TWISTEX (a

backronym A backronym is an acronym formed from an already existing word by expanding its letters into the words of a phrase. Backronyms may be invented with either serious or humorous intent, or they may be a type of false etymology or folk etymology. The ...

for Tactical Weather-Instrumented Sampling in/near Tornadoes Experiment) was a

tornado A tornado is a violently rotating column of air that is in contact with the surface of Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, although the ...

research experiment that was founded and led by

Tim Samaras Timothy Michael Samaras (November 12, 1957 – May 31, 2013) was an American engineer and storm chaser best known for his field research on tornadoes and time on the Discovery Channel show ''Storm Chasers''. He died in the 2013 El Reno torn ...

Bennett, Colorado Bennett is a statutory town located in Adams and Arapahoe counties, Colorado, United States. The town population was 2,862 at the 2020 United States census with 2,443 residing in Adams County and 419 residing in Arapahoe County. History Benne ...

, US, that ended in the deaths of three researchers in the

2013 El Reno tornado The 2013 El Reno tornado was an extremely large, powerful, and erratic tornado that occurred over rural areas of Central Oklahoma during the early evening hours of Friday, May 31, 2013. This rain-wrapped, multiple-vortex tornado was the wide ...

. The experiment announced in 2015 that there were some plans for future operations, but no additional information has been announced since.

Background

The project normally ran from mid-April through the end of June with a domain that covers the

Great Plains The Great Plains is a broad expanse of plain, flatland in North America. The region stretches east of the Rocky Mountains, much of it covered in prairie, steppe, and grassland. They are the western part of the Interior Plains, which include th ...

and portions of the

Midwestern United States The Midwestern United States (also referred to as the Midwest, the Heartland or the American Midwest) is one of the four census regions defined by the United States Census Bureau. It occupies the northern central part of the United States. It ...

. The project was normally at full strength for most of May and June with four vehicles, all equipped with roof-mounted mobile

mesonet In meteorology and climatology, a mesonet, portmanteau of mesoscale network, is a network of automated weather and, often also including environmental monitoring stations, designed to observe mesoscale meteorological phenomena and/or microclima ...

weather station A weather station is a facility, either on land or sea, with instruments and equipment for measuring atmosphere of Earth, atmospheric conditions to provide information for weather forecasting, weather forecasts and to study the weather and clima ...

s. One of the vehicles transported an array of

in situ is a Latin phrase meaning 'in place' or 'on site', derived from ' ('in') and ' ( ablative of ''situs'', ). The term typically refers to the examination or occurrence of a process within its original context, without relocation. The term is use ...

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. TWISTEX was one of the featured teams in seasons 3, 4 and 5 of ''

Storm Chasers Storm chaser or stormchaser may refer to: Weather * Storm chasing, the pursuit of any severe weather condition * Storm chaser, colloquial term referring to scammers who enter areas recently afflicted by disasters offering false or shoddy servi ...

'' on the

Discovery Channel Discovery Channel, known as The Discovery Channel from 1985 to 1995, and often referred to as simply Discovery, is an American cable channel that is best known for its ongoing reality television shows and promotion of pseudoscience. It init ...

. The group was also featured on

National Geographic Channel National Geographic (formerly National Geographic Channel; abbreviated and trademarked as Nat Geo or Nat Geo TV) is an American pay television network and flagship channel owned by the National Geographic Global Networks unit of Disney Enter ...

's "Disaster Labs".

May 31, 2013 deaths

On May 31, 2013,

, 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. They were unable to escape along gravel roads as the funnel rapidly expanded to envelop them. Their

Chevrolet Cobalt The Chevrolet Cobalt is a compact car introduced by Chevrolet in 2004 for the 2005 model year. The Cobalt replaced both the Cavalier and the Toyota-based Geo/Chevrolet Prizm as Chevrolet's compact car. The Cobalt was available as both a coupe a ...

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. Several other storm chasers, including

The Weather Channel The Weather Channel (TWC) is an American pay television television channel, channel owned by Weather Group, LLC, a subsidiary of Allen Media Group. The channel's headquarters are located in Atlanta, Georgia. Launched on May 2, 1982, the channel ...

Mike Bettes Michael Bettes (born 1972) is an American television meteorologist and Storm chasing, storm chaser who works for The Weather Channel in Atlanta, Georgia. He was a co-host of ''America's Morning Headquarters, AMHQ: America's Morning Headquarters'' ...

, were also caught in the tornado but escaped with only minor injuries. Bettes and the Tornado Hunt crew were lifted up by the wedge tornado in their sport utility vehicle. Four other people who were not involved with storm chasing also died in this tornado.

