April 25, 2008

Statistics:

Initial Target: East of Davenport, IA
Departure: University Park, IL 2:45 pm
Arrival: Bolingbrook, IL 7:15 pm
Intercepts: East of Davenport, IA
Tornadoes: 0
Hail: None
Wind: Non-Severe (not measured)
Features: None
Miles: 310

Summary:

Cold front and negatively tilted system was forecast to move through upper east IA/MO, into WI/IL with decent instability in the warm sector.  Targeted cold front initiation in decent terrain of west IL, departing after work.  Despite increased tornado outlook probabilities, tornado watch, and warnings, cold front line fell apart before I could intercept.  Turned around near the Quad Cities as tornado warning expired, noting lightning and heavy rain but little structure.

Crew and Equipment:

Solo chase.  Equipment: TH-F6A Tribander, and GPS/Cell Phone equipped laptop.  Photography by Skip Talbot.

Details:

I wasn't too excited about this setup when it appeared on the models.  A cold front was expected to move through and you usually don't get very good play on these days, with undercut, linear lines.  As the day approached however, the system took on a nice negative tilt that looked to provide some better directional shear, and the potential existed for some discrete cells, possibly in the warm sector ahead of the front.  I made plans the day of for a solo chase.
A line went up right on the cold front in central MO around noon.  Cells were not that discrete and looked fairly linear, however, the potential still existed for additional development ahead of the line, or organized supercells to develop within it.  I left right after work, heading west on 80, and encouraged by the 20z outlook, which bumped up tornado probabilities to 10% and a newly issued tornado watch.
A few tornado warnings went up near the Quad Cities, but the line had long since fell to mush by the time I showed up at 5pm.  I turned around before I crossed the river noting little structure at all except this mediocre gust front as I got back out ahead of the line.
A new line developed in central IL ahead of me and I drove into the back end of it.  It never organized and only produced a few scattered severe hail reports.  Looking east at the back end of the new line:
 
Conclusion:

Today was a big bust, but my expectations weren't that high anyway for the cold front play.  The watch and warnings sure got my hopes at the start of the chase, however.  Even if I had been able to leave work earlier (or not work), I doubt I would have seen much more with the Iowa tornado warnings.  The cells never looked very organized and were always embedded.

Other Chaser Logs:

 

Lessons Learned:

  • Cold fronts spit out mostly junk.