Oklahoma City HP Ice Machine
Oklahoma City to Ada, OK (16 May 10)
SHORT: Observed fast-moving HP supercell from eastern Oklahoma City to between Seminole and Ada, then let storm pass by into southeastern OK.
LONG:
In the couple of prior days, I had considered some potential for severe storms across the region — mainly between I-40 and I-20 where it appeared the strongest midlevel winds would occur in a belt south of a mid-upper level trough over the central plains. The problems seemed to be lack of coherent initiative foci, rather weak moisture (resulting from the air mass to our S over TX being scoured by huge convective complexes), and weak near-surface winds that would keep hodographs small.
With far more negatives than positives apparent, I (along with many other storm observers) didn’t pay a great deal of attention on the day of the event. In fact, I was eating late lunch in Moore with Elke, Rich Thompson, Jack Beven and Jim Leonard — all experienced chasers of many decades in aggregate — when a supercell materialized out of a clump of convection NW of us near Okarche. The hook echo on the TV display and on our phones definitely got our attention.
Yes, a quick look at the surface map showed weak, mainly SW winds at the surface, though there was a sharply defined, E-W boundary extending N-NW of OKC. Turn the entire setup (including NW-SE storm motion) leftward 30-45 degrees, and you’ve got an east-moving storm with light SE winds. That’s not bad. Surface dew points in the inflow region were on the low side at about 62 degrees F, but the presence of the storm told us that was more than sufficient! Bellies full, we all scattered to our respective domiciles to get camera gear, and ended up separately observing the supercell.
Elke and I headed N from eastern Norman intending to photograph the storm coming over downtown, but its gradually accelerating motion precluded that. Instead, we first got a good look at it to our NW near the junction of I-240 and Sunnylane, with lots of buildings, wires and such contaminating the foreground. It was moving SE at 35 mph and accelerating further, and we had to head E on I-240/40 to stay ahead, if we wanted any hope at a good view without getting demolished by the baseball to softball size hail that was pounding northern and eastern Oklahoma City. We also drove right past the intersection of Choctaw Road and I-40, where a violent tornado had destroyed a truck stop and caused casualties the previous Monday. No time to look…we had to keep going!
Along the way there, we were listening to the radio simulcast of KFOR-TV, where Mike Morgan was saying, “We’re under attack at the KFOR studios! Skylights are breaking, baseball hail falling right here! We are under attack! This storm is taking no prisoners.” Now, Mike is not exactly the dignified, stoic gentleman of 1960s/70s television, seriously delivering the dire news of impending meteorological doom. He is no Harold Taft by any measure, and never could be. That said, while his penchant for over-exuberance and occasional exaggeration is well-known, he wasn’t too far from the truth this time.
Meanwhile, eastward we forged in search of a vantage. In this part of central Oklahoma, the Eastern Crosstimbers arboreal province, it’s very difficult to get a good view of a storm, with the trees, hills, and buildings rampant. We pulled off I-40 several times in futility, but finally and briefly found a very nice look about 2 SSW of Dale, on OK-102. To our NW, the north part of the storm (where the mesocyclone was) sported a beautiful tail (stinger) cloud, with a cream/reddish wall cloud rotating weakly. It was obviously being undercut by outflow and in no danger of a tornado. Given all the tornadic destruction of six days before, this was a good thing; because folks in these parts are hypersensitive to big, mean-looking storms.
I managed to photograph the south part of the supercell (looking W) before the storm closed in. We zigzagged S and E to Seminole, edging the hail core (nothing damaging), and driving past more of the previous week’s tornado destruction along Highway 9. Not wanting to get munched by a hail core in Seminole, we charged S to 12 N of Ada, and let the outflow-dominant storm race across the road right behind us.
All in all, this was an unexpectedly rewarding afternoon for a couple of storm observers who hadn’t counted on seeing much. Unfortunately, Oklahoma City took an epic beating from the hailstorm, the costs of which will run into the tens (maybe hundreds) of millions, not counting the insurance premiums that are sure to skyrocket even more. Since we stayed (mostly) ahead of the storm, I don’t have any hail photos, but the brief episode of photogenic structure near Dale was well worth the effort.
