NOTE: I never got around to finishing this on time, but here it is. This post refers to our storm chasing day on Friday 6/1/2018
It was really nice to have an off day on Thursday, because Friday ended up being an exhausting day. A vigorous shortwave trough centered over the northern Plains drew warm, moist air originating from the Gulf of Mexico northward while bringing strong westerly winds aloft, and the combination of high CAPE, substantial wind shear, and dynamic uplift along this storm’s cold front was predicted to create a long-lived, very powerful line of storms known as a derecho. Like Wednesday, damaging wind and hail – not tornadoes – were the main threats, but we were still expected to see some discrete supercells capable of tornadoes. Unfortunately, the storms that formed in the afternoon/evening were weak and short-lived, and we spent much of the day frantically moving from one blossoming storm to another, only to have that storm die by the time we got there. After approximately 500 miles of driving, we decided to call it a day and get some grub at “Tub’s Pub” in Sumner, Nebraska.
But while we were munching on fish’n’chips and strawberry rhubarb pie, the derecho forecast by the models formed right over us, prompting a swarm of severe thunderstorm warnings and an extremely wet trot back to Chris’ car after we had finished eating. Driving back southeast through these storms was very treacherous, but once we were out of the heavy precipitation, we were found ourselves under the storm’s massive and apocalyptic shelf cloud. I’m actually having a lot of trouble putting this experience in words as I write this blog, but I’ll just say it was mesmerizing, otherworldly, and thrilling, especially since we had an intense, fast-moving derecho right on our tail!
One of the many wonderful things about storm chasing is that you can get a pretty late start and still have enough time to get in a good location to see storms initiate. We left Lexington, Nebraska around noon and drove 180 miles NNW to Cherry County, Nebraska, which is where the HRRR and NAM showed storms initiating.
Credit: Storm Prediction Center
On our trek northward, we talked about how quickly tornadoes can change direction and how it is always necessary to have an escape route. It goes without saying that the road network over the Plains is a tad less dense than the ones us city folk are used to, so it’s necessary for you to be aware of your escape routes should you need to flee from a storm. This is easy now with GPS; I can’t even imagine how tough it would be without it!
Keeping with our theme of encountering weirdly-named locations, we crossed the “Dismal River” while driving on Highway 97. I can only imagine the story behind that name.
Credit: Wikimedia user Ammodramus
As Chris drove north, I marveled at the waves of wind dancing on the grass as we continued to make our trek north towards Cherry County. Unlike the most of the other regions we’d been to so far (Texas Panhandle through Western Kansas), Nebraska had a fair amount of rolling hills with natural grass, at least along the major highways.
Slightly past noon, we saw some cumulus clouds forming along the cold front to our west, but many of these cumulus clouds had a flat top, as the capping inversion over the area was too substantial for them to even become altocumulus castellanus (accas) clouds, much less cumulonimbus clouds. A strong capping inversion can prevent storms from initiating in the first place, but it can also help storms develop much more explosively, as they are able to tap into all the CAPE in the atmosphere at once when the cap finally breaks in the late afternoon.
Credit: Storm Prediction Center
At 1:30, we checked the latest Storm Prediction Center outlook and noticed they had upgraded the risk from “enhanced” to “moderate” over Central Nebraska, so we stopped in Thedford, Nebraska to re-evaluate our target areas. By this time, these flat-top cumulus had grown into accas, indicating that updrafts were becoming more vigorous due to daytime heating and that the cap was eroding. By 2 pm, storms were firing in southern South Dakota, so we quickly (and legally!) headed north out of the moderate risk area to Valentine, Nebraska to catch these storms.
However, motoring up all the way to Valentine did not yield the results we were hoping for. Storms began popping up all around us once we got there, and each new storm cut off the warm, moist inflow that fed the older storms. As a result, we simply ended up with a rainy, thundery conglomerate of thunderstorms and didn’t get any storm remotely strong enough to spin up a tornado. We chased storm after storm for the next hour hoping to find something, but at 3:50, we finally headed SE towards Ainsworth to get away from this rainy blob and into the “moderate” risk area, where there was a better risk of seeing a strong supercell and potentially a tornado.
