December 23rd, 2015 Low Topped Supercells

Tornadoes: 0

Highest Wind Gust: 50 mph (estimated)

Largest Hail: N/A

Other notes: A VERY photogenic chase, prepare for image overload!

This chase was one that was planned surprisingly well ahead of time, particularly for December. It appeared that that typical insane-o-shear that exists with wintertime systems would overlap with modest instability of 500-1250 j/kg of CAPE somewhere in Illinois, leading to decent threat for tornadoes in a time of year where we should be buried in snow. Meanwhile, a much more substantial threat would be present down south, where long-tracked and deadly tornadoes would occur. However, the threat in Illinois was rare for this time of year, and that made it stand out.

Started off the day with my eyes on Galesburg as a target. The models had shifted the whole system west compared to the day before in response to the more rapid deepening of the low. The setup was reliant on atmospheric recovery from morning convection, which is much more typical of a May or June severe weather event. We were still forecast to get around 1000 CAPE, and west-central Illinois did begin to see some sunshine by late morning. The SPC issued a Slight Risk for severe weather with most notably 5% tornado probs for IL.

A mesoscale discussion was issued as we walked out the door around 1 PM, and a Tornado Watch was issued as we approached Galesburg.

As we approached from the west, near Kewanee, we could see low-topped cumulus towers located in eastern Missouri on the western horizon. It was really exhilarating to be able to watch this again, since it's been months. These towers would eventually organize into our storms and cross the Mississippi River into Illinois.

After a quick stop in Galesburg, we continued south then west. The first photo was taken south of Abingdon, while the second was taken west of Roseville along Highway 67, right when we got a decent view of an updraft base.

We sat here for a while, noting another updraft base to our southwest associated with a mmore vigorous storm that had some decent rotation on it. If it dropped a tornado, it would be perfectly visible to us as it came in our general direction. The low sun angle made for some neat visuals and some nice contrast.

The base on this storm became much more shelfy and outflow dominant, as can be seen by the last image, although there was probably still an attempt at a wall cloud occurring. There was also a very nice broken rainbow being cast onto the rain curtains to the northeast.

It was at this time that a Tornado Warning came out for the storm to our south. A confirmed tornado was on the ground only 5 miles away, on the other side of its core. Crap.

So we turn and head east to catch it as it crosses the road we're on, hoping any tornado is still with it. We cross primarily ahead of the core, with the sun filtering through the curtains of rain.

The updraft base became visible, and to my dismay, the tornado had dissipated. However, it appeared that there was renewed circulation. As it approached and came closer, thin rain bands wrapping rapidly around it became evident as the RFD surged, with a clear slot to boot. It was really a majestic sight to behold, with thin, delicate curtains racing south to north around a mesocyclone that glowed golden.

I was convinced another tornado would drop with the rather textbook supercellular processes, but unfortunately it never even came close. What a shame too, as that would've been the photo opportunity of a lifetime. A glowing orange tornado extending from a glowing orange supercell, with a bright glowing orange sunset in the distance. But even without the tornado, THIS was definitely a great show. And it got even better. To our south, another storm yielded an incredible mammatus display lit up orange and pink. One of the better, if not the best, displays I've seen.

The storm we were observing eventually fully occluded and lifted off to the northeast, and we tried to keep up with it as best we could. It still had a crisp updraft tower with its own mammatus as it raced along.

A while later, yet another Tornado Warning was issued for the storm, for Knox County. I was perplexed at the fact that it was warned with such mediocre radar returns.

It turns out that a spotter reported a funnel cloud, which I didn't see even with a fairly clear view of the base from behind (desperately trying to keep up), so not sure if it just slipped past me or if the report was mistaken. It very well could have slipped by me, as a wall cloud was present from our viewpoint when the warning was issued. Either way the NWS in Lincoln was taking it seriously.

The wall cloud can be noted beneath the updraft tower of the storm in this image:

Watched closely, but nothing became of it. I was able to take note of an uptick in lightning from the storm during this time, going from essentially zero to one every 15 seconds or so.

We fell very behind the storms once we eventually hit a rough patch in the road network, so I decided to get out of the car for a few minutes to take some longer exposures of the convection.

We then grabbed a quick bite to eat in Kewanee and got home by 7 o'clock.

A video overview of the two supercells during the daylight hours...absolutely stunning color:

I have some mixed feelings about this chase. The first emotion that comes into play is frustration. We missed a tornado by only miles, and would've seen it had we realized the first storm we were on had little chance with its outflow dominance and moved to the next cell down the line. But at the same time, I just had among the best chases of the year in late December. Simply having the OPPORTUNITY to miss a tornado in December is a privilege. It felt like April again, really. It was the most photogenic chase for me by quite a long shot as well. The low sun angle just lit everything up. The chase terrain was absolutely incredible. And not to mention, my forecast wasn't too far off as a whole, which is a big step in the right direction for me. In fact, my initial target of Galesburg was under a Tornado Warning at one point. Not bad.

GPS History:

SPC Storm Reports: