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The TWISTEX crew and the vehicles on equipped with mobile mesonets.

TWISTEX (a backronym for Tactical Weather-Instrumented Sampling in/near Tornadoes Experiment) was a tornado research experiment that was founded and led by Tim Samaras of Bennett, Colorado, US, that ended in the deaths of three researchers in the 2013 El Reno tornado. The experiment announced in 2015 that there were some plans for future operations, but no additional information has been announced since.[1]

Background

The project normally ran from mid-April through the end of June with a domain that covers the Great Plains and portions of the Midwestern United States. The project was normally at full strength for most of May and June with four vehicles, all equipped with roof-mounted mobile mesonet weather stations. One of the vehicles transported an array of in situ thermodynamic and video probes. Due to graduate and upper-division undergraduate student participant availability, a reduced vehicle compliment consisting of the in situ probe deployment truck and one support mesonet station vehicle was used in the first few weeks of the project.

The research objectives were to better understand tornado generation, maintenance and decay processes and to gain insight and knowledge of the seldom sampled near-surface internal tornado environment. Progress on these research fronts was aimed toward increasing tornado warning lead time, while the internal tornado near-surface sampling provided essential ground truth data for structural engineering analysis of the interaction of tornadic winds with homes and buildings.[2]

TWISTEX was one of the featured teams in seasons 3, 4 and 5 of Storm Chasers on the Discovery Channel.[3] The group was also featured on National Geographic Channel's "Disaster Labs".

May 31, 2013 deaths

The crushed remains of the TWISTEX vehicle near the intersection of Reuter Road and S. Radio Road approximately 4.8 mi (7.7 km) southeast of El Reno, Oklahoma.

On May 31, 2013, Tim Samaras, his 24-year-old son Paul Samaras, and 45-year-old California native Carl Young died in the record wide EF3 multiple-vortex El Reno tornado.[4] They were unable to escape along gravel roads as the funnel rapidly expanded to envelop them. Their Chevrolet Cobalt was caught by a subvortex, and Paul and Carl were ejected from the car. Tim was buckled in the passenger's seat, and was killed as the car was thrown approximately half a mile by the storm. Hinton resident Richard Henderson, who decided to follow the twister, lost his life in that same area. He snapped a picture of the storm from his cellular phone before it struck him.[5] Several other storm chasers, including The Weather Channel's Mike Bettes, were also caught in the same sub-vortex but escaped with only minor injuries. Bettes and the Tornado Hunt crew were lifted up by the wedge tornado in their sport utility vehicle. That storm threw them two hundred yards off U.S. Route 81. The SUV was destroyed afterward.[clarification needed] Bettes and his crew were later found and rescued by Reed Timmer and his SRV Dominator crew who were chasing for KFOR-TV Channel 4 in Oklahoma City with their storm chasers when they came upon the wrecked Great Tornado Hunt SUV.[6] Four other people who were not involved with storm chasing also died in this tornado.[7]

TWISTEX personnel

Students from the Atmospheric Sciences Department at Iowa State University rotate shifts into the mesonet vehicles during the project.

Former TWISTEX personnel

Killed by the record breaking EF3 tornado in El Reno, Oklahoma:

Tornado core sampling

The HITPR probe used to take in-situ tornado measurements.

Several hardened instruments will be deployed in paths of tornadoes to collect the following datasets: atmospheric pressure, temperature, humidity, wind speed and direction, and visualization for accurate debris/hydrometeor velocities and for verification of the tornado-relative location of the in situ sampling.

The thermodynamic probes are called Hardened In-situ Tornado Pressure Recorders (HITPR). All of the hardened instrumentation can collect/store the datasets. Measurements are recorded at 10 samples/second, and stored on non-volatile flash cards.

TWISTEX will also have video probes that will provide visualization using 7 cameras each for a total of 14 cameras being deployed into the tornado core. Collectively the two camera probes will be used for photogrammetry purposes to visualize/measure tornado-driven debris and hydrometeors as well as for determining the tornado-relative location of the HITPRs.

New additional technologies will be used by deployment crew members to collect photogrammetric data from tornadoes as close as possible. One technique will be to record close tornado imagery using two digitally synchronized high-resolution high-speed cameras running at 500 frames per second for stereo photogrammetry techniques. This technique will provide excellent time resolution for velocity determination of low-level tornado core winds and lofted debris.

Tornado proximity environment sampling

Two of the TWISTEX mesonet vehicles, M1 and M2.

While there are abundant kinematic datasets gathered by mobile radar of the tornadic region of supercells, the number of quality mobile mesonet or sticknet thermodynamic datasets of the flow field proximate to the tornadic region, generally within the supercell rear-flank downdraft (RFD) outflow, are comparatively rare. Even rarer are mesonet datasets reaching within about 1.5 km of tornadoes and datasets sampling the thermodynamic evolution of the RFD outflow.

Each of the participating TWISTEX vehicles will have a mobile mesonet (MM) station mounted on the roof including the probe deployment truck. The mobile mesonet will be attempting to gather near-surface thermodynamic and kinematic data in as many quadrants of the RFD as possible. When coupled with the in-situ probe array data which represents another effective mesonet station, it is hoped to obtain thermodynamic and kinematic mapping that will describe characteristics of the flow reaching the tornado. Even if the hardened tornado probes do not take a direct hit, a peripheral tornado sampling is still very worthwhile.

TWISTEX publications

Participants of the TWISTEX research project have contributed to many publications.[12]

AMS Journal and Conference Papers
National Geographic (Book and articles about Samaras research)
American Society of Civil Engineers
ABC News (Article about Samaras research)

TWISTEX on television

Main article: List of Storm Chasers episodes

TWISTEX was featured in seasons 3, 4, and 5 of Discovery Channel's Storm Chasers.

References

  1. ^ "Twistex's Facebook page". Facebook. Retrieved 8 August 2019.
  2. ^ twistex.org.
  3. ^ Discovery Channel Online. Meet The Teams, TWISTEX, 2009-11-25
  4. ^ Jake Carpenter; Catherine E. Shoichet (2 June 2013). "'Unpredictable' storm in Oklahoma turned on three chasers". CNN. Retrieved 29 June 2018.
  5. ^ Clay, Nolan (June 3, 2013). "Oklahoma storms: Amateur storm chaser took photo of tornado that killed him". The Oklahoman. Retrieved June 4, 2013.
  6. ^ "Weather Channel's Storm-Chasing SUV Destroyed by Tornado (Photo)". The Hollywood Reporter. 31 May 2013. Retrieved 29 June 2018.
  7. ^ News, U.S. "At least 16 dead after rain, twisters lash mid-US; storms head east". Retrieved 29 June 2018. ((cite web)): |last= has generic name (help)
  8. ^ twistex.org. TWISTEX Investigators, Dr. Bruce Lee, 2009-11-25.
  9. ^ twistex.org. TWISTEX Investigators, Dr. Cathy Finley, 2009-11-25.
  10. ^ "Error - Discovery". www.discovery.com. Retrieved 29 June 2018.
  11. ^ "Error - Discovery". www.discovery.com. Retrieved 29 June 2018.
  12. ^ twistex.org. Articles, 2009-11-25.

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