The “HP Drum” Storm
Delhi/Clinton/Greenfield OK, 12 May 10
SHORT: Observed HP supercell from S of Delhi OK to Clinton area, with some lightning after dark near Greenfield.
LONG:
The main surface cyclone was ejecting northeast over Kansas with a slowly progressive cold front southwestward across NW OK and into the TX Panhandle, intersecting the dryline in the extreme eastern Panhandle. I normally don’t like cold frontal setups such as this for tornadic storms, with upper flow nearly parallel to the front and barely rightward of the dryline. Still, with the boundaries intersecting only a couple of hours to the west, dew points in the mid 60s to near 70 F in the moist sector, and 50-60 kt 500 mb winds aloft, in the eastern Panhandle region in mid May, it’s advisable to chase. The basic ingredients of moisture, instability, lift and shear would be there. The biggest question, of course, would be the relative geometry of kinematic fields and boundaries, offering a dominant tendency for linear storm mode.
Ryan and Corey, whom I had chased with the two prior days, had other obligations on this day of more marginal tornado potential; so I hopped in the truck and headed W on I-40 to await the day’s convection. It was easy to ignore a rapidly-moving, leftward-deviant hailer down by LTS, and wait near W edge of a thick cirrus plume for heating back along the dryline.
Towers kept erupting along the cold front and feeding NE into a backbuilding line, which I preferred not to go after. Storms also were forming off the dryline into SW OK, but almost instantly turned linear as well. Instead of going after either right away, I hung out near Leedey for a spell, shooting around an abandoned homestead while waiting for the convective mess to sort itself out better.
Sometimes linear messes do break up into supercells, and that happened here. The activity to my SW began to knot up into inflections and semi-discrete embedded storms, one showing increasing rotation on the N end near Erick. As I headed down that way, it got tornado-warned, apparently producing a brief one early in that cycle. By the time I got there, the storm was nearly featureless and photographically unworthy, a hopelessly huge cascade of cold rain falling into its inflow from yet another intensifying, embedded supercell farther SW.
I dropped S out of Sayre and intercepted this storm with a big, robust velocity couplet near Delhi, not knowing yet that Mike U and Matt C (who had been hanging out in the eastern Panhandle for a few hours) already had abandoned their initial target, dropped SE, and had seen a brief tornado with it down near Vinson. As this drum-shaped, heavy-precip (HP) monster came into view (24 mm wide angle), a tremendous, frightening and dangerous barrage of CG lightning to its NE (and all around me) reminded me how little lightning we had seen with the tornadic storms the previous two days! It also kept me inside the truck, only briefly opening the window to shoot an occasional photo as the storm churned toward me.
There were good east, southeast and northeast escape options, so I could hold this typically more treacherous viewing position for longer than usual, until either the HP mesocyclone got too close or the hail got too big. If this sucker were to produce a tornado again, the most probable way to see it would have been from within its path to the NE. At one point, it seemed willing! Alas, the feature had far more rising motion than rotation, and devolved into a scuddy tail.
When the nasty part of the storm’s core got close, I zigzagged NE toward OK-152 E of Sayre and took that road to Cordell in incremental fashion, occasionally lurching E to get out of vault hail that started beating on the vehicle before the stones got big enough to cause damage. That’s what was going on as I took this wide-angle shot back toward the mesocyclone, looking SW from a point 8 SSE Elk City. The low-hanging, scuddy area was rotating, but not alarmingly fast, with a clear slot drawing around. That was the best that occlusion process could do, however, and I kept going along 152 to stay ahead of the huge hail that surely made life miserable on some farmsteads soon thereafter.
I was repositioning through a remote area NE of Cordell and E of Bessie, at a relatively distant position, when the storm produced the brief spinup along I-40, and couldn’t see it in the dark murk. After dark, and after the storm go N of I-40, it turned somewhat more leftward again, its propagational component and mesocyclone each weakening with time, while persistent nonsupercellular storms formed on its SW flank. The complex yielded several episodes of CGs (photographs 1, 2, 3) after dark between Greenfield and Watonga before I headed home into the last of the 70s dew points for some time to come.
