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Motherships and Cows

7 June 2001, Pawnee Buttes to New Raymer, CO

On our first notable chase of 2001, we saw (after protracted driving around) a sunset-lit supercell just south of Colorado Highway 14. The storm had a beautiful LP structure, and was definitely rotating rapidly. After viewing the storm (with attendant wall cloud) until after sunset, we left the storm and headed for home. The story behind this storm, however, is much more interesting. Read on for details!

Chasers: myself, Chris Rozoff, John Haynes, Sean Miner, Justin Shaw, Curtis Marshall on data.

The chase started around 1:00pm on Thursday afternoon, but as always, the pondering started days in advance. After busting hard the previous Sunday and being out of position on a Monday chase, we wanted to pick a target ahead of time, and then get out there. The night previous to this chase the forecast progs were looking like a SE WY/SW NE chase, but the morning revealed a low cloud deck north of the Cheyenne ridge that just wouldn't go away. Deciding to aschew the cold air pooled north of the ridge, Chris picked his initial target to be New Raymer, and the rest of us agreed heartily.

Satellite images of N CO showed two airmass boundaries over our target; our goal was to get in front of the boundaries and chase the best-looking towers. Punching east on CO Hwy 14, we made it to New Raymer at about the same time as the boundary, which kept rolling to the east. To our north, numerous turkey-towers were firing, collapsing, and firing again, but not much of interest was happening overhead.

We decided to chase the boundary and wended our way east to Sterling. After a long runabout through the town, whose road layout was apparently designed by wild geese, we found the city library. Radar data, as well as expert advice from Curtis showed that Sterling was a pretty good place to be. Appealing to our restauranteer nature, we then went to the Sterling Wendy's and ate lunch, while perusing maps and memorizing the road network south of town, towards Akron. After lunch, we decided to head east and observe the large tower going up southeast of Sterling.

Out east of town, we noticed appreciable chaser convergence at a gas station just off I-76. All attention was directed towards the cell to the south, which was really trying to get organized. The storm kept putting up towers on its rear flank, which discouraged our chase troupe. However, this storm did O.K. - radar analysis after the fact shows the storm finally settling down, and anchoring in over Akron. Matt Parker has really cool video clips of rotation, with menacing lowerings, once this storm got its act together.

None of this impacted our little rolling circus too much, however, seeing as how we took off to the north of town. We were after towers that, while smaller and less evil-looking, were staying together and not back-building as much. Against orders from Curtis, who told us to get to Akron, we headed to the reservoir north of town, and set up. Damnably, the towers started back-building, and we were forced to chase them west as they kept pulling us away from Sterling. Finally, up against the great Pawnee Road Void, and feeling the wrath of Curtis upon us, we finally stopped on a dirt road just east of Hwy 71 in abject despair. Our moods were lightened by the delightful cavorting of the local bovine population, who approached us out of curiosity. Having no storms to photograph, we consorted to taking silly cow pictures. I'm pretty sure our mental health was suffering at this point in the chase.

The storm, however, hadn't given up on the impressive CAPE in the area, and while we were thinking about why we did things like call Curtis only to ignore his sage advice, the back-building finally stopped, and an LP cell began to take form over Pawnee Buttes. We watched in relief as the tower started to stand up against the shear, and a broad base develop next to the precip shaft. Inflow increased, and the sky grew darker. We knew this was our storm, and we headed to the furthest western vantage point to view this storm (which was at the time, located in the center of the Pawnee National Grasslands.)

With the towering anvil overhead, we made it to Colorado Highway 71, just north of Stoneham, CO, as the Avalanche game started. Parking by a bar ditch on the southbound side of the highway, we stopped to watch the storm to our northwest, moving southeast, as it developed a rotating wall cloud. With the storm headed in our general direction, we decided that we'd watch until it was time to go, and then run south, staying in the clear inflow of the storm at all times.

As the storm grew closer, we made the decision to head south. We piled into the car and listened to the local radio station report a severe thunderstorm warning on the storm. Predictably, as we heard the severe report, we looked out our back window, and the storm looked as if it had expired. I can't explain what happened - maybe we lost sight of the updraft base, maybe the storm was briefly choking on the outflow of the Akron storm, maybe we're just idiots, but it looked like our storm was over. We headed south, hoping to catch one last glimpse of the Akron storm before the sun set.

Braving a smackdown from Curtis, we called one final time to get the information on the Akron storm. Instead of reading us the riot act, however, Curtis informed us that the Akron storm had petered out, and there was a strong storm to our north...the storm we just left.

Sure enough, we looked back and our old storm was looking much, much better. We raced back north to the Weld county border, and as we got closer, we started to notice some great features. I'd seen mesocyclones before, but never a sunset-backlit LP cell. We stopped to take pictures, and I found myself wishing for a 17mm lens - it was impossible to get the whole storm structure captured on my 28mm lens!

As we stood there, we were aware of the wind shifting from directly behind us, to somewhat to our left, to dead calm. We suddenly wondered what the hell we were doing in the updraft of the storm, and decided to boogie south, back into the inflow.

And so we scooted back into safer territory, as the storm continued to experience RFD surges, and wall clouds continued to rotate. Heading south on county roads just east of Colorado 52, we stayed ahead of the wall cloud as it would cycle from menacing to missing. Inflow winds were strong, but as we moved closer to the cold pool left behind by the Akron storm, we knew that our storm's lifetime was limited.

We set up one final time on an east-west road with plenty of south options and watched the final exciting cycle of the storm. This last wall cloud was really, really trying to produce - rotation of the storm was visible to the naked eye, and the wall cloud was low and menacing. But we never detected a spin-up underneath the storm, and had there been one, it's not likely we'd have seen it anyways, due to the darkness. Eventually, the wall cloud dissipated, and the storm began to take on multicellular characteristics. With precious little daylight left, we called it off and ran south to clear air.

We drove south and west to get back to Highway 52, and after a brief stop to converse with a Texan chaser far, far from home, we headed to Fort Morgan for some Arby's. We sat by the tennis courts and watched the lightning show to our north while munching our dinner, and ruminated over our day on the plains. And despite it's bovine beginnings and hectic pace, this day really was a fine outing.