June 28, 2020


Initial Target
Storm Intercepts
Spencer, IA
Sioux Falls, SD 9:00 AM 6/28/2020
Sioux Falls, SD 10:44 PM 6/28/2020
0 mph
Orphan Anvil


Warm front play in norhwestern Iowa. Targeted Sioux City to Spencer, IA for evening tornadic supercells. After spending the afternoon being interviewed by a film crew, we intercepted a sunset orphan anvil near Larrabee, IA and called the chase a cap bust.

Crew and Equipment

Chase partners: Jennifer Brindley Ubl, Anton Seimon, Tracie Seimon, Hank, Schyma, Zack Canepari, Drea Cooper. Equipment: Samsung Galaxy S9.




From my morning "chasecast" storm chasing forecast discussion email list:

"Day 1 Today: Target picks from yesterday largely remain, just perhaps more focused in location:

1. Big Horns to Devils tower for afternoon/evening supercells. Problems with thermodynamics in the low levels suggest to me that this will be cold, gusty laminar hailers, rather than robust bubbly tornado producers. Tornadoes would likely be brief boundary layer spinups. Additional laminar supercell structures up on 94 corridor too. Possibly in the Great Basin of Wyoming early if there's enough residual moisture in there, and might be the sneaky tornado play out west.

2. Minot, ND mix of MCS and supercells by evening on the cold front. Better action may occur north of the border in Canada making this target logistically difficult for most.

3. Sioux City, IA and points east north to Orange City and the Minnesota border, possibly up to Albert Lea area. Extreme CAPE airmiass as robust moisture plume lifts north along the Missouri with strong low level jet. Quasi warm front draped northwest to southeast atop this plume, but is not super sharp with instability just tapering off into Minnesota. Would try to pick up initiation just south of the intersection of the high CAPE axis and the warm front, around Sioux City by 7pm. Mistimed midlevel impulse suggests problems with deep layer shear and a transition to MCS may happen fairly quickly. Still, given extreme stretching in the low levels, kicking LLJ and backed surface winds, a significant tornado might be possible while storms stay discrete in their early phases. So get on storms closer to initiation. Differences in convection allowing model evolution. NAM NEST showing beautiful ring of fire animation, like someone filled all of Iowa to a few inches depth of gasoline and then dropped a match near or east of Sioux City. HRRR lazily gets cells up after 0z once the boundary layer starts to cool. Might be enough low level instability and inhibition might hold off long enough that these storms could be surface based for a bit and pose a tornado threat into the evening hours.

Secondary target hinted on the warm front from say Albert Lea to Minneapolis and earlier in the day, later afternoonish. This could be a tornado play as well but worried about these storms overrunning the better low level instability into a quasi elevated environment. These storms are either bait or the real show that leaves everyone else scrambling from way upstream. "

Morning Gust Front

9:42 AM
Departing Sioux Falls for Sioux City.

Team Meet-up

12:20 PM
Looking like Evil Dr. Hank in his surgical mask.

Hood Mount
4 miles SSE of Sioux City, IA
12:46 PM
We assembled in Sioux City at a truck stop. Zack and Drea, the film crew tagging along with us, affixed a high end camera to the hood of Anton and Tracie's van. They bagged and taped it to keep the rain off of it. Supposedly it would have enough hold and protection to drive through the core of a supercell, and we hoped to test that.

Interview in the Park
1 miles SSE of Spencer, IA
3:35 PM
We repositioned to Spencer, our final target. Zack and Drea interview Anton in a scenic park.

Cap Bust
2 miles N of Larrabee, IA
8:14 PM
It looked like we'd have intiation just upstream to our southwest. We rolled for the intercept, but all we found was an orphan anvil from a failed towering cumulus and a smattering of rain drops in clear air. The feeder cumulus were gone. Haze and thin cirrus were all that remained, stifling the last of the surface heating as the boundary layer cooled and the cap was ushered back in. We called the chase a cap bust and headed back to Sioux Falls for the night.


A solid cap bust, but the day wasn't a total loss, as we got some interviews in for the film crew, tested out a camera mount, and were on the way to bigger days yet to come.

Lessons Learned

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