TWISTEX personnel

* Tony Laubach; Mesonet Team Leader & Video Archival/Production, Meteorologist * Matt Grzych; Software & Systems Development, Atmospheric Scientist * Ed Grubb; Mobile Mesonet Navigator, Mechanical Guru * Dr. Bruce Lee; Mobile Mesonet Director, Atmospheric Scientist * Dr. Cathy Finley; Mobile Mesonet Co-Director, Atmospheric Scientist * Chris Karstens; Mesonet Team Leader & Software Development, ISU Atmospheric Sciences Ph.D. Student * Ben McMillan; Mobile Mesonet Driver, Team Medic Students from the Atmospheric Sciences Department at

Iowa State University Iowa State University of Science and Technology (Iowa State University, Iowa State, or ISU) is a Public university, public land-grant university, land-grant research university in Ames, Iowa, United States. Founded in 1858 as the Iowa Agricult ...

rotate shifts into the mesonet vehicles during the project.

Former TWISTEX personnel

Killed by the record breaking EF3 tornado in El Reno, Oklahoma: * Tim Samaras; TWISTEX Director, scientist, engineer * Paul Samaras; videographer * Carl Young; Probe Driver, meteorologist

Tornado core sampling

TWISTEX deployed several hardened instruments in the paths of tornadoes to collect the following datasets:

atmospheric pressure Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1,013. ...

temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...

humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, dew, or fog t ...

wind speed In meteorology, wind speed, or wind flow speed, is a fundamental atmospheric quantity caused by air moving from high to low pressure, usually due to changes in temperature. Wind speed is now commonly measured with an anemometer. Wind spe ...

and

direction Direction may refer to: *Body relative direction, for instance left, right, forward, backwards, up, and down ** Anatomical terms of location for those used in anatomy ** List of ship directions *Cardinal direction *Bearing (navigation) Mathemat ...

, and visualization for accurate debris/

hydrometeor In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwealth ...

velocities and for verification of the tornado-relative location of the in situ sampling. The

thermodynamic Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of th ...

probes were called Hardened In-situ Tornado Pressure Recorders (HITPR), and could collect and store the datasets. Measurements were recorded at 10 samples/second, and stored on non-volatile flash cards. To provide visualization within the tornado core, TWISTEX also had video probes. These probes utilized 7 cameras each for a total of 14 cameras. Collectively, the two camera probes were used for

photogrammetry Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring and interpreting photographic images and patterns of electromagnetic radiant ima ...

purposes to visualize/measure tornado-driven debris. Additionally, hydrometeors were used to determine 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

