Saturday, April 25, 2009


April 25, 2009 storm chase summary

In the early afternoon, I noticed some accas over head. A chance of thunderstorms was in the forecast for today, so I decided to see what was cooking for this afternoon. I came across a couple of severe thunderstorm watches issued for the Windsor and Sarnia areas due to a bowing squall line along the cold front coming in from Michigan. A lake breeze convergence zone was also shaping up from around London through Waterloo and north. The line of storms had a tail end charlie down in the Detroit and Port Huron area that was resembling a small but punchy bow echo. A thiner line of storms extended north of the bow echo segment and were crossing over Lake Huron. I decided to wait and load a few more satellite images and give my uncle and chase partner Dave Szozda a call to let him know of the situation. After a couple more satellite scans, it appeared the lake breeze convergence zone was shifting more west of Waterloo... perhaps the boundaries from Lake Ontario and Lake Erie seemed to be pushing stronger inland than the one coming off Lake Huron. Around 18Z I noticed the southern bow echo was starting to show signs of falling apart... at one point it did hit a 67.5 dbz reading on GRLevel3 but I figured that spike was the storm "downbursting out". Sure enough, the 18Z SPC mesoscale discussion had mentioned that area was starting to stabilize and sure enough, the bow echo weakened. However, we were keeping our eyes on the northern stuff to our west which was still holding over Lake Huron! Were the border customs being nice today? It was nearing Goderich around 3pm. I was hoping the squall line would intersect the lake breeze convergence and re-intensify. I loaded the RUC and saw that CAPES were about 1300 with a lifted index of around -6 to our west. Okay good... instability? Check. Lifting force? Check. Moisture? Check. The downside? The line was clocking at a good speed - 70 mph! Yikes!

We finally made our final decision that it would be best to head west towards the Listowel area for today's chase. I honestly was not expecting too much from today's chase, although I really had the itch to get out there again. If there were no tornadoes or structure, I wouldn't mind having a little bit of wind or hail. I also wanted to give my Streets and Trips GPS on the laptop a test run before leaving for the alley in a week. All good reasons to head out today, right?

Uncle Dave showed up around 4 and we headed north and west on hwy 85. There were a lot of elevated clouds in the area now due to the convergence zone. As we neared the line, we noticed a small shelf cloud off in the distance. As we neared it, I noticed how elevated it had appeared, and I couldn't believe the color of the precip core in behind... it was black with a slight hint of greenage!

We pulled off on Regional Road 11, just south of Conestoga Lake and pulled off the road onto the shoulder. I got out and was wowed by the amount of dust from the dry plowed farm fields being kicked up under the shelf cloud. Knowing that the storm was moving at a good speed, I had to grab my pictures right away and quickly before we would get blasted.

Around a quarter after 4, the winds had started to increase, so I decided to get my Kestrel to get an accurate wind reading, however, as soon as I turned it on, the intense winds and dust hit. WHOOOOOOOOSSSSHHH! Ow my bare legs! Ow my eyes! Ahhhhhhh! Luckily, I was still behind the van at this point, so that sheltered me a bit. I covered my face and hung on. Dirt piled up in my shoes, in my clean hair and inside my shirt, and Uncle Dave tried to open his door... he opened it only about 4 inches before the wind slammed it shut on him again. I figured it was time to get INSIDE the van. Uncle Dave finally got inside as well. Dust was blowing from the fields like mad! We estimated the winds to be very close to 100 km/h if not stronger. I was not able to get that accurate wind reading afterall, but with a dust blasting like that, I was more concerned about protecting my eyes and the camera. I looked out the windshield and saw a white structure tumble for a good distance in the field... it almost looked like some kind of metal shed. After the dust, the heavy rain hit. Winds were still pretty strong, but we were able to turn around carefully and head back on hwy 85. We saw a couple of felled branches and broken signs. I decided to try calling Canwarn to give a report but I couldn't hear anything due to the heavy rain and winds. I wanted to get ahead of it again, but unfortunately that was not possible. The leading edge was way ahead of us by now.

With it being such a thin line earlier, I was amazed at the amount of rain this storm was dumping. I believe the lake breezes may have helped played a roll in today's setup. We pulled back at my home close to 5pm, all covered in dirt but happy. It was a pretty good chase considering I was only expecting a LITTLE bit of wind and rain. I don't think we could have planned it better to intercept today's action.

Distance: 58 km
Time: approx 1 hour