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