STORMTRACKThe Magazine for Storm Spotters and Chasers
July-August 2000(narrative only)
Volume 23, No. 5
TIM MARSHALL, EDITOR
TIM VASQUEZ, ON-LINE EDITOR
STORMTRACK is a non-profit publication intended for the scientist and amateur alike who share an avid interest in the acquisition and advancement of knowledge concerning severe storms. It is published bi-monthly by Master Graphics in Lewisville, Texas. David Hoadley founded the publication in 1977 and STORMTRACK has continued to grow and improve ever since. David Hoadley still contributes drawings and sketches. Darlene Egli designed the current cover. Right now, we have about 700 subscribers!
Anyone can submit an article or letter to STORMTRACK. Articles should be single-spaced and contain proper English. Right justified margins are preferred or the editor can retype the text. High contrast photographs reproduce best. Diagrams should be clear and legible, subject to photo-reduction. All articles will be edited.
Subscription rates are: U.S. First Class mail $18/year. For Canadians, it's also $18/year in U.S. Currency. Overseas is $22/year in U.S. Currency. The hardcopy publication will end with the November-December 2001 issue. STORMTRACK is available on-line free of charge at http://www.storm-track.com. Individual regular back issues are available for $3 each, expanded issues $5 each, and double expanded issues $10 each. Hard copy back issues are available for $18 per year from 1996 through 1999 and the complete 20 year set (1978-1997) can be purchased on CD-ROM for $65. To subscribe or renew, send a check or money order PAYABLE ONLY to Tim Marshall, 4041 Bordeaux Circle, Flower Mound, Texas 75022-7050.
STORM TRACK CLASSIFIEDS
Sell or swap your wares. Only 30c per word with a 20 word minimum = $6. Quarter page ads are $70, half page ads are $130, and whole page ads are $250. Send your request for the next issue by September 30, 2000.
HARD COPY STORMTRACK TO END WITH NOVEMBER 2001 (25th ANNIVERSARY) ISSUE
Those of you who are up for renewal with this issue and would like to extend your subscription to the end of this publication (eight more issues until November 2001), can do so for $24.00. All subscribers will be asked to renew their subscription with the November 2000 issue and credit will be made for those of you who are renewing in the year 2001 (i.e. those of you renewing in November 2000 will be asked to remit $18.00, January 2001 $15.00, March 2001 $12.00, May 2001 $9.00, July 2001 $6.00 and September 2001 $3.00). A note will be attached to every issue in November 2000 indicating the amount of your subscription owed. No NEW yearly subscribers will be accepted after the January 2001 issue and submitted checks will be returned.. The last issue will be an expanded one. Thanks...
THE MAY 3, 1999 OKLAHOMA TORNADO OUTBREAK- This video is a collection of tornado footage from the historic outbreak which ravaged central Oklahoma. Ride along with Tim Marshall up the Bailey Turnpike witnessing tornado after tornado including a close look at the F-5 Moore tornado from the top of a bridge. Travel with other chasers too as they witness tornado after tornado with a second storm to the west. You'll also take part in the damage survey following the event.
1999 - STORM TREK: This second chase video of the year highlights the chases other than the tornado outbreak on May 3rd. It includes the tornadoes at Carrier, OK, Allenread, TX, Goldsmith, TX, Sitka, KS, and Ft. Gibson Lake, OK. Each chase takes you through the forecast, the hunt, and the tornadoes. 90 minutes.
Both videos are 90 minutes each, VHS only, color with sound. Each video is $25 U.S., $30 Canada, $45 overseas (U.S. Currency please) Send check or money order to: Tim Marshall, 4041 Bordeaux Circle, Flower Mound, Texas 75022-7050.
I. COMMENTARY CERTIFYING STORM CHASERS?
There has been much discussion online about certifying storm chasers in response to a proposal and meeting held at the state capital in Oklahoma recently. In brief, legislation is being considered to regulate storm spotting and chasing in Oklahoma. Among the requirements for certification are: 1) completion of a spotter training course each year by a certified training meteorologist, 2) completion of a basic first aid training course, 3) completion of a driver improvement course every two years, 4) completion of an emergency vehicle operations course, and 5) payment of $28 per year fee. Upon completion of these five items, you would receive a certificate that would identify you as a trained spotter/chaser and would allow you to pass through police road blocks in advance of a tornadic storm. A fact finding meeting was to be held to see if such a proposal is needed and warranted. I don't know if the meeting was held or what the outcome was. However, I am against such regulation.
I realize that storm spotting/chasing has become a national pasttime like baseball and hords of people are now driving into harm's way in trying to observe a tornado. Police as well as myself are becoming frustrated by all the congestion around a storm (especially in May and June) and realize that someone is going to get killed or hurt by a tornado, lightning, or vehicular accident. I also would be the last one to resist more education of spotters/chasers. However, such a proposal brings up additional questions. Are all officers (state, county, local) going to know about this certificate allowing you to pass through their road blocks? How do we get around people forging such a certificate? Will there be reciprocity for such a certificate in other states so that you won't have to go through all the requirements for each state in which you chase? Can you train online or do you have to go to each state in which you want to chase and become certified? What are the requirements to become a certified training meteorologist? Who can be exempted from such requirements?
I have encountered a few road blocks during my chases in recent years. The road blocks usually were on busy paved roads and there usually was a line of cars blocking the lane. In some instances, it was difficult to drive up to the head of the line to ask the officer to pass. Those officers to whom I have spoken, have let me through after I explained my purpose. Proper identification was helpful along with showing them my SKYWARN card. I also have found that the more antennas you have on your vehicle, the easier it was to get past such a roadblock. However, not all of the officers were standing outside their vehicles waiting to talk to me. Some officers were sitting inside their vehicles that straddled the road. In such instances, I have simply taken a secondary road to avoid the roadblock. A good road map was essential to conduct such a manuever.
II. CHASER NEWS
SEPTEMBER 11-15: 20th CONFERENCE ON SEVERE LOCAL STORMS was held at the Radisson Twin Towers Hotel in Orlando, Florida. There was a special session on the May 3, 1999 Oklahoma City tornado. Two nights of slide and video presentations were held. A summary of the conference will be featured in a future edition of STORMTRACK. The conference was sponsored in part by the American Meteorological Society. You can visit there homepage at http://www.ametsoc.org/AMS and see a listing of future conferences.
OCTOBER 7: CENTRAL PLAINS SEVERE WEATHER SYMPOSIUM will be held at the Nebraska Center for Continuing Education at 33rd and Holden Streets in Lincoln, Nebraska from 8:30am to 5:00pm. For more information, see their web site at http://hpccsun.unl.edu/nebraska/CPSWS.html or you can contact Dr. Ken Dewey at firstname.lastname@example.org
CORRECTION: An error appeared in the last ST regarding the regarding the amount of the renewal to the end of this publication. It should have been $27 instead of $24. Those who sent in $24, don't worry about it. Your subscription was extended to the end of the publication.
IV. EMAIL TO THE EDITOR
Martin Lisius writes: "Some of you publish your photo stills on the Internet and would probably like to protect them without adding text directly on the photo. Some photo software like Adobe Photoshop allow you to add a virtually invisible digital watermark to each photo. In Photoshop, it's a breeze. Open your photo, go to "filters" then "Digimarc" then "watermark." First, though, you have to register. If it's the first time you tried to add a Digimarc watermark, Photoshop will prompt you to register on-line. It takes about five minutes. You'll get an ID on-line at the Digimarc site. Then, use your ID to continue with the watermark filter. It's easy. I registered today. Now we can use our photos at our web sites with less fear of photo pirates. You can go to the Digimarc web site to find out what other photo apps offer their watermark filter as a plug-in. If you don't have a good photo app, and you want one for under $100, I just read that the Ulead Photo Impact is supposed to be one of the best low-cost apps. Photoshop costs $500-plus. I'm not sure if the Ulead offers the Digimarc watermark though.
Here are the details for Photoshop users regarding Digimarc Filters. These filters let you add copyright information to Photoshop images and notify users that an image is copyright-protected via a digital watermark that uses Digimarc PictureMarc technology. The watermark-a digital code added as noise to the image's lightness channel-isn't visible and does not affect image integrity. The watermark can withstand many image operations including color corrections, some filter operations, halftoning, printing, and some cropping. To use the technology, you first register with Digimarc Corporation-which maintains a database of artists, designers, and photographers and their contact information-to get a unique creator ID. You can then embed the creator ID in your images along with information on the image use such as royalty-free or restricted use. Copying an image with an embedded watermark also copies the watermark and any information associated with it. On opening an image, Photoshop 4.0 scans it for a watermark. If Photoshop detects one, then the program displays a copyright (c) symbol in the image's title bar, to alert users to use the Digimarc. Read Watermark filter to determine the image's owner.
