Another week in May

Sunday, May 22

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.

One week in May

Sunday, May 8

In elementary or middle school, my class read excerpts from Kiowa author N. Scott Momaday's The Way to Rainy Mountain.  I don't know why I remember that, but that same Rainy Mountain--not really a mountain at all--poked up over the farmland to our south-southwest as we launched a balloon north of Gotebo, Oklahoma.  Storms had erupted off the dryline in the western part of the state and up into Kansas.  Without enough low-level directional shear for the storms' induced pressure perturbation fields to favor right-moving supercells, they began splitting.  A couple left-movers became dominant, including a visually impressive one to the south.

Left-movers are notorious hailers.  We bailed east and south out of the left split's baseball hail swath, trying to get into the inflow of the lone healthy right-mover within striking distance.  The other crew had started farther south and made it south of the storm near Lawton, but we found ourselves coming in on the north side of the hail core.  We rolled slowly through Lawton on I-44 and had to stop a couple times in half-dollar hail and zero visibility.  We turned east on Hwy 7 in heavy rain and intermittent small hail with strong rear-flank downdraft winds throwing leaves and twigs all over the road.  At Hwy 65, our last reliable south option for over 10 miles, we were given a green light to continue east and possibly break out of the precip.

Radar showed a tight mesocyclone moving dangerously toward Hwy 7 ahead of us.  Still unable to see any features of the storm in driving rain, we decided against going farther and dove south through the hook.  Minutes later, there was a small, weak tornado just a mile or two south of Hwy 7 near where we would've been.  We would likely have had an ideal view of it.  But continuing between the precip core and a possible tornado, without visibility, is asking for trouble; the tornado could just as easily have been on the road and hidden in rain.  The mobile mesonet dataset we collected in the core and RFD leading up to tornadogenesis is probably valuable in its own right.  There are always other storms--and we had no idea how soon.

Monday, May 9

When we got the chat message to turn around and come back north after launching a 3 p.m. weather balloon behind a gas station at the Marietta, Oklahoma I-35 interchange, I had never seen a killer tornado.  The dozen or so I'd encountered were weak, brief whirls over open country, except for a couple that did damage near Pampa last November.  I was fine with that.

As we headed north, our sounding showed strong convective instability and more than sufficient deep-layer shear for supercells.  Storm-relative helicity was lacking at our location near the Red River, but the sounding crew a county or two to the north reported a sickle-shaped hodograph supportive of strong tornadoes.  Our target was a blip of reflectivity that had been floundering northeastward from the dryline near Duncan.  We were thinking towers to our south on the opposite side of the river looked more robust.  That was our own bias (though the Gainesville cell did go on to produce tornadoes in the Red River Valley).  We just wanted to punch through to the south side of a maturing supercell.  Instead, we rolled up I-35, wondering if the fuzzy anvil in the distance would survive or if we'd be going home empty-handed.

By the time we closed in on our next launch site, a hilltop east of Springer sprinkled with rain from a struggling cell just south, we realized the storm was going to do more than survive.

Successive distinct fingers of reflectivity appeared along the storm's southern flank and slid northward, congealing into an organized precipitation core.  That's how the 2013 Moore storm evolved just after initiation.  The similarities didn't stop there.  As we turned north on Route 177 near Gene Autry, the other crew was watching a violent, highly visible cone tornado doing damage in Katie.  Our next assignment came in:  Mill Creek, back to our southeast and away from the storm.  We had two choices to get there in time.  We could double back to an obscure road of unknown quality that led directly east to Mill Creek.  Or we could continue north into Sulphur, jog east on Hwy 7--maybe seeing the tornado--and drop south into Mill Creek on Hwy 1.  Easy call.  We caught a split-second glimpse of a high-contrast stovepipe tornado with a large debris cloud between stands of trees in the rolling, forested terrain south of Sulphur and flew into town.

Finally we emerged from Sulphur, where dozens of locals stood on street corners staring at the sky, onto a hill overlooking town.  Several chasers and the other NSSL crew were there.  We parked on the shoulder.  I switched on my camera, jumped out, ran across the road, and got exactly one shot of the Katie tornado fully condensed in the distance.

The funnel lingered halfway to the ground for several minutes longer, but that was the end.  We were just about to launch a balloon from that site when we realized the storm to the south was intensifying and sliding north toward our supercell, taking its developing mesocyclone directly over us.  We had to dodge west and south away from the storm as it was clearly about to tornado again.

Our van stopped several miles south of Sulphur and, with a local man excitedly showing us the video he'd just shot, we attempted another launch.  That sonde promptly got ingested by the massive storm (now producing a wedge tornado) and stopped transmitting in midlevels.  Mill Creek became our target again, and we decided to get there the same way we'd tried to get there before.  On the hill east of Sulphur, this time there was no chance of seeing the large tornado through the rain wrapping around the south side.  The only view was to the tornado's east, and that was directly out of our way.  We reluctantly turned south toward Mill Creek.

We were closing in on the town when a sunlit funnel or tornado suddenly appeared in the back side of a new supercell due east of us.  Open views are nearly impossible to find in southeastern Oklahoma, so we settled for a field where we could see all but the lowest part of the funnel.  We ran up to the fence and started taking photos.  I wasn't sure if there wasn't a tornado warning yet or if Radarscope just hadn't shown it because of our spotty cell service, but I called NWS Norman.  They seemed to know about it.

Then we launched near Mill Creek, sped eastward behind the southern storm, and put up a final sonde near Atoka as that storm dissipated.

After further review, the sunlit tornado wasn't the EF3 Connerville-Bromide tornado as we and the NWS had originally thought.  This was a freakish circulation hanging off the west side of the cluster, between the Sulphur and Bromide storms, weak and barely detectable by radar.  KFOR chopper video showed it on the ground toward the end of my series of photos, but it may or may not have been down at the beginning.  The path was never surveyed.

I made three stupid storm reporting mistakes that I won't make again.  First, I didn't even think to call it in until a couple minutes had elapsed.  (As it turned out, this tornado didn't hit anything and the deadly one to the south was warned a couple minutes before my call, so it didn't make a difference, but it could have.)  Second, I didn't nail down the location of the possible tornado, going along with NWS Norman's understandable but wrong assumption that it was on the next storm south.  Third, I reported a tornado without confirming that it extended all the way to the ground, even though I've never seen a funnel get so close for so long without making it.

Later, we found out the EF4 Katie tornado had killed an elderly man toward the end of its path, which is hard to fathom because every local TV station was carrying a spectacular live stream and at least some were simulcasting on radio.  The skinny little tornado we saw from miles away was the worst thing that ever happened to someone.  Everyone in the weather community deals with that differently, but for now, I don't want that one hanging on the wall.

Wednesday, May 11

Wednesday wasn't a supercell day and we didn't operate, but a boundary draped across central Oklahoma kicked off some nocturnal storms that produced CG lightning in south Norman.  The thunder from this one was an immediate crack.

Friday, May 13

Mini-MPEX passed on Friday, a marginal and somewhat unorthodox setup for the middle of May with a narrow window for high-based supercells ahead of a cold front.  By midday, the HRRR locked onto a small target area at the far southwestern corner of Oklahoma.  I made for Hollis, the last town before Texas on Route 62 out of Altus, and stopped on the north side of town just in time for the show.  A few other chasers were scattered around the storm, but I saw none within a mile of my spot.  That's rare for a kicking supercell in May on the Plains even with tornado probabilities near zero.

The storm was evolving from a small multicell cluster into an intense right-moving supercell as it came into view.  At times the lightning in the forward flank had so many return strokes I could hit the camera button when I saw a flash and still capture the last few strokes.

As I headed south to get back ahead of the storm, which was taking a hard right toward the Red River, a thin laminar cloud appeared near the updraft base right before I lost sight of it in Hollis.  Having just seen dust blasting south in outflow near that spot, I couldn't believe it was a tornado, but I cut back west to make sure.  Nothing was there.  A Warning Decision Training Branch scientist who saw it tweeted that it could've been a small rope, but nobody confirmed it and the official count for the day remains 0 tornadoes.

A new core had appeared almost directly over Hollis, and I raced east out of town in 50 dBZ big drops and what sounded like a couple small hailstones.  For the next hour of escaping south into Texas, Verizon data was nonexistent.  I wound up in Crowell before it magically reappeared.  The supercell had faded after diving west of Hollis and was growing upscale.  Showing a little shelfy structure, it came close enough for some sunset lightning shots that don't approach doing justice to the anvil crawlers overhead.