© Gibson Ridge Software (GR2Analyst)
Tornado-warned supercell moving over home-base shortly after 7:00pm (00z) on June 5th, 2010
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2012 Summary:
Here's my climatology of 2012 based off my surface observations from my Davis Vantage Pro2 weather station. (Above) you'll find surface temperature observations for the entire year graphed including 2011 and 2010 as well. You'll also find the monthly average temperature for my location (Kewanee, IL) throughout the entire year as well. A typical histogram is clearly present with the monthly average high temperature bar graph which corresponds to the change in seasons quite nicely.  Below, I have a case study of a notorious severe weather outbreak that occurred on June 05, 2010 that I chased...Hopefully this spring will allow me to publish another case study of a severe weather outbreak in this area. Anyhow, a case study of that event from (2010) can be found below:
© Gibson Ridge Software (GR2Analyst)
A radar animation illustrating the supercell moving directly overhead on the evening of June 05, 2010 (talk about a little too close for comfort)
06/05/10 Case Study:
On the morning of June 5th many of the numerical weather models were agreeing on a good ole' tornado outbreak across west-central Illinois. The night before the "event" I targeted Burlington, IA. Why? Well, southeast Iowa looked to be where convective initiation would begin as conditions looked very favorable for supercells and tornadoes ahead of a cold front and nearby warm front/triple point intersection. Remember you always have to leave good road options available to you based off your target as well especially with the Mississippi River nearby. Anyhow, instability and shear looked very "good" in this area for the next day. 2,500-3,000J/kg CAPE in a strongly-sheared environment especially in the low-levels (0-1 SRH above 300 m2/s2. Add in sufficient lift present with a 700mb trough that would erode the cap and the show you'd think would be on. The big question was "if" morning convection could clear-out by midday however. That would in turn allow for destabilization to take place and the chase would be on. Indeed, this is what occurred as thunderstorms began to initiate shortly after 6pm. I headed west on U.S. 34 west of Galesburg, IL to intercept the developing supercells and witnessed a brief tornado near Kirkwood, IL in Warren County that intensified near Abingdon, IL. On the drive home, my attention turned to another developing supercell that had its eye on my hometown and my house. This supercell quickly tried to wrap-up and the mesocyclone ended up passing right over my Davis outdoor weather station in turn recording a nice pressure-drop. It didn't produce a tornado at that time..thankfully, but my parents witnessed a nice rotating wall cloud in the backyard. Some people were not so lucky however as this sucker would later produce a damaging tornado near Streator, IL later that night. One of the few times I had to call off a chase to make sure a tornado didn't hit my hometown...
This graph (above) illustrates the supercell and its mesocyclone moving overhead as a distinct pressure-drop can be observed as the supercell passed to the east on the evening of June 5th. You can also see a nice couplet on Doppler radar (right) showing the change in wind speed and direction as the supercell moved into Stark County, IL.
© Gibson Ridge Software (GR2Analyst)
A nice couplet and Tornado Vortex Signature (TVS)  illustrating the rotating supercell as the mesocyclone passes a 1/2 mile to the south...
© Gibson Ridge Software (GR2Analyst)
Cross-section of the supercell (sliced) (above) This illustrates the updraft and "vault" as raindrops and hail are suspended aloft. This also shows the supercell has good "juice" (inflow) to it's southern flank which in turn would allow this storm to produce a damaging tornado later in the evening...
This image (right) shows a classic hook echo and the beginning of a cyclic supercell that later produces several tornadoes to its east. This supercell didn't have a monster updraft, but 30,000ft high is not too shabby albeit low-topped though. The severe weather reports including the tornado reports can be found via the Storm Prediction Center (SPC) here.
© Gibson Ridge Software (GR2Analyst)
The graph (above) shows the entire event via my surface weather observations.

Things of note:

1.) Destabilization begins shortly after noon.
A key ingredient needed to set-up the supercell environment.
2.) A moisture-rich environment is present (65-75°F dew point).
3.) Tornado-warned supercell moves overhead shortly after 7pm.
4.) Frontal passage takes place before midnight (cold front) as the severe weather outbreak ends.

If you are more interested in this event the National Weather Service (NWS) in Lincoln, IL and Davenport, IA have detailed accounts of the event. Including the mesoscale/synoptic weather setup and photos can be found below:

ILX Severe Weather Event: 06/05/10
DVN Severe Weather Event: 06/05/10

My photos from the event and write-up can be found on my blog here.