Why tornado numbers see a brief spike in November

From May to October, severe generally tends to wane across the United States. However, when you look at tornado data between 1950-2011, November sees a brief spike in tornadic activity during this time.

Why is that?

Well, during the spring and summer, we see a lot more sunshine, which means we have much warmer and in most cases more humid air available in the atmosphere. Heat energy tends to be a main driving force for severe weather during the warm seasons.

The transition from fall to winter is a little different. Cold, dry air becomes much, MUCH stronger this time of year as we lose sunlight, and the sharp difference between the very cold, dry air and what little is left of the mild & moist air of summer can stir up extreme amounts of wind energy to create thunderstorms.

So while the product of severe weather is the same for both seasons, when you look at the storm from the bottom to the top of the atmosphere, they tend to differ quite a bit.

While parts of Missouri see this brief bump up in activity, the focus for tornadoes in November will be in Mississippi and Alabama where there were over 150 significant tornadoes (OR EF-2+) between 1950-2011. Missouri still makes top ten for November’s significant tornado count, coming in at number 9.

Late-spring severe weather still reigns supreme, with May averaging just over 12,000 tornadoes nationwide, but this is just a reminder that they can strike anywhere, anytime of the year. And as always, we’ll be tracking it.

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