June 22nd 2015 Harmon, Coal City Illinois Tornado

Dec 01, 2015

Summary:

Tracked monster supercell that tracked across Northern Illinois, producing at least 10 tornadoes along its way.

Stats:

Tornadoes: 1
Hail: n/a
Wind: est 80mph inflow

The Forecast:

Strong jet streak moving atop stalled frontal boundary, with extreme values of instability in place. Rich, deep gulf moisture with dewpoints in the upper 70s to near 80. Early morning MCS would lay down outflow boundary to potentially enhance shear even more, coupled with the strong instability values already in place. Some models suggested the primary target would be further north into WI along a warm front, but prospects of a morning MCS would send the critical boundary further south, and kept me in Illinois. SPC began the day highlighting both targets, but quickly adjusted for where the primary event would focus.
Capture

Detailed Account:

Today had big potential from the get go, but was a very challenging forecast. Models showed big things, and some downright scary parameters. This late in the season though, mesoscale details become even harder to determine ahead of time, because they are so dependent on what early morning storm activity does, especially in situations with slow moving/stalled weather systems. The primary cold front/surface low was focused out in Iowa, and it appeared thats where initiation would occur, with storms having their best chance at being discrete. This setup reminded me a lot of June 5th, 2010, almost a carbon copy in fact.

I decided to apply lessons I learned that day to see if they would change the outcome. Illinois was socked in clouds much of the day and having trouble destabilizing. In fact, around 2pm I posted a status on facebook saying the day looked hosed thanks to a cold pool of air that was sitting over Northern Illinois in the wake of earlier storms. Meanwhile, Iowa was clearing out, and storms were developing. Illinois was still socked in clouds. I met up with Ben Holcomb and Bart Comstock briefly in Annawan, IL – which was a little further west than I wanted to be, but despite knowing better, I wanted to keep both IA and IL in play.

Comparing today to June 5th, we moved back east. Around 4pm things began clearing out and the air was re-destabilizing. We were sitting in Princeton now, but in different spots. Clearing had surged well north of us now, and I was watching the satellite like a hawk. I spotted what looked like an obvious outflow boundary. Suddenly a tower erupted on it. That was going to the storm.
convo

I wasted no time making my move. It appeared the storm was slowly getting organized as I made my approach, and when I finally caught up to it near the town of Morrison, I was greeted with a stunning visual indicator of the outflow boundary. The storm, now warned, was inhaling this boundary right into it.10003486_10152967722028807_8766694245914843657_n

Motion underneath was chaotic and with evident rotation. The terrain/road network here is not as favorable as it is in most parts of the state, and staying in position with the quick moving storm was difficult. The very HP nature meant I had to stay close. While staying in the cage I came across a downed tree that blocked my path and had to backtrack. I fell behind the storm, just as it gained a tornado warning with a funnel cloud. I couldn’t believe it…but luckily terrain and road network improved and I was able to get back where I needed to be. Still no visuals of a tornado, the storm was one of the most HP I have ever encountered. The air was so humid it was hard to snap photos due to the camera lenses fogging.
Harmon Supercell 1 Harmon Supercell Illinois Storm

I nudged myself deeper into the notch, things seemed to be a bit backwards, the areas of rotation were not where I would normally expect them to be. A Spotter Network report came in saying the RFD cut around, choked off the storm and tornado threat would not be imminent. Suddenly I noticed an area of intense rotation and what I was damn near sure was a funnel cloud.
Harmon

I could never confirm a touchdown, but more than likely it did at some point. I moved east with the storm as a new area of rotation quickly develop, and undeniably touched the ground as a tornado near the town of Harmon.
harmon 1

While filming the developing tornado, a car approaches and honks. It is Ben and Bart, randomly bumping into me in the bears cage where noone else seemingly was. We moved east, the tornado grew in size to a fatter cone briefly.
Harmon Illinois Tornado

It was approaching fast, and we sat perhaps a little too long, the tornado approached and got very close in the field.
Harmon Illinois Tornado 2

The condensation funnel dissipated shortly after, but the larger scale rotation impacted us as we repositioned in the blinding rain. Driving too fast on a dirt road in the blinding conditions, a downed telephone pole emerged from the rain. I didn’t have time to stop and slid into it.
Tornado Damage

