Roger Edwards chase account: On Wed, 7 May 1997, Gilbert L. Sebenste typed: > At 7:45 they (and 14 students) have a hose in Gray County, TX...near roads > 293/70, from what I can tell. EXCELLENT gate to gate shear on that cell > right now, and as I speak, they see another rapidly rotating wall cloud! > Going for two!!!!!.... Rich Thompson, Jack Beven and I were chasing in the Meatwagon and had just met up with Paul and his young flock just north of that intersection, immediately before that probable tornado (which I have since called in to be relayed to AMA). Here is the chase summary: We left Norman shortly after noon, having made a forecast target area in the Memphis/Clarendon vicinity, and having not called back for guidance or seen any weather data whatsoever after leaving. We arrived at a good lookout vantage just W of Lakeview TX after 4 pm, observing much better vertical development to cumulus to the N and NW than any other direction. This was near of the north rim of the Palo Duro Canyon, a noted hotspot for terrain-enhanced convective initiation, which we thought was quite possible. We spent most of the next 2.5 hours slowly drifting north with a few long observation stops, between there and Clarendon. We observed several turkey towers bubbling and frothing above the canyon to our W, and passed the waiting time by collecting interesting rocks, sawing off some leafless roadside mesquite to take home and use for grill wood, and atomizing caliche chunks with powerful swings of a softball bat. All the while, there were warnings (including a tornado warning) for the Dumas cell; but it wasn't quite southeast enough to be in our forecast area and we weren't particularly interested in it. We felt the best S-R flow in the area would be slightly farther SE. [Patient chasers, we.] We did observe an orphan anvil and some adjacent new high-based towers distant SW (this agitated area later yielded the Hall County storm); but it was just a little too far SW of our forecast area and too far to reach much before sunset. [While going N to the last stop S of Clarendon, both DOWs passed us going S.] Finally, we observed hard towers erupting up through some pre-existing cirrus to the NNW, just N of I-40; this cell would later become the Gray County/LeFors supercell. Being on the N edge of our target area, with only a couple hours of daylight left, we decided to head up to it (only to miss very late development of a small but apparently photogenically tornadic storm near Memphis around 8:22 pm!). After crossing I-40 W of Groom, it became apparent that our target storm was just one member of a series aligned generally zonally just N of hwy 293. We began to see evidence of a deep mesocyclone while still S of that road. There was also a prominent but rather featureless rain-free base distant W, S of Pampa. We headed E on 293, paralleling and overtaking a well-developed, rapidly rotating wall cloud. We were driving E about 70 mph (the speed limit on that section of 293); and individual cloud tags in the south rim of the skirt (around the wall cloud) were still moving E faster than us. What fantastic rotation! Meanwhile, forked, staccato anvil CGs were as numerous as I have ever seen and in all directions, prompting Jack to say that the anvil appeared to be "walking on CGs." Some of the strikes were occurring several miles to our S and SE, way out into the low level inflow region, well removed from any precip and many miles away from the meso. We reached hwy 70, realizing quickly that we could not get NE to LeFors before the meso crossed 70 to our N and cut us off. So with no E road option N of I-40, we sat just N of the 70/293 intersection and watched that whirling dervish of a wall cloud cross 70 to our N. Paul Sirvatka's vans pulled up next to us and people poured out [there was still an unnerving number of anvil CGs around, but decreasing in frequency]. We chatted a bit with Paul while watching the wall cloud move to a position about 2 miles to our NE (8 SW LeFors), when a well-defined front-lit condensation funnel appeared underneath, extending at times at least 3/4 of the way to the ground. Unfortunately, poor contrast and wet ground prevented enough of a debris cloud for us to see; so until I either see confirming video or get a good damage fix, this "probable" tornado cannot be confirmed. [Gilbert - can you find out for me if anyone in Paul's crews got video of the tube? We didn't -- see below!] It lasted slightly more than a minute before becoming diffuse and hidden by wrapping precip curtains. Unfortunately, we had made the mistake of not synchronizing our clocks; my watch said 7:39 but was probably slow; and Rich's video camera was 7 minutes faster. Shortly thereafter, Paul talked to Gilbert and received word that this meso had a TVS (no s***). Rich had unknowingly left his video camera on "pause" while he *thought* he was filming the hose, and didn't get it on tape! I had the time to reel off a couple stills. HOWEVER -- It was extremely dark under that base; and I had to shoot 1/15 sec hand-held (no outside tripod set up due to the possibility that I could be turned into a big piece of charcoal). The stills may not come out. Such are perils of chasing! That meso got away to the NE; and a huge new one quickly formed to our NW. This evolved within minutes into a rotating wall cloud and then a bookend vortex for a bow echo that began surging SE toward us. We were pummeled with winds estimated to be near severe; but inherent human subjective imprecision prevents us or anyone from making a scientifically useful speed estimate. The Meatwagon was also pelted with hail to 1.5 inches in diameter - with no damage of course. We headed SE along 287 toward Memphis then E thru Altus to avoid the most destructive part of the resulting MCS, meeting with Gene Rhoden and Tim Vasquez for a late dinner. In all, it was a very entertaining and educational chase, with lots of rapid evolutions in storm character, as well as lessons in patience and in photography. Of course, I am quite interested in any others' accounts of either this event or the two W/SW OK supercells of 1 May (which Rich, Steve Goss and I observed). --------------------------- *** No disclaimer necessary; this is my personal account! *** "I'm a @#$%& legend!" ===== Roger Edwards ===== - current chase partner ( ) Forecaster former NHC Forecaster :::::::::: http://www.wildstar.net/~tornado :::::::::: "I FEAST ON THE SMORGASBORD OF ATMOSPHERIC VIOLENCE."
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