Methods+of+Storm+Chasing

While storm chasing is defined as pursuing any severe weather, the most common form of storm chasing is chasing storms that produce tornadoes. Understanding the development of tornadoes is a difficult and dangerous task.

Since the ‘90s there have been many research projects looking at the development and motion of severe storms. Understanding this development of tornadoes can help with the prediction process and in turn allow for quicker reaction time among populated areas. Although forecasts are not perfect, it is important to raise public awareness for these events. Within the last decade storm chasing has become popular, not only among scientists but among [|amateurs] as well.

Storm chasers generally use radar vehicles to collect experimental data, however, other methods are used as well such as balloons equipped with radiosondes, probes to drop in the path of the storm, armored vehicles to drive into the storm, and the newest method of unmanned aircraft systems (UAS) [4], [8], [11], [13], [17], [18].

Storm chasing has a long history which has led to better understanding of severe weather. Throughout the history of storm chasing, the technology has changed from large radar equipment, to radiosondes and probes, and more recently to unmanned aircraft.

In the mid 1950s the act of storm chasing began in North Dakota. In 1972 the [|Storm Intercept Project] initiated the beginning of “organized severe storm intercept efforts” [4]. This project was a combined effort of the National Severe Storms Laboratory (NSSL) and the University of Oklahoma (OU). Their efforts were to study the impacts of severe weather and the formation of tornadoes by intercepting the storm [4], [5]. Following the Storm Intercept Project, in 1994 the Verification of the Origins of the Rotation of Tornadoes Experiment or VORTEX project established the first mobile data collection equipment as they attached a [|Doppler radar] to a vehicle and drove near the storms [16]. The VORTEX project studied the [|rotation] development of a supercell storm, as shown in figure 1.
 * History **

 At the same time as the Storm Intercept Project and VORTEX, the Tornado and Storm Research Organisation ([|TORRO]) in the UK was developed. Beginning in 1974 TORRO was founded to develop databanks for severe weather including tornadoes and waterspouts [6].

The VORTEX project quickly turned into VORTEX 2 in 2009-2010. [|VORTEX 2] partnered with universities around the country to gather tornadic data in order to better predict tornadic activity. VORTEX 2 incorporated additional equipment such as balloon soundings which could be launched into the storm to collect more data [23]. In addition, VORTEX 2 was the initial start of using unmanned aerial systems (UAS) where the University of Colorado at Boulder (CU-Boulder) launched the [|Tempest]. The Tempest was part of a collaborative effort with CU-Boulder and the University of Nebraska at Lincoln (UNL). The Tempest was a newer method of balloon soundings as it could be more accurately controlled into the path of an oncoming storm [20].

Throughout the late ’90s through the present day, there are a couple main projects focusing on tornadic research. The Tactical Weather- Instrumented Sampling in/near Tornadoes Experiment ([|TWISTEX]) focused on collecting data near the tornadic circulations using mobile instruments. In addition, TWISTEX looked at both the forward and rear flanking downdrafts of a tornado. Another recent project, Sampling Severe Local Storms and Related Phenomena Using Unmanned Aircraft Systems ([|STORM]), was a collaboration of UNL and CU-Boulder during 2012. The overall goal of STORM was to implement the use of UAS to sample severe local storms using similar instrumentation as past projects such as satellite based radar [17], [18].

While some storm chasers find the adrenaline rush of chasing severe storms to be the most important part, there are other aspects of storm chasing that are important. For instance, capturing footage of the storms to inform the public or improving warning times by collecting data can be important aspects of storm chasing.
 * Motive of Chasing **

The overall goal of storm chasing is to collect data and from the data look for patterns to help with the storm prediction process. Convective outlooks are currently the best method for storm prediction as they can be accurately issued up to three days in advance. These outlooks highlight the areas of the country with the greatest area of concern for severe storm activity. Using data such as wind and temperature profiles as well as [|dual-polarimetric radar], the computer processors are able to provide better predictions. The radar polarimetric data explores the [|microphysical] side of the storms. This data can be used to identify areas of low-wind shear and tornadic development [1], [3], [10]. Although a severe storm could be predicted the day of or even the day before a severe weather event, the amount of warning time for a tornado is only a couple hours in advance.