Martin Smith writes: "Recently, I have seen several TV documentaries on the subject of storm chasing. Although these productions are short on time to present the subject adequately, the TV media has taken to repeating the same diatribe on chasers and chasing. Ultimately, this is a disservice to the notion of storm chasing in particular, and the weather enthusiast in general. By refusing to provide a balanced account of storm chasing, with new information and insights more appropriate to a burgeoning activity such as this, such programs only serve to "dumb down" the chaser idea for mass consumption. Chief among the problems that infest such programs is the poor use of the term "chaser". For the most part, these shows refer only to "tornado" chasers, when there are as many types of chasers as there are types of storms. Perhaps tornado chasers are the most obvious segment of this community. I realize these producers are aiming their shows at a particular viewer, but they inadvertently offend anybody who knows anything about chasing. For the sake of diversity, and in fairness to the true diversity of storm chasing, it would be nice to see chasing defined more broadly. Not everybody goes looking for tornadoes on the Great Plains, and a storm chaser isn't less of a chaser simply because he/she does not embark on such a hunt. Non-tornadic research is important too!" Email: email@example.com
Mauro Giovannoni writes: "I'm an Italian storm chaser. Please visit my web page: http://members.xoom.it/tornadoit/ The site is growing very fast and from all Italy many people send me their incredible images (you can see them clicking on the link "le foto e I reportges" (http://members.xoom.it/_XOOM/tornadoit/foto.htm ). I think that you will never see so many pictures coming from other european countries. I saw a F0 from my window in 10/26/98 while a strong rotation was present directly over my house. In September and October 2000, I will lead a group selected in my meteorological association in the very first "massive" storm chasing day in Italian history. With 4 or 5 cars (I hope more) we will place ourselves all over the Lazio's coasts (the region of Rome) while a group will coordinate our movements from home with few instruments (included a new lighting visual sensor with a range of 400km). Our region is actually out of radars range! In that period Central Italy is often interested by powerful squall lines: tornadoes and waterspouts are very common in these days. I hope that we will come back with results (but I know how much it will be difficult). I've already tried to chase alone but it is impossible!! If you have suggestions please send me an email! Very funny to read about your casual encounters with Dr. Howard Bluestein. In Italy we say "Il mondo è piccolo" which means "The world is so small". Hear you soon, Email: firstname.lastname@example.org
MAY 11, 2000 BLACKHAWK COUNTY, IOWA TORNADOES
by Roger Hill
When David Gold contacted me about teaming with him on Silver Lining Tours this year, I jumped at the chance. Since I had given thought to opening my own tour company, this was a golden opportunity, and now will be an every year event with David.
I arrived in Oklahoma City for the first tour on May 10, and met David and Bill Reid, who had also teamed up with David. The chase situation was looking poor as we headed out into Kansas to wait for possible action in Nebraska late on the 10th. Moisture was not returning fast enough to fuel anything more than a few isolated weak storms (until late in the night), so we chose to drive through the evening to get to Des Moines, Iowa for a possible play on the 11th. The set up in Iowa was less than ideal, but it was the only game in town. CAPE and instability values were tremendous, and there was enough shear for rotating storms. Two major problems were evident though. One was that the models were not phasing the upper level and surface winds very well, and the other was a tremendous cap forecast to be over most of the state on the 11th.
So we arrived in Des Moines for the night and woke to pleasantly find high dews with low clouds overhead streaming in from the southerly low level jet the night before. Some convection had developed overnight and tracked across northern Iowa and Minnesota leaving a cool pool with northerly winds into southern Minnesota. Morning analysis revealed an ideal set up with a surface low in northeast Nebraska moving into northwest Iowa. Surface winds in eastern Iowa were fairly stout southeast-to-east with dewpoint temperatures in the mid-70's as far north as Waterloo. The strong cap was evident as surface air temperatures soared to over 100 degrees in southwest Iowa as all cloudiness dissipated in that area. This line of clearing skies was moving in our direction. We decided to head north and east of Des Moines to stay close to the warm front and east of the surface low pressure center where the cap was the weakest. That took us to Charles City, Iowa, the site of another violent tornado some 30 years ago. We stayed in that area until late afternoon as we watched towers bump against the cap only to dissipate. Finally just before 6 p.m., something changed. It looked like 6 p.m. magic was happening. Towers were finally exploding through the cap and soon a tornado watch was issued for the entire area. Weather radio tones were heard as the first severe thunderstorm warning was issued to our southwest in Butler county, and was soon followed by a tornado warning, all in less than an hour. Reports of a tornado on the ground were filling the airways. We quickly jumped in the vans, tourists and all, and headed south on Highway 63 towards Waterloo to get in front and south of this, now monster storm. I saw the anvil spread rapidly northeast, and about the same time David also saw a major backshear to our southwest. We had no choice but to core punch this rapidly strengthening storm, and was glad to see only small hail was in the core at that point. Reports were coming in of a tornado near the Waterloo airport, which was less than ten miles from our location.
As we cleared the core, a large, truncated cone tornado was visible about three miles to our west, and was approaching our location. Bill Reid and his group were about two miles behind us and became cut off from dropping south by the tornado. We made it just south of the tornado and stopped for pictures and video. Bill and his group drove east in front of the tornado, as we stayed on Highway 63 watching this now large, violent tornado get ever closer. I was standing in a field shooting video when I could hear strong RFD (rear flank downdraft) winds approaching from the back of the tornado, now directly north of us less than a mile away. We estimated RFD winds approached 100 mph as I continued to video the tornado. After it passed, our National Geographic photographer let me know that the entire half of my face and body facing the tornado, was caked with mud, dirt and debris from the strong RFD winds. Guess I should have taken shelter behind a building, but couldn't get myself to leave my location. Within ten minutes, the tornado crossed Highway 63 and headed east. So we jumped in the van and also headed east on Dunkerton road. The tornado continued to churn across farm fields, occasionally lighting up the sky with power flashes and houses were destroyed, as if to remind us of the awesome power still being unleashed on the poor residents of Blackhawk county.
Nearly 30 minutes after touching down, the tornado started its dissipation stage, only to have another tornado form about five miles east of the occlusion. This tornado was visible by a debris cloud on the ground, and soon filled to the cloud base appearing as a multivortex. This tornado partially destroyed the town of Dunkerton, which had been severely damaged the year before by a flood. We drove through Dunkerton parallel to the tornado and watched as this tornado dissipated, about ten minutes after touching down.
All of a sudden, a third tornado started forming from a wall cloud east of the dissipating second tornado. We drove east of Dunkerton about five miles and headed north a mile on road C-66 to get close to the third tornado. It quickly dropped out of the wall and was heading straight for us, less than a 1/8 mile away! We all jumped back in the van and headed south to safety and stopped about 3/4 mile from it out of its path. The structure of this tornado was awesome, with a large funnel at cloud base rotating rapidly, extending about halfway to the ground and debris rising up to meet it. A small satellite tornado formed just to its east. The amazing thing about this tornado was its very audible sound from our location. You could hear the rush of the winds as the they tore up the countryside. Also, many CG (cloud-to-ground) lightning strikes were seen from the funnel center. This tornado continued eastward, so we dropped back to Dunkerton road and proceeded east to stay with it. As we did, the tornado grew into a very large multivortex tornado. A small scorpion tail shaped tornado dropped out of the forward flank and stabbed the ground several times kicking up dirt and debris. It made for quite a sight watching this large multivortex tornado with the smaller tornado in front of it.
As nighttime approached, power flashes continued to fill the sky as more tornadoes continued to form from the monster classic cyclic supercell. I have never seen such a sight in 15 years of chasing. Finally as the last visible tornado wrapped in rain, we gave up and headed east to catch some lightning shots. We arrived in the wee morning hours in Dubuque, reliving every moment over and over in our minds. After review of all 45 minutes of my video, I have now concluded there were at least 7 tornadoes caught on tape. What a catch!
WATERLOO, IA TORNADIC SUPERCELL OF MAY 11, 2000
by William Reid
This past winter I received an e-mail from veteran storm chaser Dave Gold, as he wanted me to work for his company, Silver Lining Tours. I would drive a van filled with customers, help Dave with the forecasting and chase strategy, see spectacular storms on the Great Plains, and I would get paid to do it! It was not difficult for me to decide. I had to give this tour thing a try. I told Dave that I would be happy to join Silver Lining Tours for Tour Number One, which was scheduled from May 9th through May 18th, 2000. My Pathfinder's outside thermometer read 106F as I motored through Abilene on May 7th. Yuck. The strong upper high which typically covers Texas in summer seemed to be getting an early start this year, and I had a feeling that Tour One would not be spending much time south of Interstate 40. I met Dave in Dallas, we drove the two 15-seat tour vans to Oklahoma City, and on May 8th, we waited for the paying customers to arrive.
Joining our tour were two freelance videographers from Great Britain. Alistar Chapman and Simon Atkins were working for National Geographic, and they were wizards with the wiring of the vans! They helped to install the radios and the antennae and the onboard laptops with the GPS software. This National Geographic team sought to capture the thrill of the chase in part by chronicling the experiences of the Wynne family, which also came over from across the pond. David and Sheila Wynne, and their daughter Sarah, arrived from England with the hopes of seeing first hand some of that wild Great Plains weather that they have seen on television. Andre Vieira, freelance photographer from Brooklyn, arrived with about 20 camera equipment bags draped over his shoulders. He was shooting for the Fox News web site and for a German magazine. Other tourists included John Gould, a family physician from Falmouth, MA; Jeffrey Buss, a job estimator from Lincoln, Nebraska; college student Austin Ivey and his father, Doug, from Georgetown, Texas; William Hale, a chemist from Katy, Texas; Robin Davies of Herts, England, and Kathy Gould, of Milwaukee, Wisconsin. Kathy hoped that this experience would help rid her of her fear of tornadoes. (Unfortunately, on the first day of the tour, Doug had to suddenly leave because of business in San Francisco. He rejoined the tour about five days later.) I had the pleasure of meeting Roger Hill for the first time. Roger has chased for years from his home in Denver, and he had great success in 1999. Dave hired Roger to drive and to share his chase expertise. I figured that our chaser lineup would be hard to beat---I couldn't see all three of us messing up at the same time!
Day One of Tour One was a down day, so we visited NSSL and the NWS office in Norman. It appeared that storms were possible in western Nebraska on Wednesday, so we made our way to Dodge City for the night. On Day Two we headed north towards North Platte, but it became apparent by mid-afternoon that low-level moisture would arrive a little too late for supercells before dark. Computer models indicated a low-pressure system headed for Iowa on Thursday, Day Three. Dave instructed Roger and myself to head east on Interstate 80, and he booked hotel rooms in Des Moines.
It was lunch time on Thursday, May 11th, and Dave and I were hunched over his laptop at a Boondocks restaurant along Interstate 35 and U.S. 20, about an hour north of Des Moines. We liked what we were looking at! A surface low was moving eastward into northwestern Iowa. Surface moisture was more than adequate as it surged northward into southern and eastern Iowa. The winds at mid and high levels were excellent. If a storm could form in this environment, then we could make our tourists very happy. We had one big potential problem, though. It was the cap. We were not certain that storms would be able to form. I had only chased in Iowa on one other occasion -a high risk day, July 1, 1997. That day was a big disappointment, as the cap held strong until dusk and tornadic storms did not materialize. I did not let my hopes get too high, and I told the tourists that we were kind of looking at an "all-or-nothing" scenario. We needed to find a sweet spot in front of the surface low, a spot with a lot of sunshine.
