May 22, 2013

Listowel – Creemore, ON

You can’t hope to chase a storm in Southern Ontario with much better structure than the supercell that traveled from Listowel to Creemore on May 22nd.

I woke up that Wednesday morning and looked over the models, having been excited about the prospects of a good setup for the past few days. The St Marys area looked good to me initially, but by mid-morning everything was pointing to a corridor from Goderich to Palmerston for initiation. The best dynamics seemed to be coming together over that area and, in particular, I liked that EHI values were forecast to approach 200; a brief tornado or two couldn’t be ruled out. It was still early, but I was focusing on Gorrie, just east of Wingham, as a possible target.

By early afternoon I shifted my target slightly south and eastward to Listowel, based on a little better clearing to the south than I had been expecting. I set off for that town, confident that the day’s chase corridor would be between Mitchell and Minto, eastward.

I hopped on the 401 to Kitchener and then onto Highway 86, heading northwest. Unfortunately, as soon as I got onto 86 I could see that a storm was already developing right over Listowel; commitments in the city earlier in the day had prevented me from getting out sooner and now I worried that I would be late catching the storm. It was traveling to the northeast at a good pace, so I decided to head up Highway 12 to try to intercept north of Arthur.

Halfway between Arthur and Conn on Cencession 16, I got my first view of the base of the storm. I was pleasantly surprised. The storm had a dark and low base with a large blocky wall cloud hanging low over the horizon. I parked and spent several minutes photographing and filming its approach from the west.

My view of the wall cloud was improving rapidly as the storm approached, however I was still too distant to be able to confirm whether or not it was showing signs of rotation. I drove north toward Conn for a better vantage point. As the wall cloud neared it took on the appearance of a large bowl, and I was able to confirm weak and broad rotation. After several minutes the wall cloud began to fall apart, so I turned east onto Highway 89, heading toward Shelburne as the storm cycled.

To the west of Shelburne, I pulled over to watch as the storm ramped back up and the wall cloud redeveloped. Although surface winds had been relatively calm around the storm up until this point, suddenly inflow picked up and began rushing in. As it passed overhead just to my north, the now rapidly rotating wall cloud was spinning like a top, and for a few minutes it appeared a tornado was imminent.

However, as the wall cloud passed, the inflow slowed and it became disorganized. I followed the storm northeast to the Creemore area while it continued to cycle up and down, though it was now generally on a weakening trend. At Creemore the storm was undercut by a shot of cold air as it was finally overtaken by the front. After a fun few hours, I decided to pack it in and make my way home, pleased with such an exciting and photogenic first Ontario chase of the season.