Mini-MPEX headed out I-40 into the Texas Panhandle, expecting initiation on a confluence axis ahead of the dryline, which lagged near the New Mexico border. Storms erupted quickly as we launched on the north side of Pampa, becoming tightly spaced with several left splits. A cell to the south produced a tornado near Howardwick, but the most discrete cell was to the north, near Spearman. We set up on a gravel road in a remote, wildflower-dotted part of the Canadian River valley and released a sonde in strong inflow with a wall cloud and brief funnel to our north.
The storm failed to produce a tornado there, and we had to race out of the river valley to avoid a left-mover colliding with our storm from the south. But later in the evening, we collected a series of inflow soundings on the same storm as it produced a couple of large tornadoes somewhere between Canadian and Spearman. Howling inflow winds whisked the last sounding up from the ruins of the Gageby Store on Route 83 with mammatus hanging overhead.
Monday, May 23
Mini-MPEX had a head start after waking up in Shamrock and downing Texas-shaped waffles at the Sleep Inn. Both vans and the CLAMPS trailer met up in Hammon, north of I-40 back in Oklahoma. The vans started south through Granite, the most aptly named town in the state, and the unusually green Wichitas to Route 62 in southwestern Oklahoma; the near-field van continued into the Texas Panhandle to launch on a young storm.
Despite an apparently favorable environment with strong instability and deep-layer shear, the storm evaporated, hampered by extremely dry midlevels. We seemed snakebitten all day. The other van encountered a flooded road and had to turn around. A jackrabbit ran under our wheel. One of the thermometers on our van started reading over 100 degrees Celsius. The spare tire cover under our van came loose and started bouncing on the road, hanging by a cable. Other new supercells in the eastern Panhandle formed, but quickly split and disappeared one after another. And as we headed back to Norman, two supercells northeast and south of our target area produced tornadoes, one near Woodward and one near Turkey, TX.
Tuesday, May 24
This was mini-MPEX's down day with CLAMPS needing maintenance. We'd operated on every Southern Plains severe weather day of note since late April and expected to do the same the rest of the week, so I left after lunch on a personal chase in a caravan of OU met students. We arrived in Buffalo, OK, where familiar faces and research vehicles were around every corner, all looking for the same thing. As we baked in a gas station parking lot on the north side of town, I was beginning to think the optimal environment, an area of enhanced low-level shear near the subtle remnants of an outflow boundary, would go without a robust storm. Suddenly a thick tower was exploding over the rooftops and trees across the street to our northwest. We were on the road flying toward it before it even broke 30 dBZ. It was just a tiny blip--but the fine line marking the boundary was curving out into the blip as the updraft sucked in vorticity.
In that environment I thought it was possible that we'd come up on the storm in Minneola, KS, to find a tornado already in progress. But the updraft base was high, and we navigated a stream of chasers to find a relatively quiet dirt road intersection where we could watch the new supercell evolve. The base lowered rapidly into a wide, ragged wall cloud. Then the storm toyed with tornadogenesis for 10-15 minutes in a couple different locations before finally extending a condensation funnel into a whirl of dust.
The tornado grew into a fat cone. We realized a little too late that while we had been mesmerized, the storm had been moving to the north, and we never quite got back to a good viewing range and angle. We took off in pursuit. The tornado slid back into the rain.
Another tornado appeared after the first roped out and it wasn't long before the ground-scraping wall cloud to its east produced simultaneously. We stopped with the twins for a minute or two before giving chase again.
The storm was headed toward Dodge City just north of us. There were some tense minutes on the way east to Route 283 and northward toward the town. We had already seen at least one tornado that produced a horizontal vortex as it faded into the rain, an exclusive hallmark of a strong to violent tornado, and the updraft base was almost to the ground in some places. The storm looked poised to do something nobody wanted to see. With a parade of chasers filing into town on 283, we chose not to risk being in the way of first responders should Dodge City take a direct hit and instead detoured eastward.