As the afternoon hours passed, it was evident that our sweet spot was somewhere in northeast Iowa. Dave, Roger and I picked out small towns in and around Chickasaw County where we thought that our convective dreams might come true. We spent a few hours in and around Charles City, watching the stratocumulus sail northward, and urging those pathetic little cumulus puffs to try harder. "These poor tourists," I thought. They've spent all of this money, come from as far away as England, driven through four states in three days, and they haven't seen a decent storm, haven't seen a lightning bolt, and haven't even seen a rain drop. And here they are, bored and sweating on a hot Iowa afternoon, probably thinking that this storm-chase tour business is a big crock. What will they be thinking if we bust again? The sky was looking better and better after 5:30 p.m., as the little stratocumulus puffs were now growing considerably. We decided that it would be opportune to eat, as the next chance to do so might not be until well after dark. We heard thunder as we carried our food back into the vans from the McDonalds in Charles City. On May 11, 2000, the Iowa cap would be the loser.
A couple of storm towers soared overhead as we waited near Bassett around 6 p.m. A Tornado Watch was issued. We couldn't see very far, due to haze and clouds, and we needed to know what was happening nearby. Dave phoned a friend who was monitoring radar for him, and we kept an ear to the radio. A severe thunderstorm warning was issued for southeastern Butler County, for a new storm between Parkersburg and Shell Rock, about 35 miles to our south-southwest. It was moving northeast, according to the NWS. The CHASE IS ON!
Dave and Roger were in Van One, the lead van, and I followed in Van Two. With me were Robin, Jeff, John, Andre, and Austin. Alistar followed us in a rental car. At 6:31 p.m. we passed through Ionia, and soon after a tornado warning was issued for our cell in Butler County. At 6:45 p.m., near Horton, in western Bremer County, Dave spotted a very impressive back-sheared anvil through the broken stratocumulus to the southwest. This was the real thing! Though we could not see it, we knew that our warned storm had a powerful updraft, and we were a scant 15 to 20 miles north of it. We weren't in an ideal position to intercept the cell, however, as the precipitation core was developing between us and the updraft base. By 7 p.m. we were in moderate to heavy rain in Waverly. Heck, a tornado might be just to our south, but we still could not see anything. We had to get in front of this thing. The storm was reportedly moving eastward at 30 mph. Dave decided to get farther east. We blasted eastward through the rain on Highway 3, and, seven miles later, dashed south on U.S. 63. We put up with five to six more minutes of rain and small hail, and entered Blackhawk County.
Finally, at 7:13 p.m., we exited the precipitation and the sky brightened considerably to our south. Dave and Roger and Van One were almost a mile ahead of me and Van Two. "Truncated cone tornado to our west-southwest! We are getting south of it!" yelled Dave on the radio! Indeed, a massive wall cloud carrying a large funnel cloud was to our southwest! A wide swath of dust and debris swirled beneath it. Dave implored us to move quickly: "You guys, be advised, it's only a mile-and-a-half west of the road, so you got to get south now, you got to do it! LARGE TORNADO! GET SOUTH!"
"Look at that thing, that is a MOTHER!" said John, who was sitting in the front passenger seat. "I'm feeling my tornado!" I did some quick geometry in my head. I should be able to easily get ahead of a tornado which is to my southwest and moving east at 30 mph. "It's almost over us!" a very concerned John declared. I could see that the tornado was not an imminent threat to us, but I had to watch the road more than the storm. "Are we going to beat it, guys?" I asked. (Boy, that must have been a reassuring question for these people!) "I think we are," said John. "We're going to beat it! We're going to make it! Go, Bill, go!" I had the van moving swiftly southward on U.S. 63.
Twenty seconds later, with the large condensation funnel cloud teasing the ground to our west-southwest, I saw flashing headlights pointing towards me, in my lane, on my side of the divided highway. "What's this IDIOT doing in my lane?!" I screamed! It was a law enforcement vehicle. A policeman was no doubt alerting me to the danger of proceeding. I passed him in the right-hand lane as he moved into the median to get out of my way. Dave came back on the radio: "You guys, you're in danger, we've got RFD doing damage! You got to do it, man, YOU GOTTA HURRY! Are you back there?" I was too preoccupied to reply. We were again dealing with some rain, but winds were not strong yet and the tornado was perhaps three-quarters of a mile to our west. I saw the sign for the road to Dunkerton, which went east. "I'm going to turn left here! Hold on!" Alistar, following in the rental car, continued south to rendezvous with Van One.
It was 7:16 p.m., and I had found the perfect road, Blackhawk County Road C66, on which to stay ahead of the storm. We definitely needed some breathing room, though, so I blasted farther east. Right after we turned, Andre asked, "Can I get out?" to which everyone exclaimed: "NO! You'll get killed!" A potentially violent tornado was on our tail, and another smaller tornado started to develop in a field just to our northwest.
"Where are you guys at?" inquired Dave on the radio. I told him we were headed east on the road to "Duncanville" (I would call Dunkerton about three different names in the next hour). I told Dave that we were in front of the tornado, and that I thought that we were okay. I don't think that Dave heard my reply. He and Roger and Van One were stopped a mile south of Road C66, along U.S. 63, on the northern edge of Waterloo. They watched the large, intense, and mature tornado tear through the fields less than a mile to their north. The group was practically on the southern fringe of the tornadic circulation, and they were suddenly blasted by winds, dirt, and debris headed eastward at 80-mph plus! A trash dumpster bounced by. Dave thought that the nearby utility poles might go down, and his eyeglasses were blown off of his face. Some of the tourists got back into the relative safety of the van, and the wind broke the hinges on the van's doors. Roger and Alistar continued to videotape while outside the van, and they were plastered with dirt, mud, and cow manure. Kathy remained inside the van, shooting video, and hyperventilating. She later said that this experience failed to diminish her fear of tornadoes. Alistar instinctively jumped into his rental vehicle to get out of the blast and to follow Van One. "Where is the steering wheel??" The Englishman had to get out and enter the vehicle like an American chaser. "Holy Crap!" said Austin. "It's a monster, it's a monster," I remarked as I looked in my rear-view mirror! "Oh my gosh, it's a huge tornado!" said Austin.
Amazingly, we were passed by a few other vehicles that were heading to the west! "Do not proceed!" I muttered. How could some people be so stupid? "They are driving right into it!" said Austin. I stopped the van about two miles east of U.S. 63. The guys got out and shot stills and video, and I realized that my tripods were in Dave's van! We had a large blocky wall cloud with a large tornado to our west, with great contrast. The tornado was perhaps a full quarter-mile wide, a quasi-wedge, on the south side of the wall cloud, beneath a vertical, barrel-shaped updraft which was being scoured severely by the descending rear-flank downdraft on its west and south sides. A smaller, dusty satellite tornado continued on the north side of the wall cloud. Austin used his cell phone to call his dad: "Dad, there's a huge tornado, and we're right in front of it! Holy crap!" "We better get going, that looks close," said John. The dark grey mass approached to within about a mile, the winds increased and it started to rain, and we had to move east again to stay safe. It was 7:21 p.m.
I headed east again, and sounded my horn as we passed some houses to try to alert anyone inside. After three minutes we stopped again, and we enjoyed an excellent and safe view of the powerful and wide stovepipe-shaped tornado, a few miles to our west. Dave came on the radio to ask we if were okay, and I reassured him that we were. He and Van One were now playing catch-up, and dealing with strong winds and dust associated with the RFD. From our vantage point the wall cloud morphed a bit, and the narrow updraft and tornado kind of became one and the same. A plume of RFD dust surged skyward to our southwest, and a long tail cloud pointed from the tornado to the northeast. After about five minutes, we scooted east another few miles.
It was 7:32 p.m., and the strong tornado continued, slightly north of due west. It appeared that it was occluding, not moving eastward very fast any longer, and drifting north, too. We had actually moved a lot farther east than was necessary to remain safe from the Waterloo tornado, maybe five miles distant now. Jeff and Andre pointed out a new lowering and a new circulation just to our southwest, and I rattled off something about the mesocyclone, failing to answer Jeff's question if it was going to form anything. At the time I failed to realize what was happening. We were a mile west of Dunkerton. Lightning flashed, thunder crashed, and the winds picked up suddenly from the northwest. "Is that rotation above us?" inquired Robin. "Oh my gosh, look right above us!" said Austin. Uh-oh. It was 7:34 p.m.
Moments after we got back onto C66 to head into Dunkerton, a new tornado developed about a half mile to our south. "We got contact, dust whirl on the ground," Jeff and Austin reported. "Do you see rotation in the clouds above?" I asked. Three voices said "Yes!" "We have an incipient tornado," I said. We entered Dunkerton at 7:36 p.m., and the funnel cloud and dark debris swirl at the surface were starting to come together just southwest of the small town. "Sound the sirens! Tornado southwest!" I yelled out the window at people who were standing around in town. Trees and houses were obstructing their view of the sky to the southwest. As we cleared the eastern side of Dunkerton, the tornado came into full view again. Dust rotated up to cloud base, and a rotating wall cloud loomed above the town. "Oh, no, it's gonna hit the city!"
We stopped on a small rise exactly a mile east of Dunkerton. A massive and starkly contrasted brownish-black column slowly encroached upon the southwest edge of Dunkerton. The condensation funnel came about half way down, somewhat cockeyed out of an adjacent and larger lowering to its north. The dark tornadic swath at the surface exhibited rather weak rotation. It was more like a massive dust devil, circulating in slow motion. The dust and debris
along the edges splayed outward a bit, which suggested to me that the tornado was weakening, or was just not very strong. It was a good thing for Dunkerton, which sustained only minor damage for the most part. The gang and I nervously watched and photographed for about two minutes as the twister drifted slowly northward along the western edge of Dunkerton. We bailed east a couple of miles and watched the dusty mass move slowly north of town. It was 7:47 p.m.
