50th Anniversary of April 21, 1967 Tornado Outbreak

[Hoosier]

We are coming up on the 50th anniversary of the April 21, 1967 tornado outbreak. First I will post some general background on this event, and then focus more specifically on what happened in northern Illinois.  More detailed information from other areas affected is welcomed as well.  In northern IL, this is the worst tornado outbreak on record (at least since the late 1800s, from a fatality/number of higher end tornadoes standpoint).

Here are some weather maps from that day, courtesy of Jonathan Finch:

 

Text of tornado watch issued by the Weather Bureau.

 

A plot of tornadoes from that day.  With nearly 4 dozen documented tornadoes, this was one of the higher 1 day tornado totals at the time.

[Hoosier]

As mentioned, this is the worst tornado outbreak on record in northern IL.  All 58 fatalities in this outbreak occurred there.  3 F4 tornadoes occurred in this area, making it only the second time that 3 or more tornadoes of that strength have occurred in northern IL in one day (5/18/1898 being the other day).  A paper was written some years ago to determine what the environment may have been like on that day, which is linked below.  In short, a rerun model simulation showed SBCAPE of 1000-1500 J/kg, 0-3 km SRH around 300, 0-6 km shear around 55-65 kts, 0-1 km shear of 30 kts with decent speed/directional shear in the area where the 3 F4 tornadoes occurred.  These values by themselves may not scream high end tornado potential, but it's certainly more than sufficient for tornadoes and it proved to be just the right balance of ingredients on that day.  Also of note is that the environment was evolving rapidly.

http://www.caps.ou.edu/reu/reu04/Margaret Nitz Final Paper.pdf

[Hoosier]

For the NWS Chicago cwa, this outbreak is responsible for approximately one quarter of all tornado fatalities from 1880-2014. For reference, a county by county map put together by NWS Chicago is provided below. You can see the effect of the 4/21/1967 outbreak, with all 24 fatalities in Boone county occurring on this day.  Even the lone fatality in Lake county Illinois occurred on this day, along with 33 of the 59 tornado fatalities in Cook county.

 

More info on specific tornadoes to come at a later time.  While researching, I came across some things I had not seen/known before which I am looking forward to sharing.

[Hoosier]

Some more info.  Much of this can be found on the NWS Chicago website, with other sources being the April 1967 issue of Storm Data and online newspaper archives... mainly the Chicago Tribune unless otherwise noted.

In northern IL, the first tornado of the day was a brief touchdown in Whiteside county, which destroyed a shed.  Shortly after this, the infamous Belvidere tornado occurred. This tornado largely tracked through rural areas but heavily damaged the southeast side of Belvidere, killing a total of 24 people. At one point, this tornado was over 3/4 mile wide.  The tornado first struck at 350 PM two miles southeast of Cherry Valley. The tornado passed the Chrysler plant near I-90 where 300 new cars and 100 employee cars were destroyed. The tornado continued east northeast through the southeast side of Belvidere. One hundred twenty seven homes were destroyed, and hundreds more were damaged. The most notable and horrific part of this tornado was the mayhem at the Belvidere High School. Buses had already picked up the elementary school children and were loading the high school students when the tornado struck. Twelve buses were rolled over. Students were flung like leaves into the muddy field. Thirteen of the 24 fatalities and 300 of the 500 injuries in this tornado occurred at the high school.  The tornado ended in McHenry County, about two miles north of Woodstock.

There is only one known photograph of the Belvidere tornado, but it is so distant and low quality that it is not worth posting.  

