May 20, 2017

Team Duck’s (John and Rose) Forecast:

“General feeling is that today is a complex scenario where interactions with the stationary front are going to be key to getting sufficient shear for supercells and increasing tornado potential (SPC has 2% - and based on how crappy their higher probs have been over the past week I like those odds). Deterministic guidance paints the best instability into northern IN, but the complicating factor is the approaching MCS from the west that is currently heading toward the Indiana border. How the models handle this in terms of CAMs differs substantially, with NAM proceeding with a more optimistic dissipation, contrasting HRRRs persistence at least in the southern half of the domain. Given the terrain and favorable environment space, the 12Z HRRR solution certainly looks more in favor of what we are after with a few discrete supercells on the lifting front/ahead of any line west of Indianapolis. HRRR has been trending somewhat westward however and does seem to have a good handle on this mornings MCS. Thus I suggest for an initial target Champaign, IL with adjustments as needed once details become more clear.”

Saturday, May 20, was our fifth day on the road chasing in a three vehicle caravan conducting tornado research under a grant from National Geographic. It had been a grind too. Our second season with this project, we had yet to get a usable tornado shot. We had also missed big or photogenic tornadoes on the previous three chase days, having only snagged a few brief spin-up vortices on the May 18 Kansas high risk. We had consistently swung at and struck out on the warm front, and I was getting weary of these setups. May 19 on the Missouri warm front was particularly dismal, with us chasing for hours and catching little more than rain. May 20 was another warm front, and the parameters looked even less favorable. Brindley had to get home and was done chasing junker setups so she departed Springfield the morning of the 20th, while the rest of us made plans to pick out a warm front target. At least it was relatively close to home for me, and on the way home for the others. Our three teams converged at Parkland College in Champaign, IL and there we awaited storm initiation. Horizontal convective rolls streamed past slowly building vertically.

By late afternoon storms were finally starting to take off, explosively even with a pileus caps above some of the towers. We ran north up 57 and then east out of Paxton, John leading the group toward the most robust development.

Numerous cells were going up in the warm sector south of the warm front. We targeted the most robust one that was out ahead of the group and planned to intercept it just across the border in Indiana.

Early attempts at wall clouds were noted to the southeast on the still low topped convection, a great vote of confidence for our target and positioning.

Our cell matured in front of us, the bulk of the forward flank precipitation core conveniently crossing the highway just ahead so that we could get easily get to inflow side of the storm.

We were across the Indiana border and on the eastern side of the storms. The lines of storms erupting out of the convective rolls sported lengthy shelf cloud like gust fronts beneath low topped convection in the modestly unstable air mass. I wasn’t expecting to see much more out of the day.

A cell to our northwest went tornado warned. It looked like little more than a shower on the radar reflectivity scan, but had prominent rotation on velocity and spotters were reporting a confirmed tornado in progress. “The cell found the boundary” John noted on the radio, meaning it had crossed the warm front where directional shear was maximized leading to strongly rotating updrafts. Meanwhile, our storm’s updraft looked substantially more robust on the radar and it had yet to cross the boundary as it was miles further south than the tornado warned storm. It was our turn next. Our cell looked like it was taking on supercellular characteristics even. A distinct rear flank downdraft with inflow band or wall cloud was noted to the west.

Our cell rapidly organized as it approached the warm front, a new wall cloud taking shape beneath the updraft base. A tornado warning was issued on the storm a couple minutes later. The chase had quickly gone from a low expectations play to a classic supercell chase.

The wall cloud dissipated and the rear flank filled in with rain, although there was still a bowl lowering and active tornado warning. Other cells along the warm front were picking up tornado warnings now as well with several reports to the west. It was turning out to be a much more active day than expected for a 2% tornado outlook and no tornado watch. Our storm wasn’t producing, however, and looked like it was cycling. Again I thought to myself that this is probably all we were going to see: a tornado warned mini-supercell, but having missed the brief fluke tornadoes on the other small cells.

As the storm cycled, an even more robust wall cloud condensed beneath the base. At one point, we found ourselves almost directly underneath it, the bowl shaped back end sporting modest rotation. We bumped into chasers Don McCracken and Kyle Gillett as we stair stepped east and north to track the northeast moving storm. They were basically the only other chasers we had seen all day, a far cry from the convergence we had seen on previous days, but this was a low expectations event and far removed from the Great Plains. Most storms chaser wouldn’t make the drive for such a long odds chance.

Anton thought he had spotted a funnel cloud in the now low, shaggy wall cloud, but it was difficult to see what was happening through the mass of clouds and above the tree lines. We continued to race east and north on the grid to get in a better position downstream of the northeast marching cell.

