Southeastern Nebraska: June 11, 2018
Lowering, rotating cloud base.
I started the day focused on southeastern Nebraska with the potential for a few tornadic supercells. By mid-afternoon, storms in northeastern Nebraska started to rotate fairly quickly, but I wanted to hold off for more discrete activity, either down the cold front or along an outflow boundary in the warm sector. Once a few cells started to develop southwest of Omaha, I zeroed in, even though I was not thrilled by the prospects of chasing near a metropolitan area.
The chase basically went from 0-60. I dropped south near South Bend and noticed a lowering cloud base that started to rotate. What captured my attention from the start was how low the cloud bases were and that will be a common theme throughout this account. At first, the rotating cloud couldn’t have been more than 100 feet wide and it wasn’t a funnel cloud, but I don’t think it was a true wall cloud either. Either way, the storm was organizing and doing so very quickly.
Just moments later, the feature consolidated into an expanding, low-hanging wall cloud. I found a spot to set up and was prepared to broadcast live via Periscope on Twitter.
https://www.pscp.tv/stormchaserQ/1yoJMVRVoNlxQ
The next 20 minutes was spent driving through downtown Louisville, dodging debris and racing east to get out of the residential area. As a result, the growing wall cloud was not clearly visible, so it’s likely that I missed seeing a tornado due to structural and terrain obstructions. The next decent photo I captured of the storm at this stage was at 5:59 p.m., 3 miles east of Louisville:
The low wall cloud is clearly visible, with inflow to the east. It was also around this time that the mesocyclone started turning right, so in anticipation, I dropped south and east. I did not want to be directly under the mesocyclone in case the whole thing dropped.
The next photo comes in at 6:06 p.m. and isn’t all that different from the previous photo, except that it’s not a panoramic. It shows the low, rotating wall cloud just to the north.
The terrain for the rest of the chase was increasingly hilly, causing terrain to block a clear view of the wall cloud and any brief spinups that a few chasers reported. At 6:25 p.m., I reported “very close to wedging out… 4 ESE Louisville, NE.” The large wall cloud was probably near its lowest point, as it looked as if it was only 100 meters, or so, above the ground. As I was driving, I was focusing on the road ahead, so I let my rooftop video camera take in the footage. At no point was there a wedge tornado, despite reports. It was simply terrain playing tricks on eyes. As low as the wall cloud was, through confirmation from numerous chasers, the storm did not “wedge out.”
Here’s a video that runs from approximately 6:18 to 6:36 p.m. I sped the video up to 16x the actual speed to condense this portion of the chase and enhance the rotation/evolution of the mesoscyclone:
The final photo that I’ll share is from 6:35 p.m. and it shows the striated mesocyclone, just minutes before the storm was absorbed by convection along a cold front to the immediate west.
I shifted south to stay ahead of the strong outflow winds the evolving convective system was producing. I thought that I might catch a discrete storm on the southern flank of the system and I made it into northeastern Kansas before I called the chase off. A few storms around sunset showed brief rotation, but nothing from my vantage point looked like anything else besides a shelf cloud.
Overall, I found the chase to be exciting, as it featured what was probably the closest thing I’ve seen to a tornadic supercell this year. It did produce multiple, brief tornadoes, even if I did not conclusively see any of them. Despite that, it displayed one of the lowest wall clouds I have ever encountered and the storm structure was very photogenic.
