Green Sky Chaser

31 May 2010 Chase Log

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Target Area: Boise City, Oklahoma to Springfield, Colorado to Johnson City, Kansas (Click on city names for Yahoo! maps links)

Chase Area: Campo, Colorado to Boise City/Guymon, Oklahoma

Observations: multi-vortex tornado, five or six funnel clouds, three or four wall clouds, one supercell, ping-pong to golfball-sized hail, lightning, and Dorothy and Toto

Distance: 780 miles

Time: 14 hours

Chase Team: Dean Narramore, Willoughby Owen, Rob Warren, Rob Lee, and myself

SPC Convective Outlook: Slight Risk (Click to see SPC products, data, and storm reports)

Chase Setup: Primarily zonal flow across the U.S. with a few embedded shortwaves in the mid-levels. One subtle shortwave was expected (and probably verified) over southeast Colorado. Outflow from the previous day's convection helped push a front southward to Texas, but southerly surface winds aided in bringing the front back north to around the Oklahoma Panhandle by late in the day. Dewpoints in southeast Colorado into the Oklahoma Panhandle were near 50 °F. Steep mid-level lapse rates of 8 °C km-1 and higher and MLCAPE of 1500 to 3000 J kg-1 indicated moderate instability in the Oklahoma Panhandle into southeastern Colorado, where effective SRH was around 150 to 200 m2 s-2 and 0 - 6 km bulk layer shear was between 30 and 40 knots. A few multicells and supercells were expected, with the threat of large hail.

Blog Entries:

First Colorado Chase (after)


Chase Log: We started out the day in Enid, Oklahoma, and headed out for somewhere in the eastern Oklahoma Panhandle to southeastern Colorado. This was a very marginal day, and seemed to be highly dependent on upper-level forcing. However, although we did wind up with a beautiful tornado this day, any shortwave that did exist was too small to really be evident on 500 mb maps after the fact.

By the time we got about halfway through the Oklahoma Panhandle, we heard that a lone supercell in southeastern Colorado had already produced two tornadoes. Feeling rather disappointed, thinking that we would not make it to the storm in time to see anything else it had to offer, we pushed on for the next hour and half or so until we finally reached the Colorado border.

The slow-moving supercell seemed to have waited just for us, as we had plenty of time to approach it and got up right next to a wall cloud. Some time around then we realized that we were low on gas, and might have to abandon the storm for a bit so we could run up to Springfield and fill up. However, as a new wall cloud began to form and a couple of funnel clouds appeared, we opted to stay where we were.

The storm was moving towards the southeast, so before long we found ourselves in the bear's cage, between a wall cloud and the hail core (which was producing baseball-sized hail).

As the wall cloud began to tighten up and quickly rotate, nearly overhead, and with large hail stones coming our way, we almost left our position to back off the storm just a bit. Just then a solid funnel cloud appeared under the wall cloud and began to needle its way down. At 6:09 pm Mountain Time, I saw my first Colorado tornado and my first tornado in Mountain Time as the funnel cloud touched down. This gorgeous stovepipe was just a few miles south of Campo.

With the high contrast of the silver-gray tornado against a bright blue sky and another supercell on the horizon, we witnessed one of the most beautiful tornadoes I have ever seen. We guessed we were less than half a mile away (probably about 500 m) from the tornado while it touched down in an open field next to us. Our position yielded a great background against which to photograph the tornado; had we been on the other side of the tornado, with it coming towards us, we would have had the dark hail core for a background.

Hail started to fall and eventually we had to get in the car and drive away from the hail core (but towards the tornado) as we began to get pelted by golfballs (Dean got a couple of bruises on his arm from two stones, and I got hit by large ones on the back of my neck and my nose, which was rather painful).

The tornado briefly scared us when it crossed the road in front of us and nearly hit a house, but thankfully the tornado did not cause any damage beyond a few broken power poles and a windmill.

We realized the tornado must have been multi-vortex when we saw a few suction vortices around the bottom of the debris cloud. We then saw the tornado become rain-wrapped for a couple minutes, before coming back out of the rain and passing over a brilliant double rainbow. We lost sight of the tornado in the rain at 6:37 pm Mountain Time.

We arrived in Boise City just before 8 pm Central Time / 7 pm Mountain Time, at which time Dean saw and got video of the rope out of the tornado. Unfortunately, none of the rest of us saw it, as we were inside the gas station or filling up the car. We later saw this tornado was reported as a separate tornado rather than the same one, so Dean actually got to see two tornadoes.

After following the storm eastward for several miles, watching a nice, stacked plates mesocyclone and some great-looking convection to our southeast, we stopped near dark to get some lightning shots.

Later that night we drove up to Hays, Kansas, where we spent the night, in preparation for chasing in Nebraska the next day. On our way up to Hays, we briefly stopped at the Wizard of Oz Museum in Liberal, where we were able to get photos (even at midnight!) outside the museum on the Yellow Brick Road with Dorothy, Toto, and other characters from the Wizard of Oz.

What a great ending to a great day!

The Pueblo NWS has a brief write-up and maps of the tornado tracks on this website.


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VIDEO (opens to YouTube)