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Terry’s Take: 50 years of tornadoes…no EF-5′s

Posted on: 2:36 pm, April 23, 2013, by , updated on: 10:53pm, April 23, 2013

Terry Swails Weather Blog

I came across some neat information from the Storm Prediction Center on local tornadoes from 1961 to 2011. Over that 50 year period 613 tornadoes have touched down within 120km of the Quad Cities (see the track plots on the graphic). Most were short tracked and weak tornadoes in the classification EF0-EF1…the blue and green plots on the graphic below.

TORNADO TRACKS WITHIN 120KM OF THE QUAD CITIES 1961-2011

TORNADO TRACKS WITHIN 120KM OF THE QUAD CITIES 1961-2011

PEAK TIME AND MONTHS FOR QCA TORNADOES

PEAK TIME AND MONTHS FOR QCA TORNADOES

Of the 613 twisters, only 36 were considered violent (EF3 or greater, winds of 150mph+). Of these, 31 were EF3, just 5 EF4 and none were EF5. What this tells me is that we average 5 days each year where tornadoes touch down and 1.6 days where EF2 or greater occur within the 120km radius. EF4 or greater days are extremely rare, occurring only once every ten years (a 0.10 chance). Clearly, violent, long tracked tornadoes have been absent from our area the last half century. At least from a statistical standpoint, they are not common to the Quad Cities and surrounding area. Great news!

ANNUAL NUMBER OF TORNADOES PER STATE

ANNUAL NUMBER OF TORNADOES PER STATE

However, a word of caution. It’s been decades since a major outbreak and (from what I can gather) more than a century since a documented EF5. What this implies is that statistically…using the law of averages, the odds are stacked in our favor that a significant outbreak of violent tornadoes is in our future (we are way overdue)! It may not be this year, or for that matter it may not be for another 5 or 10 years, but it will happen. Don’t let your guard down. Mother nature has a way of balancing the score and she is known to be an equal opportunity employer!

AVERAGE ANNUAL TORNADOES DEATHS PER STATE

AVERAGE ANNUAL TORNADOES DEATHS PER STATE

TORNADOES PER COUNTY 1952-2010

TORNADOES PER COUNTY 1952-2010