June 9th, 2018 Iowa Supercells
Tornadoes: 0
Highest Wind Gust: ~20 mph
Largest Hail: N/A
After a quiet peak season in Tornado Alley, I was incredibly eager to get a good chase in. June 9th looked to be a decent potential day for a few tornadoes across northern into eastern Iowa. Aloft, a small, subtle impulse in the mid-to-upper levels was progged to move across Iowa (of course, in 2018 anything more is too much to ask):
At the surface, a low near the IA/MN border would drape a warm frontal boundary across northeast Iowa, and trailing cold front would likely initiate storms in northern Iowa. Winds would be backed across the warm sector, with a destabilizing atmosphere through the morning and early afternoon. SPC issued 5% tornado probabilities for the target area:
Matt Zuro, Daniela Barrios, and I targeted Mason City, where storm initiation looked most likely. We wanted to catch storms early in their life cycles to maximize potential for discrete storm mode, and therefore tornado potential. We left a bit early compared to when we thought initiation would occur to account for potential that storms may develop early. As we were still south of Cedar Rapids on the way there, the first tornado warning came in. My first reaction was laughter. Of course this would happen. Right near the target, just several hours earlier than anticipated. We thought we were accounting for early initiation, but we ended up being late to the show. No tornado reports came from this storm, but it set the tone for the day. Under an hour out from Mason City, we were chatting with other chasers in Messenger as the main show of storms just started firing. They were struggling to get organized, and I voiced confidently that I thought we were making good time. Only a few radar scans later and the main storm had a much better radar presentation and went tornado warned. Now some panic began to set in. We were only about 20 minutes away from the storm when tornado reports started coming in over Twitter. We were only minutes from being able to see the base in the distance, so we were racing to get west to get a better look. It was a brief tornado, however, and we stood no chance of being able to see it.
We eventually arrived in Clear Lake, where we dashed to get gas (and could see the base from the gas station), then headed north out of town to get a better visual on the storm. Pulling over on the gravel road, we hopped out to observe the storm structure.
We were south of the RFD surge, but a prominent area of rotation on the RFD gust front was present. A small but rapidly rotating funnel descended from the cloud base for about 15 seconds:
The storm was moving southeast toward our location, and not wanting to get caught in RFD, we headed back south through Clear Lake. Sirens were blaring as we were caught at a red light, rain-wrapped updraft region raging about a mile to our north. We found a location southeast of Clear Lake ahead of the now monster HP supercell. It was difficult to tell where the main updraft base was located, as a big outflowy shelf generally dominated the storm structure, and I suspected it was actually obscured, buried back into the heavy precipitation shield. It was a very dramatic scene, with high-contrast shelf cloud fanning out from a turquoise-glowing core:
Like before there appeared to be several eddies along the shelfy updraft base, each one showing displaying modest to briefly rapid rotation. The storm was moving fairly quickly to the southeast at this point, and it was only a few minutes later that we needed to move. We dropped south and found a good east-west highway with occasional paved north options to get closer to the storm. We played a bit of cat-and-mouse, making it a few miles eastward, then turning north to get a closer view, and soon after dropping back south to the highway to do it all over again. You can see the very outflow-dominant structure:
We couldn't tell if the sign was warning of the little bump in the pavement or the big bump a couple miles ahead.
The image above was from one of our final northward treks. Inflow structure is evident with the clouds in the background, with RFD gust front shelf extending toward our location. An RFD-carving out of the meso is even discernible on the left side, but the bottom of it is heavily rain-wrapped. We could have chased in the bear's cage, but we didn't want to risk using the (actually pretty decent) unpaved road network in the chaos of the updraft region of a monster HP supercell. Additionally, I was pretty sure it was done producing tornadoes, so it wouldn't make sense to put ourselves in danger if a well-maintained gravel road unexpectedly turned to mud. We once again dropped south a few miles to another east-west highway as the storm tried wrapping up again, but kept growing increasingly shelfy and outflow dominant. Eventually it turned into a completely linear cluster producing damaging winds:
We drove closer to intercept, hoping for some decent straight line winds, but as we let the storm roll over, the strongest winds couldn't have been over 15 mph. Expecting hurricane-like conditions, we got little more than generally calm, heavy rain. Eventually, we pushed back south out of the storm and into clear air, thinking our chase might've been over. New storms were firing to the southwest, however, and we headed towards those. These storms struggled for a while, and we abandoned them as well. More storms kept firing to the south of that, and we headed back down close to Cedar Rapids to see if one of them would organize into something promising. From our view at a distance, one storm began to take on supercell structure to our west:
It was organizing on radar, too. We started driving closer and there was a noticeable increase in motion. I was getting a bit irritated by my dashcam/phone mount rig creating a huge reflection in the windshield with this lighting:
We found a good spot with a great view of the updraft base. Rotation was rapid and gradually getting stronger. RFD rain curtains began to dance from left to right in front of the circulation, and rotation peaked in this time frame. A tornado may have been imminent, and we were ready if one were to drop.
Rotation began to slow a bit, and the adrenaline crash started to set in. It came very close, at least visually, to producing a tornado. We followed the storm for one more cycle, but it was becoming increasingly rain-wrapped, messy, and disorganized. Even more storms were firing all the way down to the I-80 corridor, one of which had gone tornado warned. We had already begun heading southward to head home if nothing else, and now found ourselves scrambling to intercept this newly tornado warned storm or the increasingly organized, not-yet warned one just to its north. On our way, we noticed a moderate rain shower on radar that we were going to have to drive through. I didn't think much of it. That is, until we realized what it was. An LP supercell, just innocently churning across the eastern Iowa landscape. I was unable to get great images of it while driving, but I did manage to get some phone pics:
There was a large dry RFD clear slot/horseshoe in the updraft base as well. While we were only just passing by, this was one of those little chasing "treats" that can really be appreciated.
Finally arriving in the town of Vinton, we went to intercept the northern supercell, now also tornado warned. Night was falling at this time, though, so we relied on lightning flashes to illuminate the updraft base of the storm. Although we did get good visuals at times, the base was relatively boring and never came close to producing from what we saw:
Storms soon after began to congeal into a linear cluster as we headed to Culver's in Cedar Rapids for a bite to eat before heading home.
SPC Storm Reports:
The tornado near Fertile, IA, west of Mason City, that we missed was a brief but intense drillbit that I do wish we'd been able to witness. It's not the end of the world, but I still hadn't seen a tornado in 2018, and that tornado was a decent video shoot if you were in the right spot.
GPS Location History:
Notice how scatterbrained our chase route was. Lots of storm hopping was necessary to maximize odds of witnessing a tornado. Of course, none of them would do it for us.
