TBT: The Tropics Come to Illinois

Photo from Galena Area Historic Photos Collection, Illinois Digital Archives –
A service of the Illinois State Library & the Office of the Secretary of State
Last Tuesday and Wednesday, some parts of Illinois received a very light rain, less than a quarter of an inch in most places. These were last remnants of the once-powerful Hurricane Irma which had caused so much destruction across the Caribbean and in Florida just a few days before. The storm came inland, losing strength as it moved over land, drifted northwest across Georgia and Alabama, and then into the Ohio Valley where it finally dissipated mid-week.

As surprising as it might sound, Illinois frequently finds itself in the path of tropical weather patterns. Of course, in the middle of the continent, Illinois never gets hit as hard as coastal states do, but storm damage from the remnants of these tropical systems is not unheard of in Illinois. One storm a few years ago was even strong enough to damage a monument in Randolph County dedicated to our first governor. 

The National Weather Service (NWS) forecast offices for Central Illinois and Chicago recently compiled the tracks of the tropical weather systems that have crossed their regions of Illinois since the NWS began keeping records back in the late 19th century. They found that the traces of 14 tropical systems have passed over Northern Illinois during the years they have kept records, which works out to an average of about once every nine years. The Chicago NWS office calculates that this figure means their area has about a 10% chance of being visited by a tropical system in any particular year. Farther south, the Central Illinois region has been hit a little more frequently.

As shown in this nationwide map from the National Hurricane Center which dates back to 1851 for Atlantic basin storms, Illinois is just about the northwestern-most point in the North American continent for a tropical system to reach inland and strike. NWS Chicago attributes this phenomenon to the fact that “as (storms) move north after landfall, they become more steered by the mid-latitude westerly winds.”

Many of these tropical system impacts to Illinois have occurred in September, which is also the peak of hurricane season throughout the Atlantic. Most of the storms made landfall on the Gulf of Mexico coast and then came to Illinois, but not all of them. Some of the storms that eventually made their way to Illinois are among the most destructive hurricanes on record, including the 1900 Galveston hurricane which remains the deadliest storm in American history.

All of these storms had lost most of their punch by the time they reached Illinois, but as recently as September 2008 the remnants of Hurricane Ike struck Illinois hard enough to lead to severe storms and flooding. Ike’s remains followed on the heels of the former Hurricane Gustav, which had passed through the area just days before. The combined effect of the two systems caused enough damage from flooding that sixteen Illinois counties were declared disaster areas by FEMA after the storm.

Not surprisingly, no storm has reached Illinois while still classified as a hurricane. But according to the NWS records, one storm did make it all the way to Central Illinois while still strong enough to be considered a Tropical Storm. A Tropical Storm is defined by the NWS as “a tropical cyclone in which the maximum sustained surface wind speed (using the U.S. 1-minute average) ranges from 34 kt (39 mph or 63 km/hr) to 63 kt (73 mph or 118 km/hr).” In 1941, before tropical systems were given names, one such storm slammed ashore in the Houston area and maintained enough strength to still be a Tropical Storm when it crossed into Illinois. It got as far as the town of Flora in southeastern Illinois before it lost enough strength and fell below Tropical Storm parameters. Rainfall of 1.5 to 2.5 inches fell throughout the area.

One of the first storms on record to reach Central Illinois is an exception to the earlier statement about Illinois-bound storms coming from the Gulf of Mexico. In 1898, a storm which came ashore near Jacksonville, Florida, tore through Georgia, killing 179 people, and then made its way across Tennessee and Kentucky, skimming the eastern edge of Illinois. The NWS did not have any information on this storm’s effects once it reached Illinois, and it appears to have curved off and turned back east into Indiana.

Accounts of the effects these systems have had on Illinois have been similar through the years. A 1902 storm which passed from the St. Louis area across Illinois and into Indiana dropped 1.5 to 3 inches of rain along its path, which followed present-day Interstate 70. In 1916, another storm hit the Alabama coast then came north to Illinois as a tropical depression. Its remnants left 2-3 inches of rain all along its path into northern Illinois.

There were similar effects from storms that came up from the Gulf in 1923, 1932 and 1949. The first named storm to hit Illinois was Carla in 1961, which had been a Category 5 hurricane in the Gulf before hitting Texas. When it arrived in Illinois it brought 3-5 inches of rain and caused flooding in northern Illinois, before moving all the way to Canada.

Illinois has been visited by the remnants of some storms which have gone down in history for their destructiveness upon landfall. The 1900 Galveston storm is one obvious example. In 1988 Hurricane Gilbert set a mark at the time for the lowest barometric pressure ever recorded on an Atlantic storm before it hit the Mexican coast with Category 4 strength. It swung northeast and kept its tropical characteristics all the way to Mason City, Illinois, just northwest of Springfield. In 2005 Hurricane Rita; which struck a devastated Louisiana just a few weeks after Hurricane Katrina; drifted up the Mississippi valley and reached the Effingham, Illinois, area before dissipating.

In all, the Central Illinois NWS office found 18 tropical systems which made it to their regional warning area since 1898. The Chicago office’s records indicated 14 such storms in their area going back to 1886, though a few of these would have passed through both areas and shown up on both lists. These figures for Illinois come from just two of the five NWS regional offices which cover some part of the state, so there are likely more storms that have made it to Illinois but are not reported in this study.

While tropical storm systems will not rise in Illinois to the same level as the thunderstorms, floods and winter storms that we are more familiar with, they do offer reminders of the importance of being prepared for emergencies. September is National Preparedness Month. Visit www.ready.illinois.gov for tips on how to prepare for disasters and how to help those in need in their aftermath.