23 May 2008

Chase partners:  Scott Longmore, Kate Musgrave, Jonathan Vigh, Eric Hendricks, Andy Newman, Nick Parazoo

Result:  Multiple tornadoes in southeast Wyoming
 
After the tragic events in Greeley and Windsor the previous day, the large scale weather pattern remained very similar on Friday the 23rd. The upper-level low had hardly moved, and the surface low had shifted only slightly to the northeast. Moisture would once again wrap around the north side of the surface low, and the shear at all levels would be extreme in that area.

A group of us left the department around 1:30 with an initial plan to just head out toward Ault on Hwy 14 and see what developed. But shortly after we left, some strong cells went up in northern Weld County with a track toward Cheyenne. We ventured north on I-25, meeting up at the Flying J truck stop just south of CYS. A few cells had already moved to the north of the area at that point, as storm motions were very fast again. From the truck stop, we saw a storm to our southwest developing rapidly.

We continued north on I-25 and exited onto Horse Creek Road a few miles north of CYS. Shortly thereafter we saw a tornado form to our north, which lasted a short while and was then followed by a larger tornado. This was followed by a large wedge, and tornadoes continued to cycle with this storm for about 25 minutes. (My video timestamp shows the first tornado at about 3:14, with tornadoes intermittently through about 3:37.) We ended up following this storm well out into some higher terrain before it appeared to weaken and we couldn't get a view of it anymore because of the mesas in the area.

Video (which is pretty shaky at times, sorry) from this first storm can be seen here. (4.5 minutes, 54 MB)


First tornado northwest of Cheyenne. Photo Copyright Scott Longmore.



At that point the two cars got separated. The other car raced off quickly, and we ended up taking a bit of a wrong turn and driving through downtown Cheyenne, but finally made our way back out to I-80 east to try to intercept some storms moving up from Colorado. We exited at Hillsdale and continued north, eventually getting onto US Highway 85. We encountered a very picturesque scene, with vicious-looking clouds to our north over some nice terrain features. As Scott and I were watching this part of the storm, Kate pointed out a developing tornado on the west edge! This tornado had striking bands of cloud wrapping around within the mesocyclone above the funnel, with a mesa (called Bear Mountain, apparently) in the background. It was quite a stunning scene.

We watched this storm for a while before the tornado dissipated, and then continued north on 85 to see yet another tornado develop to the northwest of Hawk Springs. This one also lasted for 8-10 minutes, with at least two different condensation funnels appearing from the bottom of a well-developed wall cloud.

We followed it farther northward and stopped in the town of Yoder, where it was trying to produce another tornado but it didn't quite happen. Then we started feeling outflow from other convection to the east and our storm quickly died.

Video from the storms along Hwy 85 can be seen here. (8 minutes, 99 MB)

This was one of my best chase days ever for a lot of reasons: multiple tornadic storms with long-lived tornadoes; the beautiful terrain in southern Wyoming; the tornadoes occurred over primarily rural areas, so they fortunately did not affect a lot of people like the previous day's storms did; most other chasers were in Kansas, so we felt like we were all by ourselves on these storms; it was a pretty short drive from home and we were back to Fort Collins by 9 pm.

I was mostly taking video (which is shaky again...I would've had time to get out the tripod too!), so my still images are interspersed with better ones taken by Scott:


Ominous clouds over Bear Mountain, Wyoming.


Tornado west of Bear Mountain. Taken from US Highway 85, looking NW, at 5:49 pm. Photo Copyright Scott Longmore.


Photo Copyright Scott Longmore.


Tornadic supercell northwest of Hawk Springs, Wyoming at 6:02 pm.


Photo by Scott Longmore.



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