I thought I'd make a thread as we come up on the anniversary.  This event is perhaps not as well known as the 1965 outbreak, but it wreaked havoc in a similar manner.  In fact, the 1920 and 1965 outbreaks were focused in essentially the same area.

This event produced over 30 tornadoes (and probably more as weaker tornadoes may not have been counted) and killed at least 153 with some estimates much higher than that.  Northeastern Illinois was one of the hard hit areas.  The Fort Wayne News and Sentinel wrote this regarding a tornado that tracked through Wilmette, Illinois:

The storm had a spectacular career in Wilmette suburban home of scores of Chicago millionaires.

It cut a path 200 feet wide directly through the heard of the fashionable suburb. The only things it left untouched were a glass conservatory, two churches and the offices of the local weekly newspaper.

Here are some 500 mb and surface maps from that day:  

Wikipedia article provides a good summary and links to the other 2 significant Palm Sunday outbreaks.

http://en.wikipedia....ornado_outbreak

This is also a good read:

http://books.google....tornado&f=false

What worries me is that the 1920 and 1965 events were 45 years apart. We are slightly overdue. These things can come in cycles.

What worries me is that the 1920 and 1965 events were 45 years apart.  We are slightly overdue.  These things can come in cycles.

It's hard to know how often an outbreak of this magnitude occurs in the lower lakes.  It was certainly a synoptically evident setup.

Thought I would bump this thread. I've been looking further into this setup to get an idea of what the conditions were like that day. This is obviously complicated by data issues or the lack thereof, but there is enough available to make some educated guesses.

First off, the system that spawned this outbreak had a very deep surface low. The surface low was located near Sioux City, Iowa during the early morning of the 28th and moved into southern Minnesota by noon (around the start time of the outbreak), reaching approximately 980 mb. Noon surface observations from Chicago revealed a temperature of 60 degrees with 84% relative humidity. When you know the temperature and RH, a very good estimate can be made for the dewpoint. In this case, the dewpoint at Chicago was around 56 at noon. Based on this and other obs, it is fair to assume that mid/upper 50's dewpoints made it at least as far north as Chicago and southern Michigan. Temperatures reached the 70's in much of IN/OH with even some 80+ readings noted.

Based on 700 mb and 500 mb charts, it appears that fairly steep mid level lapse rates existed across the area, which would've helped boost instability. CAPE is an integrated value so the following should be treated as rough estimates, but based on temps/dewpoints/lapse rates, I'm guessing that there would've been something like 1000-1500 J/kg CAPE in central/southern Michigan, trending toward 2000+ J/kg southward through IN/OH and south from there. Given this and the very strong system and presumably strong deep layer shear, we can only imagine what soundings would've looked like.

I put together a map of significant tornado tracks. Locations and ratings are from Tom Grazulis.

#1.....Vanzant, MO.....F2

#2.....S of Cortland, IL to NE of Sycamore, IL.....F2

#3.....SE of LaFox, IL to Wauconda, IL.....F3

#4.....N of Channahon, IL to Wilmette, IL.....F4 (likely 2 tornadoes)

#5.....E of Elkhorn, WI to W of East Troy, WI.....F2

#6.....SE of Baroda, MI to E of Sodus, MI.....F2

#7.....Bridgeview, IL to Chicago, IL.....F2

#8.....Cedar Springs, AL to N of Jacksonville, AL.....F3

#9.....N of Milner, GA.....F2

#10.....N of Deatsville, AL.....F2

#11.....Red Hill, AL to West Point, GA.....F4

#12.....W of Leroy, IN to Beatrice, IN.....F3

#13.....W of Hart, MI to Weare Township, MI.....F2 (started over Lake Michigan)

#14.....S of Freesoil, MI to Sherman Township, MI.....F2

#15.....S of Mishawaka, IN to NW of Union, MI.....F3

#16.....Cory, MI to S of Climax, MI.....F2 (possibly a family)

