Pawnee Grassland Supercell and Sterling Sunset
Filed under: Summary
Cheyenne WY to Sterling CO
15 Jun 13
SHORT: Chronically photogenic storm from CYS to Sterling.
LONG:
We began the day in Ft. Morgan with increasing (but still marginal) low-level moisture feeding two forecast plays:
- The dependable Cheyenne Ridge/Laramie Range region, which seldom fails to pop a storm under upslope flow and substantial surface heating, and
- Palmer Ridge/Front Range area farther S, similarly dependable but under weaker flow aloft.
My privately posted chase forecast discussion read, in part…
“This pattern strongly resembles several that have fired grand supercells off the LAR mtns NW CYS — some with spectacular tubes — though moisture today is a little less than I’d like to see it for tornadic action. Postfrontal winds should turn around after 18Z and go upslope into that area. If a storm can fire over there, it could proceed ESE through the extreme SE part of WY and eventually in an oblique path across the NE CO border…”
That was the scenario we selected; and fortunately, that’s exactly how it worked out. Such success doesn’t happen as often as I’d like, so we should celebrate when it does. On this day, we celebrated with some splendid stormscapes and one of the best Great Plains photography days of the year.
First, however, we ate a great buffet lunch at a highly-reviewed place in eastern Ft. Morgan, away from all the main highways: the Country Steakout. Try them next time you’re in the area, especially if you want to get really full, before a chase. We then trekked through the Pawnee National Grassland on the way to the CYS initiation target. [We would return through this amazing area later in step with the supercell.] Along the way, we found an abandoned farmhouse that showed us decent photo opportunities even at midday (samples: outer wall texture, another outer wall scene, light and shadow through a window and on the floor, more exterior boards).
After that, a lone Cb arose off the WNW horizon, which satellite imagery confirmed was firing off the southern part of the Laramie Range, just as hoped and predicted. We headed through CYS, passing Mike U and a few other chasers along WY-211 (Horse Creek Rd) to find an excellent vantage for the approaching storm, which offered a large and textured but ragged and elongated updraft base.
Peeling itself off the highest terrain and heading ESE, the storm kept that elongated-updraft look after crossing the Colorado border near Hereford. Although this storm flirted with excessive downdraft production and outflow-dominance on several occasions, it was able to maintain just enough proximal inflow to keep from gusting out–remaining photogenic all the while. A view to the E, from the same spot as the last shot, showed multiple, parallel, cumuliform inflow bands feeding into the high base. What an interesting and beautiful process to behold!
Road voids over the buttes and mesas (here spotlit with sunlight against a dark storm background) kept us somewhat distant from the storm at times, and/or relegated to its SW side, but that was obviously not a problem from a photographic standpoint. In fact, we stayed on the western fringes of both the storm’s rear-flank core area and the Cedar Creek wind farm to take advantages of (and marvel at) scenes like this and like this.
Back roads delivered us healthy and well to CO-71, whereupon we headed S to CO-14, stopping along the way to view the gorgeous towers to our NE over the shortgrass prairie. Eastward we moved on 14 to get back near the SE-moving, high-based supercell, which seemed to be accelerating. Daylight fading, we decided to stay in good light and on the storm’s back side as it approached Sterling, and let the rear-flank gust front and its wondrous collection of tinted cloud material pass over the green wheat fields.
Sunset time was a dazzling experience, with elevated storms that were growing to the W helping to cast differential light, shadow and hue across the convective sky to our immediate SE. I had to slap on a multi-stop graduated neutral density filter to offset some of the dynamic range (old-fashioned, I know…but it worked out well). At times, the colors were out of this world…seldom have we witnessed such a variety of light and texture in such a small part of a convective sky! The experience was amazing–parked on a remote, dirt back road with nothing but us, the sky, the cool breeze, and some singing meadowlarks for company. This is why we travel to the High Plains every year.
The convection to the W grew larger and started putting on a fairly furious electrical show after dark, but we had to forgo lightning photography to get Elke some suddenly-needed medicine in Sterling. That wasn’t available, so we headed promptly down I-76 to to the outskirts of DEN for the night, enjoying the flickering light show in our side windows and rear-view mirror while hoping she would be healthy enough to chase the following few days (great news…she was, and we had a fantastic chase in the Nebraska Sandhills the next day!).