March 25, 2007

Statistics:

Initial Target: Mason City, IA
Departure: Iowa City, IA 9:30 am CDT
Arrival: Bolingbrook, IL 1:00 am CDT
Intercepts: None
Tornadoes: 0
Hail: None
Wind: Non-Severe (not measured)
Features: None
Miles: 602

Summary:

Chased Moderate Risk setup in northern IA/southern MN with Jenny Acosta.  Targeted Mason City, IA for 21z initiation.  Wound up in Lime Springs, IA with 77 temps and snow on the ground.  Met up with Darin Kaiser and Dan Dimitroff in Spring Valley, MN.  Followed line of high based showers before they completely evaporated.  Called it a bust at 6pm and made it home by 1am.

Crew and Equipment:

Chase team included Jenny Acosta. Equipment consisted of a TH-F6A Tribander, and GPS/Cell Phone equipped laptop.  Photography by Skip Talbot.

Details:

Sunday was shaping up to be a nice chase opportunity.  Originally the models had a dryline over IA with excellent shear.  As the event approached, however, the moisture axis became more diffuse and was pushed further east.  The ugly terrain of  the upper MS river valley came into question.  It was the weekend, though, and it still looked promising for supercell initiation in northern IA/southern MN.

Jenny accompanied me on this chase which was a nice treat.  She had not chased with me in two years, and I was hoping to show her a real storm this timed.  We spent the night in Iowa City at my cousin Kelly's apartment after spending a night visiting her and her boyfriend Ben.  We got up not so early the next morning and plotted our course north to Mason City.  We stopped in Waterloo for grub at Panera and then the nearby mall so Jenny could pick up some things.  We proceeded north on 63 toward Chester, IA instead of Mason City, as it pappeared the action would be more to the east than we had hoped.

As we left the mall in Waterloo I could see a developing cumulus field to our north, which looked promising.  We went all the way up to Chester only to realize that there was no cell signal here.  The one router in town was locked, and the owner of the house just happened to come out when we pulled up.  "Getting a good signal?" he asked.  "Nope, trying to get on my cell phone here..." I replied almost sheepishly.  Busted.  We left town and headed south to Lime Springs, where we picked up an open Linksys router almost immediately.
One of the most amazing things about this chase was that the temperatures were soaring to near 80 and yet there were large piles of snow still on the ground.
While we waited for initiation I had Jenny fake a softball sized hailstone out of a ball of snow... just in case we busted.
We waited around at Lime Springs, took a walk through the town.
A line of weak thunderstorms had fired south of Minneapolis extending almost to the Iowa border.  These storms would probably be the only show of the day so Jenny and I headed north into Minnesota.  We stopped in Spring Valley, MN where we met up with Darin Kaiser and Dan Dimitroff.  We intercept the line of weak, high-based showers just north of town stopping for some photos.  Darin and Dan claimed to have seen a possible wall cloud on a distant cell but it didn't last long.
Looking south at some convection.
We kept up with the line on I-90.  One of the rainshafts looked like a landspout so we snapped a picture of it.
The radar indicated that the line was weaking.  Capping issues as well as the southwest flow mixing out the dewpoints, were keeping our storms from taking off.  Sunset over Minnesota:
Jenny, Dan and Darin.
We called it a chase and split up.  Jenny and I stopped for icecream in Madison at place that had every square inch decked out with a carnival theme.  It was quite scary actually.  We were back in Chicago before 12:30 and I was home by 1.
Conclusion:

A classic bust to north Iowa/Minnesota.  The best storms actually went up in central Wisconsin where the chase terrain is terrible.  Other chasers reported seeing a brief wall cloud on one of the cells in the weak line of showers in Minnesota.  One of the biggest problems with the chase was that the surface winds shifted southwest when it was originally hoped they would stay more southerly.  This caused the dewpoints to mix out.  Capping issues were present throughout the day which also suppressed severe convection.

 

Lessons Learned:

  • Southeast Minnesota has chaseable terrain
  • Southwest surface winds and flow aloft can ruin a chase