June 26, 2020 El Paso County, Colorado Chase
Spectacular Tornado-Warned Supercell

by John Farley

The setup:

With a stalled cold front from central to southeast Colorado, upslope easterly flow north/northeast of the front, dewpoints in the 50s, and a weak shortwave passing, all necessary elements for severe storms and, in the early stages of storm development at least, supercells would be present in parts of Colorado east of the Rockies, particularly near I-25 and the Palmer Divide. Dewpoints in the 50s aren't great for severe weather in the Midwest, but on the high plains of Colorado that is plenty. With that degree of moisture and daytime heating, CAPE of at least 1,000-2,000 appeared likely, with perhaps some pockets of even greater instability. There would also be wind shear, with the low-level easterlies and westerly winds higher up. Models both the day before and the morning of the event were showing a particularly strong combination of instability and shear roughly between Denver and Colorado Springs, perhaps spreading south to Pueblo as the day went on. In this area, storm-relative helicity would be around 300 in the lower 3 km of the atmosphere and 100-125 in the lowest km. And the stalled front would offer a boundary for the storms to form on, helped along by the wave passing through and perhaps terrain effects of the Palmer Divide. Storms were forecast by various convection-allowing models (CAMs) to develop over the mountains between noon and 2:00 p.m. and shift east or southeast into the I-25 corridor shortly thereafter. There was some disagreement among the CAMs in the areal coverage and southern extent of the storms, but they all agreed with this general idea. Also, it was expected that the storms would start out as supercells, though they might gradually evolve into a larger complex of less isolated, more numerous storms. Everything said pretty clearly to me to be somewhere a little east of Colorado Springs by around 2:00 or 3:00 p.m. That was my idea both the night before and the morning of the chase day, and nothing really changed. My approximate target was around Peyton, CO and that is exactly where I ended up, passing through there and starting a short distance northwest of there, then passing through again moving toward the south staying ahead of the storms.

The chase:

I was on the road out of Pagosa Springs before 9:00, and into Walsenburg to grab some lunch around noon. No storms yet by then, but by the time I was getting into Pueblo for a gas stop around 1:00 p.m., I could see some in the distance. At 1:10 p.m., I think while I was in the Pueblo area, a severe thunderstorm watch was issued basically for the eastern half of Colorado. The watch text mentioned the possiblity of hail to 2" in diameter, wind gusts to 70 mph, and a tornado or two possible. That came about an hour after SPC had issued a mesoscale discussion indicating an 80 percent likelihood of a watch in that area. Before I reached Fountain, where I planned to exit and head east and north to my target, I noticed on radar that what appeared to be a supercell had formed just southwest of Denver. At 2:00 p.m., the first SVR warning of the day was issued by the Denver NWS for parts of Douglas, Arapahoe, and Jefferson Counties, with Castle Rock, among other places, in the path of the storm. Figuring the storm would continue southeast from there, my strategy of heading north toward Peyton seemed just about perfect, though I did delay myself a few minutes by making a wrong turn in Fountain. But I was able to right that and get on track fairly quickly, and as I was heading north toward Peyton, the storm to my northwest gradually came into better view.

3:00 - By around this time, I was on the storm NW of Peyton, near the El Paso/Elbert County line. The storm, to my NW, had by now had three SVR warnings from the BOU NWS for areas such as Castle Rock, and including Elbert County. The storm seemed to be building to the SW as it tracked SSE from the Castle Rock area, briefly forming a wall cloud a bit down the line SW of the main core. After a little while, the area around that wall cloud filled in with rain and hail and the wall cloud disappeared. A SVR warning was issued for NW El Paso County at 3:20 until 4:00 p.m. by the NWS in Pueblo. I was along and eventually a mile or two west of Elbert Road, northwest of Peyton and south of Elbert. Gradually, I could see to my NW what I at first thought was a shelf cloud but as it got closer I determined that it was actually the meso, as the storm had taken on something of an HP character - there was heavy precip behind the lowered area and both to its left and right. Here are a couple pictures, shortly after this feature came into view and a little later with lightning as the feature surged to the SSE:

One nice thing about this storm was opportunities, from various angles over the course of the chase, to get pictures of it together with ones of Pike's Peak. Here is a photo of the ominous cloud base as it began to move between Pike's Peak and my location northwest of Peyton.

