Fall tornado outbreak: November 16
Kansas is no stranger to tornadoes, ranking second nationally with an annual tornado average of 96 (NCEI). Tornadoes occur typically in spring across the Central Plains, with a peak for Kansas in May. However, there is often a second peak of tornadoes in the fall (usually October) across the Plains. Fall, like spring, is a transitional season in which warm air masses are often clashing with cold, fueling strong storm systems. These gradients provide ample opportunities for thunderstorms. To get tornadoes, however, substantial wind shear is also required, which is more difficult to achieve during the fall. Therefore, tornadoes in November are much rarer in the state, with an average of only one over the 20-year period (Figure 1).
Figure 1. Average number of tornadoes in Kansas and other states by month (ustornadoes.com).
November 16, 2015 saw one of those rare storm systems across the United States. As the system moved over the Rockies during the day, an unseasonably warm, moist, air mass pushed northward across the Plains in advance of it. This air mass was overspread by strong upper level winds which provided ample shear for severe thunderstorms. With these ingredients in place, storms developed across the High Plains in the afternoon and drifted north/northeast into the overnight hours. Numerous severe weather reports, including multiple tornadoes, were associated with these violent storms that extended from Nebraska to Texas.
Figure 2. Preliminary tornado reports in Kansas on November 16, 2015.
What made this system especially unique was the duration of many of the storms as well as the intensity of the tornadoes. In Kansas, 16 tornadoes were reported from Seward County to Sheridan County (Figure 2). Of the confirmed tornadoes (10 as of 12/4/15), there were 3 EF3’s, 5 EF1’s, 1 EF2, and 1 EF3. One of these (Kismet-Haggard EF3) had a track of over 50 miles, width of 2000 yards, estimated winds of 155mph, and was on the ground for roughly 70 minutes (Figure 3). This unprecedented tornado was only the second EF3 ever recorded in Kansas in November. It eclipsed the previous F3 tornado (November 27, 1960 in Cloud County) for the strongest, as well as the longest and widest tornado ever confirmed in November (Tornado History Project). Previously, between 1950-2014, only 17 days in November have had recorded tornadoes. Of these 17 days, there were 65 confirmed tornadoes, the most on a single day being the November 27, 2005 with 19. The last recorded tornado in November was an EF0 in Stanton County on the 10th in 2008.
Figure 3. Zoomed view of the Kismet-Haggard EF3 and nearby tornadoes on November 16, 2015 (National Damage Assessment Toolkit). Orange diamonds represent nearby Kansas Mesonet stations (mesonet.ksu.edu).
Luckily, no one was hurt nor killed during this tornado outbreak. This event proves that despite typical expectations of severe weather in the spring, it can happen whenever the elements come together – regardless of the month. What set this system apart was the strength of the tornadoes, the widespread area of impact, and their location in the High Plains. It pays to be prepared regardless of the season. Always have multiple ways of receiving warnings and heed them!
Christopher “Chip” Redmond, Weather Data Library
Mary Knapp, Weather Data Library
Storm Prediction Center, Accessed 12/1/15, http://www.spc.noaa.gov/climo/online/
NCEI, Accessed 12/3/15, https://www.ncdc.noaa.gov/climate-information/extreme-events/us-tornado-climatology
Ustornadoes.com, Accessed 12/3/15, http://www.ustornadoes.com/2013/03/19/monthly-tornado-averages-by-state-and-region/
Tornado History Project, Accessed 12/3/15, http://www.tornadohistoryproject.com/tornado/Kansas/November/table
National Damage Assessment Toolkit, Accessed 12/3/15, https://apps.dat.noaa.gov/StormDamage/DamageViewer/