This is a picture of the low-level rotating meso. The picture wasn't that great, and the scan is even worse. The storm was photogenic, I just didn't have my camera and was short on film.
Note the curved area of the cloud. That is what was rotating.
July 29, 1996
Paul Vincent Craven,AA0PE
After being caught a bit by surprise, I left work in West Des Moines at 4:00 p.m. after belatedly hearing that we were under a tornado watch. I was going to be chasing hot air balloons that evening, but luckily storm chasing and balloon chasing are mutually exclusive hobbies.
I drove south on I-35 where I met up with my brother Steve (KA0ZDA). We headed south on I-35 driving through some heavy rain and soon passed out from under that cell. Didn't look like much was happening, so we continued south towards another cell which looked to be building fast. That cell looked more impressive, but the view was obstructed and I couldn't see where that cell was topping out at. Later radar analysis showed 500, with a mesocyclone and hail. The cell we had just driven through tops at 300, and no rotation.
We turned east on the exit for G50 (or there abouts, I wasn't driving) to travel between the cells and keep an eye on them. All this while remaining in the clear. We soon heard on the 146.76 repeater, that Monty (N0XEL) had spotted a wall cloud. My brother and were exceedingly doubtful, since NA0R at the NWS hadn't been reporting any mesocyclone on that smaller cell, and the ham didn't see and distinctive rotation. Well, NA0R soon came back with a confirmation of the wall cloud and mid-level rotation, saying that cell was loosing energy due to competition with nearby cells.
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This is a picture of the low-level rotating meso. The picture wasn't that great, and the scan is even worse. The storm was photogenic, I just didn't have my camera and was short on film. Note the curved area of the cloud. That is what was rotating. |
We went after the small cell, where the wall cloud had been sited. My brother and I topped a rise and soon all doubt disappeared as a text-book example of a wall cloud appeared ahead of us. As we followed it, it appeared to break-up, and we thought it might soon disappear. We got just ahead and to the side of it and stopped to get out of the truck. After a while of watching, we were able to pick out a rotating mesocyclone. Soon we were able to pick out vapor being pulled upward into the center as the updraft took a hold of it. The cell passed nearly over our heads and on to the south-east. My father (N0PDK) also was watching the rotation in a separate location. After the storm had gone by, my brother and I (based on my poor advice) took a turn that brought us into heavy rain and strong winds. We soon lost site of the wall cloud, and by the time we had gotten out of the rain, we could not find it again. My dad stated that most of the rotation had dissipated, and we followed the storm to Indianola. Most of the storm had collapsed into heavy rain at that point, and the cloud tops weren't very high at all.
South of us looked to be quite interesting on the radar, don't know it anyone was down that way.