science

TWISTEX

TWISTEX is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand TWISTEX rather than just read about it. In short: TWISTEX (an acronym 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 with the deaths of three researchers in the 2013 El Reno tornado. The project later announced in 2015 that there were plans for future operations; however, no such operations had occurred afterwards.

Key takeaways

TWISTEX belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect TWISTEX to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of TWISTEX from memory before moving on to harder problems.

Reference excerpt

TWISTEX (an acronym 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 with the deaths of three researchers in the 2013 El Reno tornado. The project later announced in 2015 that there were plans for future operations; however, no such operations had occurred afterwards. 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 on the Discovery Channel, where they worked alongside VORTEX 2. The group was also featured on National Geographic Channel's "Disaster Labs".

2013 El Reno tornado

On May 31, 2013, TWISTEX Researchers Tim Samaras, his 24-year-old son Paul Samaras, and 45-year-old California native Carl Young died in the record-breaking 2.6 mile 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 mobile mesonet vehicle 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 around half a mile away 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's Mike Bettes, were also caught in the tornado but escaped with only minor injuries. Bettes and the Tornado Hunt crew were lifted up by the tornado in their sport utility vehicle. Four other people who were not involved with storm chasing also died in this tornado. The car's remains were located at 35.479104, -97.900385 near El Reno.

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 rotate shifts into the mesonet vehicles during the project.

Former TWISTEX personnel Killed by the record-breaking 2013 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, 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 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 purposes to visualize/measure tornado-driven debris. Additionally, hydrometeors were used to determine the tornado-relative location of the HITPRs.

Tornado proximity environment sampling

Each of the participating TWISTEX vehicles had a mobile mesonet station mounted on the roof including probe deployment trucks, usually designated with M. The mobile mesonet gathered near-surface thermodynamic and kinematic data in quadrants of Rear flank downdraft (RFD). When the in-situ probe array data was in use alongside the mobile mesonet stations, it could capture thermodynamic and kinematic mapping that represented the flow reaching the tornado, even if the probes had not been hit head on by a tornado.

Notable TWISTEX Operations

During TWISTEX's operation, multiple field experiments occurred annually, with the goal varying each time. TWISTEX's operations usually ended by June, marking the end of Tornado season.

TWISTEX 2010

Conducted throughout late May to June 2010, though officially concluding on July 1, 2010, TWISTEX most notably intercepted a large EF4 tornado during the operation. On May 22, 2010, TWISTEX intercepted a violent multiple-vortex EF4 tornado near Bowdle, South Dakota, during a large tornado outbreak during the later weeks of May. The objective was to determine if Rear Flank Downdraft (RFD) had any contribution to tornadogenesis. TWISTEX used an array of four mobile mesonet vehicles, which sampled atmospheric variables every second. Surges of RFD were reported in datasets across the vehicles, with gusts sampled the most during intensification and dissipation phases of the tornado.

TWISTEX 2009 Conducted from May to June 2009, the experiment was assisted by VORTEX 2 and had their debut in Discovery Channel's Storm Chasers. On June 17, 2009, TWISTEX successfully intercepted an EF2 tornado near Aurora, Nebraska via their thermodynamic HITPR probes. They gathered rare datasets of air parcels within RFD gusts. TWISTEX members afterwards suggested the tornado was likely the best tornado TWISTEX had ever sampled at the time.

TWISTEX publications Participants of the TWISTEX research project had contributed to many publications.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with TWISTEX

Start with the simplest possible case. Write down what TWISTEX claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to TWISTEX before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about TWISTEX ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of TWISTEX

In research: TWISTEX appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses TWISTEX in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: TWISTEX is common in secondary-school and first-year university syllabi. It links to neighbouring topics Meteorology research and field projects, Storm chasing, Tornado, so understanding it makes those chapters shorter.
In everyday life: Look for TWISTEX outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study TWISTEX in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what TWISTEX means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain TWISTEX out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is TWISTEX in simple terms?

Why does TWISTEX matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study TWISTEX?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on TWISTEX.