June 6, 2018

By Wednesday, June 6, I had been on the Plains for ten days. We'd been after scraps since the big Cope, CO event. My "secret weapon" forecast parameters lit up this day near Laramie, WY. The previous day's NAM showed a pool of 0-3km CAPE and and a negative lid strength index, two parameters I most rely on when discriminating tornadic vs non-tornadic targets. And it's what you want to see when trying to score a long shot upslope tornado. It was a sleeper play, not synoptically obvious, and not even on the Storm Predicition Center's radar, but the signal was there. The problem was, however, that our teams were way too far away for what looked like an early afternoon initiation. Ending the previous day's chase in Dickinson, ND, we decided we weren't willing to commit to driving long into the night or geting up before dawn to hit such a marginal target. We instead decided on a compromise of sorts, and would play a more conventional and popular upslope target off the Big Horn mountains in north central Wyoming, which the SPC did highlight with a 2% probability.

Our closer target still took hours to get to. We drove into Montana and then south to the Big Horns, arriving by late afternoon to see upslope initiation underway with cells already coming off the Big Horn range. Phil and I setup for some time lapse shots while Anton watched for a dominant supercell we could target.

South of Buffalo, more robust cells were taking shape over the mountains. The plan was to catch them as they moved off the high terrain. We ran south a a couple dozen miles on sparse ranch roads for the intercept.

Radar depicting a severe warned supercell drifting slowly over the mountains. We couldn't get any closer, but would simply have to wait for it to move east into the plains.

We setup for some time lapse shots again, and while waiting for our storm to get closer, we saw what was happening down by Laramie. Chasers were sharing pictures of a stout, clear air, perfectly lit stovepipe/barrell shaped tornado. One look and we knew it would easily be one of if not the most photogenic tornado of the year. Brindley and I were devastated, after seeing the potential, but not giving the chase that extra effort to make it.

Anton, always the optimist, chasing in the moment while never disparing over a missed tornado, was focused on what our storm was doing while we brooded in the car. A distinct horseshoe shaped RFD cut was visible, a lowering underneath, obscured by terrain, appeared to dip toward the ground. The motion was rapid, tornadic even. Anton called out, "tornado!" and we scrambled to get our cameras zoomed on the feature.

The feature churned and disappeared before appearing again as a white funnel cloud. roping out above peaks probably higher than 9,000 feet. It was incredibly tough to see in person, but with binoculars I could make out rotation that was clearly tornadic. The funnel later popped right out of the zoomed in video when a little contrast was applied. There was no tornado warning, no damage report or survey conducted, and it wouldn't make the logs, but the motion and structure we captured on video was good enough for me to count it. I wrote this a couple months later to describe the scene:

"The Bighorn Mountains are a witch’s cauldron. With a pinch of upslope flow, a dash of moisture, and an incantation of differential equations, black magic brews. Through the dark, roiling clouds and cascade of bolts we could tell that something was brewing up in those mountains on the evening of June 6. We couldn’t be sure of what though. Too far for our eyes to discern, no warning, report, or survey, this was something never intended for mortals to witness. But our prying telephoto lenses coaxed it into view anyway. It sat inside the camera for a few weeks, half forgotten, just waiting to be uncovered like a haunted artifact until I finally returned to edit the season’s shots. A black shape emerged in our video, dipping out of the horseshoe updraft base, spinning away and ducking behind a peak and into the rain before reemerging as a writhing white snake. A likely tornado formed at the top of the Bighorns and danced like a demon where it thought no one was watching. The scene reminds me of “A Night on Bald Mountain” from Disney’s Fantasia."

The storm finally drifted into the plains to the east, but of course the tornado show was over by then. Brindley captured this next series of photos of pretty upslope storm structure.

Instability created by daytime heating was waning and the upslope storms started to dissipate. We called the chase and headed to Gillette for dinner and a room.

Drinking away my sorrows at Devils Tower.... actually a picture of Devils Tower at the Ruby Tuesday in Gillette.