Waking only a few hours later, I immediately reviewed data and to my dismay, realized that I was horribly out of position. The day's target had shifted to south central Nebraska; specifically an area from Aurora to York. By late afternoon, it appeared that a mesolow would be located a few miles west of Aurora at the intersection of a northeast/southwest oriented cold front and north/south oriented surface trough. Speed shear throughout the atmosphere was somewhat weak, but with favorable directional shear and CAPE values of 4000+ progged, supercells seemed likely. I expected and hoped the cap would hold until at least 5 p.m. I had just enough time to make it with my 11:00 a.m. departure from Sioux Falls.
Upon arriving in Aurora at 4 p.m., I downloaded a few radar images with the laptop and cell phone. The boundaries and mesolow were magnificently obvious on radar. The triple-point was located about 30 miles west of Grand Island, so I bumped west about 15 miles and waited.
By 5 p.m., I was beginning to get discouraged. There had yet to be any significant cumulus towers develop, and the cap looked to be holding strong. However, my hopes shot back up 15 minutes later as the first decent tower developed about 10 miles to my west. It briefly seemed to have potential. The cap continued to hold though, and within a few minutes, nothing but the top of the cumulus tower remained with a rather large and well-formed funnel dangling beneath it for a couple of minutes.
At 6:40, after receiving a nowcast from Dave Lewison concerning a decent tower noticeable to my southwest on satellite, I took Hwy. 14 south, then west on Hwy. 6. At 7 p.m., the cap broke, and within twenty minutes, there were two distinct cells. One in northern Webster County to my south that featured a rock-hard updraft tower, and a newly-developed LP near Glenvil that I was observing. The LP displayed a fairly well-formed updraft, anvil, and beaver's tail. Dave confirmed my thoughts that this cell was moving northeast along the boundary and far enough away from the southern cell as to not have its inflow disrupted. I decided to stick with it and not worry about the southern storm.
With the cell now northwest of Clay Center, I continued north on a dirt road toward Harvard. By 7:50, the cell, although a bit high-based, had organized substantially into a Classic supercell with a striated updraft and wall cloud as it continued riding northeast along the front. NWS Hastings issued a tornado warning for it at 8 p.m. Within ten minutes, the meso, which was a couple miles to my northeast, had become somewhat rain-wrapped as the RFD punched around, and features were hard to discern.
However, a new meso rapidly formed about 1/2 mile north of my location and contained intense rotation. The RFD soon began punching in, and just to my north, intense cyclonic rotation continued while the anticyclonic portion spun to my northwest. The meso produced a nice funnel that persisted for about a minute before dissipating. A large gustnado, which I mistook as a tornado at the time, also rotated across a field on the nose of the RFD.
Now heading east again toward Stockham, a large amount of dust was suddenly kicked up and began rotating under the meso just after 8:30. The large dust-whirl tornado persisted for a couple of minutes, transforming into two tall columns of dust rising into the meso before gusting out and dissipating. The RFD slammed into me soon after, sending much dust into my car.
I continued tracking the cell to Henderson, but as the sun set, the storm also appeared outflow dominant. After stopping briefly to say hello to Tim Samaras, I turned my attention toward another tornado-warned cell southwest of Giltner. However, it also died a quick death but not before producing a beautiful display of anvil crawlers as darkness fell.
Overall, a great day except for the Nebraska dust getting inside my car, which played havoc with my allergies for the rest of my vacation. I suppose that's a small price to pay though. Also, I'm obligated to extend much appreciation to Dave Lewison for the accurate and timely information he provided me with throughout the chase.