#17.....SW of Kalamazoo, MI.....F2

#18.....S of Mulliken, MI to S of Eagle, MI.....F3 (possibly a family)

#19.....Orlando, IN to SW of Coldwater, MI.....F4

#20.....S of Hickorys Corners, MI to Vermontville, MI.....F4

#21.....S of Orangeville, MI to ENE of Hastings, MI.....F3

#22.....Mason, MI.....F2

#23.....NNE of Fenton, MI.....F4

#24.....Uniondale, IN to Rabbs Corners, OH.....F4

#25.....SE of LaGrange, GA.....F3

#26.....S of Perry, MI to NE of Morrice, MI.....F2

#27.....SW of West Liberty, IN to S of Van Wert, OH.....F4 (possibly F5)

#28.....Saginaw, MI.....F2

#29.....Genoa, OH.....F2

#30.....S of Union City, IN to SE of Lightsville, OH.....F3

#31.....W of Fountain City, IN to N of Greenville, OH.....F4

More similarities there than I thought actually...

Hoosier, thanks for your research. Here is a blurb from This Day in Weather from IWX, mainly concerning the tornadoes in their CWA:

1920 -- One of northeast Indiana's deadliest tornadoes tore across northeast Wells County, northwest Adams County, and southeast Allen County killing 13 people as it smashed through the community of Townley. Edgerton, Indiana was badly damaged. Ten more people lost their lives in northwest Ohio as tornadoes proceeded along the same path into Lucas County. Another tornado swept from northeast Wayne County into southeast Randolph County, Indiana, killing 13, and then went on to near Lima killing 16 more people in Ohio. Another twister went from northern Jay County into southeast Adams County, Indiana killing 14 residents. More tornadoes continued along this path hitting Van Wert, Ohio where 5 people's lives were lost. Tornadoes ripped through 16 counties in our area. One tornado moved from Baroda to Sodus, Michigan. Another went from south of Mishawaka to northwest of Elkhart, Indiana to near Union, Michigan. A small twister moved through Saint Joseph County Michigan and passed near Three Rivers. A large tornado produced F4 damage as it moved from Orland, Indiana to near East Gilead, Michigan and then southwest of Coldwater killing 2 people. Yet another tornado, possibly an F5, moved from West Liberty in Jay County Indiana to south of Van Wert, Ohio. It demolished farms east of Geneva and south of Ceylon, Indiana, killing 17 people. In Chicago a tornado killed 28 people and did $3 million damage. Most of the losses were in the suburb of Melrose Park. The storm had formed near Joliet, Illinois.

#29.....Genoa, OH.....F2

This is my hometown and I've got many pictures saved on my computer of where this thing hit. My house would of been hit if it was built in 1920 and looking at some of the pictures it was an F3 at least. Very reminiscent of the F4 that tore through here in 2010 damage wise

Now this thread has brought up my memory of the June 5, 2010 tornadoes. I wasn't there, but the two tornadoes in the Toledo area really sort of impacted me. On Thanksgiving, 2010, I saw the damage at Oak Openings Metropark, and also in Lake Township/Moline. I'm glad that it was a narrow area of damage at Oak Openings, that is/was one of my favorite places. The Lake Township tornado was really close to a couple of important things in my life.

Now this thread has brought up my memory of the June 5, 2010 tornadoes. I wasn't there, but the two tornadoes in the Toledo area really sort of impacted me. On Thanksgiving, 2010, I saw the damage at Oak Openings Metropark, and also in Lake Township/Moline. I'm glad that it was a narrow area of damage at Oak Openings, that is/was one of my favorite places. The Lake Township tornado was really close to a couple of important things in my life.

I chased this one from Moline to out towards Genoa and it was unreal. 795 was completely covered in debris and the lightning flashes revealed an absolutely unreal twister, very reminiscent of the one that hit Tuscaloosa in all honesty. The motion was just unreal in the tornado itself. I almost got clipped by it in Millbury when I lost sight of it and it made a turn. That town is lucky it didn't take a direct hit or the death toll would have been very very high considering it was Midnight