NWS Outlook for the Growing Season in Illinois

The NOAA Climate Prediction Center has released their monthly and seasonal outlooks for the growing season.

In the near-future, the 6-10 and 8-14 day forecast indicate that colder-than-average conditions will prevail for the next two weeks. For precipitation, there is an increased chance of drier-than-average conditions in parts of northern Illinois for the next two weeks.

There is not a lot to report for Illinois at the medium range. We are in equal chances (EC) for above-, below-, and near-average temperature and precipitation for both May and the 3-month period of May-July.


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April EF-4 Tornadoes Rare in Illinois

According to the National Weather Service report on the April 9, 2015, tornadoes, the tornado that tracked through Fairdale was rated EF-4 on the Enhanced Fujita scale. This would be the first EF-4 tornado in April since 1981 for Illinois and only the 33rd in Illinois history, regardless of month, since reliable records began in 1950.

According to the NWS Storm Prediction Center database, only 33 F/EF-4 tornadoes have struck Illinois since 1950. Even more rare, only 8 have hit Illinois in April. Of those eight in April, six struck in the 1960s, one in 1981, and one in 2015:

Here are all the F/EF-4 tracks for Illinois from 1950-2014, from the MRCC tornado tracker tool. Unfortunately, we cannot screen out just the April events at this time. While this is a screenshot of the tool, the actual tool allows you to zoom in and out. If you point to a track then you get a pop up window with the details of that track. Check out the tornado tracker tool – it’s free.


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On this Date in 1953, First Documented Tornado Hook Echo Captured on Radar

Today is the 62nd anniversary of the first documented case of a tornado detected by radar. Illinois State Water Survey staff, at Willard Airport in Champaign, IL, captured the historic event on film on April 9, 1953. This discovery helped lead to the first national weather radar network in the United States.

Radar hook echo
First recorded radar hook echo associated with a tornado, April 9, 1953, near Champaign, IL. The radar was located to the south of Champaign-Urbana at Willard Airport. The tornado was located north of Champaign-Urbana. Photo by Illinois State Water Survey, Prairie Research Institute, University of Illinois. 

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Hail in Champaign-Urbana

Here is a shot of the hail dents on our hailpad at the Illinois State Water Survey in Champaign from this morning’s storm. Most of the dents where in the 1/4 to 1/2 inch range.

To construct a hailpad, we use sections of flourist or floral foam covered with aluminum foil. It is low tech but an excellent way to record hail sizes and density, especially when no one is around.


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Cold, Snowy March for Illinois


The statewide average temperature for March was 38.2 degrees, 3.1 degrees below average. This follows on the heels of a slightly colder-than-average January and much colder-than-average February. As a result, the year-to-date temperature for Illinois was 27.8 degrees, 5.1 degrees below average and the 16th coldest on record. In comparison, the same period in 2014 was 24.4 degrees and the 4th coldest on record.

According to the latest NWS forecasts, the first two weeks of April are expected to be warmer-than-average.



March precipitation – click to enlarge.

The statewide precipitation for March was 2.44 inches, 0.52 inches below average. However, it was not evenly distributed (left). Northern Illinois was dry with less than 2 inches of precipitation in many locations. Central Illinois was close to average with 2 to 4 inches widely reported. On the other hand, Southern Illinois was much wetter with 4 to 8 inches of precipitation (shades of blue). The largest reported total for the month was in Belknap (far southern Illinois) with 8.43 inches.

The heavy rains in southern Illinois contributed to moderate flooding on tributaries of the Wabash and Ohio Rivers.

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USDA Soil Moisture Report for Illinois

Yesterday, the USDA released their report on soil moisture conditions for Illinois. Overall the state looks moist, especially in southern Illinois after weeks of rain. Statewide, 95 percent of the topsoil moisture and 93 percent of the subsoil moisture is rated as either “adequate” or “surplus”.


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

I am a little late in post 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.


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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