We soon saw some weak rotation on a cell near Wood Lake between Valentine and Ainsworth, so we stopped on a side road around 4:30, climbed up to the top of a hill, and snapped some shots of the mesocyclone that marked the center of the rotation. One thing that was really visible from this vantage point were the clear skies directly behind the storm marking the location of the cold front, and we could tell we were ahead of it due to the warm and very humid air mass over us. Within 10 minutes, light rain began to fall and it became very windy, so we continued our trek down to Ainsworth.
After reaching Ainsworth, we continued heading south to catch some new storms that were firing down there, and at 6:08, we noticed that one of the cells near Merna, NE, approximately 60 miles to our SE, had a TVS, which stands for a “tornado vortex signature.” These are determined via radar and often don’t lead to a tornado (this storm didn’t even have a severe thunderstorm warning at the time), but all the chasers flocked to it (including chasing legend Reed Timmer!) and we decided to follow suit. It soon garnered a severe thunderstorm warning for quarter-sized hail, but the cell weakened very quickly and lost its severe thunderstorm warning less than a half-hour later.
We were admittedly pretty frustrated by this point, as we had been searching all day for a tornado and hadn’t seen much of anything. To add insult to injury, we were less than an hour from Lexington at this point, which is where we had started our day. We stopped at the Ritz Cafe in Sargent, Nebraska to fill up on some grub and took a quick gander at a storm to our north before continuing south, where new storms were firing up on radar. This storm had quite a bit of lightning, and Chris got an incredible shot of a bolt that struck several miles to our north.
This storm also had well-defined mammatus clouds, which are formed by sinking, cool pockets of air and are typically found under the anvils of strong thunderstorms. We can occasionally get mammatus in the Pacific Northwest, but our mammatus are nothing like the mammatus you see with the strong thunderstorms over the Great Plains.
We stopped again near sunset to capture some more lightning and got a spectacular shot of a back-lit shelf cloud approaching us. I’m sure that house has seen its fair share of thunderstorms!
Tub’s Pub and the Whale’s Mouth
After stopping to view the sunset/shelf cloud, we called it a night and headed south towards Sumner, Nebraska to get a late dinner. We ended up eating at a hole-in-the-wall pub called “Tub’s Pub.”
Our stop in Tub’s Pub was a good way to finish what had thus far been an underwhelming day. But while we were eating, multiple severe thunderstorm warnings and even a tornado warning interrupted the scheduled programming on the various TVs around the bar, as a powerful squall line of thunderstorms had developed right over us while we were eating our food. This caught us off-guard, but it really shouldn’t have, as all of the models showed an squall line rapidly forming after sunset at our location. This squall line was the very beginning of a much larger derecho that would persist through the morning hours and travel all the way to Kansas and even western Missouri. We were just so wiped after our day that we assumed the stars that we saw when we pulled in for dinner would still be there when we got out. On the contrary, we were treated to extremely heavy rain, strong winds, frequent lightning, and even some small hail as we headed back to the car after our short dinner.
We decided to go south and punch through this squall line while simultaneously avoiding the nastiest parts, but that proved to be easier in theory than practice. We were hit by some quarter-sized hail that made some uncomfortably loud noises when it hit the car, and we had to camp out for a little bit under a tree in a residential district to the south of Miller, Nebraska and let the rain and hail lighten up a bit before continuing our trek due south on I183.
We eventually got out of the rain/hail from the storm, and once we did, we were treated to an incredible sight: nearly-constant lightning illuminating the turbulent, ominous base of this squall’s well-defined shelf cloud. The base of the shelf cloud is known as the “whale’s mouth” (due to its resemblance to the mouth of a whale, I guess), and the turbulent base is due to the shearing between the cool downdraft/gust front associated with the squall and the updraft ahead of it that forms the shelf cloud. For convenience, here’s the picture I originally posted at the top of this blog of us under the whale’s mouth and trying to outrun the intense squall behind us.
We kept on traveling east and stopped at Windmill State Park at 11:30 to take some more pictures. Chris took a much nicer picture with his DSLR of the whale’s mouth here. The wind was whistling through the power lines when we were here and the turbines were spinning like crazy.
After this, we decided to call it a night for real. We’ll have a quiet next couple of days, as this system ushered in a much cooler, drier and more stable air mass.
I’ll leave you with a brief video Chris made from some dashcam footage taken during the latter half of the day and after our stop at Tub’s Pub. The footage of us driving under the whale’s mouth does not do it justice, but hopefully it offers some insight into what it was like.
Thanks for reading,
Charlie