Buried Tornadoes by the Border

February 28, 2014 by · 1 Comment
Filed under: Summary 

Chugwater WY to Kimball NE
22 Jun 13

SHORT: Intercepted 2 supercells in SE WY, first photogenic, second became dark and nasty HP with about two tornadoes buried inside and barely/intermittently visible. Lightning and photogenic outflow formations with tail end of resulting MCS in NEb Panhandle.

Having made a full-circle back to Chadron from five days before, we did a little late-morning photography of abandoned antique vehicles that we had seen previously, then bid farewell to our favorite north-central High Plains town to head SW. We targeted as promising of an upslope-flow supercell scenario in southeastern WY as you’ll ever see, realistically. The previous day’s boundary was shunted southward toward the Cheyenne ridge, flow behind it veering throughout the day to both advect unusually rich low-level moisture upslope (beneath favorably strong midlevel winds) and yield a big hodograph. That moist air rising up the Laramies would do the heavy lifting, with help from hours of sunshine. Since we actually weren’t far away and were leaving before noon, I was as confident in seeing a tornadic storm on this day as any the entire June trip. Slap those hands together, fill the tank, hit the road, and get ready to rumble under some spinning sky.

Supercells rolling off the Laramie Mountains under similar flow patterns and even less moisture have produced delicious tornadoes on several occasions in the last 15 years. For some reason, we (and I, before marrying Elke) had been late to the party for most of them, either missing the tubes or barely catching their end stages. The 2010 Chugwater storm was, of course, a wonderful exception. Even early initiation wouldn’t be a problem, given the long N-S roads of eastern WY and the good visibility away from the E slopes of the escarpment between Hawk Springs and Chugwater.

Over the hills and into Wyoming we went, fueling in Lusk under the midday sun as anvils began streaming off the northern limb of the Laramies. This was early initiation indeed…for which (for once) we were ready! The most vigorous cell, near Dwyer, appeared to be turning right and organizing into a supercell fairly quickly. Fortunately, it was aiming right down US-26 toward the Lingle area, where getting ahead of it would be easy. No wondering what was over the horizon, no driving 150 miles after an early-forming Wyoming storm already in progress! When we got just S of Lingle, there it was, in youthful supercellular splendor, to our W.

The supercell traveled ESE as another developed to its SW, with rain from the newer storm cascading into the established supercell‘s upshear region. After briefly encountering fellow storm observers Vince Miller and Matt Crowther, we moved a few miles S, stopping briefly to watch a beautiful phase of the otherwise shrinking and rising cloud-base configuration, characterized by a clear slot with tightening rotation. Nothing came of that; the occlusion downdraft cut too tightly into the rotation area and dry entrainment eroded what was left. The older cell then slowly weakened at the expense of the rapidly strengthening upshear storm, and we headed S toward Veteran to get in front of the latter.

What we found there was an entirely new animal–one that would turn into a menacing, growling, teeth-baring, attacking beast in short order. Looking SW at the reasonably large updraft area, ragged, slowly rotating shelf/wall cloud hybrid and dense core, it was easy to predict that this beautiful mess of a storm would become an HP in short order. Since the entire storm was moving ESE, this was an unsustainable viewing position; the forward-flank core and its hail would impose its will on us if we stayed put much longer.

A quick zigzag E and S out of the Veteran/Yoder area took us onto US-85 NE of Hawk Springs and NNE of LaGrange. We had to bolt S ahead of the strengthening mesocyclone to our SW in order to take the east option toward WY-151/NEb-88. First, however, we had a few minutes to stop, observe and admire a very rapidly intensifying circulation–a photogenic and menacing wall cloud that quickly evolved into wide, rapidly rotating, nearly ground-scraping bowl, a mesocyclone that clearly meant serious business. A small funnel briefly whizzed around the left (SE) side of the bowl, but with no clearly discernible debris beneath. The entire spinning mass of gas still was moving ESE and we were NE of it. No time to tarry…we had to go!

We skirted the E edge of the orbiting precip curtains from N-S as the mesocyclone quickly wrapped in rain and the storm took on a mean, nasty HP form. I’m used to tangling with those in north TX, but not on the more road-sparse plains of the WY-NEb border. Fortunately the east-151/88 option was conveniently located to offer a chance to get safely ahead of the whirling dervish for awhile, albeit in the eventual path. A brief glance at radar indicated a rapidly tightening and potentially tornadic mesocyclone to our NW as we approached the border. I stopped there to observe and thought I might have seen the tornado (see photos in table below), one about which I was more certain that night, after viewing the photos via camera display and talking with the NWS office. Given its S of E movement, we couldn’t stay too long.

After charging E across the border, after a mesocyclonic cycle, and while I still was driving to gain some distance, Elke took a look at the radar display and saw this rather alarming SRM signature a few miles to our NW. There was obviously another tornado somewhere in that dark precip mass–and likely a significant, potentially violent vortex to boot! It also was moving ESE, meaning we would have to stair-step along the W-E highway in multiple stops to stay safely ahead of it, and of the wrapping precip.