Supercell South of Woodward
Briefly Tornadic (11 May 10)
SHORT: Intercepted brief storm attempt W of Cordell and briefly tornadic supercell S of Woodward.
LONG: Ryan, Corey and I trekked out again on the “day after the day” with hopes of finding a tornadic supercell somewhere near the remnant frontal zone, which was retreating north as a warm front across western OK, or the dryline not far to its S. Deep-layer shear would be more than sufficient to support this potential anywhere along or S of the warm front, and the frontal zone itself promised backed flow, maximized boundary layer vorticity and enhanced low-level SRH for any storm that could form along it, or the nearby dryline and interact with the front. A stout cap and more nebulous low-level forcing yielded considerable uncertainty for this day, which was reflected in the justifiably low unconditional tornado probabilities in early outlooks. Compared to the frantic racetrack nature of storms the day before, one advantage would be cell motions far more manageably interceptable.
We waited a long time at Clinton, watching the warm front pass to our N and gradually deepening Cu in the warm sector. With little of note happening along the warm front or its intersection with the dryline, we took a look at a short-lived Cb that erupted not far away, S of I-40 and W of Cordell. Disturbingly skinny, the updraft seemed to suffer from too much dry entrainment, and left behind an orphan anvil. We only messed with this briefly before hastening back up to the warm front to await any chance of diurnal initiation.
We passed the warm front near Leedey and sat at an overlook near Camargo, one apparently prized by the research community for its utility as well! Shortly afterward, a V.O.R.T.EX.-2 radar truck appeared, their occupants wishing to use our parking space to set up surveillance for the nascent storms bubbling along the front to our W. We were pleased to oblige, and I had some enjoyable conversation with a few of its occupants from NSSL (Kim Elmore driving, Conrad Zeigler and Gabe Garfield onboard).
We had sustained, deep-convective initiation, at long last…8 o’clock magic! The more distant young anvil in the previous shot became the easternmost of a storm pair in short order, and was targeted by the field project. Meanwhile, we instead targeted the more vigorous young storm to its immediate W, blasting W on US-60 from Vici and ignoring the crappy-looking eastern storm. Even though we got on it early in its lifespan, we still were almost too late! The western storm went from barely having a radar signature to a strong mesocyclonic couplet in just a few volume scans. While going rollercoaster-like through hills W of Vici, we began to see the distant base(s) of that more distant storm, as it interacted with the vorticity-laden environment of the warm-frontal zone.
The more distant of its two main bases — already deeply occluded, suddenly spawned a brief, fuzzy, but obvious condensation funnel that fleetingly made ground contact off to our distant WNW. The tornado was at 2025 CDT in SW Woodward County, N of Harmon. We were driving westward in a remote, somewhat hilly area with no AT&T service, about 7-8 miles W of Vici (pronounced Vy-sigh) at the time, and the tornado was gone before we could find a place to pull over and shoot, so…no photos. However, scanning StormTrack, I found one photo of it from C.D. Collura…
http://www.sky-chaser.com/image/mwcl2010/m11tor3.jpg
…which definitely was our tornado.
I did call it to the WFO in a few minutes later when we were in a window of some cell coverage. Unfortunately I had trouble giving a specific tornado location because my road atlas was falling apart in my hands as I was trying to call and while we were driving, with pages falling everywhere! By then of course the storm had cycled another (non-tornadic) occlusion, and had a cold, fuzzy, increasingly elevated look (also mentioned on the phone). That “cheeznado” was the storm’s first, last and only hurrah in that regard — truly, a needle in the haystack that shockingly few of the numerous storm observers chasers in the area appear to have witnessed. It would have been easy to miss. By the time we found a safe and closer pull-off, the old occlusion was decaying further (left, in this photo, looking NW-N), while the new mesocyclone (at right) never could tighten up enough, and had a colder, more stable appearance.
By the time we got back E to Vici and N again toward Woodward, we began to see some great structure in fading twilight, but most of the colors that other chasers (who had been farther E) photographed so well were about gone. We ate a late Arby’s dinner in Woodward with two Environment Canada meteorologists (Neil Taylor and Dave Sills) and Matt Crowther, then headed back on the long drive home.