At 7:50 p.m. we stopped at north-south road V62 in Buchanan County, as Road C66 ended here. We waited a minute or two for Van One to catch up to us, and then drove north a half mile. Another spectacular scene was about to unfold. The Dunkerton tornado had dissipated, but impressive, rotating lowerings and funnel clouds continued just to the northwest. A funnel cloud descended just to our north, maybe a mile away, and dirt and debris began to quickly stir beneath it. The weak tornado persisted for a good six minutes to our north, moving only slowly east. This tornado looked more like a West Texas tornado than an Iowa tornado, as a distinct condensation funnel never reached the ground. What was most impressive was the classic "cinnamon swirl" look to the rapidly rotating clouds surrounding the funnel cloud. Lightning flashed behind the tornado, another small satellite tornado touched down in front of it, and finally a rather chaotic mishmash of dust and lowerings with little rotation drifted off to our northeast. We needed to drop south a couple of miles to D16 in order to head east again to keep pace. I will call this tornado that crossed V62 the "Littleton" tornado, as the small town by that name was only a few miles to the southeast. In less than an hour we had witnessed a large and violent tornado, two large but weak tornadoes, and a couple additional minor tornadic spinups. Believe it or not, this storm was just getting started! The time was 8:01 p.m.
At 8:06 p.m. we were following Van One eastward through Littleton on D16. The supercell was now several miles to the north, and we were afforded our first good look at some of its structure. The mid-levels of the updraft had that beautiful, curved laminar look, and below was a circular miniskirt of scud which surrounded an absolutely monstrous wall cloud. "Multiple-vortex tornado north-northwest!" Dave announced on the radio. The massive black lowering was silhouetted nicely against a bright, slightly peach-colored background, and a wide veil of dust followed along underneath. Another tornado, which was not associated with the large wall cloud, formed on the leading edge of the updraft base and persisted for a minute or two. This one had a thin condensation funnel hanging about a third of the way down, and a distinct, narrow column of dust which extended about a third of the way up to cloud base. It looked like a short landspout.
Road D16 ended at Road W13 a couple of miles east of Littleton. Dave led us northwestward briefly on W13, and then the road continued north. The forward flank tornado, which had weakened, came back to life briefly, looking like something from Mars against the murky-orange sunset sky background. Close on its heels was the massive wall cloud/multi-vortex tornado with the brownish-gray pall below. We passed several other chasers and stopped. I finally retrieved my video tripod from Van One, but as soon as I set it up some rain began to fall and Dave yelled that we had to move again. "We gotta go north two-tenths of a mile to get east! We've got to!" It's a good thing that we didn't have to go three-tenths of a mile, as winds suddenly picked up and dirt and debris began slamming the vans just as we turned east onto an unpaved road. New circulations were developing beneath the base which was bearing down on us. We quickly drove eastward out of harm's way. After a mile and a half our east option ended, and we turned south towards Otterville. A spinup was observed only a quarter mile away in the field to our west, and then another one near it! "Developing multi-vortex tornado....we can go east in three-tenths of a mile!" We wound up getting out of the way again by continuing south to Otterville and then east to Highway 150.
As tourist Jeffrey Buss remarked, we were like gluttons in a storm chasing buffet, as we headed north again on 150 to get another good glimpse of the updraft base. At 8:28 p.m. we could see lightning illuminate a large wall cloud to our north. It was getting dark, though, and there was now almost no contrast between the lowerings and the background. We turned east again on a dirt road, and saw some power transformer flashes beneath the wall cloud. This was basically the same large wall cloud that had developed north of Littleton, 30 minutes ago. It never did develop a into strong tornado with a full condensation funnel on the ground, at least before dark.
By 9 p.m. we had given up on trying to stay close to the updraft base. We tried to get far enough east to get a good view of the storm structure and some lightning video, but a deer jumped in front of Van One along U.S. 20 west of Manchester, and the chase was over. Everyone in Van One was okay, but we had to work for 30 minutes to get the bumper away from the tire.
How do you summarize a chase like this?! The Waterloo supercell had a tornado (or two) on the ground almost continuously for two hours during daylight hours. We were very close....sometimes too close, to each tornado. The entire chase seems like a big blur now. Thank goodness for video so I can recall everything that occurred! Those two hours were filled with awe, fear, delight, and uncertainty. We got rooms at a hotel in Dubuque, our heads still spinning as fast as the weather we had seen. Sixty minutes on Blackhawk County Road C66 had turned our Silver Lining customers into a very satisfied bunch!
SOME OBSERVATIONS ON THE IOWA TORNADOES OF MAY 11, 2000
by Fritz Kruse, NWS, Dodge City, Kansas
I have reviewed the CAPS/ARPS data for 00z on May 12, near the time of the tornadoes in northeastern Iowa. The tornadic supercell formed from an initial split north of Waterloo, and the tornado came from the right split and right mover. The cell movement was 15 to 20 knots to the east, with the Slater profiler showing 55 knots at 500 mb. (Slater is between Des Moines and Ames). This would give very good mid-level storm-relative flow of 30 to 35 knots, which is what I like to see for deep mesocyclones and for internal storm-scale dynamic forcing. Apparently this right split formed on its own outflow.
The tornadic supercell formed between two upper jets, with the nose of a subtropical (and weaker) jet of 60 knots poking into northern Missouri, and a much stronger polar jet to the west of Iowa. CAPS analysis showed maximum upward motion between the two jets, where the supercell occurred. Also, there was a 16-unit vorticity max at 500 mb, with a 850 and 700 mb trough. Moisture at 850 mb had wrapped almost completely around the backside of the low, and surface dewpoints in the 60s were west of the low.
A 990 mb surface low was near Marshalltown, with a warm front northeast of the surface low, with low 70s dewpoints and backed surface winds to the southeast along the warm front. The moisture was deep and to 750 mb with pronounced drying above. Dewpoints at 850 mb were 15 to 16C, and 700 mb temperatures were near 10C. The weak 700 mb trough was bringing in cooler temperatures, with the cap weakening near the surface warm front. The cap was too strong to overcome south of the area.
Early on, CAPS showed CAPEs at 4000 J/kg. These jumped up to 5000 J/kg before the tornado. This was a very explosive situation, with strong mid-level flow and drying moving over a weakening capped area...with deep moisture and high vertical instability near the nose of theta advection along the warm front and east of the surface low. Of course, if the cap was just a little stronger, no storms would have formed. However, if storms were to form, given this environment, I would expect to see a significant tornado.
I was concerned with the general weakness in the upper-level wind fields. The sounding at DVN only showed 60 knots at 250 mb, with the main polar jet way west of the area. I am now convinced beyond any shadow of a doubt, after analyzing the upper level wind fields during the time of significant tornadoes, that you do not need to have a big honking jet overhead. However, the storm-relative anvil-level flow still seems important. I find that the following general combination of parameters is necessary for significant tornadoes:
1. Mid-level storm-relative flow >30 knots
2. CAPEs over 3000 J/kg
3. Surface positive theta advection
4. Deep moisture, over 12C dewpoints to 850 mb
5. Backed surface winds from aloft
6. Low LCL/LFC heights (lifted condensation level and level of free convection)
7. Mid-level vorticity, 500 mb/700 mb trough
8. Strong cap that is breakable
9. Mid-level drying
10. Dewpoints near 70F
11. Mid-level winds near 50 knots
12. Surface boundary by RFD or other
If all these parameters are together, alarms start going off in my head. Still, I think the biggest challenge is determining when or if the cap will break. You can go from High Risk to High Bust in an hour. As for initiation, I like to use the front part of the shortwave area of PVA area at 500 mb. That is where mid-level cooling and/or upward vertical motion induced by the vorticity could help break the cap. Note: These parameters are for lower plains regions and have to be tweaked for the High Plains of Colorado, New Mexico, etc.
MAY 16, 2000 CHASE SUMMARY by Shane Adams
Eric Collins, Mark McGowen, and I left Norman, Oklahoma around 8a.m., headed to the Nebraska Panhandle. Little did we know we'd end up much further west. Fortunately for us, Eric is an aggressive (but responsible) driver, and we were able to make good time through the horrific and seemingly eternal Kansas/Nebraska road construction zones. I called Dwain Warner as we drove by the south end of Scottsbluff, Nebraska. He told us storms were firing in southeast Wyoming, so we decided that to keep on going west into Wyoming. The storm wasn't moving too fast, and soon we could tell that we indeed would be venturing into Big Sky Country. The storm looked like a possible supercell at the end of a line, but Dwain called and told me that it was a single storm, with anvil rain all the way into South Dakota! So, knowing this, we headed for the storm with high hopes. As we neared the town of Ft. Laramie, Wyoming, we could see the core of the storm just to the west-northwest, and it was looking more ominous by the minute. We made our way to a really nice spot about three miles west of town and stopped on the highest spot around. Basically perfect. The storm we'd been chasing the entire way was moving off to the north, and a call from Dwain confirmed that this storm had lost its organized rotation and was in a transition phase. This did not please me. But, then he told me a new storm had formed southwest of this one, and was showing rotation at mid levels. I looked due west, and noticed a large lowering, which seemed to have nice inflow from both sides. It was so close to the original storm that I mistook it initially as the backside of the original storm, when in fact it was the rain-free area of the new storm.