Aerial photo of damage in Belvidere:

[Hoosier]

Several more tornadoes occurred during and in the minutes immediately after the Belvidere tornado.  Then, almost exactly at 5 pm, the next F4 in northern IL touched down, impacting the Fox River Grove, Barrington Hills, and Lake Zurich areas.  Lake Zurich Manor, a subdivision 1 1/2 miles northwest of the center of town was hardest hit. Around 75 homes were completely destroyed. Another 200 homes had extensive damage. Seth Paine School was destroyed. Acorn Acres, a new subdivision of luxury homes northeast of Lake Zurich Manor had spotty damage and debris. About a dozen homes had extensive damage. More homes had extensive damage in Hawthorne. At Gilmer and Route 63, four homes, a brewery and a plastic factory were destroyed. Much of this area was rolling wooded hills where there were large trees damaged. Several residents who were interviewed saw no noticeable funnel or roar until it was upon them, just heavy low black clouds swirling.  Like the Belvidere tornado, this tornado threw vehicles that were occupied, but fortunately with much less loss of life.  Only 1 person was killed by this tornado.

[Hoosier]

Less than 15 minutes after the tornado above did its last damage, the next F4 initially touched down in Palos Hills and would go on to be known as the Oak Lawn tornado.  The cell that produced this tornado was first noticed on radar west-northwest of Joliet at 4:45 pm.  At 5:15 pm, an off duty Weather Bureau employee 10 miles north of Joliet saw a rotating cloud mass over his house near Route 53 and Naperville Road which is now Romeoville. At 5:24 pm, an observer at The Little Red School House at 99th and Willow Springs Road observed a lowering funnel just to his south. This was the first report of the funnel to the Weather Bureau. The tornado touched down in Palos Hills just east of 88th Avenue between 105th and 106th Streets at 5:24 PM, 24 minutes after the tornado warning was issued for Cook county... excellent by today's standards and probably almost unheard of by 1967 standards. The tornado destroyed trees, bent power poles and picked up mud for the first part of its journey. The tornado hit its first homes around 83rd Avenue and 103rd Street. The tornado crossed the Tri-State Tollway and then hit an area of homes near Harlem Avenue and 98th-99th Streets. The tornado then hit a drive in movie theater near Chicago Ridge an hour before it was set to open. The screen’s steel supports were bent and speakers and speaker stands were pulled from the ground.

The tornado then moved into the heart of Oak Lawn where it did the most severe damage. The tornado was a block wide at this point. Many homes were leveled. The busy intersection of 95th Street and Southwest Highway was clogged with Friday evening traffic when the tornado struck. Twenty five to 40 cars were thrown in all directions. The greatest death toll, about half of the total number of fatalities, occurred in this area. The high school was hit as well a bus garage. Buses were thrown like toys, one landing on a house. The tornado weakened slightly from here but intensified again near Cicero Avenue and 92nd Street where a mobile home park and roller skating rink were leveled. A receipt from Oak Lawn would later be found nearly 75 miles away in Benton Harbor, Michigan. The tornado then ripped through Hometown, causing heavy damage to many structures.

The tornado swept across St. Mary's Cemetery, knocking down 200 monuments. It then moved on to Evergreen Park. It weakened slightly through this area. At 5:32 pm, the tornado entered the city limits of Chicago near 87th and Western, moving through the Dan Ryan Woods. It hit a more populated area again near 87th and Damen Ave. Damage was mostly to trees, roofs, windows, and garages. It crossed Halstead near Vincennes Ave where it damaged apartments and factories. The tornado crossed the Dan Ryan Expressway at 5:35 pm, flipping a semi. There was so much debris thrown on the highway that it had to be closed for hours. Damage was lighter beyond this point - mostly roofs, chimneys, and windows. The path widened and became more diffuse as the storm approached Lake Michigan. The final report was at 5:39 pm at the water filtration plant at 78th and the lakefront, where a 100 mph wind gust was recorded. The tornado made the 16.2 mile trek in 15 minutes, moving across the ground at over 60 mph!  In the 7 minutes that the tornado was in Chicago, it knocked down thousands of trees, broke a countless number of windows, and caused severe structural damage in some areas. Based on the survey that was performed, we can infer that most damage in Chicago was F2 or weaker.  However, there were likely at least a couple spots/swaths of F3 damage, especially in areas west of the Dan Ryan expressway as some homes/apartments suffered complete roof loss with some walls collapsed.

