May 20th 2014 Chicago Severe Weather

May 25, 2014

Summary:

Got on southeast moving supercell that tracked through Chicago suburbs encountering  intense straight line winds, hail up to golfball size. Also witnessed numerous powerflashes while following storm to attempt lightning photos. Turned around from home once storm moved out of area.

 

 

Stats:

Tornadoes: 0
Hail: 1.75″ (golfball)
Wind: est 70mph.

The Forecast:

Slowly sagging cold front into warm/moist unstable airmass. Lack of  focus for ascent created some uncertainty as to whether storms would initiate. Low level shear was nearly non existent south of adjacent warm front but mid level flow was plentiful along it so if storms were able to form they would stand a decent chance at becoming supercells capable of very large hail, straight line winds, and perhaps a tornado threat if a storm was able to find a favorable boundary to enhance its low level shear. SPC went with modest SLGT risk probs for tornadoes, but high end SLGT for hail threat.

Detailed Account:

Today looked pretty marginal from the get go, as such I wasn’t planning on chasing so I went to work like always, but did bring the camera along in case there were storms nearby to photograph some lightning after I got off. Conditions began to improve throughout the day though, and by 5pm storms were beginning to initiate along the IA/IL/WI border and were sporting great supercellular characteristics. Large hail reports started pouring in, and the storms were showing great supercell characteristics on radar. Danny Neal, my normal chase partner wanted to meet up after I got off work to go for lightning shots. That is all we were planning for. I raced home, grabbed the laptop and video camera just as he pulled up and we were off.

I used to chase my home turf quite often, but in the past several years have mostly given it up since it consists of dense metro population, clogged roads and numerous stop lights, so this would be my first in awhile. It looked like a supercell was diving Southeast right towards my house, so we just made a leaisurely jog to find a high point, which are few and far between around here where the terrain is flatter than a pancake and covered by buildings. I figured the shoulders of expressway onramps would be our best bet so thats where we went. As the storm picked up intensity we moved into position near the suburb of Bollingbrook. We arrived and found a view just as the intense CG barrage got underway. Still learning my camera I was unable to get my settings ready in time and rain began pouring down, to make matters worse the head on my tripod is loose and wobbling all over, so my attempts to take photos were a failure. Danny snagged a few though.

It was actually a pretty intense barrage of lightning with lots of vivid strikes and loud, earth shaking thunder. I was enjoying just being in the storm, but it wasn’t done yet. The core began to overtake us so we decided to reposition back into the rain free area to attempt more lightning photos when suddenly the wind picked up fiercly amidst blinding rains with zero visibility, the next thing I know a medium size tree branch strikes the front of the truck so I stop at a spot where some dead trees lined the road and they began to snap and fall over next to us. The winds had to be gusting 70mph at that point so we rode out the core for several minutes, enduring this assault which was much more intense than I expected. Every now and then there would be hailstones up to quarter size mixed in.

A powerflash just ahead as we ride out the core

Once the core let up a little bit we decided to move again, only now our winds shifted direction so we started wondering if we were dealing with a broad circulation. It was raining so hard I had a hard time finding the road as lightning also knocked out all the power but we found our way back to I-355 and moved south. That was slow going since the winds blew over a bunch of construction cones and barricades that were now scattered all over the highway as traffic crawled around it. To our amazement the storm displayed a classic hook echo shape on radar and was diving even harder southeast. Something we would normally see in the high plains of Nebraska was occurring on home turf!

We decided to reposition in the notch…just in case…and took I-80 east towards Indiana, we got into the notch and could see some pretty classic supercell structure in between the lightning flashes, a series of powerflashes lit up the ground under a lowered area of the storm, but was likely just straightline winds doing damage. A close CG knocked out the power on the expressway and we were chasing dark. We took I-57 to stay in the notch of the southeast moving storm, as we did this we noted scud being sucked into the storm. It was really trying to get organized and go tornadic, but the lacking low level shear was preventing it from doing so.

We observed and followed the storm futher south to attempt lightning shots again, eventually we let the storm move away and turned around for home.

Conclusion:

What started out as a lightning photography adventure turned into a right moving, supercell chase through the heart of my home turf. I was not expecting such a classic chase scenario to unfold today. The storm latched onto the warm front and rode it the entire time which is what allowed it to maintain its supercellular strength. It produced damaging winds and significant hail through the Chicago area during its entire life. It was the best local supercell chase I had since June 7th, 2008 where I filmed a tornado crossing I-57 just south of Chicago. Had there been more low level shear for the storm to work with, I am fairly certain it would have gone tornadic. That ONE ingredient was missing today, and the area got lucky. I got a nice local chase. Something needed in this sub-par, slow year. I only wish it was light out so there would actually have been structure to see on video.

NWS Radar loop of the southeast moving supercell: http://www.crh.noaa.gov/images/lot/20May2014%20Severe/14May20Zloop.gif

Video:

Map, arrow shows where we rode out the core near Bollingbrook.

SPC Storm reports:

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