June Severe Weather

Washington, D.C. storm

Due to its unique geography, the United States averages more tornadoes in a given year than any other country in the world with annual totals of over 1,000 common.  Tornadoes have been recorded in all 50 states, but are most common in a region of the central United States from Texas northward through South Dakota; known widely as “Tornado Alley.”

Traditionally, thunderstorms form from large, long lasting thunderstorms known as “supercells” that travel long distances.  Ideal circumstances for tornado outbreaks occur commonly during the spring when warm, humid air from the southeastern United States clashes with cooler, drier air from the north and western regions of the country.  Consequently, the U.S. averages more tornadoes during the month of May with almost 400 than in any other month of the year according to statistics from the National Climatic Data Center.

As the jet stream – a river of air that guides storm track – assumes its typical summertime position farther north the cool, dry air retreats into Canada.  This allows warm, humid weather to envelop most of the central and eastern United States.  Therefore, the northern Great Plains states – Iowa and Nebraska to Minnesota and Wisconsin typically see the majority of their severe weather from June through August according to scientists at the Storm Prediction Center.  A thunderstorm is considered “severe” if it contains any of the following: 1) hail at least 1” in diameter; 2) a wind gusts of at least 58 mph within a thunderstorm or 3) the presence of a tornado.

Just last week there was a major severe weather outbreak in the Upper Midwest with more than 100 tornadoes reported in a four-day stretch from June 16 through June 19 with the highest concentration in Nebraska and the Dakotas east through Iowa, Minnesota and Wisconsin.  Tragically, this tornado outbreak proved to be both damaging and deadly.  So that heightens the importance of the public to remain vigilant and take safety precautions when severe weather watches and warnings are issued.  That’s true across the United States wherever extreme weather may occur.