, this outbreak was one of the worst on record in November for the north-central States.