I watched as the inflow stayed somewhat steady, but as time wore on, it began to decrease gradually. I wasn't too happy. Soon, rain began to fall from the wall cloud, or just in front of it. In either case, it looked very benign, and I was beginning to lose hope. Soon afterwards, a second wall cloud formed just south of the first one, but it looked just as dead. I went ahead and let my camera roll, on tripod, since there was nothing else around, and darkness was only an hour away. I sat and talked to another chaser from Colorado as the north wall cloud began to change shape. It was starting to look interesting, so I put my face to the viewfinder and zoomed in. I was surprised to see rotation, and subsequently a funnel, all within five minutes of a non-rotating raining wall cloud. I didn't notice it at the time, but the first funnel touched down briefly, becoming tornado number one. This funnel persisted for over five minutes, although I can only confirm a brief touchdown based on my video. Other chasers reported it on the ground for a longer time. Eventually, this tornado/funnel lifted back up into the wall cloud, but the rotation stayed intense. After about five to seven minutes, a large near-horizontal funnel began to snake down from the now disorganized, yet still rapidly rotating wall cloud, becoming tornado number two. This tornado was on the ground for at least a minute, I believe closer to three minutes, based on its behavior and my video. Towards the end of its life, it began to rope out into a snake-like tornado, as the setting sun was shining through the back side of the circulation, making a dramatic, classic image of a tornado with sunshine behind it. It was a dream come true, the one moment during the 2000 season that made up for all the disappointment. They were Eric's first two tornadoes on his first chase with me this season, after a disappointing two-chase outing last year that yielded nothing for him. Email: email@example.com
GUERNSEY, WY TORNADOES: MAY 16, 2000by Scott Blair
The chase day started around 6:30 a.m. at the Comfort Inn in Colby, Kansas. A quick look at data suggested the target area would be across eastern Wyoming. There were several variables coming into play. SPC (Storms Prediction Center) had picked up on the situation, but highlighted the greatest threat a little to the east of our target area. We left Colby just after 9 a.m. heading north on Highway 25. Skies were overcast with a few breaks during the early to mid morning hours. (Note- for rest of the account, Mountain Daylight Time will be used) We arrived in Sidney, Nebraska at 12:30 p.m. We stopped at the local McDonald's for some hot food and made a trip to the local library for some updated discussions and surface obs. We ran into Gilbert Sebenste gathering data. Moisture advection had done its part by sending decent moisture into the high terrain of Wyoming. I decided it would be best to catch the storms at initiation, so we left Sidney at 2p.m.
We headed north on Highway 71, then east on Highway 88 into Wyoming. At 3:45 p.m., we briefly pulled off south of Hawk Springs on Highway 313 to view the sky and listen to weather radio. By 4:00 p.m., skies were mostly clear with a few cumulus dotting the sky. A cirrus shield was visible to the west. In the vicinity of the cirrus, a few towers developed around 4:17 p.m.. The towers were organizing and rapidly building. At 4:40 p.m., we took I-25 northbound at the Chugwater exit. By 5:15 p.m., we arrived in Wheatland. The NWS in Cheyenne issued a severe thunderstorm warning for northwest Platte County. Topping off our gas tank, we continued north. Just after 5:20 p.m., a new rain shaft developed to the northwest of our location. We left the interstate at exit 92 and setup outside of Dwyer on Highway 26. By 6:00 p.m., we were in good position. The precipitation core became very strong and well defined. A severe thunderstorm warning was reissued over northwest Platte County. After a dozen minutes, we decided to find better contrast. We headed east and stopped outside of Guernsey, Wyoming. The terrain was absolutely picturesque. This added to the serene scene. The only other car on top of this hill was Dave Hoadley. We chatted and admired the many inflow bands that flowed into the core of the storm.
The rain free base was visible and became rapidly better structured and defined. A little precipitation began to fall around the base. Shortly after around 7:00 p.m., a wall cloud developed and a large funnel protruded toward the ground. The funnel was sustained for nearly five minutes with a tornado touching down for about half the time. A small needle would occasionally be seen dancing around the base. I was amazed due to everything developing so rapidly. The tornado lifted with no lasting signs of a funnel. We decided to head slightly west to get a better view. After three minutes, a rope tornado quickly developed. The tornado was almost a horizontal tube as it clearly touched down. After two minutes, the tornado lifted and the condensation broke apart. Beautiful contrast existed with both tornadoes.
We found a good place to pull off and watched the mesocyclone. An obvious clear slot associated with the RFD (rear flank downdraft) had developed. This filtered in golden sun along the base of the storm. Decent cyclonic rotation persisted just to the north. A small anticyclonic swirl in the clouds passed the road to the west. Within seven minutes, the RFD quickly advanced towards us with a large plume of dust following. In approach of the RFD, the air temperature dropped a good ten degrees. As we pushed east, precipitation wrapped around the mesocyclone. We received hail up to 1.25 inch for a few minutes before the winds abruptly shifted back to the southeast and all precip ended.
The sun was beginning to fall close to the horizon. The end result provided a plethora of colors across the storm. The supercell became outflow dominant. We shot a few more pictures and called it a day. We stopped in Torrington at the local Pizza Hut. We met a few other chasers including one group from Colorado that had their window busted by hail plus Jim Leonard and R.J. Evans associated with Cloud 9 Tours. After eating and visiting, we arrived at 1 a.m. and stayed the night in Ogallala, Nebraska. What a classic High Plains event!
TORNADOES OF MAY 16-17, 2000by Richard Conn
Wyoming became my favorite chase area as a deep upper low made it into western Colorado, allowing moist air to move up from the plains into eastern Wyoming for some wild weather in the North Platte river basin. Storms began in the Laramie Range just southwest of Douglas, Wyoming and marched southeast into Guernsey, 15 miles east of the intersection of I-25 and U.S. 26 by 1900. When I arrived, there was strong outflow from storms just north of the intersection. Racing down U.S. 26 past Guernsey, I overtook the strong (40 mph) inflow from the east-southeast with Tt/Td of 74/53 (deg.F). But at that moment tornado #1 was visible at the leading edge of the outflow to the southwest. I had to content myself to watch from a distance as desert roads in Wyoming besides the main ones are nonexistent. But a minute later a second tornado formed to the northwest! In the middle of the outflow area I had run away from. Racing back to I-25 a little faster than the now-60 mph inflow, I came within a few miles of #2, still to the west, and watched it rope out quickly. A new outflow came with a vengeance with winds of hurricane force I'm sure. Then it was a game of leapfrog down U.S. 26 to Torrington watching incredible near-tornadic turbulence against a backdrop of clear desert air always present far to the west of the Laramie Range. (The Laramie Range extending down to the Front Range to the mountains of New Mexico always stop any severe storms from going further west) It was quite a festive occasion as about 75 storm chasers had convened; even Dave Hoadley was there who I met for the first time.
On day two, I aimed my destination for northeast Colorado as I thought a settling cool air mass from the Dakotas would couple with strong easterly flow around the big slow moving upper low. There was no surprises as I broke out of 52/51 (degF) outflow/cold front northeast winds of 35 mph to 66/64 (degF) east winds at noon at the intersection of U.S. 71 and state road 14, 30 miles north of Brush, Colorado. The east winds were 55 mph with gusts to 70 mph. The upsloping cumulus were spectacular. There were at least a dozen turbulent funnel clouds extending almost to the ground. Some had the classical shape of long tubes rolling on their sides. I (very) briefly drove south to a clearing to find a vast arena of clear dry air with 75/45 (degF) and southwest(25 mph gusting to 35 mph). It was the other side of the upper low! I (very) quickly drove back into the turbulence while the local rock station at Sterling, Colorado, 15 miles to the east announced that a tornado had been sighted five miles south of the city and moving west-northwest towards me at Highways 71 and 14. But chasing has it's anxious moments. The cool outflow from the northeast was over-running the narrow corridor of warm moist easterlies and had enough momentum to eventually reach the dry air and cut off this extraordinary wedge. Would the integrity of the tornado be damaged by the under-cutting cool northeast wind with 52/50 (degF) temperature? After a brief heavy rain with one inch hail it appeared to the southeast. It was hurting and by eye-balling the speed of it's circulation, had winds of less than 100 mph. As I drove west the tornado on it's west-north path approached Highway 14. I should take the opportunity at this point to recommend that no one try this at home: As the tornado moved onto the highway I drove into its east flank. The wind shifted from northeast to the south. Politely, I backed off and let the whirlwind cross the road without my company. (By the way, the clear westerly winds to my south extended all the way to south-central Nebraska and it's leading edge formed the dry line convergence zone that was responsible for the tornadoes near North Platte, Nebraska). I wrote this chase account from my car the next morning as I was stopped at a roadblock in Cheyenne. The pass to Laramie on I-80 had been closed for 12 hours. Every good storm on the high plains has a 'backside'; in this case: 15 inches of blowing snow at the summit. From: firstname.lastname@example.org (Richard Conn)
BRADY, NEBRASKA TORNADO: MAY 17, 2000
by Jeff Piotrowski and Brian Stertz
After chasing a tremendous late evening supercell near Torrington, Wyoming the night before, we prepared for a more active severe weather chase in Central Nebraska on Wednesday. The forecast models were very persistent in developing an intense surface low over southwest Nebraska, and a very strong (negatively tilted) mid-level shortwave lifting from southwest Kansas/eastern Colorado into northern Kansas and Nebraska wednesday afternoon. A tornado outbreak looked likely, but as we noticed Tuesday, the strong cap was going to be the critical factor. If a weaker cap was in place, then the likelihood of a major damaging tornado outbreak was great. However, if the cap was going to be of the very strong, then the focus of our chase was going to have to be aimed at where the strongest forcing was going to setup, closer to the surface low.
Based on the strength of the shortwave, we believed initially the cap was going to break violently resulting in several explosive supercells. A moderate risk was forecast by the SPC (Storms Prediction Center) for much of Nebraska, central and eastern Kansas, northwest Missouri, and western Iowa. The mention of very damaging tornadoes was listed, especially across Nebraska, and northern Kansas. We left Torrington, Wyoming early in the morning and headed to get to our target area by late morning just in case of early development. Our initial target area was going to be the area between Kearney, Nebraska and Concordia, Kansas. This area was in the left front quadrant of the jet, and where the 850/500 mb jets were in balance. Also, this area would have incredible convergence ahead of the surface low. A very interesting note from the previous day's chase-the majority of the upper support was remaining further to the west across the High Plains, and this was a sure sign that Wednesday's main action was going to be further west than the forecast models were showing. It also indicated that the cap was going to be alot more of a factor. We did not recognize this at first, but as the day progressed, it became very clear as to what was happening.
