On Saturday, November 11, 1911, a cold snap, known as the Great Blue Norther or 11/11/11, affected the Central United States. 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 front produced severe weather and tornadoes across the upper Mississippi Valley and a blizzard in Ohio; the windy conditions upon front passage caused a dust storm in Oklahoma. Alongside the dramatic temperature swings, the cold front brought a destructive tornado outbreak to parts of the Midwest. At least 13 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. Thomas P. Grazulis stated in 1990 that this outbreak was one of the worst on record in November for the north-central States.
Background
left|thumb|[[Surface weather analysis|Weather map on November 11, that shows the low-pressure area that produced very cold temperatures, and the tornado outbreak ]]
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.
Impact
The cold front was so strong that while several states saw record monthly highs on November 10 and 11, they saw record cold monthly lows on November 12 and 13. This was especially true in Missouri, where one station had a high of before the storm, and after the storm, another station had a low of . The cold front began on November 9. Rapid City, South Dakota, went from at 6am to at 8am. Between November 10 and 11, Denver experienced its eleventh largest two-day temperature swing, from , a change.
On November 11, temperatures in Kansas City, Missouri, had reached a record high of 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 , a difference in 14 hours. In Springfield, the temperature difference was even more extreme. Springfield was at at about 3:45 p.m. CST (21:45 UTC), before the cold front moved through. Fifteen minutes later, the temperature was with winds out of the northwest at . By 7:00 p.m. CST (01:00 UTC) on November 12, the temperature had dropped a further , and by midnight (06:00 UTC), a record low of was established. It was the first time since records had been kept for Springfield that the record high and record low were broken in the same day. The freak temperature difference was also a record breaker: in 10 hours. The low on the morning of November 12 was . St. Louis dropped from in just ten minutes. Record highs and lows were established on the same day in Oklahoma City as well, with a high of and low of ; temperature difference: . Both records still hold. It also produced a dust storm. Tulsa, Oklahoma, had an even more dramatic plunge from in the afternoon of November 11 to by the morning of November 12, although the temperature at midnight is not known. Independence, Kansas, saw the temperature drop from in one hour. While this wasn't Amarillo's biggest temperature drop, the drop from is still an impressive drop. Nearby Dallas also saw an impressive plunge from by midnight and by the next morning the mercury was . In Chicago, Illinois, people died separately of heatstroke and cold, respectively, within 24 hours, the first such incidence on record in the city. The temperature dropped from during the event. Across central Illinois, up to of snow fell, and in Peoria, Illinois, after a high of on November 11, the temperature crashed to by midnight, and the high on November 12 was . While only the southern and eastern parts of Iowa felt the Norther, the impacts there were nonetheless powerful, as Albia, Iowa, fell from in twelve hours.
The front did not reach Columbus, Ohio, until 3:00 a.m. on November 12, but when it did, temperatures plummeted from , just a degree from a record high, to in an hour, and down to - a record low - that night. By November 13, temperatures dipped further to . Lexington, Kentucky, also saw the temperature drop on the 12th, when it went from nearly down to a record low of . It dipped to another record low of on November 13, and a record cold high of was also established. However, the record low for November 13 was broken in 2019. Bowling Green, Kentucky, saw the drop across the entire day on November 12, from . Temperature plunges ranged from on the East Coast.
Tornadoes
On Saturday, November 11, 1911, a regionally and seasonally significant tornado outbreak affected the Great Lakes region of the United States. The outbreak generated at least 13 tornadoes, including a violent, long-tracked F4 that impacted Wisconsin, killing at least nine people and injuring 50 more. Other intense tornadoes occurred in Illinois and Indiana, resulting in four additional fatalities. Several other tornadoes were reported from multiple states. In all, the outbreak killed 16 people and injured at least 101. Total losses exceeded $1.755 million (1911 USD). Tornado researcher Thomas P. Grazulis considered the outbreak to be the worst in the month of November on record at the time in the Great Lakes region.
Some cities experienced tornadoes on Saturday and a blizzard on Sunday.
{| class="wikitable sortable" style="width:100%;"
|+ Confirmed tornadoes – Saturday, November 11, 1911
! scope="col" style="width:3%; text-align:center;"|F#
! scope="col" style="width:7%; text-align:center;" class="unsortable"|Location
! scope="col" style="width:6%; text-align:center;" class="unsortable"|County / Parish
! scope="col" style="width:5%; text-align:center;"|State
! scope="col" style="width:6%; text-align:center;"|Time (UTC)
! scope="col" style="width:6%; text-align:center;"|Path length
! scope="col" style="width:6%; text-align:center;"| width
! scope="col" class="unsortable" style="width:48%; text-align:center;"|Summary
|-
|bgcolor=# | F2
|W of Davenport
|Scott
|IA
|18:55–?
|
|
|The first known tornado of the outbreak touched down west of Davenport and tracked northeast. Along its path, five farms sustained damage and a barn was destroyed. One person was injured by the tornado.
|-
|bgcolor=# | F4
|Avon to Lima
|Rock
|WI
|20:00–?
|
|
|12 deaths – The most powerful tornado of the outbreak caused extensive damage to Rock County, Wisconsin. Beginning at 2:00 p.m. CST, the tornado tracked north-northeastward past Orfordville, passed through Hanover, skirted the northwest edge of Janesville, struck Milton, and dissipated in Lima. The worst damage occurred near Milton. Several farms were also leveled near Milton. Overall losses from the tornado reached $1,000,000. Blizzard conditions ensued within an hour of the tornado's passage. Estimates of the death toll vary, with one publication listing nine deaths. 50 people were injured along the path.
|-
|bgcolor=# | F2
|Waterloo
|DeKalb
|IN
|03:00–?
|
|
|A significant tornado struck the town of Waterloo, damaging or destroying at least 100 structures. An opera house in Waterloo collapsed due to the tornado. Just outside town, several farms were also severely damaged. Losses from the storm reached $75,000.
|-
|bgcolor=# | F2
|SE of Battle Creek
|Calhoun
|MI
|03:00–?
|
|
|Tornado touched down well to the southeast of Battle Creek. Several barns were leveled and homes were damaged.
|-
|bgcolor=# | F2
|Laingsburg to Owosso
|Shiawassee
|MI
|04:05–?
|
|
|2 deaths – Extensive damage took place in Owosso. Five factories and twenty homes were destroyed. Two people were killed when the upper floor of their home collapsed on them. 21 people were injured throughout the town. Just outside Laingsburg, 15 barns were destroyed by the tornado. Overall losses from the storm reached $500,000.
|-
|bgcolor=# | FU
|Unknown
|Kankakee
|IL
|
|
|
|A study in 1993 chronicling all tornadoes in Illinois prior to 1916 revealed that a tornado touched down in Kankakee County.
|-
|bgcolor=# | FU
|Unknown
|Cumberland
|IL
|
|
|
|A study in 1993 chronicling all tornadoes in Illinois prior to 1916 revealed that a tornado touched down in Cumberland County.
|-
|bgcolor=# | FU
|Genesee to Lisbon
|Waukesha
|WI
|
|
|
|Homes, barns, chicken coops, sheds, and various outbuildings were unroofed or blown off their foundations.