Brett Roberts, a graduate student in meteorology at the University of Oklahoma and storm chaser, captured some of the most amazing photographs of thunderstorm structure and lightning I've ever seen last Friday, June 14. The photos were taken in West Point, Nebraska.
Roberts, who attended high school in the D.C. area, agreed to share some of his work with Capital Weather Gang readers and graciously answered some of my questions about his photo shoot and storm chase trip.
Q: Set the scene. Why were you in Northeast Nebraska and how did you track down this storm? What made the scene special?
A: The 2013 storm season on the Plains thus far can best be described as bi-polar. March, April, and even the first half of May were about as quiet as you'll ever see, pushing many storm chasers to the brink of depression (especially after a lackluster 2012). Then the second half of May came around, and as anyone not living under a rock well knows, it more than made up for lost time. However, the tragic events of May 31 in Oklahoma quickly gave way to another prolonged stagnant pattern, so I had not chased at all in June prior to Friday. Thus, even though the potential for big-time supercells and tornadoes would normally seem marginal to warrant a 400-mile drive, I set off for my target of Norfolk, NE, around 8 a.m.
When I arrived late in the afternoon, an outflow boundary was draped just to my east, roughly along the Nebraska-Iowa state line. After sitting in a gas station parking lot blasting the A/C for well over an hour, a lone storm finally developed just southeast of Norfolk around 6:30 p.m., right along the westward-drifting boundary. It was initially quite lackluster and showed signs of struggling against a cap, or layer of relatively warmer air aloft. Fortunately for me (and the dozens of other chasers nearby), it gradually strengthened over the following hour into what can only be described as a beast. It remained almost stationary near the town of West Point, which allowed me to capture video and stills at a leisurely pace from the area around Dodge and Snyder.
Q: What camera settings, equipment, etc did you use to capture these images?
A: I shot all these photos with a Canon 6D camera and Samyang 14mm f/2.8 lens. I also used a Manfrotto 055XPROB tripod, which was especially helpful for capturing the images with lightning; they require long exposure times, so you can't handhold the camera unless your steadiness is superhuman!
Q: In layperson's terms, describe the conditions that helped to give the storm its dome-like "mother ship" structure.
A: Supercells acquire their broad rotation by tilting vorticity (a tendency to spin, in layman's terms) that's initially oriented along a horizontal axis into the vertical. The pre-existing horizontal vorticity is a result of wind shear in the lowest few kilometers of the atmosphere above the ground.
On Friday, the low-level wind shear in eastern Nebraska was substantial, allowing for any discrete storms that formed to begin rotating quickly. The reasons for the specific, unique visual appearance of a given supercell can be difficult to pin down, though. For this storm, the presence of multiple "stacked plates" or tiers is likely linked to relatively stable layers of air. A squall line had moved through the area earlier in the afternoon, leaving slightly cooler and more stable air in its wake. Without this cooling, the storm I saw might have had a better chance at producing tornadoes, but also lacked this jaw-dropping structure.
Q: Are these among the best structure/lightning photos you've taken? Or, have you encountered similar/better thunderstorm photo opportunities?
A: The visual structure of the West Point supercell was definitely among the top 10 I've witnessed in eight years of storm chasing. I don't consider these shots to be my very best, but that's partially because I was not in an optimal position. The "stacked plates" were most prominent on the east side of the storm updraft, and I was viewing it from the south-southeast, at a bit of an angle. Thus, chasers who were located more east or east-northeast of the updraft were treated to an even better show (example, from Mike Hollingshead). If I had to pick my personal favorite supercell structure from all my chases, it would probably be June 16, 2008, in southwest Oklahoma.
Q. After the events of 5/31 in Oklahoma City, have you changed any of your storm chasing practices ? Is there any more trepidation when you chase?
The loss of Tim Samaras and his colleagues on May 31 is as shocking as it is tragic, given their level of experience and professionalism. It was a blunt reminder that storm chasing is inherently risky business, no matter your credentials. I've spoken with many fellow chasers in the aftermath of this incident, and several have indicated they will take a more conservative approach going forward when a tornado is on the ground -- even some who have historically played it very close. Personally, I often stay back at least a couple miles in order to capture both the tornado and overall storm structure in my photography -- yet, even I was caught off guard on May 31 and felt unsafe for a time.
The El Reno supercell was nearly a worst case scenario for storm chasers and quite anomalous in many facets, but one never knows when the next anomaly will strike, and I think it was a major reality check for all of us in the chasing community.
Timelapse of West Point, Nebraska supercell, June 14, 2013, by Brett Roberts
For more of Brett Roberts' storm photography and videos, visit his website: skyinmotion.com