Part of tornado prediction includes warning the public. Anyone can report a tornado as a visual observer, however, there are certain people that are trained to chase tornadoes and report them to the National Weather Service [2], [4]. The only problem with visual observers reporting tornadic activity is sometimes even after a report has been made it takes the weather forecasters up to an hour to inform the community [2]. This is very problematic as severe tornadoes can move incredibly quickly and change directions with the wind.

Warning the public can be difficult as the public is a widely varied group of people, therefore, multiple warning systems are used. In addition to tornado sirens near active tornadoes, the National Weather Service, the National Oceanic and Atmospheric Administration (NOAA), the Storm Prediction Center (SPC), the Weather Channel, Weather Radio, other internet sources, as well as other emergency management resources including reverse 911 and texts are used to mass message the community [2]. Using multiple warning systems is important as it leads to the highest level of understanding in the community.

<span style="font-family: Arial,sans-serif; font-size: 12pt;">The majority of storm chasers use radar vehicles that drive close to the storms. Almost all vehicles are custom built and therefore most are privately owned [12]. The Doppler radar vehicle is a large truck equipped with a Doppler radar attached to the back. This vehicle drives near to the storm and deploys the Doppler radar collecting data as the storm moves. Generally this vehicle re-positions a couple times during the storm. In addition to using radar vehicles, storm chasers deploy balloons, probes and radiosondes into the storm to collect data [19], [23].
 * <span style="font-family: Arial,sans-serif; font-size: 12pt;">Storm Chasers **

<span style="font-family: Arial,sans-serif; font-size: 12pt;">Another method of data collection is storm intercepting. [|Storm interceptors] are defined as storm chasers that drive armored vehicles into the path of the storm and collect data from inside the storm. Storm intercepting is the most dangerous method of data collection, however, it provides valuable data that cannot be collected otherwise.

<span style="font-family: Arial,sans-serif; font-size: 12pt;">In the last decade, the fascination with storm chasing has increased and become “popular”. With this increased popularity, more storm chasers are out on the roads. With the increased number of chasers on the roads, the dangers of storm chasing have increased [15], [24]. While death is rare, many scientists are surprised that death is not more common, especially among the amateurs. For instance, in 2013 an experienced storm chaser Tim Samaras died chasing an extreme storm near Oklahoma City [7].

<span style="font-family: Arial,sans-serif; font-size: 12pt;">The most common equipment used includes Doppler radar, anemometers or wind sensors, and pressure and humidity sensors. In addition, [|radiosondes] are used to measure wind speeds and direction. <span style="font-family: Arial,sans-serif; font-size: 12pt;">The Doppler radar produces velocity data about objects in the distance. An example of the Doppler radar equipped vehicle is shown in figure 2. This can provide information such as cloud cover, reflectivity, humidity levels, and much more [10], [21]. This information allows scientists to create an atmospheric model in real time and allows them to forecast future cloud movements [12]. Anemometers measure wind speed and can be incredibly important for predicting supercell activity [14]. Most supercell activity occurs a high wind speeds up to seventy-five miles an hour [16]. Anemometer data allows scientists to predict wind patterns and future storm development [13]. In addition, having this information allows the SPC to create a storm warning for areas to warn citizens. The pressure and humidity sensors provide crucial information about the temperatures and different levels of atmospheric conditions within the clouds. For tornadoes to form, there needs to be a low pressure and corresponding high-pressure system combining forcing warmer, more humid air upward in a rotational form. In figure 2, the rotation and formation of a supercell storm is described. <span style="font-family: Arial,sans-serif; font-size: 12pt;">
 * <span style="font-family: Arial,sans-serif; font-size: 12pt;">Current Technology **

<span style="font-family: Arial,sans-serif; font-size: 12pt;">In general, radiosondes are attached to balloons and launched directly into a forming supercell [9]. These sondes are not intended to be recovered but can collect important data without presenting a direct threat to storm chasers. Most sondes are equipped with similar equipment as radar vehicles including pressure and humidity sensors and anemometers.

<span style="font-family: Arial,sans-serif; font-size: 12pt;">The newest form of storm chasing equipment is the UAS. Each model of UAS is equipped with different technology for its particular mission. The Tempest for example is equipped with a pitot probe to measure wind speeds as well as a pressure and humidity sensor [20]. On the other hand, other UAS are equipped with balloon radiosonde dropping capabilities [17].

