I was really on the fence about this day, since I had just gotten back from a solid 5 weeks of chasing as a part of
VORTEX 2. However, the setup looked good enough to make me want to drive to southeastern Nebraska; Dan and I left mid-morning to make the relatively long trek northward. By the time we got to Wichita, we saw the developing supercells in extreme northern Kansas and southern Nebraska east of Belleville. Shoot. One of these supercells apparently produced a tornado near Marysville while we were somewhere near Salina. The 12z EMC 4km WRF that I looked correctly forecast late-morning initiation of supercells in far southeastern NE and northeastern KS, with nothing substantial forecast after this initial wave. By the time we reached Concrdia and, particularly, Belleville, we knew that we had to make a decision... We could either jet eastward to catch up with the northwestern supercell near Seneca, which may take us out of position for afternoon convection in south-central NE, or we could blow off the northeastern KS supercells and continue onward towards our target. Since the nearest supercell was about an hours drive from us, and moving away, we didn't want to risk being out of position for the main show. So, we continued northward.
Through the next few hours, we shifted westward in southern NE as the outflow from the morning and early afternoon supercells expanded west and northwestward across southern NE. Near Red Cloud, we noticed sustained convective development along I80 and along the edge of an apparently strong cap, so we blasted north. We eventually got a look of the base north of Minden, or east of Kearney, and we plotted are route to get a better view of the meso. At first glance, we saw a nice RFD clear slot working around a good low-level meso. While driving N out of Gibbon several miles, we saw a tornado to our NNW or NW; the tornado was a decent elephant trunk that lasted less than a minute or two (need to check my tape). After this occlusion, the storm took on a bit more of an HP appearance, with a wet, rain-filled RFD.
By the time we reached Alda, the newest RFD clear slot was relatively rain-free, and we were treated to at least a couple of very impressive, extremely rapidly-rotating low-level mesocyclones between Alda and Grand Island. In fact, I'm still amazed that these low-level mesocyclones did not produce substantial tornadoes. The RFD seemed rather warm, and motion on the low meso and wall clouds was impressive. I didn't think we could get ot Hwy 34 on the south side of GRI, so we dropped south to I80 and continued eastward to Giltner Rd. At this time, the structure was fantastic, though even this jaunt to get out ahead of the storm didn't get us far enough ahead to get a really good view of the storm structure.
At any rate, the low-level meso to our NW looked to produce one short-lived tornado as we were positioning on Giltner Rd between US34 and I80, before a more intense and long-lasting tornado developed between Phillips and Aurora. The track of the tornado was relatively predictable, and visibility was good, so we ended up taking roads
that got us close to the tornado (~1/2-3/4 miles) while still leaving us comfortable (we were south and southwest of it at this time). The tornado started off as a truncated cone with big dust whirl at the surface, and it grew in size as it progessed eastward. For the first 50-60% of the life of the tornado, I thought it looked a lot like the
Attica tornado from 5/12/04; in it's largest state, it had a nice barrel shape (NOT a wedge that I heard reported!). We followed the storm through York, NE, before calling off the chase in darkness.
Overall, I'm very pleased with this chase. The motion at cloud was and associated with wall clouds and low-level mesocyclones was fantastic (again, I have no idea why there wasn't at least one substantial tornado west of GRI). The structure was also very good when we got out ahead of the supercell enough to see it, and we got a good view of the largest tornado west of Aurora. The
NWS damage assessment of this tornado rated it an EF2, probably at least 1/4 of a mile wide at it's widest, and on the ground for ~18 minutes. I'm happy that we made the right decision in terms of not chasing after the northeastern KS supercells in the early-mid afternoon and sticking with our original target. The roads were very good for the most part (every 1 mile, pretty good gravel state, etc), and the supercell moved slowly enough and nearly parallel to the E-W roads to make chasing quite easy.
MORE PICTURES AND VIDEO AT
http://www.tornadocentral.com/chasing/2009/06172009.php
