Was this most recent tornado outbreak a rare occurence? Are storms happening in the winter a sign of global warming? Let's take a look at some historical data of significant tornado events in the US during the months from December to February:
February 19-20, 1884 - A devastating tornado outbreak struck much of the southern and eastern US, considered to be one of the worst tornado outbreaks in American history. Estimated casulaties ranged from a few hundred to over 1000.
January 12, 1890 - An outbreak of tornadoes hits the mid-Mississippi Valley including the city of St. Louis, resulting in 16 deaths.
January 11, 1898 - An outbreak of tornadoes in Arkansas results in 56 fatalities.
February 23, 1917 - A tornado outbreak in the Southeast US claims 17 lives.
January 18, 1929 - Tornado outbreak across the Mid-Mississippi Valley states, 10 fatalities.
February 5-6, 1942 - Tornadoes in the Southeast US states result in 22 deaths.
January 26, 1944 - Tornadoes across Oklahoma result in 2 casualties.
January 29-30, 1947 - Mid-Mississippi Valley and Southeast US tornado outbreak results in 8 deaths and 155 injured.
December 31, 1947 - New Year's Eve tornado outbreak of 1947 hits the southern US with 20 fatalities.
January 3, 1949 - 60 deaths result from a tornado outbreak in Arkansas.
December 5, 1953 - Louisiana and Mississippi are hit by a tornadoes, resulting in 38 fatalities.
February 1, 1955 - Mississippi and Alabama tornado outbreak claims 23 lives.
February 24-25, 1956 - Central US tornado outbreak, 6 fatalities.
December 18, 1957 - Illinois and Missouri tornado outbreak kills 17.
February 10, 1959 - Tornadoes in the St. Louis area claim 21 lives.
January 24, 1967 - St. Louis area tornado outbreak results in 7 casualties.
January 23, 1969 - Mississippi tornado outbreak kills 32.
February 21, 1971 - 14 tornadoes kill 119 people across the Southern Mississippi Valley.
December 14-15, 1971 - 40 tornadoes across the Central US kill 2.
January 9-12, 1975 - A three-day outbreak of 45 tornadoes takes the lives of 12 people in the Southeastern US states.
December 2-3, 1978 - Tornado in Louisiana kills 2.
December 2-3, 1982 - The Mid-Mississippi Valley is hit by a tornado outbreak resulting in 4 deaths.
December 23-25, 1982 - Tornadoes across the central and southeast US result in 3 fatalities.
February 22-23, 1998 - Tornadoes in Florida kill 42.
January 17-22, 1999 - 100 tornadoes across Arkansas, Tennessee and Mississippi claim the lives of 16 people.
February 13-14, 2000 - Tornadoes in Georgia kill 19 people.
December 16, 2000 - 12 fatalities result from tornadoes across the southern US.
February 2, 2007 - Tornadoes in Florida result in 20 deaths.
February 28 - March 1, 2007 - Tornadoes in the Plains and Southern US states kill 20.
January 7-9, 2008 - Over 70 tornadoes across the central US result in 4 deaths.
This data dramatically illustrates the fact that the United States never has a tornado 'off-season'. 'Tornado Alley' is not confined to the Great Plains in the spring - it moves around the country with the changing seasons. The central and southern US has a formidable peak tornado season during the winter months, and what we saw this past Tuesday was the latest example of that.
People take vacations to the Caribbean in the winter - why? Because it is still nice and warm there! That tells us that the warm, moist air that thunderstorms need to thrive is only a short distance away. A developing weather system during the winter only needs to produce a few days of southerly winds to pull that juicy air from the central and southern Gulf of Mexico northward into the central and eastern US. The southern states are more likely to see this warmth and moisture on a regular basis during the winter, and thunderstorms are quite common from December to February across southern Texas, Louisiana, Mississippi, Alabama and Georgia. Occasionally, a stronger system will draw the moisture and warmth even farther north, to the midwest and even the Great Lakes.
North of a line marked by Interstate 40 across the US (including the midwest and northeast), winter thunderstorms are lesser in number. Any one location in these regions may not see a December-February thunderstorm for several years, leading one to conclude that it is a rare phenomenon for their local area. But if one were to monitor weather conditions outside their home area, they'd see that lightning would be commonly occuring somewhere in the country during these months.
As a storm chaser, I have witnessed plenty of winter thunderstorms to the point that I know that they aren't rare at all. In fact, I expect them! My cameras are ready and my XM weather data subscription is active year-round - because 'storm season' in the United States never really ends.
Here are a few things I've seen in recent years during what would probably be considered the 'off season' for storms: