Thunder Basin Thunder
Ogallala, Thunder Basin and Buffalo Gap National Grasslands (NE/WY/SD)
17 Jun 13
SHORT: Early elevated storm CDR, back-of-MCS mammatus show eastern WY.
LONG:
BANG! That was how our day started, as a very close lightning strike awoke us from slumber in our motel room. Elevated storms had been rumbling overhead for some time during the early daylight period, their rain pattering a stay-asleep-please lullaby outside; but that vicious blast on the trailing side of it all was a literal eye-opener. [During a later visit to CDR, we found out from the motel proprietors that the strike split a tree in half about a block from there.] I PINGed the rain, of course.
Anticipating that any storm potential on this day would be roughly on the way between CDR and our intended destination of Buffalo WY, Elke and I started the day with a short driving tour of CDR that we have been wanting to do for years, then saw another long-desired destination there: the Mari Sandoz High Plains Heritage Center at Chadron State College. Though small, the museum was well worthwhile–a great tribute to the life of the High Plains pioneer writer and documentation of the hardscrabble life she and her parents led in settling the Sandhills.
Leaving the museum, we saw the sun peek out but also heard distant rumblings to the W. A small, elevated thunderstorm was riding the top of the outflow pool from the morning convection. While Elke gathered some supplies at Wal-Mart, I found a nearby hilltop from which to enjoy the view. The verdant prairies of a Nebraska Panhandle springtime can make even an ordinary, elevated storm seem majestic and beautiful! We ate lunch from that hillside Country Kitchen with the grand SW view, then hit the road NW into the SW corner of SD.
Forcing for deep convection appeared rather muddled on this day, with marginal shear for supercells. Still, with…
- A weak cap in modified UNR sounding,
- An outflow boundary from the morning storms arching back across eastern WY to our SW and W,
- Orographic features in the form of Black Hills and Bighorn Mountains looming to the NW and NNW, and
- Prospects for strong and sustained insolation…
…we had good cause to expect seeing a storm at some point this day. We planned to dabble in whatever convective pleasures the atmosphere offered, then settle into Buffalo for the night with a trip through the Bighorns planned day-2 and some Montana chasing on the docket day-3. Only a few days out of Norman, our Oklahoma home nonetheless seemed so far away and long ago as we trekked across the grand vistas of the northern High Plains and around the SW rim of the Black Hills.
Visiting the adjoining Ogallala (NEb) and Buffalo Gap (SD) National Grasslands for a spell, we did some short hikes over the wide-open Plains, dodging flowering cacti while watching persistent but non-deepening high-based convective towers to our SW, over WY and along the boundary. In the distance, convection built over the Black Hills and small, fuzzy anvils started to spread off the eastern slopes of the Bighorns.
We zigzagged the mixture of paved and unpaved roads characteristic of southwestern Fall River County, skirting just close enough to the Black Hills convection to see that it was rather high-based, poorly organized, incipiently outflow-dominant and unlikely to survive in any chase-worthy form after peeling out of the hills. Meanwhile, the persistent towers to our SW stayed about the same height they had been for two hours, and the anvils got enticingly dark and thick to our W. A check of radar during a brief data-availability interlude, however, revealed a very messy multicell-supercell clustered structure that was starting to accelerate SSE across WY and surf its own outflow.
Rather than make a mad run 100 or more miles to our S to get ahead of the charging convective mess, while adding 4-6 hours to the journey to get near or past CYS (and well out of our way) then back up, we decided to take a more leisurely approach. We remained on the planned westerly track, let the growing convective mass gather its cold pool and pass off to our SW, then slip in behind its bowing forces of rampage and see what storm light would greet us. This choice didn’t disappoint!
Appropriately named on this day, the Thunder Basin National Grassland hosted a spectacular display of mammatus (looking overhead at first, then toward the S). The amazing mammatus field evolved into sinuous forms resembling pods of swimming marine mammals (view with landscape foreground), as it moved fairly rapidly southward across the open rangeland apace with the parent MCS that, by this time, was blasting parts of SE WY with no mercy whatsoever.
We stood in cool outflow air, thoroughly immersed in the resplendent scene passing off toward the southern horizon, until sunshine came out and limited contrast. Once the convection and mammatus departed, so did we, shuffling off to Buffalo–Wyoming that is, via Gillette and I-90. A fine dinner in town and a day in the Bighorns area lay ahead.
===========
Our PING trail for this day.