Illinois tornadoes: Looking back over the last 50 years.

Illinois is no stranger to severe weather.  Severe weather - thunderstorms, damaging winds, flooding rain and tornadoes - are not only limited to spring and summer, but can also occur during the late fall and winter months.  In fact, the two most recent notable tornadoes that have occurred in Northern Illinois were the 2008 EF3 tornado that hit Poplar Grove and the 2011 EF2 tornado that hit Caledonia.  Of course, we can't forget the EF4 tornado that destroyed Washington, IL November 17th, 2013.  This tornado was the strongest tornado on record for Illinois during the month of November since record keeping began back in 1950!

State Climatologist Office for Illinois, 2011

This week is Severe Weather Preparedness Week and even though there's still snow on the ground, it's important we make that transition in our minds from winter weather to spring weather.  With that in mind, do you know what month we typically experience the highest amount of tornadoes in Illinois?  If you guessed April, May and June - you're correct!  Those three months make up about 66% of the historical tornadoes that have occurred in Illinois.  However, tornadoes can occur during any month and in any season.  As you can see from the graph to the left, tornadoes have occurred in all 12 months!

State Climatologist Office for Illinois, 2011

What about the time of day?  Do you know the time of day that tornadoes typically occur?  Tornadoes rarely occur during the early morning hours, but notice the number isn't zero.  Overnight storms can often times be the most dangerous simply due to the fact that we're not aware the storms are coming and most of us are still asleep.  After Noon, the number of tornadoes rapidly increases each hour until about 5pm.  After that, there is a slow decline through about 8pm/9pm. The reason for the late afternoon spike is because it takes time for the atmosphere to heat up.  As heat continues to build through the afternoon it allows the instability to grow stronger which helps fuel severe storms. 

As we go further and further into March and eventually into April, I challenge you and your family to come up with a severe weather plan.  Sit down, detail out what you would do, where you would go - not only at home but if you were at school, work or at the store - and practice that plan.  Just like you would a fire drill.  Another challenge is to make sure you're armed with the means of receiving weather alerts - whether it be via your cell phone or a NOAA Weather Radio.  A Weather Radio would be a great tool to have, especially for the night, because at night you're likely sleeping and not watching TV to be alerted when severe weather threatens.

Over the next week, we'll continue to look further into detail at severe weather and what you need to do and what you need to know to help keep you and your family safe.

Dr. Jim Angel, State Climatologist with the Illinois State Water Survey, has done some wonderful statistical work regarding the frequency of tornadoes, fatalities and injuries.  Click here for a complete list of his work.