Luckily the trucks grill guard prevented any serious damage. Trees were down as well and a nearby residence had some minor structural damage. We backed up and moved to keep up with the storm. Daylight was beginning to wane and we tracked the storm to the Mendota area, several times we had debris raining down on us but could never gain a visual on any tornadoes again. Once in the town of Mendota I spotted a damage path, including a small medical center with half a wall knocked down. I reported the tornado damage. Unbeknownst to me, the building was actually under demolition (oops) but the rest of the damage in the area was a later confirmed EF-1 tornado, so at least I don’t look like a total fool.

I got stuck in Mendota briefly trying to find a way out that wasn’t blocked by damage, but I eventually wiggled my way through.
Mendota

The storm had gained some ground on me and was approaching I-80, but luckily the route was clear and I could gain some ground. The signature on radar was growing quite scary, and I couldn’t believe I was tracking a monster like this so close to home.
11055310_10152968011298807_1481341354216412415_n 11402834_10152968009803807_4564156972254584142_n

Coming from behind I was starting to get nervous, if I could not beat the storm to I-80 and get ahead of it, an in the dark hook slice would be the only option. Palms sweating, I gulped and went for it. Blasting east on 80 in blinding rain and paying ever close to the wind direction, someone suddenly flipped a switch. It was dead silent, with no wind. Suddenly positive CGs began crashing down one after another.
CG Seneca

I was in the cage, time to goooooooooooooooooooooooooooooooooooooooooo. Wait for the wind to tell me where I’m at. I knew the forward flanking core would get me eventually. Suddenly the winds picked up again, at first they were out of the northeast so I was not concerned, but suddenly they abruptly shifted out of the south east. Inflow. I could see no power flashes or other visual clues as to where a tornado might be and was getting quite nervous. Semi traffic was now stopped on the interstate in the blinding rain. I couldn’t proceed and decided to hunker down near an overpass (not the smartest move, but I will debate that sometimes.) the wind began screaming directly out of the east, rocking the truck back and forth. It shifted back from the northeast. I was *safe* now, as this indicated the circulation was now moving to my south. I proceeded slowly down the interstate, as it was dark and the rain was by far too blinding.

I had no easy way to get back infront of the storm, so I let it go. Shortly after I began hearing reports of heavy damage in Coal City, a town that also took a direct hit from a tornado during the November 17th 2013 outbreak. I stopped at a rest stop in Morris that amazingly still had power to gather myself and monitor what was happening. Loads of concerned people came up to me to ask what was going on, recognizing I was a storm chaser. I informed them they were safe as long as they stayed put for the next half an hour, but that there was heavy damage to the south and to avoid going that way unless they lived there.

I continued my way home, doing several media interviews along the way. News was out, a major tornado event had just occurred across Northern Illinois. I arrived home around 1030pm and could not sleep. I stayed up all night monitoring the situation out of Coal City, as well as other areas that were hit. Meanwhile it was still storming at home. What a year it has been across the midwest.

Conclusion:

The NWS in Chicago confirmed at least 11 tornadoes with this monstrous storm, and over 150 miles of continuous damage from when it first formed near Morrison, all the way through Coal City and beyond. The Harmon tornado we documented was given an EF-1 rating. The Coal City tornado ended up being the strongest, with an EF-3 rating. Amazingly enough, there were no fatalities. From a forecast standpoint, I am glad I stuck to my guns, and used a real life case study (June 5th 2010) to aid in my decision making for this day. Chase wise, the Harmon tornado was a very difficult tornado to catch, so it says a thing about positioning. Hook slicing in the dark on I-80 was probably a stupid move. I was more scared than I lead on to be, and will think twice next time. The storm happened to be cycling as it crossed the interstate, but it produced damaging tornadoes on either side. All in all a chaotic day.

Video:

NWS Survey Map:
2 Overview Map IL with Cities

Chase Map;
Red arrow shows where Harmon tornado was documented
Mendota damage is circled
Orange arrow shows encounter on i-80
Coal City is denoted by a star
6-22m

SPC Reports:

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