June 29, 2020

Statistics

Initial Target

Start

End

Storm Intercepts

Tornadoes

Hail

Wind

Features

Miles

Glendive, MT

Sioux Falls, SD 6:59 AM 6/29/2020

Dickinson, ND 10:27 PM 6/29/2020

Wibaux, MT; Killdeer, ND

0 mph

Wall Cloud, Shelf Cloud, Mammatus

847

Summary

Chased behind surface trough for tornadic supercells in far eastern Montana. Intercepted developing supercell with wall cloud near Wibaux but it gusted out and was undercut before it could produce. Chased dramatic structure on line of storms east of Killdeer before ending in Dickinson.

Crew and Equipment

Chase partners: Jennifer Brindley Ubl, Anton Seimon, Tracie Seimon, Hank, Schyma, Zack Canepari, Drea Cooper. Equipment: Photography courtesy Jennifer Brindley Ubl shooting on a Nikon D4s.

Video

Map

Details

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

"Primary target for a tornado is far northeast Montana, Glendive north to Plentywood and east to the ND border. Dews forecast to wrap around the back side of the surface trough with a northerly inflow that is unstable. Huge 3cape pool and surface vorticity max out there. Big red flag that screams tornadoes.

Next best target is top of the north south line forecast to initiate on the surface trough in western North Dakota. Get the top of the line where the northernmost cell heads into more favorable T/Td spreads and back surface winds up from say Williston to Stanley, ND.

Possible spout play down the line toward the SD border where high based storms stretch some vorticity on the wind shift there. You'd want to be on the line at initiation to see that, but tough to not go for the regular tornado plays north and west."

This was our first major chase opportunity with the full team and a documentary film crew of the 2020 season. The setup was giving us vibes of our amazing May 28, 2019 chase with northerly flow wrapping around the low coupled with strong surface vorticyt and 0-3km CAPE. Our four vehicle caravan made the long haul from Sioux Falls to Fargo, all the way across North Dakota to Montana, arriving by early afternoon just in time to see developing supercells coming out of Glendive. We went northwest out of Wibaux, MT on a rocky road for the intercept.

The storm was organized rapidly with a wall cloud.

Flat Tire and in the Path
6 miles WNW of Wibaux, MT
3:59 PM

Meanwhile, Woodchuck had called out on the radio before we stopped that they had a low tire pressure warning light. Sure enough, amid the scrambling to set up cameras on the storm, Anton and Tracie saw one of their tires was flat. It was probably punctured by one of the large, sharp pieces of red rock of which the road was made. We were immediately downstream of and in the path of a rapidly organizing supercell turning a frustrating setback into a potential emergency. After weighing our options for a few moments, we decided to split into two teams. "A Team" was tasked with fixing the tire using Fix-A-Flat and a portable air compressor. In case that failed, "B Team" would concurrently unload the most necessary gear from the Woodchuck vehicle and distribute it among the other three vehicles in preparation for abandoning the vehicle.

Rotating Wall Cloud
6 miles WNW of Wibaux, MT
4:10 PM

Low level rotation ramped up in the storm. Streaky bands of rain started to carousel around the wall cloud. Tornadogenesis seemed imminent. We relocated the three team vehicles down the road to get a photogrammetry shot for our research mission.

But just as the show was about to start, cold outflow blasted the wall cloud to pieces. Our short term chances for a tornado were gone, as was any hope of recovering Tumbleweed's van. The tire repair didn't hold, and we were forced to abandon the vehicle as the storm approached. Anton jumped into our car, Tracie and the dogs went with Hank. Of the seasons we made it into Montana, this would be our third in a row with a vehicle failure after the transmission on my van failed in 2016, Woodchuck struck a deer in 2018, and now this flat in 2020.

We chased back into North Dakota and went north out of Beach. The storm was thoroughly outflow dominant by then, undercut by a surge in the cold front, and starting to merge with a line forming in western North Dakota. A May 28, 2019 repeat was not in the cards. We cut north and then east through the core of a developing storm. It was not yet warned, but rain hammered us and the sky went green. Emerging east from the line, we stopped outside of Kildeer for structure shots. A dramatic shelf cloud spanned the west sky, framed against the prairie grasses and red rock roads of the Northern Plains.

The Scientist
13 miles SE of Killdeer, ND
6:41 PM

Anton Seimon in his element.

Shelfie Time

QLCS Inflow Notch

7:54 PM

We chased the line for a bit. We had a textbook QLCS inflow notch due west of our position, but couldn't pull a tornado out of it.

Advancing Gust Front
10 miles NNW of Richardton, ND
7:58 PM

Mammatus over Dickinson
2 miles N of Dickinson, ND
8:51 PM

Lightning, roll clouds, and sunset mammatus captivated us on our drive back to Dickinson for the night.

Conclusion

Hopes were high for a tornado on this chase given the parameters and pattern, and although we didn't bag one, the supercell structure, wall clouds and shelf clouds made the chase for us. Dealing with the flat tire added a little excitement to the mix. Anton returned with a service vehicle the next morning to find his van intact, and was rolling for the next day's chase.

Lessons Learned

Be prepared for a vehicle failure at the worst possible time.
Watch out for a surging, undercutting cold front when playing wrap around on the west side of the low.

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