Needless to say, I slowed down really quickly and turned into a northward-directed side road to stare hard into the rotating cylinder of precip. At times, during the second of two different stops along NEb-88, I could make out the tornado ‘s condensation funnel–briefly, barely but confidently. We stopped again after turning S on NE-71 past Harrisburg.

What follows is a chronological table of links to a selection of photos taken at the stops, looking NW at first, then WNW. The photos show the region as it looked with eyeballs (“PHOTO”), heavily enhanced (“ENHCD”) and in a few cases, enhanced and annotated (“ANNOT”) to bring out the tornado where possible, and to illustrate the motion. Curved arrows on some ANNOT images show the area of very intense rotation. All of these were processed within a few weeks after returning and provided to the CYS WFO for their evaluation. [I have them prelim track and time estimates the same night via phone call using adjusted camera times (camera was 4 minutes fast).]

[Please scroll down to see the tornado-photo table and the rest of the post. I don’t know how to fix this gap.]

Sequence Number & Viewing Location

Normal and Edited Photos

4. 3 E Stegall S Rd on NE-88 PHOTO NO ENHCD NO ANNOT
5. 3 E Stegall S Rd on NE-88 PHOTO ENHCD ANNOT
6. 3 E Stegall S Rd on NE-88 PHOTO ENHCD ANNOT
7. 3 E Stegall S Rd on NE-88 PHOTO ENHCD ANNOT
8. 3 E Stegall S Rd on NE-88 PHOTO ENHCD ANNOT
9. 3 E Stegall S Rd on NE-88 PHOTO ENHCD ANNOT
10. 4 NE Harrisburg on NE-71 PHOTO ENHCD ANNOT

Because the tornado on the Wyoming side of the border (images 1-3) appeared to shrink and get deeply occluded into the precip, and because NWS CYS surveyed a distinct tornado track on the Nebraska side, I now very strongly believe (>95% certainty) that the Wyoming and Nebraska tornadoes were separate. On the Nebraska side–yes, there also was another dark, columnar area to the left (SW or WSW) of the tornado cyclone in a few images (mainly 4-5), but I could not tell what it was. The rotation of precip around the tornado in each photo was furious and obvious. Even when I couldn’t see the tornado at all (which was most of the time), there was no doubt of its presence.

Due to lack of visual continuity, I also can not state definitively if the Nebraska tornado was continuous between stops, or two separate events. NWS surveys indicated one path in Nebraska, so I’ll count this as a single, second tornado for now, given no firm evidence to the contrary. The tornado only hit a few things, earning an EF1 rating due to sparse/weak damage indicators. However, its WSR-88D radar signature is consistent with many strong to violent (EF3-4) events, based on a study underway by Bryan Smith and others at SPC. We’ll never know its true strength.

The tornado moved almost directly toward my position in image 9, but dissipated before it got to NE-71. By that time, we had bailed S, out of the way, and found a hilltop S of the 71/88 intersection. There, we tried to view the deeply occluded, embedded meso as it got thrust back out of the rear side of the precip area (enhanced. There may have been a weak tornadic (or nearly tornadic) circulation still going at that point (enhanced), as visible cloud-base rotation still was reasonably strong. I can’t say with complete certainty. By this time, a big gust front and shelf cloud had surged well ahead of the mesocyclone. The supercell was evolving into a linear structure with more storms erupting to the SW–we had an MCS and QLCS on our hands.

Plenty of daylight remained, so…time to go tail-chasing! We proceeded S to and past Kimball in search of a vantage, and found one 3 SSW of town on County road 28, right along the N side of Kimball airport (IBM). This was a treat! Even though the complex was decidedly outflow-dominant at this stage, its arcus underside and photogenic lightning were just plain fun to observe. The core passing to our N fired a good volume of electrical artillery from the same general area (including one whose most visible segment was “questionable”). One bright outlier, an outflow-influenced channel and a few other strikes followed as the core moved E. Meanwhile, the arcus’ underbelly passed overhead and to the S with fantastic sharpness to its turbulent texturing. What a crazy, interesting sky!

Ravenously hungry by now, and chilling uncomfortably from all the outflow, we snapped the shutters at a few more strikes from the last passing core, then headed into town for dinner. Amidst that huge and expansive puddle of outflow, we didn’t imagine that an updraft would blossom to the E that was surface-based, and produce a brief tornado (seen by a few observers still afield) before being undercut. That’s how it goes sometimes. While somewhat disappointed, we could live with it. We had seen some serious tornadic action already, and the hot pizza tasted mighty good going down. Here was one final look at the back side of the complex from the pizza-parlor’s parking lot, as the storms retreated into the suppertime sky.

After checking into the motel in Kimball, I got the tornado time/track info to the CYS WFO to the best extent possible, then reflected back upon another long but very rewarding chase day–one fruitful both photographically and in terms of both tornadic and nontornadic storm experiences. Forecast guidance also indicated that we had one more day of decent storm potential in CO before we had to head home. Our time in Montana was growing ever farther away in the rear-view.

Our PING trail for this day. [PING date is ending date in UTC.]