NOAA's National Centers for Environmental Information
This analysis is based on preliminary data available from the Storm Prediction Center. Final tornado counts published by the Storm Prediction Center and NCEI's Storm Events Database might differ from this report. For a more detailed climatology, please visit our tornado climatology page.
According to data from NOAA's Storm Prediction Center, during December 2015, there were 86 preliminary tornado reports. This is well above the 1991-2010 average of 24. Tornado activity during December can vary greatly; the most on record was 100 in 1982 and the least was zero in 1963. Most of the tornadoes during December 2015 occurred during two separate outbreaks across the South on December 23rd and 26th-27th. During these outbreaks there were 57 preliminary tornado reports. December was also the deadliest month of the year with 24 tornado-related fatalities report. Prior to December, 2015 was on track to have the lowest number of tornado-related fatalities on record. The deadly tornado count marked the first time on record that during a calendar year, December had the highest tornado fatalities when compared to the other 11 months.
The December tornado count pushed the annual total to a preliminary count of 1,183 with 948 confirmed tornadoes from January-September with 238 still pending for October-December. This is below the average of 1,253. However, this will be the first year since 2011 that the annual tornado count has been above 1,000. More information is available in the annual report.
Significant Events
On December 23rd severe thunderstorms were spawned ahead of a cold front moving through the Mid-Mississippi Valley. Ahead of the cold front, an air mass with record breaking temperatures and extremely high dewpoints was present. Behind the front, much colder conditions were observed. Along the boundary of these two environments extremely high wind shear was present, creating ideal conditions for tornadoes. One single-track severe thunderstorm produced two-long lived tornadoes through northern Mississippi into western Tennessee. The first tornado, an EF-3 with winds of 160 mph, travelled 63 miles through northern Mississippi, killing two people. The second tornado, an EF-4 with winds of 170 mph, travelled 75 miles from northern Mississippi into Tennessee. This tornado caused nine fatalities and was the deadliest tornado of 2015. Another EF-2 farther to the northeast caused an additional two fatalities in Perry County, Tennessee. This outbreak was unusual when compared to the rest of the 2015 season. It produced one of the few EF-4 tornadoes observed during the year. The outbreak produced both the highest fatality county of the year, and produced the deadliest single tornado of the year.
A two-day tornado outbreak on December 26th and 27th spawned an estimated 25 tornadoes across Texas, Oklahoma, Arkansas, Louisiana, and Mississippi. The deadliest day of the outbreak was the 26th when a swarm of tornadoes, including two EF-4s, impacted the Dallas, Texas metro area. According to preliminary estimates at least 1,000 structures, homes and businesses, were damaged or completely destroyed. In Garland, TX, an EF-4 killed eight people with two other tornadoes resulting in three fatalities. Summerlike conditions were present prior to the outbreak, with the temperature reaching 80°F in Dallas before the outbreak. This outbreak contributed to the seventh consecutive day of at least one tornado confirmed in the U.S., marking the longest such streak on record for the U.S. during December. On the 27th, 19 tornadoes, mostly weak in nature were observed further to the east.