April 3rd Iowa Supercells

Feb 26, 2012

Iowa v2011 round 2.
Summary:
Departed thinking the day would be mostly spent under the cap with storms going up near dark. Storms fired earlier than anticipated and provided gorgeous structure shots with some hail and lightning.
Stats:
Tornadoes: 0
Hail: 1.00″ [quarter]
Wind: est 45mph thunderstorm and non thunderstorm gusts.
Detailed Account:
I had been watching the models toss this chase around dramatically for over a week. As has so often been the case this season, good dynamics were forecast to largely go to waste due to a strong EML keeping things capped until after dark. A few days before the event though the models began to show this cap eroding just before sunset with storms initiating along the MS river near the IA/IL border. I was excited for a local chase. The night before, however my heart sunk as the overnight models showed the cap no longer eroding and initiation being further west. I decided to still chase though, hoping these overnight runs were wrong…and they were.
I left Chicago along with Danny Neal and Matthew Cumberland which, in these times of $4/gallon gas prices was nice to have people to split the cost with. I wanted to leave early in case we had to end up further west as the more obvious target for the day was around Kansas City. The cap was forecast to be even stronger down there, but so was the CAPE as well as the lapse rates. We decided to stick near the IL/IA border though, where we spent several hours waiting in the 80 degree temps which is always as nice feeling to a winter weary Chicagoan in early April. HRRR guidance also showed storms going up earlier than anticipated which caused us to hold our ground near the IA/IL border. If only we could get a daytime storm.
A look at a typical storm chaser meal, a Casey’s club sandwich!
Skies were quite hazy given the strong heating, impressive moisture return and EML overhead. At least Iowa has some good chase terrain.
After sitting on this road for awhile I noticed a tenny tiny blip on radar, I joked it was our storm going up but to our pleasant surprise it actually was. The cap had broken earlier than anticipated and explosive development had begun. Explosive is an understatement. These storms went from tiny cumulus clouds to towering behemoths with severe storm warnings and massive hail cores within 15 minutes. The radar exploded to life and after being completely blank all day now looked like this.
You can see we, as well as most chasers are a bit far away at first due to the storms initiating a little farther west than anticipated, but we would make good time catching them due to favorable road network.
I got my first real look at the towering thunderstorms as we drove through the town of Washington. Nice, rock hard, solid convection! I was getting excited.
The evening sun behind the storms along with the hazy sky made for a somewhat difficult view at first. I knew there was some awesome structure lurking back there.
As we got closer we began to finally have a view of the base. Note the impressive rain foot off to the right and also the c-rays from the suns angle.
We sat there and let the storm come to us, as the view became clearer the wonderful structure was revealed. I didn’t think I would get such a picturesque storm today. A wall cloud began developing as the storm inhaled rain cooled air being pushed out by the precip core.
Unfortunately this storm was not in an environment favorable for tornadoes. Veered surface flow and a temp/dewpoint spread of 25 degrees meant this storm would have a very hard time developing rapid rotation and thus produce a tornado. Regardless some weak rotation did develop as the wall cloud morphed shapes for awhile.
A spotter reported double funnel clouds around this time. I can only imagine they were referring to those pointy, scuddy lowerings.
Matt and Jim Parsons [who asked if he could follow us along] observing the storm.
Alas, an RFD cut came in and the storm began to go through a cycle, but it was apparent the outflow was beginning to win, as the wall cloud began to elongate and lose its rotation. We noted the curling upward motion suggesting the outflow was surging ahead.
We decided to move and keep up with it, noting we had another storm coming up from the SW we could easily get into position for once we decided to abandon the storm we were on. As the RFD surged in it made another attempt at a wall cloud, though it is hard to see with the flash from my crappy camera reflecting off rain drops as we begin to lose daylight.
We let this storm go once the wall cloud became completely wrapped in rain and the storm would pull away from us. We decided to let the core of the next storm roll over us with GR3 indicating hail up to baseball size. However once the core and went I was disappointed that we were only dealt a brief, 30 second long blow with maybe hail up to quarter size. I was hoping to test out the new hail guards.
We made our move to drop south infront of the next storm, being a good distance in between the two storms. It is quite hard to see our position but we are in between the bottom 2 storms near the large hollow green triangle.
The departing storm to our northeast had an good mammatus display under its anvil.
While at the same time the approaching storm to our southwest was showing off its updraft and anvil as well.
I just love looking at these towering monsters. It amazes me how massive they can be, the largest structures made by man dont even come close to being comparable in size to these things. I was definitely pleased with the structure the day had given me. I was expecting a grungy, linear mess near dark and instead was treated to some gorgeous structure in clear skies. Upon moving infront of this storm we were dealt some more hail but by now an entire line had begun blowing up and it was quite evident the tornado threat, which was never really there to begin with, was definitely over. We called the chase and had dinner at Hardees in Mount Pleasant.
Here is video from the first storm in the day. It is time lapsed in the beginning with the real time footage shown after that. The lightning coming out of it was incredible and thus I wanted to show both clips.

Conclusion:
On a day where I had relatively low expectations I was more than pleased with the results. This is why I will always gamble with a setup when its in relatively close proximity to where I live. You just never know what you are going to get. If it not had been for the veered surface flow the first storm we were on could have been a serious tornado producer. Overall the entire day saw no tornadoes anywhere, so other than getting some larger hail I’m not sure how I could have done any better. Iowa has been making some attempts at redemption this year.
Map. area circled is where storms were chased and intercepted.
SPC storm reports.
Bring on #3!

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