March 31, 2007

Statistics:

Initial Target: Quad Cities, IA
Departure: Bolingbrook, IL 11:30 am CDT
Arrival: Bolingbrook, IL 8:00 pm CDT
Intercepts: Blairstown, IA
Tornadoes: 0
Hail: Severe (0.75 inch)
Wind: Non-Severe (not measured)
Features: Gust Front
Miles: 525

Summary:

Chased slight risk setup over IA, initially hoping to target warm front activity over I-80 corridor in IL, but had to continue west.  Intercepted weak line of a few cells northeast of a mature, severe warned squall.  Followed cells noting some weak bases, but had trouble pursuing fast, north moving cells through rural Iowa roads.  Dropped to squall when northern comma head went tornado warned.  Noted gust front and some severe hail as storm passed overhead, but no tornadic activity.  Broke out ahead of line on I-80 near Iowa City, calling it a chase.

Crew and Equipment:

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

Details:

I was still in shock from my awesome March 28 chase, so I wasn't overly anxious about this setup.  There was a strong surface low moving through, part of the same system that sparked the March 28 event, and it was going to lift a warm front up through Iowa and Illinois with backed surface winds and decent upper level shear.  Good  helicity values and marginal instability were forecast up along the I-80 corridor in IL so I was hoping for more of a local chase.  SPC initially only had a 5% hail, wind, and tornado on the first Day1 outlook, but they later upgraded.
I wasn't too quick to leave, hanging around until 11:30 before I saw things starting to come together out in Iowa with an MD going up mentioning a tornado watch.  I headed west on 80 for Iowa, seeing that Illinois was probably not going to initiate and that all the activity would be in Iowa.  The watch went up for portion of western Iowa where a cold core type event was underway.  A new red box finally went up for eastern IA, and I made for a cluster of small cells that were near Iowa City.  I finally caught up with them west of Cedar Rapids as they had merged into a short line.
I tried to keep up with the southernmost cell.  There wasn't a good north/south highway west of Cedar Rapids, and I didn't want to get too close to that city.  The group of cells was also moving north at about 50 mph.  The bases I observed were weak, shower types.  There was a little bit of scud activity under them that resembled a lowering, but it was nothing to get excited about.
Meanwhile a mature, severe warned squall line was underway south of me, extending into Missouri.  When a northern cell in the line, a comma head, went tornado warned, I finally abandoned my storms and dropped to the squall.  I put myself right in the middle of the warning polygon, not seeing much of a couplet on radar and figuring I could ride the storm out relatively safely.
I found an excellent lookout spot near Blairstown, IA. It was atop a hill overlooking some fields.  There was some twisted sheet metal nearby that made for an interesting foreground.  I watched the gust front, looking for any tornadic activity or rotation, but saw nothing.  Whatever was triggering the warning was probably well embedded into the rain.
I set the video camera up and watched the squall roll in.  When the rain picked up I relocated to inside the van.  Just before the gust front hit I decided that I probably shouldn't be sitting near a bunch of loose sheet metal with a tornado warned storm so I moved down the road a ways.  The gust front hit with very strong winds and some marginally severe hail that I reported via Spotter Network.  Most of the stones were pea sized and came with the barrage of wind and rain, but a few stones got up to penny size as the rain tapered off.
I worked myself east on country roads to 380 before I got back onto 80 near Iowa City.  I had to weave through the slow Iowa drivers, but I finally broke out ahead of the squall again.  The line was dieing down and the activity out of ahead of it was weak and unorganized so I decided to make for home. 

I was watching Mark, Darin, and Jarrod's car on Spotter Network and noticed I was fairly close to them now so I made a call out on the ham radio.  Instead, Jerry Funfsinn replied.  While Mark and co. stayed in southern IA, Jerry wound up on the same tornado warned cell as I did.  From his location he saw some interesting motion under the gust front, but no tornadoes.  Mark, Darin, and Jarrod saw a brief wall cloud on one of the cells in the line but it dissipated quickly.

I followed Jerry back to his place, which was on the way home, and he gave me a copy of his superb March 28 footage on DVD.  I made it back to the house at around 8pm, encountering some driving rain in town.  The squall line later made it all the way back to Bolingbrook, severe warned, and hit with some strong winds and heavy rain.
Conclusion:

This was a fun little chase that bordered on the edge of a bust.  However, I wasn't expecting much, and since I got right on a tornado warned portion of the line with some severe hail, I won't count this one as a bust.  The only tornado activity was associated with the squall line as it dropped a couple tornadoes in Wisconsin near Dubuque and in Saint Louis.  Some chasers did catch funnels and rotation on the cold core activity further west by the Nebraska border and Des Moines, however.

 

Lessons Learned:

  • Try not to get stuck on the interstate, behind a squall line, with city traffic.