Chase Log: October 29th, 2004


Click on any of the SPC products below (Convective Outlooks, Watches, or MCDs) to see the SPC's "Severe Thunderstorm Events" page pertaining to this event.


MAP

Total Distance: 350 miles
Target Area: Shawnee to Henryetta, OK
Chase Area: Wetumka to east of Checotah, OK
Maximum SPC Risk category: Slight
Watches: Tornado Watch 872
Mesoscale Discussions (MCDs): 3276 and 2379

Given the time of year, I just had to chase as I knew it would most likely be the last chase opportunity until spring. Moderate instability had built across eastern Oklahoma as a strong upper-wave opened and ejected into the northern plains by evening. A strong low-pressure system was to move across central Minnesota by late evening, dragging a cold front and dryline across central and eastern Oklahoma. I had been targeting northcentral and northeastern Oklahoma, but winds had veered to southwest across that area by early afternoon. Therefore, we opted to head east on I40 about 2:15pm.

Essentially, we drove east on I40, hoping for one of the towering cumulus near us to break the cap and give us something. As we drove east of Shawnee, we noticed a nice cumulus congestus to our south that was getting larger in time. When we saw that it was precipitating, we headed south and southeastward towards it. When the base come into view, we saw a nice wall-cloud right under the updraft, to our amazement. Our hopes quickly grew as we came closer to this nice supercell.

We followed the storm for the next couple of hours east-northeastward. We witnessed several relatively textbook mesocyclone occlusion as the RFD punched around several times. Despite the several wall clouds that developed that looked like they'd be able to produce a tornado, no tornado ever developed. As the sun set around 6:45pm, we gave up the chase as the storm appeared to be weakening anyways.

Despite failed tornadogenesis, the chase was still pretty nice. Afterall, how often can you see a pretty textbook supercell in the last couple of days of October? There are a couple of interesting things to note about this supercell. First of all, the storm had no anvil. Looking at the nearby soundings, this comes as no surprise given the low equilibrium level courtesy of warm mid-level temperatures. Nonetheless, it looked more like a big towering cumulus than anything else. Second of all, the storm looked very small on radar and produce little if any hail (if it had much, we would have experienced it given our location relative to the storm a couple of times). The Tulsa NWSFO labeled the storm a mini-supercell, and our observations agree with this.

Can't wait for next year...

10-29-2004 Chase Pictures

Click on any photo to see a larger version

The first look at a 'suspicious' feature underneath the updraft. We were a little surprised at this given the cumulus congestus-like appearance that storm had at this point. A nice picture presented itself as we drove eastward on I40 near Henryetta. You can nicely see edge of the mesocyclone, as well as a rather ragged storm base. This is a developing wallcloud not too far north of I40 near Lake Eufaula. The wallcloud continued to develop just to our north. A more substantial wallcloud now to our northwest as we continued on I40 eastward, looking to get past Eufaula Lake. You can start to see the RFD clear-slot on the left side. The lack of an adequate stopping spot meant that we had to shoot out whatever window we could. We found a nice hill onto which we could set up our tripods. The RFD action was pretty intense at this point. Notice the precipitation wrapping around the meso with the RFD. The main precipitation core is east of this feature. The wallcloud with relatively strong upward motion on the east side as the RFD punched around the mesocyclone. The wallcloud with relatively strong upward motion on the east side as the RFD punched around the mesocyclone. The RFD had advanced considerably in the previous couple of minutes. The wallcloud was now beginning to fall apart. After the previous wallcloud had completely dissipated, this new wallcloud developed as we neared Checotah on I40. At the end of the chase, heading west on I40 back to Norman, we saw these anvils from a storm well to our south. I find it interesting that the orphan anvils looks as if the storm had "puffed" several times, each time allowing a surface-based parcel to ascend for a short while before being cut-off. This parcel would result in an anvil. It almost looked like a sequence of anvils that gradually "grew" downward to the west. Just a guess, but interesting nonetheless.