Dodge City was spared by a few miles. We were far out of position but our vantage point offered a rare perspective: the full sculpted updraft of a classic supercell with either several short-lived tornadoes or one long-lived tornado visible underneath, in an assortment of shapes and sizes. The structure was something out of a storm spotting guide. There were very few other chasers around us.
We noted a left-moving supercell closing in from our south and repositioned northeastward to get away from close CG lightning. In the distance we saw one tornado vanishing into the precip in a prolonged rope-out while another formed.
Ordinarily it's a mistake to walk away from a supercell before twilight, as I've learned the hard way, but we had seen the feature presentation. Storms were merging and getting messy, road options were becoming limited, and it was a very long drive back to Norman. We left the storm early, got back across the Oklahoma line by sunset, and ended up missing virtually nothing.
Wednesday, May 25
Mini-MPEX was back in full swing and targeted south-central Kansas. Field work isn't just enjoyable because of the storms; the Plains are worth exploring in their own right, and I have a soft spot for Kansas vistas in particular. These launch sites were just outside Wellington and Leon.
Storms in south-central Kansas were LPs that struggled along for a couple hours, then evaporated. The evolution was almost identical to Monday's in the Texas Panhandle.
One storm did thrive, a supercell that produced a long-lived EF4 up on I-70, but we couldn't get there. We were glumly driving home through north-central Oklahoma when a disorganized cluster of storms near Enid congealed and, presumably with the help of the incipient low-level jet, became an intense supercell. In-cloud and cloud-to-air lightning flickered continuously on the edges of a perfect anvil in the dying light. We sped west from I-35 and launched in front of the almost stationary storm at its peak, close to the time it produced a tornado that derailed a train.
Only after we had maneuvered through Enid and onto back roads south of town for another couple launches was there time for photos, and by then clouds atop a surge of outflow were obscuring most of the lightning.
The Carrier supercell was mostly a lucky break. While we did know better than to shut everything down and ignore ongoing storms with LCLs lowering and the low-level jet kicking in, nobody on the crew expected what we got. If we'd tried to make it to the I-70 storm, we probably would have missed both. We had been unlucky with our target area Monday and missed a prolific tornado producer on our down day; things swung back our way Wednesday night.
Thursday, May 26
It was the most befuddling setup of the week, maybe of the Plains season, and for the first time I had the job of nowcasting and putting both vans in position to sample storms. Junk convection and diurnal heating played havoc with a relatively shallow moist layer, creating unpredictable pockets of dry air throughout the warm sector from Kansas to Texas. We intercepted a weak supercell in northwestern Oklahoma near Freedom; it promptly died. Discouraged, we headed into Woodward to see if anything could come off the dryline in the Texas Panhandle and survive the mediocre moisture. Finally, a struggling updraft came up through the Oklahoma Panhandle and approached two or three outflow boundaries; we committed to working that storm and were rewarded as it grew into a healthy supercell that dropped enormous hail in southwestern Kansas. We passed through Coldwater between launches with a stout updraft looming overhead.
The Coldwater storm succumbed to the flawed environment and storm interactions and lined out after a couple pairs of soundings. We tried to work transient supercells in the western half of Oklahoma after darkness fell, but we struggled to get in position on tightly spaced and erratically moving storms.
Friday, May 27
We knew this could be the final day for mini-MPEX, so we started southwestward out of Norman despite a marginal environment for supercells. After a couple false starts trying to get on a tail-end cell out of a cluster of convection that began near Lawton, we settled in on a storm that tracked across the south-central section of the state. It rarely had strong rotation and only once or twice looked like it could come close to producing a tornado, but maintained a little spin at some level well into the evening. Soundings showed ample deep-layer shear, but small SRH helped explain the absence of an intense low-level mesocyclone. Our storm finally gusted out after we followed it into the jungles of southeastern Oklahoma.
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