We made great time in getting to the Kearney, Nebraska area on I-80. Along the way, we noticed very strong warm air advection in the Ogallala, Nebraska area. Heavy drizzle and dense fog was seen between Oshkosh and Ogallala. In fact by the time we reached Ogallala, we had a ripping fog back heading west as 20-35 mph winds were blowing the very dense fog westward. This was one sure sign that things were setting up further west than the models were showing. In fact (hindsight) this should have alerted us that the probability of tornadoes was going to be as far west as the Nebraska/Colorado area near the deepening surface/850 mb lows. We were impressed by how deep the warm advection was. At the surface, winds were due east, and up above the clouds were racing west-northwest. Again in hindsight, if this area could get any heating, the tornado potential would be very high. Air temperatures were in the mid 60's with matching dew points, so there was plenty of fuel for supercells in the High Plains. By the time we reached I-80, the air temperature had risen to near 70 degrees, and there were some breaks in the cloud deck/precipitiation that would make the sky very bright almost blinding at times.
We headed east on I-80 towards central Nebraska and our target area. The further east we traveled, the scarier the sky looked. Very large breaks in the clouds started occurring near North Platte, and the air temperature jumped into the lower 70's. The dew point also was higher the further east we went on I-80. I was very concerned that the North Platte area would be primed for supercells too, and I mentioned this to Brian. He agreed with me especially with the deep east flow at the surface and lower levels. To see heating already at North Platte was certainly sign that things were going to be pretty nasty later in the day. The west edge of the moderate risk was along a line from McCook-North Platte-Mullen Nebraska, and this surely represented the far west edge of low-mid 60 dew points. We had quite a discussion about the North Platte area being an interesting area later. We decided eventually this area may get pinched off from the instability, similar to what situation had occurred on April 8, 1999 when another extremely deep surface low was over Nebraska. The April 8th southwest Iowa tornado event sure gave us some pointers on how to deal with these super deep surface lows. This helped us later in the chase that's for sure!!
The weather was in a rapid spin mode by late morning. A very deep surface low (29.20in) was located near Akron Colorado with a sharp warm front located east to near Concordia, Kansas, and double dry line situation developing over western Kansas. The forecast models all showed the surface low was going to deepen even further (gulp) and move towards south-central Nebraska (uh-oh). Major tornadic supercells appeared to be very likely across southern Nebraska and northern Kansas. One thing for sure, today was going to be rapidly changing and the tendency for instability wrapping westward north of the surface low was also going to be quite likely. We planned to head to Elm Creek, Nebraska to a truck stop that we went to last June to call up weather data. This was a great place because it had
tables, phone jacks, eats, and gas (not related to the eats). This stop was also very near our target area on I-80, with good roads in all directions. We pulled in around 11:30 a.m., and already we saw a few chasers congregating. Later the chaser city would grow to nearly 30 at the truck stop! I had a very hard time getting a good connection, but the data I was able to pull up, showed that the cap was extending northbound from Kansas. Not good!
Chasers from all over soon gathered around trying to get on the web to pull up weather data. This was certainly a critical time for forecasting. As we struggled to get connected, the warm front over Kansas started to bow north, and would soon surge up to I-80. We knew this was both good and bad for later supercells. Good because it would get the warm front into a less capped airmass allowing for storms to erupt. The bad thing was the cap was northbound and this might possibly cap off all of Kansas and a big area of Nebraska, particularly if the warm front gets deep into Nebraska. Oddly enough (more hindsight) this situation was favoring the North Platte area even more since the cap was increasing over central Nebraska. The focus would now be west-central and southwest Nebraska where the mid- level cooling would be the strongest and able to break the cap. The shear out there would also be very strong. The majority thinking among chasers was that the cap would give way across south-central Nebraska and north-central Kansas as the negatively-tilted shortwave pivoted northeast. Brian and I were also in agreement, but we also had in the back of our minds, that the McCook and North Platte areas may also be in great danger today. An earlier discussion with Steve Nelson (Tulsa NWS) also helped us a great deal in considering the McCook-North Platte scenario. This made sense because it would be less capped and in the area of extreme forcing. This region would definitely be at the nose of the left front quad of the mid level jet. At any rate, we decided the best option was to hold near Holdredge in case of the cap breaking over north-central Kansas. Conditions (other than the strong cap) looked very favorable for strong tornadoes over south-central Nebraska. One item of interest that was occuring while we waited for the storms to pop. Warm air had wrapped around the north quadrant of the surface low and several tornadic supercells were forming over Morgan, Washington, and Yuma Counties in northeast Colorado. Numerous tornadoes (some damaging) were reported on the ground there. See Rich Conns' article.
We pulled over near the Furnas/Kearney Co. line in south-central Nebraska, and were later joined by other chasers. A tornado watch soon was issued by the SPC and a few damaging/destructive tornadoes were mentioned. The tornado watch was for Nebraska only, but they did advise that a tornado watch was also to be issued shortly for Kansas as well. As we waited(and waited) for storms to erupt, the surface low was moving northeast towards the McCook, Nebraska area. It was starting to "bomb-out" so it was only a matter of an hour before things got really bad for the general public across Nebraska and Kansas. A dryline bulge was very evident on satellite and surface data from the Imperial, Nebraska southeastward to near Hill City. Towering cumulus formed along the dryline that was starting to surge northeast right for us. Gundgy premature convection had fired over Kansas and the remnants were in the process of moving out as the mid-level winds strengthened. Fortunately, the cap crushed this premature stuff, otherwise it may have ruined the airmass everywhere with rain-cooled/stable air. The thermal ridge was aimed right for us and extended from near Garden City, Kansas to between McCook and Hastings, Nebraska. We were in the favorable northeast quad of this ridge, but were also capping off even more. After reviewing the data after the chase, the 850mb winds were veering majorly during the afternoon all across Kansas and central and eastern Nebraska. This was allowing the hot cap air to advect into our location.
We watched the skies clear out rapidly as the a strong southwest jet moved in. Air temperatures skyrocketed from the mid 70's under the gundgy canopy of leftover cloud debris, to the mid 80's between Hill City, Kansas and our holding spot. Two areas started to hint at developing convection. A few small storms began to develop along the dryline bulge
from Imperial, Nebraska to northeast of Goodland, Kansas. Meanwhile, towering cumulus quickly started to form on the warm front that was aligned southwest-northeast. We watched the storms closely on radar (finally connected). The storms to the south formed quickly, and the storms over southwest Nebraska slowly back built down the dryline into northwest Kansas. Both areas developed slowly, with the more rapid storm development about 20-30 miles south of us. Initially, the storms closest to us looked great. Very diffluent anvils, vertical storm towers, and inflow bands. However in the span of about an hour, these storms went from about an 8 to about a 2 on a scale from 1 to 10 with 1 being poor. Apparently the cap had this area under control, and the strong mid-level winds very quickly ripped the main updrafts apart and pushed the storms to their demise. Interestingly enough, the storms over southwest Nebraska did not have that problem. Immediately the warning bells went off to both Brian and I. Get west and get on the uncapped storms or BUST!!!
We grabbed one last radar image off the Goodland radar, and it showed the storms were holding their own. The most interesting storm to us was a small but highly sheared storm developing near Oberlin, Kansas. This storm already had signs of rotation and was on the dryline bulge immediately northeast of the intense surface low. After getting things organized, we headed west on U.S. Highway 6 towards McCook. The track was going to be well east of McCook so we figured an intercept near the town of Cambridge. Actually, we would luck out on this intercept. There was another already severe storm on the Kansas/Nebraska border moving into Red Willow County, Nebraska. Hail up to golfball sized had been reported. In this type of situation, you have to react to ongoing/sustained convection or completely bust. As favorable as the conditions may have appeared initially, things were now a lot more harsh and negative for supercells anywhere away from the dryline. The cap had surged in and squelched any hopes for at least tornadic supercells over Kansas and south-central and southeast Nebraska. We passed through Arapahoe, Nebraska and saw many chasers pulled over watching the small but intense dryline storms. A new severe thunderstorm warning was issued for the storm we targeted. Meanwhile the storm closer to Mc Cook had slowed down. I think we found the jet split! Brian and I high fived after seeing this on the radar. Now it was time to watch these closely, very very closely!
As we closed in on the town of Cambridge, Nebraska on the Furnas-Red Willow Co. line, we had both storms bases within view. The northern storm had a fairly large updraft vault and was located about 3-4 miles west-southwest of Cambridge. The southern storm was very small, but was visibly rotating even from 8-10 miles to it's north. As with most situations with two storms in very close proximity to each other, you have to remain alert for the possibility of either a cell merger or the southern storm taking over and stealing all the inflow. We could see the large hailshaft to our west, and also started to get hailed on by the southern storm with dime-sized hail. From this point on, we lost our cellular connection and had no weather data. We listened to a good radio station out of Lexington, Nebraska that kept us informed of warnings. We pulled over for some pictures and video west of Cambridge. The cloud bases were still high, but we could see that there was some lowering of a developing wall cloud near Bartley to our northwest. This separate supercell situation continued as both lifted northward. We positioned ourselves in between the two storms and took a dirt road north to Strunk Lake. This would allow us to watch both updrafts but also would put us under the rain/hailcore of the southern storm. Both storms were now officially severe as new warnings were issued. Hail larger than golfballs was possible with the northern supercell. I classify these as legitimate supercells at this point as the bases looked to be rooted in the boundary layer now.
