Start: Wray, CO
Brunch: Otis, CO
End: Yuma, CO (469 miles)
Chase account by Tempest guest Lesleyanne, with the other TT group
This was the last chase day for the Tour 6 photo group. It would be really nice to finish up on a high note, especially since the previous two chase days had been Debbie Downers. SPC was showing just a marginal risk in northeastern CO and along I-70 in western Kansas along a stalled-out W-E boundary. Somewhat higher severe storm risk was in and around southeastern Nebraska. Since the tornado prospects weren’t really very good in any area, and since we were starting the day at Wray, and since we needed to finish the chase day within 4-6 hours of Denver, it seemed prudent to try our chances right here along the nearby boundary.
After brunch, we drifted north of Otis, CO, to an abandoned ranch. We had rather nice easterlies at the surface here, beneath 25-30 knot WSW flow at 500 mb. But, prospects for northeastern Colorado severe just were not looking that good as we got into mid-afternoon. Moisture convergence, CAPE (5000!), and SCP values were looking much better towards a weak triple-point surface low in northwestern Kansas. We headed that direction, and hoped that the good stuff would wait for our arrival. Thank goodness, it did.
It took perhaps 2 to 2.5 hours to get close, but finally we were heading south right in front of some decent storm towers near Grainfield, KS, near I-70. So far, the storm activity at this triple point had remained weak. Along and south of the west-east boundary was really hot air. The ASOS at Oakley AP showed 105F/38F and SW wind at 20 knots at 5 p.m. CDT! This hot air was blowing up against very warm and moist easterlies. At 5 p.m., Hill City had 93F/72F, ESE at 15 knots.
Now it was close to 7:30 CDT, about an hour before sunset, and we stopped close to Grainfield to watch a couple of separate updrafts develop. These struggled for a bit, but gradually the storm bases expanded in size.
I liked the western-most cell a bit more than the eastern one…perhaps because it was closer to the strong surface convergence. The storm base was quite high, which was not surprising since air temperature was near 100F nearby. We used the unpaved farm road network south of I-70 to position ourselves just southeast and south of the west cell. Lightning caused a little grass fire to our north, and outflow winds blew its smoke at us. The activity seemed to back-build a bit to the west, towards Grinnell, as sunset approached. We scooted west a little more and then north a mile or two, winding up maybe 3-4 miles ESE of Grinnell. From here we had storm bases to our NW, N and NE. Early on at this locale, the cell to our northeast was the most active with the cloud-to-ground lightning, and for a few minutes it looked like a little tornado was kicking up the Kansas dirt. The images in the group below show the dust whirl to our northeast, and plenty of CGs down the road to the north.
As you can see, the light at sunset was fantastic, and the lightning photography was easy! There were CGs every 5-10 seconds easy. I traded off the wide-angle lens (21 mm) for the long lens (70-200mm) and back again. Most of the shots above were around 2 seconds in shutter speed. With the long lens, it was somewhat difficult to choose the right area to “focus-in” on, as numerous parts of the cloud base(s) were issuing fairly frequent lightning bolts!
The amazing show continued for about an hour after sunset, and we were able to remain at the same spot. The most active area was now to the north, so I did a little zooming-in down the road.
Lightning in this direction waned a bit, but then picked up to our WNW, towards Grinnell. I zoomed in a bit again, prayed for a nice bolt in the frame, and my prayers were answered time and time again. This was an embarrassment of riches for a lightning photographer.
As the nice light of dusk ended, the lightning frequency subsided also, and it was time to head to the motel.
Below are some iPhone pics and radar screenshots from the “chase.” The following morning we visited “mom” again for breakfast, and we were the talk of the town in Otis!
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