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 Outflow may refer to: *Capital outflow, the capital leaving a particular economy *Bipolar outflow, in astronomy, two continuous flows of gas from the poles of a star * Outflow (hydrology), the discharge of a lake or other reservoir system *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.twistex.org
Articles
2009-11-25. ;AMS Journal and Conference Papers *Karstens, C. D., W. A. Gallus, B. D. Lee, and C. A. Finley, 2013: Analysis of tornado-induced tree-fall using aerial photography from the Joplin, MO, and Tuscaloosa-Birmingham, AL, tornadoes of 2011. J. Appl. Meteorol. Climatol., Early online release: http://journals.ametsoc.org/doi/pdf/10.1175/JAMC-D-12-0206.1 *Lee, B. D., C. A. Finley, and C. D. Karstens, 2012: The Bowdle, South Dakota, cyclic tornadic supercell of 22 May 2010: Surface analysis of rear-flank downdraft evolution and multiple internal surges. Mon. Wea. Rev., 140, 3419-3441. http://journals.ametsoc.org/doi/abs/10.1175/MWR-D-11-00351.1 *Lee, B. D., C. A. Finley, and T. M. Samaras, 2011: Surface analysis near and within the Tipton, Kansas, tornado on 29 May 2008. Mon. Wea. Rev., 139, 370-386. http://journals.ametsoc.org/doi/abs/10.1175/2010MWR3454.1 *Karstens, C. D., T. M. Samaras, B. D. Lee, W. A. Gallus, and C. A. Finley, 2010: Near-ground pressure and wind measurements in tornadoes. Mon. Wea. Rev., 138, 2570-2588. http://journals.ametsoc.org/doi/pdf/10.1175/2010MWR3201.1 *Finley, C. A., B. D. Lee, M. Grzych, C. D. Karstens, and T. M. Samaras, 2010: Mobile mesonet observations of the rear-flank downdraft evolution associated with a violent tornado near Bowdle, SD on 22 May 2010. Electronic proceedings, 25th Conf. on Severe Local Storms, Denver, CO. Amer. Meteor. Soc., 8A.2. http://ams.confex.com/ams/pdfpapers/176132.pdf *Karstens, C. D., T. M. Samaras, W. A. Gallus, C. A. Finley, B. D. Lee 2010: Analysis of near-surface wind flow in close proximity to tornadoes. Electronic proceedings, 25th Conf. on Severe Local Storms, Denver, CO. Amer. Meteor. Soc., P10.11. http://ams.confex.com/ams/pdfpapers/176188.pdf *Lee, B. D., C. A. Finley, C. D. Karstens, and T. M. Samaras, 2010: Surface observations of the rear-flank downdraft evolution associated with the Aurora, NE tornado of 17 June 2009. Electronic proceedings, 25th Conf. on Severe Local Storms, Denver, CO. Amer. Meteor. Soc., P8.27. http://ams.confex.com/ams/pdfpapers/176133.pdf *Finley, C. A., and B. D. Lee, 2008: Mobile mesonet observations of an Intense RFD and multiple gust fronts in the May 23 Quinter, Kansas tornadic supercell during TWISTEX 2008. Electronic proceedings, 24th Conf. on Severe Local Storms, Savannah, GA Amer. Meteor. Soc., P3.18. http://ams.confex.com/ams/pdfpapers/142133.pdf *Karstens, C. D., T. M. Samaras, A. Laubach, B. D. Lee, C. A. Finley, W. A. Gallus, F. L. Hann, 2008. TWISTEX 2008: In situ and mobile mesonet observations of tornadoes. Electronic proceedings, 24th Conf. on Severe Local Storms, Savannah, GA Amer. Meteor. Soc., P3.11. http://ams.confex.com/ams/pdfpapers/141974.pdf *Lee, B.D., C. A. Finley, and T. M. Samaras, 2008: Thermodynamic and kinematic analysis near and within the Tipton, KS tornado on May 29 during TWISTEX 2008. Electronic proceedings, 24th Conf. on Severe Local Storms, Savannah, GA Amer. Meteor. Soc., P3.13. http://ams.confex.com/ams/pdfpapers/142078.pdf *Grzych, M. L., B. D. Lee, and C. A. Finley, 2007: Thermodynamic analysis of supercell rear-flank downdrafts from Project ANSWERS. Mon. Wea. Rev., 135, 240-246. http://ams.allenpress.com/perlserv/?request=get-pdf&doi=10.1175%2FMWR3288.1 *Finley, C. A., and B. D. Lee, 2004: High resolution mobile mesonet observations of RFD surges in the June 9 Basset, Nebraska supercell during project answers 2003. Preprints, 22nd Conf. on Severe Local Storms, Hyannis, MA, CD-ROM, 11.3. http://ams.confex.com/ams/pdfpapers/82005.pdf *Lee, B. D., C. A. Finley, and P. Skinner, 2004: Thermodynamic and kinematic analysis of multiple RFD surges for the 24 June 2003 Manchester, South Dakota cyclic tornadic supercell during Project ANSWERS 2003. Preprints, 22nd Conf. on Severe Local Storms, Hyannis, MA, Amer. Meteor. Soc., CD-ROM, 11.2. http://ams.confex.com/ams/pdfpapers/82000.pdf *Lee, J. J., T. M. Samaras, and C. R. Young, 2004: Pressure measurements at the ground in an F-4 tornado. 22nd Conf. on Severe Local Storms, Hyannis, MA, Amer, Meteor. Soc., CD_ROM, 15.3. http://ams.confex.com/ams/pdfpapers/81700.pdf *Samaras, T. M., 2004: A historical perspective of in-situ observations within tornado cores. Preprints, 22nd Conf. on Severe Local Storms, Hyannis, MA, Amer, Meteor. Soc., CD_ROM, P11.4. http://ams.confex.com/ams/pdfpapers/81153.pdf *Samaras, T.M., and J. J. Lee, 2004. Pressure measurements within a large tornado. Proc. 84th American Meteorological Society Annual Meeting - Eighth Symposium on Integrated Observing and Assimilation Systems for Atmosphere, Oceans, and Land Surface, Seattle, WA., P4.9. http://ams.confex.com/ams/pdfpapers/74267.pdf *Wurman, J., and T. Samaras, 2004: Comparison of in-situ pressure and DOW Doppler winds in a tornado and RHI vertical slices through 4 tornadoes during 1996-2004. Extended Abstracts, 22nd Conf. on Severe Local Storms, Hyannis, MA, Amer. Meteor. Soc., 15.4, 1-14. http://ams.confex.com/ams/pdfpapers/82352.pdf ;National Geographic (Book and articles about Samaras research) *''Tornado Hunter'', by Stephen Bechtel with Tim Samaras. Published by National Geographic. pp. 272. Release May 19, 2009. *National Geographic in the Field - Tim Samaras, Severe-Storms Researcher (2005

*National Geographic Feature - New View of Tornadoes: From the Inside Looking Out (2005

*National Geographic Events – Inside the Tornado (2005

*National Geographic Today - Storm Chaser Deploys Probe, Makes History (2003

;American Society of Civil Engineers *Samaras, T. M., and J. J. Lee, 2006: Measuring tornado dynamics with in-situ instrumentation. Proceedings of the 2006 Structures Congress: 2006 Structural Engineering and Public Safety. St. Louis, Missouri, pp. 1–10, (doi 10.1061/40889(201)12). http://cedb.asce.org/cgi/WWWdisplay.cgi?0609031 ;ABC News (Article about Samaras research) *''World News'' - Scientists Put an Eye in the Heart of the Storm (2005) https://abcnews.go.com/WNT/Science/story?id=831857

TWISTEX on television

TWISTEX was featured in seasons 3, 4, and 5 of

's ''

''.

References

External links

Personal website of Tony Laubach

Twistex's Facebook page
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