Terry’s Take: Tornado season, not as bad as you might think

Posted on: 10:05 pm, June 11, 2013, by

Terry Swails Weather Blog

TORNADO SEASON HAS PEAKED, SO FAR SO GOOD!

The flurry of tornadoes including the two devastating EF5 tornadoes in Moore and El Reno in reality belies the activity level this spring. Despite what some politicians, environmentalists, and advocacy groups have implied, global warming is not the reason for the super tornadoes. Global warming theory has higher latitudes warming faster than low and middle latitudes. This decreases the temperatures contrast and weakens the jet stream. Strong contrast and jet streams are what drives severe storms in the spring. This spring activity is way down simply because of the extensive nature of cool temperatures. Activity increased in late May only when warmth and moisture finally pushed up out of the Gulf and southwest and battled with the cold to the north. You can see in the graphic below how this spring was predominantly cool across the central and south.

SPRING TEMPERATURES MUCH BELOW NORMAL THIS SPRING

SPRING TEMPERATURES MUCH BELOW NORMAL THIS SPRING

Despite the lack of tornadoes, there has been a huge emphasis on the violent tornadoes that have hit central Oklahoma. The endless coverage of extreme devastation and heartbreak has led many to believe this has been an active tornado season. However, when you break down the year, nothing could be further from the truth.

The “peak” of this years tornado season occurred about a month ago and were it not for 3 tornadoes, the headlines would be centered on how quiet and uneventful 2013 has been. If you look at the graphic you can see that this year is running well below the 25th percentile in terms of tornadoes compared to average. Most of this years tornadoes have occurred in the past 3 weeks in a very localized area. As of June 6th, its estimated that 432 tornadoes have touched down nationally compared to an all-time high of 1035 and an all-time low of 339.

TORNADO TRENDS AND PERCENTILE RANKS

TORNADO TRENDS AND PERCENTILE RANKS

U.S. TORNADO STATISTICS

U.S. TORNADO STATISTICS

While June is still a good tornado producing month, the numbers start tailing off rapidly by late June and the season is pretty much wrapped up come mid July. Barring anything really dramatic in the next 2-3 weeks, I would expect 2013 to go down as one of the least active years ever for twisters, probably ranking in the top 10.

TORNADO REPORTS THROUGH JUNE 6TH

TORNADO REPORTS THROUGH JUNE 6TH

Ironically, thanks to the Moore and El Reno storms, it will go down as producing 2 of the widest and most violent storms ever recorded. What this points out is that each year is as volatile to predict as the storms themselves!