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Radar as storm approached featuring 60k winds
Just a quick post for the Northern Indiana Derecho and Tornadoes of June 23rd.   This quick video took place North of Mishawaka, IN just miles and minutes away from a brief Tornado touchdown in Goshen, IN.  A shelf cloud approached within and interesting 'hook' feature near where two opposing gust fronts had collided.  THe sky was a shade of dark turquoise and green. Tornado sirens blared warning residents that these storms may spawn tornadoes or gustnadoes.  Missing from this video is footage of the 60+ mph winds that quickly followed. (hit the record button to cancel a recording instead of starting a new one)  Also not far from here, a 75+ mph gust was reported.


 
 
A powerful Mesoscale Convective System that originated in Des Moines IA, and followed I-80 well into Ohio. (note that I haven't heard this name repeated anywhere, it's the name I coined for it) Most notably it blew windows out of Chicago's tallest building, the Willis Tower and produced 90 mph winds over southwest Michigan.  Having seen it coming long before it made it to Chicago, I decided to set up a timelapse of the event.  I'm recording for the extreme northern end of the Derecho where wind speeds were about 20% weaker than near the center of the Derecho. This is a good thing, down the road from me a weekend outdoor concert was taking place with more than 10,000 spectators with little or no cover available.

For a good portion of the video, you'll see the overshooting tops of the anvil approach and darken. As the storm finally gets closer, a shelf cloud appears with it's eerie rolling motion and quickly moves in. At this point I grab the camera and switch to realtime video to witness the 40-50 mph wind gusts that accompany the back side of the shelf cloud.   Scroll down for more.
Unbelievably, another Derecho hit hours later over some of the same locations in Iowa, Illinois and Indiana.  This time it missed most of Michigan, but nevertheless we had a great view of it. Nearly constant lightning was occurring over the Chicago area, but the frequency died down as it approached the South Bend, IN area.  Here's another timelapse of the second event.
 
 
Saturday morning looked like a good day for severe weather just to our south and west.  Well within a couple hours drive.

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A moderate risk was issued for a narrow corridor across hoosier alley.  SPC handed the area a 10% risk of tornadoes as well.   We decided that our target area for that afternoon would be somewhere in the neighborhood of Dwight, IL.  This turned out to be a eerily accurate decision. 

Having been burned by using SPC alone to determine a target area several times in May, we decided it was time to look directly at the models, and learn to use them to find the characteristics we needed for a good intercept.

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Example of a forecast model for
determining sheer profiles
We made our way to Chicago, then south into Kankakee, IL.  Storm initiation had not yet begun, there were however a few small convective rain showers appearing south and west of Davenport, IA.   We made our way through small Illinois towns on route 17 and continued to I-39.  We arrived at I-39 in Wenona and took another look at the radar. Sunset was less than a couple hours away and only a few modest thundershowers had approached from out of Iowa and were now over the Kenowee, IL area.

At this point is was beginning to look like a bust.  We ventured North on I-39 with the intent of closely following a northern tundershower along I-80 and head back home. Just after we had gotten ourselves onto I-80, two of the thundershowers had quickly exploded into some modest severe thunderstorms. Within minutes, rotation appeared in both of them. A 3rd storm near Galesburg had become Tornado warned.  We began to slow the car down watching for an exit to pull of and make a decision. Before we could do this, all three storms were now tornado warned, with the southernmost storm already having a tornado report to the NWS.
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Base Reflectivity and Radial Velocity west of McNabb, IL
We rushed back to I-39 as fast as we could. The northern storm was approaching the interchange, however this northern storm was not as healthy as the storm to it's south with clear air near it's hook.  Of the three storms to choose from, we decided on the one in that was in the middle with the clear air.  That meant punching it's core to make it Lostant before the storm did. By now a very healthy rotation was visible on radar, a tornado looked imminent.  The storm was moving ESE, we anticipated the southern component to the storm so we overshot it to the south a tad, believing it might be a little close for comfort, and with darkness beginning to settle in, that would not have been a good thing.
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Wall Cloud. The NWS says an EF0 tornado was on the ground East of Magnolia, IL while this image was taken.
We arrived in Lostant and looked for a good spot to watch the wall cloud form. We began recording video. A lowering was visible to our North and West and it appeared to be rotating. We followed the rotation with the cameras as it crossed I-39. No distinct tornado or funnel was visible. We crossed I-39 and chose a lonely east-west road a mile south of route-17. The idea being that there would be less interruption from oncoming or following traffic than on 17. We also though the storm was continuing to nudge south. That was not the case. We had a LEFT mover on our hands! That can mean only one thing, There must be a tornado on the ground right now. 

We pulled over breifly at 179 and 8th road. By this point it was very dark. However each stroke of lightning revealed a classic mothership supercell was now in progress.  Suddenly power flashes were visible. Time to move! We continued east, still expecting the storm to cross ahead of us drifting south.  We paced the meso continuing down 8th road, continuing to film. Suddenly it became apparent that there was definitely a tornado in progress, and it was hitting structures.  Power flashes were frequent. the power in fact went out around us in unison with a larger power flash, indicating a main feed wire must have been cut to the area.  Since it was dark, our only indication of what was happening was numerous lightning strikes illuminating the funnel the Meso and power flashes at the ground.
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EF2 Tornado damaging Streator (debris)
See below for a map of the Steator, IL EF2 tornado path and damage.

View Streator, IL tornado in a larger map
We continued to follow the Storm east. However now it appeared the there was no longer a tornado.  Radar images continued to show a healthy storm with plenty of Rotation. But now it was headed right for the town of Dwight, IL.  Moments later, more power flashes appeared. This time it seemed much closer to us. We couldn't see anything, but the camera was still taking video. Whatever was happening was getting recorded, we could only hope there was something to see in the footage later on.
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EF3 tornado in Livingston County, IL
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Damage Path near Blackstone, IL. Click for SPC's full damage survey
We approached the town of Dwight, only now it appeared that the Tornado and Meso must be ahead of us. The power was out in town and there was significant damage.  Scary enough, it appeared that the tornado had gone through the very town we stopped at for some subway just a few hours earlier!  Needless to say now, our forecasting had gotten much better this time around.   We discovered that, by using maps from models such as the RUC and NAM, we were now able to put ourselves more accurately in the zone than just using spc's forecasts. 
The supercell we were following turned very High Precip and was becoming incorporated into a newly formed Derecho from behind.  After encountering extensive flooding in the Kankakee area, we headed north.  June 5th turned out to be a major tornado outbreak. Overnight fatalities were reported in Ohio due to the same storm system.  Tornadoes were also confirmed overnight just a county away from our homes. The supercell we abandoned in Kankakee went on to spawn an EF3 tornado in St. Anne, IL as well.