December 1, 2018

Saturday, December 1 and Illinois were not on most chaser’s radars a few days out from the event. We already had a couple major winter storms, and it looked like chasing was done for the year locally. A strong trough was forecast over the Mississippi Valley, but moisture and instability were limiting factors. Of course they were. It was December, not May. The Storm Prediction Center had only a categorical marginal risk out for the area on the Day 2 outlook issued on November 30. However, as the 0z NAM started to roll in, a couple of plots made me drop what I was doing and scramble to get the car ready for a storm chase: the surface chart and the 500 mb temps. A well-defined warm front was forecast over the I-72 corridor and westward with a surface low over the KC area and a closed 500 mb low just west of there. A lobe of cold air aloft was positioned right over the warm front. It was a Jon Davies’ cold core tornado pattern. The cold air aloft would more than make up for the marginal moisture and surface based CAPE, instead allowing for large amounts of low-level, 0-3km CAPE of 200-300 j/kg and very steep low level lapse rates of 8-9 C in the open warm sector. Low topped “mini supercells” result in such an environment with robust low level updrafts that are able to stretch the existing vorticity and directional shear to spin-up tornadoes from long-lived mesocyclones. A cold front was forecast way out west toward the Plains, but on the Mississippi River, the models plotted another boundary, a Pacific cold front that was acting like a dryline with a moisture gradient rather than a sharp, undercutting temperature gradient. Storms were forecast to fire off the Pacific cold front, rapidly explode into robust convection, and approach the warm front were storm relative helicity was enhanced. The pattern screamed tornado.

My initial target was just west of Jacksonville. Storms usually fire in the early afternoon on cold core events, and my plan was to catch one of the eastern most cells in a northwest to southeast arc coming off the Mississippi and moving northeast across the western IL warm sector. I left the house by two, under blue skies with scattered cumulus. The Storm Prediction Center had kept the tornado probabilities at a modest but reasonable 5%, but I was quite optimistic for my chances, and hopeful that I would at least get a photogenic storm as cold core events often feature discrete storms with rock hard convection in clear air.

Patches of snow persisted from the winter storm events in November. I was worried the snow would cool the surface off and suppress low level instability, but it turned out not to be a problem as coverage was pretty sparse. It was pretty surreal going for tornadoes with snow on the ground, however.

Storms were already underway before I had a visual, taking on nice pendant shapes on the radar, and making me feel like I was already late. Rounding Jacksonville on I-72 west, I had a visual on my target cell. It was discrete and robust yet low topped, and had just picked up a severe thunderstorm warning.

A few more miles and I had a view of the updraft base. It was already sporting a bowl shaped lowering, nicely backlit.

The lowering took on a much more pointy shape that looked a lot like a funnel cloud, but at my range I couldn’t confirm rotation really. It was in exactly the right spot, however.

Zoomed in on the evolving feature, there was no mistaking that it was indeed a legit funnel cloud. The storm still had only a severe thunderstorm warning on it. I scrambled to hammer out a report on Spotter Network to alert the National Weather Service of what was happening. The weather radars in St. Louis and Lincoln couldn’t get beams low enough to see what happening below the base of the mini-supercell, so they probably had no idea a tornadic supercell was already underway. The funnel cloud was associated with a weak EF0 tornado identified by storm chasers that were closer, but I couldn’t get a shot of the ground circulation itself from my position miles away.

I exited I-72 at Bluffs, heading north along the Illinois River. The funnel had dissipated in a scuddy manner rather than a tight rope-out, which made me question how serious the tornado potential was on this storm. Maybe the low topped storm was prettier than it was menacing, and I was crying wolf reporting this thing? The storm looked like it was cycling, however, and I wanted to be downstream in case it wrapped up again, so I quickly proceeded north up highway 100.