<span style="font-family: Arial,sans-serif; font-size: 12pt;">In the early 2000’s the first (UAS) was operated as a part of the VORTEX 2 [23]. While the UAS couldn’t fly into the storm due to airspace restrictions, it was able to collect important wind speed information. The UAS can provide important observations that are difficult to obtain without being in the storm environment. In 2008, the University of Colorado at Boulder and the University of Nebraska at Lincoln entered a collaborative experiment to “evaluate the benefits and potential of using UAS” [8]. The Tempest, a UAS developed by members of the collaborative experiment mentioned above, was developed to figure out the feasibility of collecting data from severe storms. This UAS took direct measurements to understand wind fields. This research was used specifically in the rear flank downdraft measurements near the “hook” which is a crucial feature of tornadic activity. Current UAS activity is focused on three main parts of supercell/tornadic activity. The forward and rear flank downdrafts are both important parts of tornadic activity and while they have been studied in the past, new UAS are able to range closer to parts of the storm. The TTwistor and Mistral aircraft are current exploring these downdrafts. The newest area of research is focused on the Torus using the newest Mistral aircraft and is currently a future goal.
 * <span style="font-family: Arial,sans-serif; font-size: 12pt;">UAS Development **

<span style="font-family: Arial,sans-serif; font-size: 12pt;">Over the past seventy years storm chasing has increased in both the scientific and amateur realm. While storm chasing will remain a hobby for many people, the future of storm chasing is moving towards more automated technology that is less dangerous for storm chasers. As we continue to use radar vehicles we will slowly merge to further use of UAS. The use of UAS as a developing research method has risen in the last decade and will continue to improve in the next couple years. Future projects such as TORUS will provide crucial information to meteorologists to better predict tornadic activity.
 * <span style="font-family: Arial,sans-serif; font-size: 12pt;">Conclusion **

<span style="color: #333333; font-family: Arial,sans-serif; font-size: 12pt;">[1] B. N. Amots, "Dynamics and thermodynamics of a tornado: Rotation effects," //<span style="font-family: Arial,sans-serif;">Elsevier Atmospheric Research //, 2016. [Online]. Available: <span style="font-family: Arial,sans-serif; font-size: 12pt;">[].
 * <span style="font-family: Arial,sans-serif; font-size: 12pt;">Resources **

<span style="font-family: Arial,sans-serif; font-size: 12pt;">[2] J. Brotzge. and W. Donner, “The Tornado Warning Process: A Review of Current Research, Challenges and Opportunities,” //Bulletin of the American Meteorological Society,// 2013. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;"> [3] S. Chaudhuri, “Identification of the level of downdraft formation during sever thunderstorms: a frequency domain analysis,” //Meteorology and Atmospheric Physics,// vol 102, no. 1-2, pp. 123-129, 2008. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;">[4] C. A. Doswell, A. R., Moller, & H. E. Brooks, “Storm spotting and public awarenes since the first tornado forecasts of 1948,” //Weather and Forecasting,// vol 14, iss. 4, 544-557,1999. [Online]. Available: []

<span style="font-family: Arial,sans-serif; font-size: 12pt;">[5] C. A. Doswell III & A. R. Moller, “Scientific Impact of Southern Great Plains Severe Storm Intercept Operations – 1972 to the Present,” //Bulletin of the American Meteorological Society,// 1985. [Online]. Available: []

<span style="font-family: Arial,sans-serif; font-size: 12pt;">[6] D. M. Elsom, G. T. Meaden. D. J. Reynolds, M. W. Rowe, and J. D. C. Webb, “Advances in tornado and storm research in the United Kingdom and Europe: the role of the Tornado and Storm Research Organisation,” //Elsevier Atmospheric Research,// 2001. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;"> [7] J. Ferrell, “Tim Samaras, Other Chasers Killed in Extreme Tornadoes,” //AccuWeather,// 10 June 2013. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;">[8] E. W. Frew, J. Elston, B. Argrow, A. Houston, & E. Rasmussen, “Sampling Severe Local Storms and Related Phenomena: Using Unmanned Aircraft Systems,” //IEEE Robotics and Automation Magazine,// Vol 19, Iss 1, 85-95, 2012. [Online]. Available: []

