May 15, 2009

Statistics:

Initial Target: Springfield, IL
Departure: Westchester, IL 10:30 am
Arrival: Westchester, IL 9:30 pm
Intercepts: Fishhook, IL
Tornadoes: 0
Hail: Non-Severe (Half inch estimated)
Wind: Non-Severe (not measured)
Features: Gust Front
Miles: 620

Summary:

Similar setup to Wednesday provided another chase opportunity in central IL.  Chased solo targeting Springfield, IL where shear and instability combo was expected with afternoon thunderstorm development.  After meeting up with Mark Sefried and Darin Kaiser in Jacksonville, blasted west down 72, intercepting tornado warned storm in Fishhook, IL noting bowing storm with little organization.  Followed storm to Jacksonville before pulling away to catch new development.  New development merged with original storm where it took on HP features.  Followed tornado warned storm from east of Springfield to Champaign without spotting a tornado or much organization.  Drove through core of storm to get home noting strong winds and half inch hail.

Crew and Equipment:

Solo chase.  Equipment:  Kenwood TH-F6A Tribander, Dell Inspiron Laptop.  Kyocera data card and router, Holux 236 GPS, Robotic camera dome with Sony XR-520V.

Details:

The trough and boundary that created Wednesday's chase was reorganizing for a second opportunity on Friday.  I targeted Springfield, IL where instability and shear was forecasted to coincide with new thunderstorm development over the favorable Illinois terrain.  On going convection across the retreating warm front threatened to cut off instability or block off discrete thunderstorm development, but there was a window of opportunity for new development to the south during the afternoon.
I was out of the house by 10:30 after reconfiguring the robotic camera dome to not suffer from the same problems that caused the recording from Wednesday's chase to be lost.  I headed south on I-55 to Springfield, and continued on to Jacksonville noting that the line of thunderstorms that would probably lead to the afternoon's show was still in Missouri.  I pulled off at the usual chaser convergence spot in Jacksonville, the Econolodge, where I was soon met by Mark Sefried and Darin Kaiser.  While chit chatting about the dome, the southern cell in the line, now crossing the Mississippi, gained a tornado warning.  The conversation was cut short as we left for the chase.  Mark and Darin stopped for gas first, and I blasted down 72 west after the storm. 
I exited near New Salem and went north to Fishhook where the storm's base came into view.  It was a very broad, bowing region.  I was unable to find a point on it that appeared to be organizing for a tornado, so I just sat at the apex of the bow waiting for development.
I moved east a ways and let the large flat base to start to pass overhead.  There was some impressive cloud to ground lightning activity, but there was still not much happening under the base.  On the radar the storm appeared to be bowing out.  I could feel cold outflow from my position, and see the gust front on the radar.  The storm was riding behind cold air which meant it was probably elevated and incapable of producing a tornado.  I followed the storm to Jacksonville, before I dropped down to 72 to follow new cells that were going up south of the warm front.
The new cells were early in their lifespan but elevated when I intercepted them.  They soon merged with the original tornado warned storm without organizing much.  I left the line and got out ahead of the storms heading east on 72.  I stopped for gas in Illiopolis.  The storm, even though it appeared that it was still north of the boundary, had taken on a huge High Precipitation (HP) mode and was still tornado warned.  This was the only play in town so I headed back west on Old Route 36 for a second intercept.  The storm had since turned into a beastly monster.  A dramatic gust front came into view:
There was a picturesque shelf cloud, but I was still not impressed with the chances of getting a tornado out of this storm, despite the tornado warning.  With the HP mode of the storm, it also would be difficult to get into a viewing position on the updraft base without being in a dangerous position.
I stayed with the storm running north and east on county roads.  The storm was moving at a good clip now, probably greater than 40 mph so it was a challenge staying ahead of it.  The roads in this part of Illinois are fantastic with almost every road in the grid being paved.  If it weren't for the quality of the roads here I would have had to retreat to the south or I would have been cored for sure by the storm.
I successfully got into the inflow notch of the HP supercell.  There was a big bell shaped base and, but the storm still seemed to me to be outflow dominant.  Perhaps there was some elevated inflow and rotation, but things did not look good at the surface for tornado development.  It sure was a dramatic looking storm, however.
This is the closest the storm seemed to get to organizing.  This might be an attempt at a wall cloud or just another outflow feature under the base.  It didn't last long.
I was able to race the storm, staying just ahead of it.  The camera dome worked well today, recording the storm while I was driving away from it and couldn't maintain a visual.
Although the storm looked impressive, it was mostly bark and little bite.  The further I chased the storm the more I was convinced that it would not produce a tornado.  I was now nearing Champaign county and had been on the storm for nearly four hours.
In Champaign county I finally decided to let the storm go.  A freight train cut off my escape route to the south, but I decided at this point that the storm had weakened to the point that it was probably relatively safe to punch the core.  I stopped for a few picturesque shots of the train going under the storm's gust front before turning north into the core.  The storm had since lost its tornado warning and I was hit with a barrage of wind, rain, and half inch hail before it tapered off to just a heavy rain.  I took 57 north back home driving in the rain almost the entire time.
 
Conclusion:

Friday was a bust in terms of catching an organized supercell or tornado.  I was treated to some very picturesque views of a high precipitation supercell, however.  This justified the chase for me.  The storm, despite its four hours of continuous tornado warnings, did not drop any tornadoes at all.  This was also one of the longest durations I had spent on a tornado warned storm.  The only reports that came in from the day were all the way down in Texas.  It was still a fun chase and it was a successful run with camera dome as I was able to record the entirety of the chase with it.

 

Lessons Learned:

  • The road network in central IL allows for the successful chasing of fast moving, HP supercells