A bowl shaped funnel cloud developed and spun-up a thin tendril of a tornado at the surface that I missed spotting while repositioning. Fortunately, after I stopped to watch the storm, a broader plume of condensation briefly kicked up again giving me visual confirmation of a tornado. I was pretty wowed with the chase at this point. It was my first December tornado, a super pretty storm, and my expectations were already exceeded. But the chase was just getting started.

The funnel persisted for a few minute while it appeared the ground circulation concluded. The storm was just now getting a tornado warning after it had already produced two weak tornadoes. I started pursuing the storm on the road grid of the Illinois River floodplain.

Stair stepping on the grid allowed me to get right underneath the updraft base. The storm looked like it was between cycles, and there didn’t appear to be any obvious or tight rotation aloft, so I thought it was pretty safe to get close to the storm’s updraft. I stopped at an intersection and got out of the car to sample the air and get my bearings. Fallen autumn leaves were blowing from the east across the road, carried by inflow winds. They then began to corkscrew upwards in a strong updraft. I held on to my sunglasses fearing they’d go flying up too as leaves and dust pelted my face. The leaves were then whisked away back the way they came by a focused jet of strong westerly outflow. The winds couldn’t have been more than 30 or 40 mph, but I was definitely standing in some kind of circulation.

I fought the strong outflow to open the door and get back in the car. Then I began looking all around for the debris cloud that might kick up in the field nearby indicating a tornado. The dashcam captured it, at my 2 o’clock to the northeast. The weather service would later confirm an EF0 tornado developed another half mile to the northeast from that point. I had been standing in the pre-tornadic vortex.

What was most interesting about this encounter beyond the experience of feeling the developing vortex first hand, was how much later it was that the rotation appeared in the storm’s updraft base aloft. The updraft base seemed benign as I was impacted by the circulation, and it wasn’t until a couple minutes later that I started to see rotation aloft. Scientists have long suspected that tornadogenesis is sometimes, if not often, a bottom-up process, the tornado spinning up from the ground, rather than starting in the clouds aloft and touching down. Being able to directly sample the developing vortex a couple minutes before it was even visibly identifiable as a tornado, and while there was no apparent rotation overhead, cemented my belief in the bottom-up process.

A couple locals towing a boat saw me on the side of the road and stopped to see if I needed assistance. I warned them about the tornado potential to the northeast, and that the storm had already produced. They seemed pretty nonchalant and told me they were heading the other direction. I didn’t know it at the time, but it was duck season and lots of folks were out on the Illinois River taking advantage of the unusually warm weekend weather. The increased outdoor traffic could have been a recipe for disaster with a cyclic supercell tracking up the river. Fortunately, there wound up being no injuries or fatalities with this storm. A video that went viral showed a group of hunters in their camo, ducks in hand, gawking at a significant looking tornado churning up the river.

I started stair-stepping northeast as the storm was cycling once again. A funnel cloud developed to my east. It looked like it was well away from the main downdrafts of the supercell off to my northwest. Perhaps it formed on the storm’s flanking line, but the weather service wound up surveying an EF0 associated with this funnel cloud. I couldn’t get confirmation of a ground circulation from my vantage though, so didn’t count it.

I kept a fast pace trying to hold a tight position on the storm. Approaching Beardstown from the south, a dramatic circulation began to develop in the clouds aloft. The spiral, stretching overhead and wrapping up tighter and tighter, left me in awe. I slowed my approach so as to not get too close.

I pulled off the road into a driveway. The family at the nearby house was outside watching, and probably didn’t even notice me. All eyes were looking north. Before I could even stop, a point funnel cloud developed in the center of the tornado cyclone. Show time.

The circulation wound itself up even tighter, the rotation increasing. It only lasted a moment, but a snaky white funnel condensed nearly all the way down to the ground. The white tornado on the dark blue background was exquisite.

A wide angle shot from the GoPro captured the whole scene looking north, with the white hail core and rear flank downdraft on the left, the tornado and parent cyclone aloft centered, the dark blue precipitation core of the forward flank on the right, and gorgeous blue skies and convection out to the east. A classic cold core tornado.

