April 11, 2008
Storm Chase
I was about to get some Ontario chasing in today, thanks to friends Tom Stefanac and Colin Williamson, and my boss who allowed me to leave work early. This would be the first time chasing in Ontario since 2006 (last year was dry and also frustrating for me, but the alley offered some goodies). The previous night, we had been pouring over the models. A triple point low would be located over Michigan, with a chance of tornadoes in southeast Michigan and southwest Ontario. I favoured the shear environment, which would allow for some supercells embedded along a linear line of storms in the late afternoon and evening hours. For an early April set up, things were looking interesting. It was also going to be quite breezy. A warm front would enter southwestern Ontario, while the cold front would be located in Michigan. We were hoping the cold front would make it into the risk area in the evening hours. Daytime heating was a concern for me though despite the amount of instability the models were hinting at. I've seen numerous warm front set ups with overcast skies which allowed for minimal storms, if any.
That morning I decided to do a quick RUC model run before leaving for work. The models had slowed the cold front down, but the LIs in southeast Michigan would be -10 with CAPE values ranging from 1000 to 2000 J/kg. One thing I didn't like was the lack of moisture at the 850 mb level... I've seen this type of thing before, with great instability but no moisture and it was a bust in the past. However, I tried to remain optimistic and hope that there would be some moisture left in the air and things would at least fire ahead of the cold front. The SPC had a 10% chance of tornadoes for the area.
I quickly checked email at work. One of my forecaster friends mentioned that surfaced based CAPES were expected to be near 1500, with a 21C/14C temperature/dewpoint and storm relative helicities near 250 along the warm front. I called Tom from work and mentioned the lack of moisture but he figured there would be enough dynamics for things to fire. I got off work at 2 pm and my dad and I went to the computer store quickly. Luckily they had a computer with internet access there, so I went on to check the situation for today. Environment Canada had issued a tornado watch for the Sarnia - Windsor - London area at 1:26 pm. I was getting excited.
Finally at around 3 pm, Tom and Colin showed up. We set up the gear and loaded my stuff in. We were amazed at the temperature gradient - it was only 5C in Waterloo, while down towards the London area, it would be closer to 20C! Now THAT is a warm front temperature boundary if I ever saw one! We just hoped that the dry slot from the triple point would track into southwestern Ontario this afternoon to allow things to heat up and destabilize on time before it got dark.
As we neared London, we left the foggy cold weather behind and saw the skies clearing - a good sign! The dry slot was moving in. We met up with Dave Patrick at the Flying J truck stop in London and decided to wait around there for things to start firing. The sky was clear and it was very warm. Dave told us he didn't like the way things were shaping up... storms in Michigan were going up but falling apart. I used my Kestrel 4000 to record wind strengths. They were light but increasing in strength as the hour went by... which was also good. I liked increasing strong surface backing winds. At one point the Kestrel recorded an almost steady 20 knot gust which was associated with the right exit region of the jet. Tom noted the jet winds cutting into the clouds just off to our east. We continued to watch radar and satellite feeds and read the sky. There was a severe storm crossing Lake Huron heading towards Goderich, but unfortunately it fell apart which did not surprise me in the least bit. It was early April afterall, so the lakes still had a lot of cold air aloft.
Unfortunately it appeared some sort of dryline from the low had set up and dried things up for us. Time was ticking and the cumulus field could be seen on satellite trying to pop up just east of the Windsor area. It looked to be a little too late for things to develop at this point. Dave decided to call it quits and headed home, and being the optimistic bunch we were, we decided to stick around for a little bit more. We finally noted some TCUs developing just our west along a boundary and decided to go towards Strathroy at 6:40 pm to check them out. They were indeed trying to go up and I noted some signs of inflow, but it was still nothing impressive. The updrafts were slightly tilted, indicating a wind shear environment, but there was just not enough punch for them to grow. We headed back towards London and cut north west to look at other TCUs that seemed to be a little more promising, but once again they didn't amount to anything more. The cold front was still situated in eastern Michigan and it was getting late in the day.
As we headed towards Stratford, a line of showers were developing along the boundary ahead of us. We saw lower level clouds being drawn into the updrafts indicating inflow. By now the bases of the TCU were becoming elevated and we encountered a stratus cloud deck and eventually crossed the warm front into the cold foggy rainy crap. We obviously busted on this one, but it still felt good to get out again and at least try to get something. We arrived back at my place at 9 pm. Shortly after that, we had a brief thunderstorm go through, probably from the line of showers along the boundary. Figures.
Total Hours: 6 hours
Distance: Approx.
300 km