The wall cloud withered away, and what was left was a suspicious nub lowering. We should have recognized it immediately for what it was: the occluding updraft circulation that was being stretched into a strongly rotating funnel. Instead of setting up for the tornado shot, we continued stair stepping north and east, trying not to lose our position on the storm and watch it drift away to the northeast once it was finally doing something.

It took several minutes to organize and really get going, but several miles south of Remington, IN as we approached I-65, it was soon quite obvious that a significant cone funnel was hanging beneath the storm. The condensation was reaching for the ground.

At this point we were eastbound on the grid, and I was stealing glances over my right shoulder while driving, trying to see what the funnel was doing as the ground was obstructed by trees and farmsteads. John wanted to keep moving north and east to stay ahead of the storm until we were sure we had a tornado. I knew we were just getting farther and farther away from a developing tornado and our shot so I called it on the radio, prematurely, that we had a tornado in progress. The funnel was low enough to the ground that there likely was a tornadic circulation at ground level, or there would be very soon, so we needed to get setup to shoot it.

We turned north on a gravel road and immediately stopped to deploy our video cameras.

The funnel hung from the cloud base for a few more long minutes, and I wondered if it was ever going to fully condense or just tease us. Instead of fussing with my cameras, I worked to get a report out through Spotter Network. A GoPro mounted to a turntable on the roof of the Forester caught the wide shot of the storm, and I haphazardly pointed the 4k camcorder out the driver window.

The report went out and I scrambled to get my camcorder shot framed properly. There was no time for the tripod; the funnel was rapidly descending to the ground. I leveled the camera on my windshield suction mount, went full zoom, and shot through the driver side window. The dark elephant trunk shaped tornado was backlit against an orangey sky. It was a beautiful and exhilarating sight, our expectations now greatly exceeded.

The condensation funnel kissed the ground only briefly before retreating, but the tornado was still very much in progress. We could see a faint dust cloud underneath and large pieces of debris being lofted and twirling around the vortex.

The tornado fully condensed again, a thin hollow tube like a syringe projecting from a thicker cone aloft.

Wider shot showing the parent storm structure as the tornado started to sweep to the right:

The funnel started to contort and take on a knobby appearance, telltale signs it was about to rope out and dissipate. The rope out on this tornado was one of the most interesting and mesmerizing I had ever seen. As it started to go, rotation within the funnel increased. Helical ribbons of condensation spun like twirling strands of DNA. Rather than the funnel slowly shrinking and withering away like you usually see during rope out, it was like it had been blasted by a downdraft. The whole tornado just collapsed within a matter of seconds and was gone.

A few seconds later, the funnel made one last gasp appearance. Caught in the storm’s collapsing downdraft, a disconnected section of rope looked like it was falling straight toward the ground. The lighting and evolution made this one of the most dazzling tornado displays I’d ever seen. The group let out a cheer once it was over.

Radar just after the tornado dissipated, showing the small, unconventional looking mini-supercell with velocity couplet:

Keep in mind that times on the log remain in Central Daylight Time, even though we had crossed into Eastern in Indiana midway through the chase.

The storm soon fell apart as it moved into cooler air north of the warm front. Invigorated by our catch, we moved quickly to catch the next cells coming up the line as they crossed the warm front. We headed east toward Monticello before dropping south toward more discrete tornado warned cells. Light was fading, but John and Anton believed they spotted a brief spin-up off to the west on a small cell. None of us could get a shot of it, however.

A tornado warned cell with reports was heading toward Kokomo. We made a brief effort to go after it but realized we couldn’t catch it so retargeted for Tail-End-Charlie on a more linear looking line that was behind all of the initial activity. The airmass there was probably worked over, but I hoped that we’d get some decent twilight backlighting and that the tail end cell might organize as it approached the front. It soon fell apart and we lost the rest of our light under overcast skies, however, so we called the chase as we came into Frankfort.

It was getting late, but we found a Mexican joint in downtown Frankfort that was still open, and so we stopped to get some food and celebrate our successful chase. This was our first time getting a 4k shot from all three teams on a photogenic tornado and spirits were high. I pushed to make it all the way back to Springfield that night, but had to detour around flooded backroads several times before I could finally pick up the interstate. I saw a couple cars push through the water on the dark unlit roads, but I knew better than that. The last thing I needed was to stall (or get swept away) after a great chase. Anton, Tracie, John, and Rose stayed in the area and returned to the site of the tornado the following morning to conduct a damage survey.