Almost all of the 33 fatalities occurred in Oak Lawn.  However, one death occurred in Chicago near 82nd and Cottage Grove when a man was electrocuted by power lines that fell on his car.  This is the last tornado related fatality to occur in the Chicago city limits.

List of Chicago's killer tornadoes/number of fatalities:

5/22/1855:  3

5/6/1876:  2

3/28/1920:  6 

3/4/1961:  1

4/21/1967:  1

 

Track map.  As you can see, this was a pretty narrow tornado and was actually at its widest near the end of the track.

 

[Hoosier]

There are less than 10 known pictures of the Oak Lawn tornado, and there were only a few up until fairly recently.  Some are pretty similar shots from slightly different angles, so I won't post them all.  

These first 2 were the first pictures of the tornado, taken by Elmer Johnson.

 

This next picture was taken by Oak Lawn resident Ron Bacon

 

This picture was taken by someone who was at home in Oak Lawn.  As far as I know, it is the only "backyard" shot.

 

A few aerial pictures from Oak Lawn

 

View at 95th and Southwest Highway:

 

Demolished car in Oak Lawn

 

The Dan Ryan expressway in Chicago

 

Audio recording from a man as the Oak Lawn tornado passed just to his north:

 

[Hoosier]

Just a few more things about the historical significance of the Oak Lawn tornado and other miscellaneous thoughts.

The Oak Lawn tornado is tied with a March 19, 1948 tornado as the deadliest tornado in Illinois since the 1925 tri-state tornado (note:  a tornado in Missouri/Illinois on Sep 29, 1927 killed 79 people, with 72 deaths occurring in Missouri).  The death toll in Oak Lawn remains the deadliest single-community toll in Illinois since what happened with the tri-state tornado.  

This outbreak was another reminder of the Chicago metro area's vulnerability to significant tornadoes, including in Chicago itself.  Of the ~17 tornadoes that have been documented in the Chicago city limits since the mid 1800s, 6 have made it to/passed out over Lake Michigan.  4 out of those 6 have occurred in March/April, when lake water temperatures are typically in the 30s/40s.  This shows that the lake is not an absolute defense against tornadoes, and it is situation-dependent.  A setup with southerly surface winds or something with any westerly component offers no defense from the lake.  Even SSE flow would have limited impact near the Chicago shore.

Out of the 10 largest U.S. cities/metros, the Chicago area and Dallas/Ft Worth Metroplex are really at the top of the list as far as tornado risk/vulnerability, especially to strong/violent tornadoes.  In the case of Chicago, I counted over 20 (E)F4+ tornadoes within a 100 mile radius of the city since 1950.  When including older data from 1880-1949, the number jumps to ~45. This blows away the number of (E)F4+ tornadoes that have occurred within a 100 mile radius of large cities such as Houston and New York City.

[SchaumburgStormer]

With the spread of the suburbs in the last 50 years, the risk of a catastrophic tornado simply increases.

Like we have rehashed on the board numerous times, it's only a matter of time before the greater Chicago area takes a significant/devastating direct hit, ala Moore, Ok or Joplin. 

[Hoosier]

2 hours ago, SchaumburgStormer said:

With the spread of the suburbs in the last 50 years, the risk of a catastrophic tornado simply increases.

Like we have rehashed on the board numerous times, it's only a matter of time before the greater Chicago area takes a significant/devastating direct hit, ala Moore, Ok or Joplin. 

Yeah, the expanding bullseye effect.

As far as potential for loss of life, one thing that helps in this area compared to others is the prevalence of basements. Basements are common in the Chicago area but not so much down south.  Still, that doesn't do any good if you're not at home to take advantage of it, which was the case on 4/21/1967 as a lot of people were still out and about at that time of day.  Warnings, and importantly, the ability to receive warnings has gotten better since 1967 but it's sort of offset by population growth since then.