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XKCD Tornado Hunters

VORTEX2: Verification of the Origins of Rotation in Tornadoes Experiment

VORTEX2 Background

VORTEX (1994-1995)

VORTEX chase vehicle near the Dimmitt tornado

VORTEX chase vehicle near the Dimmitt, Texas tornado, June 6, 1995.

The Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX) was designed to answer questions about the causes of tornado formation. VORTEX successfully documented the entire life cycle of a tornado from beginning to end for the first time in history. Field operations took place in parts of Texas, Oklahoma and Kansas.

VORTEX was unique because field resources targeted a single storm each day to gather data over a complete supercell lifecycle. A team of investigators operated a dozen instrumented vehicles, two mobile laboratories, a mobile Doppler radar and two Doppler-equipped aircraft.

VORTEX scientists found that the leading edges of pools of cooler air left behind by thunderstorms are prime locations for later tornado formation. They also discovered tornado formation seems to be linked to the character and behavior of the "rear-flank" downdraft at the back-side of the supercell storm. Surprisingly, it appears fewer supercells and mesocyclones produce tornadoes than scientists believed, with only subtle differences occurring between tornadic and non-tornadic mesocyclones. Subsequent smaller field efforts based on these discoveries focused data collection on the storm's small hook echo region. The goal of this ongoing work is to determine those types of rear-flank downdrafts that support tornado formation and those that hinder or prevent it.

Recent improvements in National Weather Service severe weather warning statistics may be partly due to the application of VORTEX findings.

Read more about VORTEX-95 »

VORTEX2 (2009-2010)

 NO-XP radar and NSSL field command vehicle go out to meet Hurricane Ike

The fleet of vehicles and instruments crowds a hotel parking lot at the beginning of VORTEX2.

VORTEX2 builds on the progress made with VORTEX to answer new and more precise questions: How do tornadoes form? What exactly causes the wind to spin into a concentrated funnel? How can we tell exactly when a tornado will form and when it will die, or how long it will last? Why do some thunderstorms produce tornadoes and others do not? What is the structure of tornadoes? What is the relationship of tornadic winds to damage?  

VORTEX2 has dozens more instruments than the original VORTEX. "The VORTEX2 experiment is designed to obtain a large number of measurements near the surface in and around the storm to better understand the relationship between storm rotation and temperature, humidity, and wind fields in this layer," explained Lou Wicker, V2 Principal Investigator and scientist with the NOAA National Severe Storms Laboratory.  Researchers have carefully choreographed deployment strategies for different types of storms and each vehicle and instrument has a specific mission.

VORTEX2 is entirely mobile, and operates in the Central Plains where the relatively flat landscape allows mobile radars to collect data close to the ground.  Operations are held in May and June, statistically the most active time of year for severe weather.  Also, storms tend move slower at this time of year, presenting a better opportunity for observation.

VORTEX2 is expected to lead to further improvements in tornado warning skill.