June 30, 2014

June 30 was day number 10 for the College of DuPage trip 5 thunderstorm lab. We had yet to get a tornado and were looking for redemption after coming so close the day before with a funnel cloud that didn't touch down. We were now extending the trip to chase as we were supposed to be home the night before or the morning of this day. We wanted a tornado, however, and this last chance looked like it might yield one. With excessive deep layer shear and moderate to strong instability across a warm front draped across central Iowa, this day actually had the highest tornado probabilities of the trip. The Storm Prediction Center upgraded to a moderate risk with a 15% chance for tornadoes. Storm coverage looked to be an issue with the lack of capping and excessive shear. The entire warm sector was expected to evolve into a fast moving complex of storms and a damaging straight line wind event known as a derecho. We were hoping to catch a supercell and tornado while storms remained discrete early on in the event, however.

Storms were ongoing as we left the hotel in Des Moines that morning. A few discrete supercells were already severe warned, but likely elevated as the boundary layer was cool, meaning tornado chances were minimal. We headed west, hoping to get some structure or catch the storm as it transitioned to a surface based supercell with the daytime heating. The sky darkened to the west, but the storms provided no views before we had to move to avoid what was now a developing line. North of Iowa 80 the MCS transition was already underway. Very rich moisture, high precipitable water values, weak lapse rates, and no capping meant storms were low contrast, mushy, and watery. Even if there were a few tornadoes and a severe weather ioutbreak, it would be extremely difficult to see through the murk.

We headed east to get ahead of the line. The group was getting fairly home sick at this point, and several people on the tour were expected back. We wanted to give it one last shot, however. We dropped south toward What Cheer, IA to get on Tail End Charlie hoping for a discrete supercell. We were met only by a low contrast base or gust front of an unwarned shower as the western sky darkened. We decided to call it a trip and head for home.

The fast moving line caught us as we went north again to get back on 80. We were stuck driving in the rain for much of the trip home. Arriving back at COD, the line moved off to the east, but anvil crawler lightning raked the sky overhead and thunder rumbled as we unloaded all of our gear and said our farewells. After 4559 miles, COD Trip 5 was over.

It felt super weird jumping in the minivan after driving the huge COD van for 10 days. I felt like I was sitting in a low to the ground sports car. I stopped by my parents house in Bolingbrook for the night, oblivious that a second, much more intense line of storms had erupted behind the first line. The lightning and shifting winds grabbed my attention so I pulled up the radar on my phone. To my bewilderment we were on the edge of a tornado warning. The hook of the storm was passing several miles to our south across the town of Romeoville. I wasn't too bummed I wasn't chasing it though. It twas after dark, tracking through suburban sprawl and I was exhausted from the ten day trip.

The derecho forecast verified, while most of the tornado reports came in after dark.