Rivers Have No Effect on Tornado Tracks

The Kansas City NWS office posted this image showing that rivers have no measurable effect on tornado tracks.

tornadoes-vs-rivers
Click to enlarge.

The case for St. Louis reminded me that one of the worst tornado disasters in US history occurred when a tornado tracked through St. Louis, jumped the Mississippi River, and continued doing damage in East St. Louis. That was May 27, 1896. Besides busting the myth about rivers, it busted the myth that tornadoes do not hit major cities. At the time, St. Louis had a population close to 500,000.

The St. Louis Public Library has a great collection of photos and newspaper articles on the event. A total of 255 people were killed in both Illinois and Missouri. It was estimated to be an F-4 tornado on the Fujita scale, based on the damage seen in photographs.

Nine days after the event, a book was published based on newspaper accounts with lots of photos. It has recently been reprinted by Southern Illinois University Press and called “The Great Cyclone at St Louis and East St Louis, May 27, 1896”. Besides the incredible amount of detail on the storm’s damage, you are treated to some vivid and lurid prose (which was the newspaper style of the day).

Example of the damage from the 1896 event.

"St Louis Jefferson-Allen Damage" by http://www.photolib.noaa.gov/historic/nws/wea00256.htm "Photo by Strauss". Licensed under Public Domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:St_Louis_Jefferson-Allen_Damage.jpg#/media/File:St_Louis_Jefferson-Allen_Damage.jpg
Click to enlarge. “St Louis Jefferson-Allen Damage” by http://www.photolib.noaa.gov/historic/nws/wea00256.htm “Photo by Strauss”. Licensed under Public Domain via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:St_Louis_Jefferson-Allen_Damage.jpg#/media/File:St_Louis_Jefferson-Allen_Damage.jpg

90th Anniversary of the Tri-State Tornado: Illinois’ Worst Tornado Disaster

I am a little late in posting this, but March 18, 2015, marked the 90th anniversary of the Tri-State Tornado that struck Missouri, Illinois, and Indiana, on March 18, 1925 (map below).

This was the deadliest tornado in U.S. history with 695 lives lost and occurred long before there were systematic forecasts and warnings of tornadoes. While it predated the common F-scale used to measure tornadoes, it was considered by experts to be an F-5 event.  A few years ago there was a push to decide if this was one continuous track or not by examining all the evidence and interviewing survivors. It was hard to decide since there was no weather radar to track the storm. Some of the areas were very sparsely populated, leaving little documentation on the possible track.

735px-Tri-State_Tornado_map
Figure from Wilson, John W., and Stanley A. Changnon, Jr. (1971). Illinois Tornadoes. Circular 103. Illinois State Water Survey: Urbana-Champaign, IL.

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Four Odd Tornado Seasons in a Row for Illinois

mapt
Click to enlarge. Source NOAA Storm Prediction Center.

So far the 2015 tornado season in Illinois and the rest of tornado alley is incredibly quiet. There are no tornadoes to report this year, except in the far Southeast and one in California. However, this quiet start is no reason to relax if the past few years are a guide.

Historically, the heart of the Illinois tornado season is March to June with two-thirds of our tornadoes occurring during those months. However, in the last few years, we have had more tornadoes occur outside of this period than inside.

And a lot of these tornadoes have been concentrated in just a few days of the year. In fact, 69 percent of the tornadoes in 2012-14 occurred on just 5 days. These high concentrations can put extra strain on forecasting, warning, and recovery operations.

Here is how 2012, 2013, and 2014 looked, compared to the historical averages. Continue reading

Historical Tornadoes in Illinois and the US

While tornadoes can happen any time of the year, the tornado season really starts to ramp up in March in Illinois (see plot below) and remains active through the spring and on into summer. April, May, and June are the three standout months historically. So far 2015 has been very quiet with no severe weather reported in Illinois so far, according to NOAA.

tornado-month

You can see more plots like this on our tornado plots page.

Historical Tornado Tracks

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Tornado Trends in Illinois – Updated

2014-03-21photo1The tornado trends in Illinois has been updated to include data through 2013. The plots in order are the number of tornado reports by year, deaths by year, and injuries per year. Click to enlarge each plot.

These plots are based on storm data at the National Climatic Data Center (NCDC). Tornado records are notorious for not being consistent over time. It is nobody’s fault – technology changes and reporting techniques have improved over time. The newer NWS Doppler radar systems were installed in the 1990s, the spotter networks continue to improve, and everyone has a cell phone with a camera.  As a result, the number of tornadoes has increased in recent years with the better accounting.

In addition, there is always the potential for over-counting the number of tornadoes as they travel. For example, you might have a report for a tornado spotted 2 miles west of Smithville, and then another report 10 minutes later of a tornado north of Smithville. Was this the same tornado or two separate ones? Hard to tell without supporting evidence, especially before the modern-day radars.

I think the number of deaths and injuries by year in Illinois may actually be more reliable than the tornado frequency because they were just as widely reported in the media in the 1950s and 1960s as they are today. One can clearly see the spike in 1967 due to the Oak Lawn/Belvidere tornado outbreak and the 1990 spike from the Plainfield tornado. Sadly, the last two years have been bad in terms of fatalities in Illinois – 2012 with 9 deaths (Harrisburg, IL) and 2013 with 8 deaths (November 17, 2013 outbreak) after 7 relatively quiet years.

If you want to look at US trends, check out the NCDC page on tornado trends.

tornado-year

fatal-year

injury-year