3:45 - The storm was getting closer to my position so, with a stop or two, I dropped back down to Peyton to keep ahead of it. As I neared Peyton, an inflow tail formed on the NE side of the now more-distinct wall cloud and extended toward the ground. This feature did not last long, but as I got into Peyton, the first of two TOR warnings was issued at 4:13, valid until 4:45. I remember glancing at RadarScope a few minutes before the warning was issued, maybe around the time of the aforementioned inflow tail, and seeing that there was very strong rotation occurring. I stopped by the post office at the west edge of town and got a few photos of the wall cloud, now extending about halfway to the ground.

I decided to move down U.S. 24 to the SW a little to get a closer and more clear view and some video. Had to get through a construction zone but after that I found a good viewing spot 3 or 4 miles SW of Peyton and stopped to get video, joined by some other chasers at that spot. There were some possible brief funnels, with the lowering extending halfway or more to the ground from the cloud base at times. Some cloud-base rotation, but no real persistent funnels. Lightning occurring included not only CG in the core but also some CC bolts coming out of the wall cloud or out from behind it. Here are a few pictures and video captures:

Golfball to tennis ball hail was reported at several locations between AF ACademy and Black Forest, perhaps 10 miles or so west of my location. The storm was spectacular in the relatively haze-free air with Pikes Peak in the background at its left, the lowerings extending at times halfway or a little more to the ground, and the lightning near the wall cloud.

4:45 - The TOR warning was allowed to expire and was replaced by a new SVR warning. The storm was getting close and a few drops of rain started to fall. I decided to move south on the N-S road from Peyton to stay ahead of the storm. About 20 minutes later 1-inch hail fell in the approximate location where I had been, and shortly later, golfball hail a little SE of there. But I stayed ahead of the storm and encountered no hail. Around 5:00, a second TOR was issued, and I stopped again to watch the storm. This was just before the two aforementioned hail reports. I was in very strong inflow now ahead of the storm, with the southeasterly inflow coming from behind me as I looked at the storm. That also showed up well on the radar velocity mode. Around the time the warning was issued, the storm seemed to be cycling. There was a lowering - could have been a funnel, but it was pretty ragged and brief - about halfway to the ground farther off to the northwest:

However, the storm seemed to cycle and a new meso seemed to be forming closer to me, and it quickly became the dominant one. With this there was a distinct though small RFD notch around the wall cloud, but the wall cloud never lowered to the extent that had occurred during the first warning:

One thing that made this storm so photogenic was the colors in the clouds. Often the deeper part of the clouds displayed the blue-green color one often sees in hail-producing storms, and the ambiant light at times gave the lowered areas of the cloud base a pinkish color. Here is a good example, shortly before the second tornado warning expired:

5:30 - I was now at the intersection with Squirrel Ridge Road, between Ellicott and Fountain. The TOR warning was allowed to expire, but the SVR warning continued and was replaced with a new warning a few minutes later. The meso, now without any distinct lowering, crossed the road I had been on a few miles north of me. The storm was moving more SE now, rather than its earlier SSE movement, so less of a right-mover than it had been. It did not look to me like there was much further chance for a tornado, and I still had some thought of trying to get home and avoid a motel stay (did not work out that way, though), so I broke off and headed back west. The last two hail reports from the storm came just east of Ellicott and a bit farther southeast just south of Truckton after I left the storm. No further severe weather was reported from this cell after 6:20, so my decision to leave it worked out OK.

8:15 - I got a nice picture of the setting sun illuminating the anvil and updrafts of a new storm looking east from Walsenburg:

A few final thoughts. One interesting aspect of this storm was the very pronounced beavertail feature that it had for much of its life. During much of the chase I was near or underneath it, so I was not real conscious of it, thinking it may just have been updraft base from its appearance from underneath. But it was very noticeable near the end of the chase when I got a little more ahead of the storm, and in looking at my pictures I could see it was also evident when I first got on the storm, while it was still pretty far away. Here are two panorama photomerge images, the first from very near the beginning of the chase and the second from near the end. The beavertail feature is quite evident on the right-hand side of both pictures:

One other thing - there were a lot of chasers on this storm. No real backups and generally people were careful and considerate, though there were a couple that did not quite get their vehicles completely off the road. But mostly no problems. One thing that surprised me, though, was to see at least 3 vans from at least two different storm chasing tour organizations. I would NOT want to spend the day right now in a vehicle with a lot of people I don't know from potentially all over the world, but to each their own, I guess.

Approximate chase distance, total round trip: 590 miles.

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