Meanwhile, a white pick-up had passed me northbound while the tornado was in progress. As if the amazing spectacle that was underway had finally dawned on him, the driver hit the brakes, put the truck in reverse, and backed-up to where I was parked. "Nooope." Another hunter heading down to the river, he was rightfully concerned about his safety and what was going on in the clouds in front of us. I assured him that we were safe at our current position, the tornado moving directly away to the north, and if he waited a bit, it would be alright to continue into Beardstown.

The funnel persisted aloft for several minutes, but the air was soon filled with glittering pieces of white debris. The tornado was very much still in progress, this one rated an EF1 by the National Weather Service.

I got back on the road to get closer while the storm moved away. A couple of locals watched as the funnel continued north of Beardstown.

I turned east onto Highway 125 once in Beardstown. The funnel was still visible to my left, and passing over a bridge I could see a smattering of damage to rooftops with debris littering the trees.

A tree was down. I swerved around the branches that were extending out into my lane and drove over piles of sticks and leaves where the narrow tornado had crossed the highway.

I turned north on to the grid and watched the funnel roping out in the distance as it crossed the Illinois River.

Fellow Illinois chasers Devin Pitts and Colin Davis were parked where the road came to a T, watching the storm drift off to the north. I stopped momentarily to say hi and bang out a report on Spotter network of debris on 125. Then I was racing off east toward IL-78. The storm looked like it would just keep going and I didn’t want to fall behind.

Looking north across the Illinois River floodplain at classic supercell structure:

A bowl lowering with spiraling rain bands developed on the north side of the horseshoe updraft, telltale signs that tornadogenesis is underway. The weather service wound up surveying an EF0 at about this time and location, but I couldn’t confirm it from my location.

The roads carried me miles to the east and away from the storm before I could turn north out of Chandlerville. The view from afar was incredible, however, allowing me to see the whole supercell with its tilted updraft and long inflow tail. The contrast and color were also surreal, and I had no issues making out a funnel cloud starting to condense even from several miles distance. This storm was a cyclical tornado machine.

Zoomed in shot of the trunk shaped tornado taking on purple hues and backlit against an orangey evening sky: This tornado tracked near Bath, IL and was rated EF1.

I watched the whole life cycle of the tornado while continuing north up 78. I didn’t want to stop and let the storm get even further away. This tornado had a more dramatic rope-out, like a writhing snake you could see dipping into the river valley.

After the tornado dissipated, the terrain started to get more hilly and dense with trees as 78 paralleled the river. I lost my view of the base for several minutes. My plan to get it back was to actually drive even further away from the storm, cutting east out on the road grid where the terrain would hopefully be flat and I could get out from under the trees. I drove a couple miles down a farm road and swung the car around. My timing was perfect. The storm had cycled while I was navigating the bad terrain on 78, and the next tornado was starting the moment I turned around and got the camera on it.

The funnel quickly condensed and filled out into the most robust tornado yet. The storm was not only cyclical but gaining in strength. I stepped out of the car to watch the spectacle and shoot a few photos, totally blown away by the chase at this point.

I was so focused on the tornado, but finally noticed the whole scene. The structure and lighting above the tornado were incredibly dramatic. I backed the video camera off for a wider shot of one of the most amazing sights I’ve witnessed on a chase.

An even wider shot from the GoPro capturing the entire supercell with tornado and bolt of CG:

The tornado continued for minutes as I watched from my position. The tornado morphed into a multi-vortex stage. It looked like rear flank downdraft surges were causing vortex breakdown. I sent another report of the new development on Spotter Network.

The storm was getting away from me once again, the base started to fill in with rain, and the fully condensed funnels retreated. I ran north on the grid to try and get closer. The tornado persisted in a multi-vortex stage and partially rain wrapped. I pulled over for a minute, watching the motion of tendrils dancing around the tornado cyclone as they loomed behind a large industrial complex with patches of snow in the foreground. The tornado tracked from near Bluff City to Lewistown over a 15.9 mile path length and was rated EF1.

