Plainfield, IL F5 Tornado of August 28, 1990

According to the National Weather Service (NWS) in Chicago, IL (2015), the Plainfield tornado was the first ever tornado greater than an F3 rating, since records began in 1950, to occur during the month of August in the state of Illinois. As of 2015, it remains the only F5/EF5 rated tornado documented in the United States during the month of August. The tornado had low clouds and rain surrounding it, making it difficult to see. Because of this, no known photographs or videos of this tornado exist. This tornado approached from the northwest, which was unusual since most tornadoes approach from the southwest.

According to the National Climatic Data Center (1990), “the surprise factor was great with this tornado because a powerful thunderstorm was in progress with low cloud bases. Therefore, the early stages of the tornado were masked by the preceding downburst. Eyewitness accounts testify to abrupt and complete devastation where people were unable to communicate the danger to others until it was too late”.

The Forecast

According to the NWS Chicago, IL (2015), the atmospheric conditions that led to this F5 tornado were typical of those leading to most severe weather cases. An upper level shortwave trough (Figure 1) was moving through the Great Lakes, while a cold front was pushing through the area (Figure 2)

Figure 1. 500mb geopotential height contours at 12Z and pressure centers on August 28, 1990 (Plymouth State University, 2019).

According to the NWS Chicago, IL (2015), the National Severe Storms Forecast Center (NSSFC) in Kansas City, MO upgraded their thunderstorm outlook from SLIGHT to MODERATE risk of damaging storms. At 1:28 pm CDT, the NSSFC issued a severe thunderstorm watch for portions of northern Illinois.

Figure 2. Surface analysis at 21Z for August 28, 1990 with mean sea-level pressure (MSLP) contours and surface plots showing temperature (C) and dew points (C). Illinois is highlighted in orange and the storm responsible for the F5 tornado is circled in red (WPC, 2017, modified by Francis Lavigne-Theriault).

Thunderstorms began initiating around noon near the central Illinois and Wisconsin border. Around the same time, it became obvious that conditions across northern Illinois were favoring supercell storms. By 3:00 pm CDT, instability values had risen to an incredible 7000 J/kg (Figure 3). The cold front could be observed crossing the state line at the same time.

Convective Available Potential Energy (CAPE) for August 28
Figure 3. Convective Available Potential Energy (CAPE) at 18Z for August 28, 1990 (NWS Chicago, IL, 2015).

Temperatures ahead of the cold front were in the mid to upper 90s (F) with dew points in the upper 70s (F). According to the NWS Chicago, IL (2015), even with the lack of low-level shear, the impressive parameters for supercell growth along the cold front allowed a storm to produce tornadoes west of Rockford at 1:42 pm CDT. Eventually, a dominant storm emerged and ventured into the extreme instability axis (Figure 3) and strong shear, where it exploded to a height of 65 000 feet.
Figure 4. Sounding taken at Peoria, IL at 00Z (7:00 pm CDT) on August 28, 1990 (NWS Chicago, IL, 2015).

Figure 4 depicts the vertical profile of the atmosphere in Peoria, IL, which is roughly 100 miles from Plainfield, IL. The sounding shows large instability values and 50-60 kt winds at the mid-levels of the atmosphere, which contributed to favorable conditions for supercells (NWS Chicago, IL, 2015).

Series of radar images from 2:27 pm through 3:49 pm. Picture from the Natural Disaster Survey Report.
Figure 5. Series of radar images from 2:27 pm through 3:49 pm CDT showing pronounced hook echo as storm moved into northwestern Will County. Times shown in UTC from (a) through (h) (NWS Chicago, IL, 2015).

The tornado reached its maximum strength (F5) from 3:15 pm to 3:45 pm CDT ([e] through [h] in Figure 5) as it moved through Plainfield and Crest Hill. The tornado dissipated in Joliet after the parent supercell produced damage and fatalities across northern Illinois for four and a half hours.

Visible GOES satellite images showing the development of the tornadic thunderstorms.
Figure 6. Visible GEOS images showing development of tornadic supercell across northern Illinois at (a) 12:46 pm; (b) 1:46 pm; (c) 2:46 pm; and (d) 3:46 pm CDT on August 28, 1990 (NWS Chicago, IL, 2015).


The Peerless and Lily Cache subdivisions in Plainfield, just south of Renwick Road, are destroyed by the Aug. 28,1990, tornado.
Figure 7. The Peerless and Lily Cache subdivisions in Plainfield, IL just south of Renwick Road destroyed by the August 28, 1990 tornado (The Herald, 2015).

The following paragraphs are taken from the National Climatic Data Center (1990) storm data publication. Some wording may be graphical in nature.

The Plainfield high school was destroyed. Six fatalities were observed in Plainfield as well as 55 homes destroyed and 205 damaged. Southeast of Plainfield, the Grand Prairie Elementary School and District Administrative Center were destroyed. At Saint Mary Immaculate, three fatalities occurred and significant damage was done to the church, school rectory and convent.

As the tornado continued southeast, several shopping malls were damaged. At Peerless Estates, 75 homes were destroyed and 148 damaged. At Lily Cache, one fatality was observed, 55 homes destroyed and 127 damaged. At Crystal Lawns, two fatalities were observed, 69 homes were destroyed and 324 damaged. At Warwick Estates, the tornado was at F3 to F2 intensity, where it killed two people, destroyed 50 homes and damaged 31.

At Crest Hill Lakes, the tornado killed eight people, some of which were thrown into fields from their apartments, and destroyed three buildings. At Colony West, 12 homes were destroyed. The tornado continued southeast into west Joliet with F2 to F1 strength, where three homes were destroyed and 88 damaged. The tornado weakened as it crossed Larkin Avenue just north of Glenwood Avenues and lifted within a half mile.
Figure 8. Scare left by F5 tornado on August 28, 1990 (NWS Chicago, IL, 2015).


According to the NWS Chicago, IL (2015), “between 3:15 p.m. and 3:45 p.m. CDT on August 28th, 1990, a violent F5 tornado ripped through Kendall and Will counties taking the lives of 29 people and injuring 350. The tornado left a 16.4 mile-long damage path which ranged from 600 yards to a half a mile in width”. More than $250 million dollars in property damage occurred because of the F5 tornado (NOAA, 2019), with a total of 470 homes destroyed and 1000 damaged.


NWS Chicago, IL. (2015). 25 Years Later: The August 28th, 1990 Plainfield Tornado. Retrieved from:

National Climatic Data Center. (1990). Storm data and unusual weather phenomena with late reports and corrections (Department of Commerce Publication No. 8, Vol 32). Asheville, NC. Retrieved from:

Plymouth State University. (2019). Plymouth State Weather Center. Retrieved from:

NWS Weather Prediction Center. (2017). Surface analysis 21Z Tue Aug 28 1990. Retrieved from:

The Herald News. (2015). Plainfield 1990 tornado was unique in its formation, destruction, rebuilding. Retrieved from:

NOAA’s National Centers for Environmental Information. (2019). Storm Events Database. Retrieved from: