Tornatrix.net

The last week of April saw the arrival of this year’s Windom High School group from southwest Minnesota, consisting of nine enthusiastic, weather-savvy seniors, their teacher, Craig Wolter, and three chaperones. Each year, Craig takes his top ten or so students on a five-day storm chasing trip to Norman, where the students get to visit the NWC and meet and greet with meteorologists there. Craig has a tight itinerary for his students upon arriving in Norman, but it can always be pre-empted by a decent chase setup. As a fellow Minnesotan, I have a soft spot for Craig’s kids, and always try to lead them on at least one chase. If there had been such a program at my high school, I would have killed to get on the trip!

Dan and I were able to take Windom group out on Monday, April 30th, after noticing an enticing setup in the Texas panhandle consisting of a trough encroaching on an outflow boundary from the previous night’s widespread convection. Upon arriving in Memphis, TX, we found convection struggling to initiate along the dryline. We drifted northwest on U.S. Hwy. 287, toward a clump of storms west of Amarillo, intercepting it as it organized into a supercell near Claude, TX. We drove about 2 miles north off of U.S. Hwy. 287 to obtain a clear view to the west.

We were presented with a beautiful, high-contrast LP supercell, and proceeded to point out all the salient features to the students. The high bases didn’t bother us too much, because we knew the Claude storm was drifting east into better moisture, and we expected great things from it once it began to realize the improved buoyancy. As we watched, the Claude storm split right in front of the students, allowing us to narrate the process live. I pointed out a small, cone-shaped lowering just south of the main precipitation shaft on the right-mover. It persisted for three to four minutes, but never extended more than 10% of the distance from cloud to ground.

Meanwhile, we noticed new Cbs to our east, rooted in the deeper moisture. The updrafts on the new towers were crisp and glaciated, so we kept our heads on swivels in case we needed to re-target. The Claude storm dropped a few nickel-and-dime hailstones on us, forcing us to jog east twice along our dirt road in order to keep ahead of the storm. The vault structure grew breathtaking. We were able to enjoy it in relative solitude, without any other chasers blowing clouds of dirt on us. Simply moving a mile or so off the main highway is proving a surprisingly effective way to avoid the hordes. (I think I’m going to require 4WD in my next chase vehicle.)

The Claude, TX supercell eventually became outflow-dominant, so we decided to re-target the next storm to the east (the Hedley, TX storm), whose birth we had witnessed about an hour before. We retraced our route southeast on U.S. Hwy. 287, then went east on TX-203. We thought we would be able to core-punch the Hedley storm without too much trouble as it lifted northeast, then emerge from its forward flank and with a view of the hook to our southwest. However, radar updates showed new storm cells erupting to the south of, then being ingested by, the Hedley storm. These processes interfered with storm consolidation and hook formation, and also resulted in our spending more time in the hail core than we expected, our vehicles pelted with nickels and dimes for nearly 40 minutes.

When we finally did emerge from what should have been the forward flank of our target storm, crossing over the border where TX-203 changed to OK-9, it was dusk. Looking back toward Wellington, TX, we caught glimpses of the hook region to our southwest. Suddenly, Dan commanded me to stop the car, chattering excitedly about a dust cloud. I couldn’t see anything from the driver’s seat, but I stopped at the top of a hill. By the time I got out of the car and fired up my camera, the dust cloud was gone, but I could see the scud finger which had grabbed his attention. My only photo of it is very poor and I had to enhance the hell out of the contrast in order to make it visible. The feature was too brief and ambiguous, the distance too far, and the lighting too poor, for us to conclusively call it a tornado.

We took a rather circuitous route back to Norman via Lawton, attempting to avoid a southward-diving hailer over Hobart, OK. We returned to Norman around 1 a.m.

In the days since this chase, I’ve read an April 30 chase account from Bill Reid, whose Tempest Tour group (including Brian Morganti) was much closer to the ambiguous lowering than we were. Even with his close proximity, he wasn’t certain what to call the feature, and after viewing his video, I can see why. However, he eventually concluded that this dusty spin-up was indeed a tornado. Bill’s a veteran chaser, and if he says it was a tornado, then that’s good enough for me. Based on his account, I was able to report to Craig that his students were no longer tornado virgins!

Update, 2012-05-07: After looking at video from the Tempest Tours group, the NWS office in Amarillo declared our “scud finger” an EF-0 tornado. So, now, it’s officially official!

Parental visits in springtime are always fraught with uncertainty. We can pack our agenda for the weekend with varied activities, only to have everything unravel the minute the atmosphere starts acting up. I had poo-poohed the chase setup for Friday, April 27th, thinking that it wouldn’t be worth driving to Kansas. However, I awoke to find the forums abuzz with excitement about the shortwave trough ejecting earlier than forecast, prompting a moderate risk on the Day 1 convective outlook from SPC. Anticipating an early afternoon chase setup, my husband and I scooped my parents up from the airport, and blasted north on I-35 into south-central Kansas, where we were greeted by clearing skies and a few turkey towers along the dryline. (Mom and Dad had flown more than 800 miles south from Minnesota to see us, only to backtrack immediately almost 1/3 of the way home.)

Near Emporia, KS, we met up with Jeff S., chasing solo. The atmosphere produced mediocre convection for hours. As a surface low approached from the west, increasing the low-level shear, it also squeezed the warm sector between the cold and warm fronts. We were forced to follow the warm air up into the Flint Hills area. This region has good visibility, provided that you’re on top of one of the hills. By the time we targeted a storm near Council Grove, KS, the warm sector (and the storm’s access to the warm, moist air within) was only a few tens of miles wide, if that. Cold rain and gusts of wind pelted us as we parked on a hilltop gravel road off U.S. Hwy. 56 near Bushong, KS, watching two cloud bases to our west-northwest. Suddenly, Jeff S. shouted to our group as a small white funnel abruptly materialized within an RFD slot to our northwest. I barely had time to re-center my video before it eroded away.

Minutes later, another funnel descended from the far bank of clouds, tickling the ground with a few suction vorticies. From my vantage point, this brief tornado dropped right behind a tree. My video consists mainly of my scrambling a few feet to the right and re-leveling my shot, by which time the tornado had already vanished. Because of the brevity of these two funnels and the shakiness of my video, I decided not to post either shot on YouTube. Screen shots it shall be.

The cold rain and pea-sized hail began to fall in earnest, driving us back into our cars. We may have glimpsed another funnel on the horizon, but lost it in the rain after a few seconds. To our north was a road hole, forcing us to head east on U.S. Hwy. 56. The remainder of our chase consisted of an attempt to catch another storm to the east of our original target. Unfortunately, it was ingesting stable air, the warm sector long since squeezed out of existence, and we decided to abandon the chase near Osage City, KS. We had dinner at Emporia, then began the long haul back to Norman.

As I’ve gotten older, I’ve gotten little more choosy about which days I chase. (I chalk part of this change up to accumulated experience, and part to having a full-time job and family to support now that I’m done with school.) However, when I have guests along, I’m more likely to bite on riskier setups with more potential failure modes. Even though it required a 5-hour drive each way, seeing one tornado is definitely better than seeing none!

Today, I broke my personal record for the number of tornadoes seen in a single day (9, 10, or 11). Two were small funnels near Freedom, OK; the remainder were produced by a single supercell that we followed from Mooreland to Manchester, OK.

I had some trepidation heading out on 14 April because it was a widely-publicized SPC high risk on a Saturday. I had no wish to re-experience the Kingfisher, OK Charlie Foxtrot of 19 May 2010 (when it seemed like every storm chaser on the Great Plains converged on one two-lane highway, with a solid line of cars from horizon to horizon – not even joking). However, the moderate risk area stretched from the Missouri River to the Red River, encompassing Nebraska, Kansas, and most of Oklahoma, so I figured the atmospheric playground would be big enough to handle the chaser convergence. We decided to target the Oklahoma portion of the high risk, where the moisture was better and supercell shear was forecast. With the storm motions progged to be 35 mph or faster, our strategy was to follow tail-end Charlie storms until they raced northeast out of our reach, then turn back southwest to catch the next in line.

Our mini-caravan consisted of two cars: Jeff S., Howie B., and John L. in the first, while I drove Dan D. and Michael H. in the second. We departed Norman just after noon and drove up the Northwest Passage. From Seiling, we headed north on U.S. Hwy. 281, then west on U.S. Hwy. 412 after the first tail-end Charlie storm. Near Freedom, OK, we caught a glimpse of a slender needle funnel as we crossed the OK-50 bridge over the Cimarron River around 4:30 p.m. About 10 minutes later, just east of Freedom, it again produced a slender needle, both of which we captured on video. We were a bit disappointed at the brevity of both tornadoes; neither lasted more than 30 s. Knowing that a new storm was forming down the line, we decided to end round #1 and head back southwest toward Woodward.

Back on U.S. Hwy. 412, we stopped about halfway between Moreland and Woodward. A second supercell with a vigorously rotating wall cloud churned past us just a few miles to our west, but did not produce any funnels. We followed that storm east along 412 almost to the intersection with U.S. Hwy. 281, where we decided to head south a mile or so and find an unobstructed view towards the next storm erupting back to our southwest. We staked out a claim on a pull-off near the top of a hill, and waited. Several other chasers joined us there.

Around 7:00 p.m., excitement began to build as the target storm grew near and a fat funnel descended about 10 mi to our west, playfully twirling a cloud of dirt at its base. That tornado had a lengthy (<15 min) rope-out phase as we trained our cameras on a new mesocyclone to its east, which also dropped a truncated funnel halfway to the ground to our NNW. We were elated to finally see some tornadoes with decent longevity and contrast, and we couldn't tear ourselves away. By the time we finally did pile back into our vehicles and headed back north on 281, yet another new meso was taking shape directly to our north. With the storm scurrying away toward the northeast, we were considerably behind it for the remainder of the chase.

The new lowering narrowed almost to a square. The lower portion then tapered into an unequivocal funnel, and tornado #5 was born. Returning to the U.S. 412/281 intersection, we found that 281 northbound toward Waynoka was blocked by two police cruisers, forcing us to turn east. The chaser crowds had by then thickened considerably, and I focused my eyes on the eastbound shoulder of U.S. Hwy. 412, only stealing occasional glimpses toward the north, where Tornado #5 was churning happily away. (I trust that my husband got HD video for me to enjoy later.)

At some point, we stopped to film again, and I witnessed a bizarre handoff between two tornadoes. (It occurs at about the 3:00 minute mark in the YouTube video above.) One vortex eroded as another descended right next to it. We can be heard disagreeing verbally about whether we were witnessing multiple vortices within the same tornado revolving around a common center, or two separate tornadoes doing a graceful dance. (Mobile radar data could have settled that question, but unfortunately, RaXPol was in the shop.)

We then drove up OK-8 towards Cherokee, OK, with tornadoes (sometimes multiple tornadoes) visible almost all the way there. On our approach to Cherokee at around 8 p.m., I shot my first-ever 3D footage of a tornado with my new Bloggie pocketcam, and was pleasantly surprised by how well it turned out. (I’ll review the camera later.)

Tornadoes continued to snake out of the storm as darkness descended. As the driver of my vehicle, I had to keep my eyes on the road rather than the tornadoes, and I didn’t particularly care about an accurate count. I was simply enjoying sharing the spectacle with my passengers.

Our chase was ended by downed power lines just after dusk, a few hundred feet north of the Kansas border near Manchester, OK. There was still an unmistakable, lightning-illuminated funnel visible to our northeast. That tornado later triggered a tornado emergency for Conway Springs, KS, southwest of Wichita, but thankfully dissipated before reaching town. We made our way back to Norman by way of Enid, OK.

After midnight, as we straggled back into Norman, word began to filter through that a tornado, spawned from a trailing line of storms, had ravaged parts of Woodward, OK. Woodward suffered greatly at the hands of an F-5 tornado in 1947, an event that still figures prominently in Oklahoma lore. Unfortunately, six fatalities resulted, and cleanup and recovery efforts are still ongoing as of this writing. Donations for the victims can be made to the American Red Cross.

Altus, OK was our initial target. As I merged onto I-44 W from Hwy. 9 with Dan D., Jana H., Jeff S., and Howie B., we saw a disorganized storm roiling over Chickasha, OK. Thinking little of it, we blew on past, targeting the a much better-looking storm down the line near Snyder, OK, and later, yet another storm west of Altus. As we approached Altus on U.S. Hwy. 62, our phones began beeping with robotexts from OU: “Emergency: Tornado approaching. Seek immediate shelter indoors.” Pulling up the radar, we saw that the storm we had blown off earlier had developed a healthy hook echo as it approached Blanchard, and tornado reports were popping up across Norman from credible Spotter Network witnesses.

Pained to have missed a tornado at our home base, we instead intercepted our target storm near Victory, OK, just west of Altus. It struggled with outflow contamination from the morning’s convection, producing only a brief wall cloud over blooming broccoli fields. As it merged with another cell to its northeast, the complex began to transition into an HP supercell. Nothing prevents an HP supercell from producing tornadoes, but they tend to be difficult to see. We decided to let the Victory storm head on its merry way.

We took another jog west to intercept a developing storm between Gould and Hollis, OK, that we thought would have access to uncontaminated inflow with better moisture. However, the Hollis storm didn’t look much better visually, and in the meantime, the earlier Victory storm had grown upscale and was leaving a trail of tornado reports in its wake. Most of the reports mentioned that the tornado was rain-wrapped – not optimal for visual documentation. We opted to stick to our target storm, hoping against hope that it would tap into better moisture and warmer temperatures to its south, staying a few miles east of it as it “chased” us back to Altus. It produced this ominous shelf cloud over Gould:

Daylight quickly faded, and we headed back to Norman just ahead of an MCS. I had forgotten to affix my new Pikepass sticker to my windshield, and the resulting 30-second delays while we aggregated quarters at each toll booth enabled the MCS to catch up, engulfing our car in blinding rain and dime-sized hail. Once back in Norman, we found large sections of town dark and surrounded by blinking Saf-T-Flares. The earlier tornado initially touched down near I-35 and Lindsey, then scraped northeast across downtown Norman, splitting trees, tossing sheet metal and demolishing a warehouse on Porter St. near the hospital. It was eventually rated EF-1 by the NWS.

Dan D., Jeff S., Mike F., and I headed west on 12 April 2012. SPC had issued probabilities for severe storms from the triple point in W KS down the dryline into the TX and OK panhandles. The discussion mentioned the conditional nature of the severe storm potential; i.e., if storms formed, then they would likely be severe and have a good chance at producing tornadoes.

We initially drove up the northwest passage. We had a shot at targeting the triple point, but opted for the dryline bulge target in TX instead, heading west out of Watonga. The entire drive, we were socked in by low-level cloud cover – not a good sign, since it would limit solar heating and limit the ability of updrafts to punch through the moderately strong cap. It was also relatively chilly for a chase day – temperatures did not rise out of the 60s for most of the day.

We set up shop in Canadian, TX, where the skies were clearing out, waited, waited, … and waited. Our eyes scanned the horizon for any sign of turkey towers. When one finally did erupt to our south around 7 p.m., we had nothing better to do, so we dropped south after it. A few bubbling cumulus clouds did develop, but none hit the tropopause, we ended up shower-chasing. We ended the chase in Elk City, where we enjoyed a decent supper at the Portobello Grill.

It was a high risk, high-reward situation, and unfortunately our numbers did not come up. In hindsight, at my own peril I opted to ignore a preponderance of model solutions that forecast a cap bust. As they say, however, if you don’t play, you can’t win.