Coming into Havana, I lost sight of the circulation. Cells were encroaching from the south, the tornado was becoming more and more rain wrapped, and in order to keep up, I’d have to drive through town and make for a river crossing. I’d lose too much ground and probably never get my view back, so I decided to let the storm go. It was no loss having to abandon the cyclical tornado machine, however. Another storm was approaching from the south with clean inflow and rapidly taking on supercellular characteristics. I turned southeast out of town and had a view of the base within a couple minutes, illuminated in shades of peach and purple in the setting December sunlight.

A large gust front spanned the western sky as I approached. Not ideal from a tornado standpoint, but the structure was dramatic nevertheless.

I turned east onto the grid to stay ahead of the storm. The storm immediately began to cycle to the northeast, developing a classic yet menacing looking wall cloud. The radar depicted a prominent hook echo now and the storm quickly picked up a tornado warning.

Meanwhile, I was getting down to an eighth tank of remaining fuel. My Subaru has a nasty habit of quitting below 80 or so miles of indicated range so I was always carry a few gallons extra in the trunk. I didn't want to abandon the chase, so I decided to tap the emergency reserve. Just to further compound the situation, cloud to ground lightning was now also striking out in the clear air east of the storm and around me. You're supposed to stay in the car, and definitely not have your feet on the ground in such a situation. So I actually managed to refuel the Subaru while crouching in the back of the trunk with the back hatch up. I must have looked like a complete lunatic if anyone had passed.

But wow did that refueling stunt pay off.

I started stair stepping northeast to play the new storm. It wasn’t even 5 o’clock yet, but my light was fading fast. The wall cloud was wrapping up. Tornadogenesis looked imminent. I drove north underneath the horseshoe updraft nosing right up to the cyclone overhead. A perfect conical funnel started to descend, illuminated a ghostly grey in the last of the December twilight.

Lightning flashed backlighting the whirling debris cloud. I managed to punch out “1 N” on the Spotter Network tornado report notes, indicating its position one mile to my north as I cautiously followed the vortex north.

I couldn't help but whistle in awe as the tornado crossed ahead of me.

The tornado condensed with a large debris plume as I turned east, and then a power flash as I turned north.

I crossed Country Road 1200 where a stop sign was half blown over, and continued north trying to keep up with the tornado. However, I finally ran out of road on the grid. Rather than backtrack and fall behind, I decided to just point the car northeast and watch the tornado move off into the distance.

With each lightning flash the tornado took on a new shape. It looked like this tornado was undergoing vortex breakdown as well. The Easton tornado was rated EF1 with an 11 mile path length and caused one injury.

The condensation funnels of the multiple vortex phase retreated, but the tornado continued on for several minutes as a debris cloud below a rotating lowering. I turned south to see if I could make a play at catching back up with the storm. A local stopped to warn me that there were lines down on Co. Rd. 1200, however. I detoured around them going a mile south on the grid before linking back up with the country road. At about this time, I saw a black line top the warnings list on my GrLevel3 software. My heart sank. The color indicated that, somewhere, a “Tornado Emergency” had been issued, rare wording for a tornado warning that indicates a confirmed, large, and violent tornado is moving into a populated area. It’s something I never want to see on a chase. Another long track, cyclical supercell had developed east of St. Louis while the Illinois River Valley supercell was ongoing. It spun-up a wedge tornado after dark that impacted Taylorville, IL with EF3 damage. Fortunately there were no deaths, a testament to timely warnings and residents taking adequate shelter.

After stopping for now badly needed fuel, I made a vain effort to make another play running north out of Mason City as tornado warnings continued. The storms were congealing into a rainy mess, however, and through the inky blackness I decided to call the chase and head for home. The trek down 29 was probably the shortest drive home I’ve had for such an epic chase, and I made it back in time for dinner even.