Team Woodchuck Damage Summary:

“The joint Duck-Woodchuck survey this morning was highly successful. We first stopped at our filming site, where John and Tracie used photos to determine our various positions yesterday with very high precision. Next, we drove 2 miles to the N-S road serving the farm with the prominent metal silos seen in line with the tornado. We noted that the farmhouse and trees out front appeared to be undamaged, but corn stubble strewn across the front lawn caught our attention. We pulled in the driveway and were greeted by the homeowners, Dawn and Trent Becket, who then walked us around to the back of the house where things got much more interesting. Dawn was home and unaware of the advancing vortex until wind and a freight train sound caught her attention, just as things began to fly around. Among other things we observed: large, heavy trailers were dragged bodily sideways; a motorboat with outboard engine mounted was thrown several meters and flipped over; a shed was destroyed; a broken 2-4 was impaled almost a meter into a plowed field; shingles were stripped from the farmhouse roof, and various objects from the back yard were thrown into the nearby fields. Overall, however, the house itself and most vegetation around it — including plants in flower — came through in good condition. The south side of the house was speckled with corn stubble, with many pieces wedged into seams and rafters. An old van was pushed sideways such that corn stubble and roofing shingles were wedged tightly beneath its tires.

An astonishing find on the southern margin of the property, immediately southwest of the southernmost silo, was a fully equipped and still-functioning Davis weather station! This is operated by the owner of the farmlands surrounding the house, whom Trent called to find out if we could obtain the observations during the tornado passage. John is going to follow up on this.

After assessing the various damage indicators on the property, John assessed the state of the field of corn stubble on the west side of the road. Here he identified a very clear and extremely narrow (1-2 meter width) swath of stubble oriented to the east that lined up with the stubble strewn along the lawn in a path just north of the driveway. Putting everything together, it appears that a micro-vortex swept cyclonically across the property curving around the south and east sides of the house, causing most of the observed damage phenomena in doing so. My take is that the broader circulation would rank as EF-0, but the micro-vortex probably extended this into EF1 range. Other than this single farmstead, we did not find evidence of damage to other habitations. John and Rose did track the path upstream and downstream, and should be able to provide coordinates on estimated start and termination points. “

Tornado path maps courtesy John Allen:

"Based on the damage alone, I think it would be reasonable to suggest a 75 mph intensity (there are a number of non-DI impacts here which are hard to quantify – perhaps most amusingly the 0.35 mile lofting of the steel patio chair), however the weather station has different ideas. Maximum recorded wind speed for the weather station in the 15-minute binned data (which is all we have at this stage – I’m working on getting better data if it is possible) suggests that the station was located in the outer edges of the circulation, with a high wind speed of 77.4 mph from the WSW which would be consistent with its location on the southern edge of the circulation. "

Team Duck Summary:

“A morning MCS persisting from the previous night’s activity moved northeastward through the potential target for Saturday. In its wake, it reinforced a weak warm front draped east to west across northern IL, IN and OH. To the southeast of this front, winds were oriented from the southeast, reflecting significant turn in wind direction with height, and thus producing enhanced helicity, particularly near the wake low-warm front interface. High 60s dew points and moderate instability combined with effective 40 knots shear, providing an environment favourable to the development of supercells, with the expectation that, as cells interacted with the boundary, they would potentially become tornadic. The SPC did not share our optimism, but extended a 2% risk for tornadoes along the warm front and south into the warm sector.

We began the day in Kingdom City MO, where it was overcast but had remained moist. Our initial target was Champaign IL, where we waited until the late afternoon hours eating strawberries and watching cumulus bubble under clearing skies. Initial cumulus was mainly a response to diurnal heating, however a couple of convective rolls oriented southwest to northeast and began to foster deeper convection.

With initial echoes developing, we moved northeast on i57 to position, then east to Rankinand onward, where we drove through the core of the immature cell to position on it’s east side. This cell exhibited a substantial degree of organisation, and shortly thereafter maintained an impressive supercell structure with a classic RFD cut. Stair stepping northeast, we positioned on this cell, awaiting its interaction with the boundary. Through a forest of wind turbines, the cell matured and underwent several occlusive cycles, before we observed a merrygoround of vortices at the cloud base associated with vorticity from the descending reflectivity core. Repositioning once again, a funnel was observed on the interface between the wall cloud and the RFD. From our vantage point approximately 2 miles away, we observed this tornado for it’s ~4.5 minute life, including damage to a farmstead before it roped out in a nearby field.

Continuing to track this cell, the environment became cluttered with a number of stronger cells which interfered with this initial storm. Dropping this cell and moving south, a weak tornado was observed southwest of Yeoman as the storm interacted with the boundary. This tornado rapidly dissipated as we drove onwards south. With convection continuing to grow upscale, we elected to continue south in attempts to intercept a cyclic tornadic supercell near Frankfort, however as we approached through the rain core, the cells began to weaken and grow upscale, and so we instead headed to dinner at Pepe’s for a little Mexican food as the sun set for the night.