We progressed north with the storms and with the help of the De Lorme Nebraska Mapbook, were able to maneuver through the rural roads without losing sight of both updraft bases. We also saw a group of locals chasing near the lake. They went on west for some reason, but the storms continued to move north, possibly a little northwest at 30-35 mph. Both storms looked just like big hail storms at this point, although the southern storm had strong rotation at mid-levels based on the laminar striations. Item of note: the southern storm eventually went on to produce the Brady F3 tornado, and visually, it had the best look of rotation the whole time.
We tracked across the open country into Frontier County finally getting our first golfball hail thuds on the car. Almost the whole time we were getting rain/small hail from the southern storm up to this point. We pulled over to watch both storms again. Both were strongly rotating supercells now. In fact the storms were becoming almost aligned side by side (east-west). The now western storm was developing a large substantial wall cloud with cloud tags/scud underneath. The eastern storm had tendrils of mid-level vortices spinning around the north side of the updraft tower that was becoming barrel shaped and very laminar. We decided to head into Stockville (Frontier Co.) to get a road option north. A tornado warning was issued for a storm we could not see about 10-15 miles northwest of the Stockville supercell. We figured that if that storm was ready to produce a tornado, the storms we were watching would soon too. We had both in sight so if one supercell did become tornadic, we could see both at the same time. The roads were very muddy and tricky as far as driving, but at this stage of the game you have to stay with the updrafts. The two storms were continuing to organize and develop mature circulations.
North of Stockville, we started to notice large amounts of hail on the road. Quarter-sized hail mostly, but a few golfball-sized hailstones were on the ground. We figured that this fell from the western supercell since we were slightly ahead of the hail core from the eastern supercell. We continued north and noticed that the western storm was starting to cycle, or in better terms was about to drop a tornado. A very powerful rear flank downdraft plowed into the updraft, and numerous small circulations developed under the udraft. Some were very strong cyclonic, but the strongest were ANTI-CYCLONIC. These ringlets spun madly, and the town of Moorefield looked to be very near this violent rotation. We started noticing copious amounts of hail (mostly golfball size) on the road as we came into the town of Moorefield (Lincoln County). A tornado warning was issued for Lincoln County for the two circulations.
One circulation was to our northwest near Wellfleet, and the other was our storm near Moorefield. Moorefield residents were outside looking for what just hit them, an occluded circulation to the northwest of Moorefield. This was immediately west of where the RFD plowed into the storm and scalloped out the supercell's back side/south side. Very strong rotation was seen on this occlusion about three-to four miles north-northwest of Moorefield. Very quickly, a fairly wide but weak (F0) tornado came down to the ground to our west. It started with a large/broad funnel cloud, and quickly corkscrewed to the ground. The tornado remained pretty much stationary and was soon joined by another weak tornado to it's south. There were now two tornadoes on the ground and violent cloud motions above the tornadoes. Was another going to make a hat-trick? As rapid as the cloud motions were, this sure seemed possible. Another tornado tried to come down but was absorbed by the initial tornado. The tornadoes remained a pair until dissipating five minutes later. Okay now things were getting very interesting! We still watched the eastern supercell that was now growing larger, but was still nearly all rotating updraft. It was spitting golfball hail on us as we watched the western supercell's tornadoes. I guess you could say it was a notecard saying "What about me?". We directed our attention closer to that storm.
As it stood, were down to one road option through some very rugged canyon lands between Moorefield and Brady. Since the storm movement was still north, and more tornadoes were imminent, we took the road. Basically, the supercells traveled right up that road. One supercell was about three-to-five miles west of the road, and the other was about two miles east of the north-south road. Talk about a chasers dream. Only one thing might make it a nightmare though. The eastern supercell was becoming meaner and we drove through continuous hail between Moorefield and the Jeffrey Reservoir. Most of the hail was tolerable (quarter size), but as we got further north, large amounts of golfball and baseball-sized hail pounded us on northwest of the large barrel shaped updraft (eastern supercell). At this stage of the chase, you just have to gut it out and keep going!!
Both supercells had long inflow bands and we could see very violent cloud motions above us. Tornadoes looked certainly likely. The western supercell cycled again as we got blasted by 70-80 mph south RFD winds. As we got to the crest of a hill, we could see a large cone tornado coming to the ground to our southwest. There was a hilltop that it had set down on and large amounts of soil/debris were being lifted. No doubt it was a strong tornado, because our winds started abruptly switching to the northeast and gusting. I do believe this is first time I have ever seen 70 mph RFD winds back all the way to the northeast and gust at the same velocity. Brian and I are sure the other supercell had an effect as well. About two miles east of the road, Brian saw some finger-like vortices forming under the updraft. This was a very serious situation now, especially with the increase in the amount of baseball-sized hail. We were pounded extremely bad by the hail but somehow avoided losing the windshield. We lost sight of the western supercell/tornado, but Brian said the eastern supercell was about to drop a big tornado. Very laminar collars were seen up the north side of the updraft now, and horizontal vorticity tubes were knifing into the updarft. Exciting times were starting to unfold right in front of us!
We approached the Jeffrey Reservoir area with caution as the hail increased in intensity. Little did we know that immediately east of the road through Conroy Canyon a developing strong tornado was about to touchdown. We passed the reservoir dam area, and could see alot of rapid cloud motions overhead and to our east. As we turned to go east on Brady Road., the tornado quickly started to organize. We were due north of the tornado that was developing over the rough terrain on the Platte River bluffs. About a mile east of the dam at an intersection, we pulled over for one of the best tornado spectacles we have ever seen. Our timing could not have been any better as the truncated cone started to come down to the ground about six miles south-southeast of Brady in eastern Lincoln County Nebraska. It was 5:15 p.m. when the Brady tornado officially came to the ground. I called 911 to warn them of the tornado and that it may affect the town of Brady. Brian and I scrambled out towards the road to get an unobscured view of the tornado that was approaching from the south. The width of the tornado grew from about 100 yards to over 300 yards wide as it moved into the valley. At first, we were in the direct path of the tornado, but the diffluence took over and directed the tornado to the northwest! We were safe from the tornado, but not from the inflow jets and occasional baseball hail that pounded Brian and I in the neck and back. Brian even had some welts on his back from the hail. Winds were rapidly on the increase, with gusts to 75 mph. The tornado was about a mile to our south and heading right for the Jeffrey Reservoir dam. Power line "pops" were seen as it moved across the open field, and into some high tension lines. Brian was doing the video and I was clicking of pictures like mad!
The tornado close encounter grew even more up close and personal as the winds roared from the east-northeast with gusts well over 80 mph. The tornado passedwithin 1/2 to 1/4 of a mile from us. The utility poles were beginning to lean hard to the north as the tornado plowed across the open field. The width of the tornado was continuing to increase and was over 400 yards across. Based on the appearance, the tornado was likely in the strong F2 to weak F3 range as it moved just east of the dam. The unmistakable roar was heard as the tornado moved to the northwest. Several farmsteads were hit by the tornado as it moved out of the bluffs into the valley. Large debris was picked up as it hit these homes and farms. We continued to hold our position as the tornado crossed Brady Road and moved towards the Platte River. It was at this point, when the tornado maxed out. The width was now approaching 1/2 mile, and large amounts of soil and now water were being drawn up into the vortex. This made the color of the tornado change to a brown and white swirl. This very interesting "blend" of colors made for some spectacular shots of the tornado that was moving away about 1.5 miles from us. We continued to shoot pictures and video, but also stood there in awe as this strong and impressive tornado crossed the Platte River valley. Interesting note: as the F3 tornado and the inflow jets moved away from our location, the loud roar had subsided, and we could no longer hear the tornado. Up until this point we could hear the impressive roar. This maybe something to be researched in the future.
The contrast of the tornado was starting to lower so we packed up quickly and headed for I-80. The tornado was moving northwest and west towards the town of Maxwell. The town of Brady was spared from the tornado, but Maxwell was now in the path, as was the rest area on I-80. We made it to I-80, and lots of weekday traffic was present. A few motorists had heard the warning apparently and had pulled over. Many did not seem to notice the tornado about 1-2 miles south of the highway. We were surprised to see how many motorists were still on the road. We could see the rest area about two miles to our west, and lots of people were stopped there. As the tornado moved west-northwest, it looked like this rest area was going to be hit. We continued west, and the tornado starting to weaken slowly. The tornado eventually shifted to more westerly component as the rope stage was beginning. Fortunately this happened before it approached that crowded rest area. We watched the dramatic rope stage start about two miles to the south of I-80 very near the Platte River. Ironically the tornado dissipated very near the Fort McPherson National Cemetery. The last sign of the tornado was a thread vortex that dissapeared under the shearing out wall cloud. This was yet another chase where we watched the tornado from start to finish, only this time it was from a close perspective!
We pulled over and watched the dissipating tornado, and watched a new tight circulation form about a mile to our east. This circulation formed just as the Brady tornado dissipated. We watched this closely, but it apparently moved north into cooler more stable air. We decided this one did not appear that it was a threat, even though a tornado warning had been issued for this newly developed circulation. We followed it for about ten minutes, but it had the sign of gusting out so we called it a chase. Just then, we started to see many other chasers, some of which were with us southwest of Holdrege. We were fairly well blitzed by the intensity of the chase, and decided we had best get the video to the Weather Channel so it could be fed by satellite to the other media outlets. We knew our video was good, but later on could not believe some of the shots we actually got.
STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK13 Z CONVECTIVE OUTLOOK
DAY 1 CONVECTIVE OUTLOOK..VALID 171300Z - 181200Z
THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING OVER PARTS OF CENTRAL/ERN NEB AND NERN KS...TO THE RIGHT OF A LINE FROM 20 SSW FLV 15 NW EMP 20 SW SLN 35 N HLC 15 W LBF 10 S MHN 20 WSW ANW 20 NW OFK 25 E OMA 30 N STJ 20 SSW FLV.
...SEVERE THUNDERSTORM FORECAST DISCUSSION...
