Monday, March 15, 2010

March 11 2010

You've already seen the images and know the jist of the story, and it's not as interesting as those Oklahoma tornadoes from the days before. That said, I've completed a full write up with some weather data and photographs from the intercept of the low topped storm north of Urbana from this past Thursday. I'll paste the text below, but if you're interested you can view the actual page here:

Early on Thursday the 11th looked like a big minisupercell day across Illinois and Iowa. However, as the day drew nearer things did not look as favorable. A warm layer at H7 was killing off much hope of deep convection, and surface winds were slowly veering and weakening across the target area. These things do not add up to a very favorable March severe weather setup. I already had the day clear of plans for a potential chase and was visiting home for spring break and was already in decent position, so I continued to monitor things at home in Champaign. Morning water vapor imagery showed the cyclone centered over Iowa, with morning thunderstorms retreating north into Wisconsin, Indiana, and Kentucky. The mid level dry punch had worked it's way into Illinois and Iowa and was allowing for insolation, but at the same time rapidly mixing out low level moisture from west to east across the state. Surface data from 3 PM showed moisture rapidly mixing out in western Illinois with dew points now in the low 40s, with surface winds beginning to veer out of the southwest. Eastern Illinois held on to mid 50's dew points however, and surface convergence was forecast to increase towards sunset so I kept my eye on the satellite. Sure enough, around 5 PM surface winds really began to converge right around my location in eastern Illinois. Satellite imagery began showing an area of agitated cumulus along the Piatt / Champaign County borders, with storms beginning to initiate further north towards Kankakee. A few returns began showing up in my area of interest just west of Champaign. I watched from the front yard as one area really began taking off. After a long winter this alone was enough to get me in the car for a short drive. Tia decided she was up for a quick outing and hopped in the car, and we were off.

This area actually began to organize fairly quickly, and by the time I had headed north out of town on Route 45 a fairly substantial low topped storm was underway just north of Urbana. Storm motions were very slow for this time of year, so I was able to easily keep ahead of it by stair stepping northeast along the county roads in northern Champaign County. Unfortunately, things got off to a late start on this one so our time together was limited before the sun began to set behind the pretty storm. The core actually strengthened healthily and produced pea sized hail which covered the ground in Thomasboro. Staccato lightning bolts also accompanied the storm at sunset, which was quite a treat to sit back and take in. March storm chasing is often -very- frustrating with low visibilities and fast storm motions, but this one was neither! A beautiful updraft tower and rain free base with storm motions that could not have been over 20 mph. That being in my home stomping grounds of extremely flat Champaign County and familiar roads were the icing on the cake in this first convective outing of 2010. Once the sun faded, I headed back towards town. Not before catching a glimpse of the storm in the twilight in the distance and having to stop once more for a couple photos. Tia and I were hungry as it neared dinner time, so we detoured to Chili's for a dinner where we played a role reversal as she devoured a massive burger, and I played it safe with a tasty pasta.

I wish the minisupercell outbreak had materialized, but short of that I can't think of a better way to start to the 2010 warm season. After the year of stress 2009 was, let's hope this is a good omen.

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