Based on the successful intercept, the following morning we backtracked to the area we observed the tornado to identify exact GPS coordinates and track the damage caused. The residents whose land was impacted were kind enough to let us take photographs and answer our questions, and in interviewing them we discovered that, delightfully, not more than 15 metres from where the tornado passed, an automatic weather station was recording data. Following this very fruitful morning, team Duck headed home north.”

Team Turtle Summary:

“Two thousand five hundred miles slogging it through the Great Plains chasing over-hyped, lackluster events. Garbage storm chasing. That was last week. It’s not just the miles. I’ll drive forever like Forrest Gump can run if the roads are good and the skies are beautiful. But this was neither. This was a grind. Hours were spent in the rain trailing behind the spray of a semi. Then it was racing east and north up the limited paved roads (the sloppy mud roads were out of the question) trying to get a glimpse of elusive needle in a haystack brief spin-up “bird fart” tornadoes. The storms were junky, grungy, grey on grey. The panoramic, epic skyscapes with “violent, long track” tornadoes were not to be found.

Northwest of Great Bend, Kansas we got what I thought for sure would be our best catch of the week: a tiny squiggly line tornado that lasted seconds. The storm had screaming inflow, but it was chill you to the bone cold. It was north of the warm front and stuck behind the lead storm’s gust front, sucking its rain and hail cooled exhaust. I would have bet money that the storm with its laminar inflow streamers and fuzzy black gust front was elevated and wouldn’t produce a tornado. And then it started kicking up several of these small vortices. They were low contrast and lasted seconds, and then we had to flee to get out of the way of the storm. The tornado itself wasn’t the amazing thing. It’s that this cold, gusty, striated beast was producing a tornado at all. It made me think that everything I know about storms and tornadoes is wrong. One of the inflow streamers this storm was sucking up must have had some buoyancy to it. Like a portion of the inflow was warm and not ice cold. Maybe it was latched onto the lead storm’s gust front and we just happened to be north of it at our position. Maybe there was enough buoyancy leftover in the parcels the storm was recycling through its RFD while we felt it sucking stable inflow. Maybe the massive inflow and outflow interfaces were producing so much vorticity the storm was just forcing up tornadic vortices despite the expected thermodynamics not being there. I don’t know, but it totally surprised me. And I should have been happy with that catch. But a brief wisp of a “tornado” doesn’t do it for me and I felt like our high risk, tornado outbreak chase had busted.

Two more days of chasing and we were still trying the warm front for some reason. The next day across Missouri was just utter rubbish with weak watery updrafts with no discernible structure. Adding insult to injury, parts of Kansas we just left were producing photogenic tornadoes in marginal conditions on the back end of the system.

So let’s play the warm front yet again, and this time do it in Indiana, on the fringe of our chase domain, where few chasers would even bother in even more marginal conditions. That’s a great idea, right? It felt like desperation at this point: chasing sloppy seconds across the Midwest on a marginal, 2% day. We were going to see some low topped convection congeal into an MCS and then go home. I could see it coming.

But instead it was the dream we had been waiting for. Convective rolls started to bubble over. We watched from a park in Champaign, IL as the lead tower rocketed up with a pileas cap and we were after it. Despite appearing as little more than a 50 dbz shower blip on the radar, our storm steadily organized into a classic supercell with wall clouds sporting lengthy tail clouds and RFD clear slots. We stair stepped the storm on Indiana’s road grid, a mix of gravel and pavement. It wasn’t quite as nice as the all paved Illinois grid, but compared to Kansas and Oklahoma it was a dream come true. We could cherry pick our position. No watch but the tornado warning had 28 minutes of lead time. Carousel rain curtains, the base wrapped up, nub funnel and then the tornado condensed. It was textbook. We saw maybe 5 other chasers the entire day. I didn’t think our final desperate play on a 2% Indiana day would upstage 15% hatched of Caprock magic and 30% hatched of Kansas outbreak, but it did.

The tornado danced around one farm, sweeping back and forth like a tamer version of the Wizard of Oz rope. You can make out one of the buildings in the foreground. A woman was home, but was oblivious to her lawn equipment and pieces of outbuilding being tossed about until she finally heard the train like roar. She and her house were fine, fortunately. The tornado will likely be rated EF0 or EF1. But it was a beaut. DNA strand like helical spirals twirled around the hollow tube funnel as the tornado danced for several minutes. And then poof, it was gone.

I don't understand the weather or know when the best time to chase is. But I'll keep trying for little moments like these.”