STRONG UPPER LOW OVER UT WILL CONTINUE TO SHIFT EWD INTO THE CENTRAL HIGH PLAINS...WITH RATHER VIGOROUS SHORTWAVE TROUGH OVER THE 4-CORNERS REGION EXPECTED TO LIFT NEWD INTO KS BY EARLY TONIGHT. IN RESPONSE...SURFACE LOW OVER NERN CO WILL CONTINUE TO DEEPEN AND MOVE SLOWLY EWD INTO SWRN NEB THROUGH THE DAY. 12Z SURFACE ANALYSIS INDICATED SURFACE FEATURES REMAIN COMPLEX OVER THE CENTRAL PLAINS...WITH A WARM FRONT EXTENDING FROM LOW CENTER ACROSS NEB AND INTO SWRN IA. SECOND WARM FRONT WAS DEVELOPING ACROSS NRN KS AND INTO SWRN MO. THIS SECOND BOUNDARY WILL LIKELY BECOME PRIMARY WARM FRONT AS IT LIFTS INTO SRN NEB AND EXTENDS INVOF THE PLATTE RIVER VALLEY BY LATE IN THE DAY.
SURFACE DEW POINTS REMAIN IN THE UPPER 60S INTO N-CENTRAL KS THIS MORNING...WITH 12Z TOP/S SOUNDING YIELDING DEEP MOIST BOUNDARY LAYER THROUGH H85 AND PW/S OVER 1.3 INCHES. HOWEVER...MID LEVEL LAPSE RATES THIS MORNING ARE AOA 9 C/KM ACROSS THE CENTRAL PLAINS WHICH WILL MAINTAIN A SUBSTANTIAL CAP. THIS CAP SHOULD AID IN POOLING LEVEL MOISTURE INVOF WARM FRONT AND AHEAD OF LOW CENTER OVER NEB AND NRN KS TODAY...WITHIN STRONGLY CONVERGENT LOW LEVEL FLOW. AS NOSE OF 120+ KT UPPER LEVEL SPEED MAX OVERRIDES THE WARM SECTOR BY THE MID AFTERNOON...CAP SHOULD ERODE AND SUPPORT SEVERE THUNDERSTORM DEVELOPMENT SPREADING OUT OF THE CENTRAL HIGH PLAINS. COLLOCATION OF STRONG...DEEP LIFTING AND MODERATE TO STRONG INSTABILITY WILL OCCUR OVER CENTRAL NEB INTO NRN KS BY LATE IN THE AFTERNOON. THIS SHOULD SUPPORT WIDESPREAD SEVERE THUNDERSTORMS ALONG AND NORTH OF WARM FRONT/LOW CENTER INTO CENTRAL NEB CONTINUING INTO THE EARLY NIGHTTIME HOURS...WITH PRIMARY THREAT OF VERY LARGE HAIL. FARTHER SWD INTO WARM SECTOR... WIDELY SCATTERED THUNDERSTORMS SHOULD ERUPT ALONG DRY LINE INTO SRN NEB/CENTRAL KS AND MOVE QUICKLY NEWD THROUGH THE EVENING. SHEAR PARAMETERS REMAIN FAVORABLE FOR TORNADIC SUPERCELLS ALONG AND SOUTH OF THE WARM FRONT ...INCLUDING ISOLATED STRONG/DAMAGING TORNADOES. EVANS
EARLY CHASES IN 2000: PART I by Matt Crowther
This was an interesting season, to say the least. On the one hand, it was fairly successful, as I personally viewed seven tornadoes, one of my higher totals over the past ten years. The flip side was that it was also a very hard season, as to get three of these tornadoes, it was necessary to take two early trips out to the Plains from Atlanta in advance of our normal chase vacation, and Betsy was unable to come with me on both occasions.
I had previously planned to come out to Oklahoma for the May 3rd anniversary conference, and took a few extra days before the event to attend Jim Leonard's 50th birthday roast. Of course I held out the hope for some chasing as well, and as it turned out April 29 and 30th provided that opportunity. I flew to Oklahoma City on the 29th after a midnight shift, so was in no shape to chase by myself. I hooked up with Jim Leonard, R.J. Evans and Charles Edwards for a trip to West Texas. We ended up near Lubbock as convection fired by late afternoon, but were a bit too late to get on any really good storms, but did manage a few decent sunset pictures. We got back to Norman late.
The next day looked more promising, this time in northwest Texas. For this trip, we were joined by Bobby Prentice. We headed down I-44 and got data near Lawton, which showed both the synoptic warm front and a pronounced outflow boundary. We decided the best action would be south of the Red River. We heard of storms firing farther west, and ended up intercepting the first storm near Crowell. It looked interesting for a while, but the appeared to become outflow dominated. So decided to intercept another storm that we heard was developing to the southeast. Dropped down to Seymour and gassed up, then continued towards Olney. When we reached Olney after driving through the northern part of the rain core, a well-formed and impressive HP (high precipitation) storm came into view southwest and west of town. We viewed the storm from the south which turned out to be a tactical error, as the view of the main tornado was more in the notch of the storm to the southwest. However, we decided that discretion was the better part of valor, and declined to risk heading into the "bears cage". Heading east as the storm bore down on us, we saw a dark rope tornado to the west. By the time we stopped to videotape it, it quickly became obscured by wrapping rain curtains and then the storm was upon us. After a moments hesitation we headed back into Olney, where we were pelted by strong winds and some marginally severe hail. Afterward we did not hear about the next supercell near Graham at dark, so headed back to Oklahoma. An interesting moment occurred near the toll booth southwest of Chickasha- a complex of heavy storms had been ongoing to our east, with an occasional anvil crawler overhead. Suddenly, a positive CG bolt struck near the road with a huge shower of sparks and a deafening crash, and a cloud of smoke quickly drifted over the car.
My next chase adventure again involved a flight to the Plains. This time I saw an impending severe event of some potential, but it looked like it would occur when I was scheduled to work. However, through a stroke of luck I was able to get an extra day off on Wednesday May 17th. Vanguard Airlines had a good fare to Kansas City, so I got a ticket and booked a rental car. As on the previous chase, I worked a mid shift right before flying out on Monday the 16th but managed to drive to Hays , Kansas, where totally by chance ended up in the same motel as Charles Edwards, Jim Leonard and Cloud 9 tours. So I ended up chasing up with them the next two days (I am very loath to chase by myself unless absolutely necessary). We decided the best shot the next day would be in Wyoming, so headed out early for the long drive northwest. We saw a storm well to the west as we got onto I-80, and learned that it was near Glendo, WY. By the time we got close to the storm west of Torrington suddenly Jim shouted over the CB rope tornado! But as luck would have it, a freight train blocked our view after a few seconds, and the tornado dissipated. The storm gusted out after that, but there were some nice photographic opportunities at sunset. We ran into a hail core on the way back to Torrington, and after dining at the local Pizza Hut, videotaped an impressive anvil zit display from the parking lot. Ended up in a motel in Ogalalla, Nebraska very late.
The next day, May 17th, was greeted with some excited anticipation, as many ingredients seemed to be coming together for some significant tornadoes. Two plays were considered, along the warm front in Nebraska or farther south in Kansas. We decided to get data at the Bossleman's truck stop in Elm Creek, Nebraska along I-80. There we found a rather massive chaser convergence, including Dave Gold and Silver Lining tours . We all hooked in our laptops and compared forecasts. The surface data showed a very impressive dry punch in Goodland, Kansas pointing right up into southwest Nebraska, and storms began firing, but looked unimpressive at first. The air north of the warm front was quite juicy with east-northeast winds, so the Nebraska target seemed to be the choice. Then a much better looking storm appeared on radar not too far southwest, and the chase was on. We moved west and south to Elwood where we observed a heavy rain core to the west and a smallish but interesting looking LPish (low precipitation) updraft just to its south. This continued to look more impressive as it moved north-northwest. We made our way back to I-80 and blasted west to get back in position. Went north out of Gothenburg a few miles and then turned west on a county road. This brought us to a ridge top a couple of miles east-northeast of Brady. Suddenly rapid rotation was observed directly south a few miles, with not too much of a well-defined wall cloud. A tornado quickly formed and went through some very interesting multiple vortices and brief satellite funnels. The tornado traveled northwest and grew larger, becoming a fat cone, but never quite reaching wedge status. As it retreated westward the storm updraft became absolutely stunning in appearance, the ultimate barber pole, somewhat similar to the Spearman, Texas storm of 1990. We followed the storm west until it roped out in the distance. Another mesocyclone closer to us, west of Brady, looked like it might tornado for a while, but weakened with time. For me personally, this was the best storm/tornado combination since I began chasing ten years ago. Interestingly, although we expected more supercells to the east later, that was basically the end of the chase. I flew back to Atlanta the next day tired but very satisfied.
MAY 17, 2000 CHASE STRATEGY by Tim Marshall
This was a classic severe weather set up across the high plains with a lot of positive features. At 17z (noon CDT), a deep surface low pressure center was located in northeast Colorado with a pronounced warm front extending northeast from the low paralleling I-80. A dryline extended south of the low through western Kansas and western Oklahoma. Plenty of low-level moisture was advecting northward into southern Nebraska. Mid- and upper-jets were rounding the base of the large trough over the Rockies and were expected to extend through central Kansas around 00z. The SPC (Storms Prediction Center) issued a moderate risk around the surface low extending eastward into Nebraska with a slight risk extending southward into Kansas and Oklahoma. The big negative was the capping inversion south of the warm front with 23 degree 850mb temperatures extending into central Kansas. However, progs were indicating a pronounced short wave trough to roar through central Kansas accompanied by a 120 knot upper speed max by 00z. Carson and I were in Dallas and couldn't make it to Nebraska, thus, we hoped the cap would break as far south as central Kansas. Our target was Great Bend, Kansas. We left Dallas around 10a.m. and crossed the Kansas state line around 4 p.m. A tornado watch had been issued for Kansas (in addition to Nebraska and Colorado) and towers could be seen to our distant northwest. The towers became Cb's but they were high based and soon died as we reached Kingman, KS around 5 p.m. We soon realized the cap would prevail and the only show would be further northwest.