As can be expected since December begins the typically quietest period of the year, strong/significant tornadoes — rated F2/EF-2+ — are not terribly numerous. Though there have been a few years with large spikes attributed to outbreaks, the overall trend since 1950 is for only a few such events. Averages fall from double digits in November to just about three in December. Since winter month statistics are heavily weighted toward outbreaks, the median of just two strong tornadoes might be a better measure for the month.
December Significant Tornado Climatology (1950-2011)
Total significant tornadoes: 392
December high: 38 (1967)
December low: 0 (13 years, 1958-2003)
1991-2010 climatological average: 3.4
1991-2010 median: 2
Dixie is a favorite spot for cool-season strong tornadoes, so Alabama and Mississippi edging out slight leads compared to third place Texas is not too surprising. The other southern states of Arkansas and Florida both have also seen more than 40 strong tornadoes in modern December history. Interestingly, the top four spots are all identical to November, though fewer cumulative tornadoes are seen in each case.
Arkansas leads the list when it comes to just F3/EF-3 tornadoes in January. One reason here is that many of the largest wintertime outbreaks have managed to include parts of Arkansas. Notably, Illinois rises into the top five behind only Arkansas and Alabama despite it’s lower ranking in overall January tornadoes, with almost half of its strong tornadoes rated F3/EF-3. Mississippi and Texas round out the top five.
Violent tornadoes are extra rare in December, as throughout the cool months. Illinois again makes perhaps a “surprise” visit to the top spot (tied), and it’s one of two states impacted by an F5 tornado in the month — Mississippi is the other. The South, including Louisiana (tied for first), Arkansas and Mississippi team with Missouri to complete the top five. All those states have seen two or more violent December tornado impacts in December.
U.S. Tornado Climatology by Month
All: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
Significant: Jan | Feb | Mar | Apr| May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
SPC tornado data obtained at the Tornado History Project. Images can be selected for larger versions. Get updates about U.S. Tornadoes on Twitter and Facebook. Official 2012 data will be available during spring 2013.
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