<span style="font-family: Arial,sans-serif; font-size: 12pt;"> [9] V. A. Gensini, T. L. Mote, and H. E. Brooks, “Severe Thunderstorm Reanalysis Environments and Collocated Radiosonde Observations,” //Journal of Applied Meteorology and Climatology,// 2014. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;"> [10] P. Heinselman, D. LaDue, and D. M. Kingfield, “Tornado Warning Decisions Using Phased-Array Radar Data,” //Weather and Forecasting – American Meteorological Society,// 2015. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;"> [11] A. L. Houston, B. Argrow, J. Elston, J. Lahowetz, and E.W. Frew, “The Collaborative Colorado-Nebraska Unmanned Aircraft System Experiment,” //Bulletin of the American Meteorological Society,// 2012. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;"> [12] E. A. Kalina, “Using disdrometer, radar, lightning, and model data to investigate severe thunderstorm microphysics,” //University of Colorado at Boulder Dissertation,// 2015. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;">[13] C. D. Karstens, T. M. Samaras, A. Laubach, B. D. Lee, C. A. Finley, W. A. Gallus Jr., & F. L Haan Jr, “TWISTEX 2008: In Situ and Mobile Mesonet Observations of Tornadoes,” //Electronic proceedings, 24th Conf. on Severe Local Storms. American Meteorological Society,// page 3.11, 2008. [Online]. Available: <span style="color: #663366; font-family: Arial,sans-serif; font-size: 12pt; text-decoration: none;">[]

<span style="font-family: Arial,sans-serif; font-size: 12pt;"> [14] B. W. Kerr and G. L. Darkow, “Storm-Relative Winds and Helicity in the Tornadic Thunderstorm Environment,” //Journals Online,// 1996. [Online]. Available: [|https://journals.ametsoc.org/doi/pdf/10.1175/1520-0434%281996%29011<0489%3ASRWAHI>2.0.CO%3B2].

<span style="font-family: Arial,sans-serif; font-size: 12pt;"> [15] A. Laubach, “Tragedy and Ethics in Storm Chasing,” //Southern Illinois University Research Papers,// 2016. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;"> [16] F. T. Lombardo, D. B. Roueche, and D. O. Prevatt, “Comparison of two methods of near-surface wind speed estimation in the 22 May, 2011 Joplin, Missouri Tornado,” //Elsevier Journal of Wind Engineering and Industrial Aerodynamics,// 2015. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;"> [17] L. Marshall, “Grand Challenge: Eye on the sky,” //University of Colorado,// 2016-2017. [Online]. Available: []. <span style="font-family: Arial,sans-serif; font-size: 16px;"> [Accessed June 10, 2018].

<span style="font-family: Arial,sans-serif; font-size: 12pt;">[18] S. K. Prasad, U. C. Mohanty, A. Routray, K. K. Osuri, S. S. V. S. Ramakrishna, and D. Niyogi, “Impact of Doppler weather radar data on thunderstorm simulation during STORM pilot phase,” //Natural Hazards,// 2009. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;">[19] E. N. Rasmussen, J. M. Straka, R. Davies-Jones, C. A. Doswell III, F. H. Carr, M. D. Eilts, and D. R. MacGorman, “Verification of the Origins of Rotation in Tornadoes Experiment: VORTEX,” //American Meteorological Society,// 1994. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;">[20] J. Roadman, J. Elston, B. Argrow, and E. Frew, “Mission Performance of the Tempest Unmanned Aircraft System in Supercell Storms,” //Journal of Flight,// 2012. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;"> [21] K. M. Simmons and D. Sutter, “The 2011 Tornadoes and the Future of Tornado Research,” //Bulletin of the American Meteorological Society,// 2012. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;">[22] J. L. Timothy, L. J. Miller, M. Weisman, et. al., “The Severe Thunderstorm Electrification and Precipitation Study,” //American Meteorological Society,// 2004. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;">[23] J. Wurman, D. Dowell, Y. Richardson, P. Markowski, and E. Rasmussen, “The Second Verification of the Origins of Rotation in Tornadoes Experiment: VORTEX 2,” //Bulletin of the American Meteorological Society,// 2012. [Online]. Available: [].

<span style="font-family: Arial,sans-serif; font-size: 12pt;"> [24] H. Yan and C. E. Shoichet, “Storm chasers: Brave researchers or dangerous thrill seekers?,” //CNN Extreme Weather,// 29 March 2017. [Online]. Available: []. [Accessed June 10, 2018].