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This is the unofficial, WWW version of the VORTEX-95 Operations Plan. It may differ from the published operations plan which is available by 15 March from the National Severe Storms Laboratory.
This document is the Operations Plan for the experiment. It is intended to serve two primary purposes: training of participants prior to the start of the experiment, and a field guide to experiment strategies and missions. All participants are urged to study this Operations Plan prior to the beginning of the VORTEX-95 field operations, and to consult with their team leader, the Assistant Director (Jerry Straka) or the Director (Erik Rasmussen) of VORTEX if they have any questions.
This experiment is being executed with a set of specific scientific hypotheses in mind, as documented elsewhere ( " Scientific Objectives" ), but the general sense of the experiment is to increase understanding of tornadogenesis, thereby enhancing the ability to anticipate tornado development. Many of the scientific objectives are closely tied to the mission statement of SELS (soon to become SPC). With the deployment of Doppler radars around the nation, it is becoming increasingly obvious that (1) even this exciting new tool has some limits in its tornado detection capability, as do all weather radars, and (2) not all mesocyclonic circulations detectable by a Doppler radar will become tornadic. Since not all detectable mesocyclones go on to produce tornadoes, it is quite crucial to tornado warning operations at the WFO level (in the reorganized NWS) that we have some means to distinguish tornadic from non-tornadic circulations (as seen on a WSR-88D). Otherwise, excessive false alarms could damage NWS credibility. Tornadoes produced from non-mesocyclonic storms, about which we hope to learn in VORTEX, are another challenge with direct application to operations.
In the warning process, it is not only important to know if a tornado is about to form, but also to be able to predict when the tornado will dissipate. VORTEX is designed to acquire new information that may allow users of WSR-88D data to interpret radar signatures to diagnose tornado dissipation, and to predict the formation of additional tornadoes in cyclic storms.
In the process, an important issue becomes the interaction between the potentially tornadic storm and its environment. Modelling work (numerical and mathematical) and some limited observational studies have suggested some ways to distinguish tornado-prone environments from those that are not, but these concepts have yet to be given an adequate test. Given that the detection of a potentially tornadic storm is more likely when the forecasters have anticipated such a possibility than when they have not, the VORTEX operating plan also includes some experimental forecasting techniques that may become prototypes for how operational tornado forecasting will be done in the future. Preventing false alarms is just as important as not missing important events. Many of the hypotheses being investigated in VORTEX are designed to resolve these important issues and explore new methods for dealing with the tornado problem.
Especially exciting will be the incorporation of some experimental numerical modelling on the mesoscale and the storm scale, with the participation of CAPS (Center for the Analysis and Prediction of Storms, affiliated with the University of Oklahoma). Operational implementation of such numerical models is in its infancy, but it appears quite likely that mesoscale and storm scale models will eventually have some role in operations. By participating in VORTEX, a number of NWS forecasters from the NOC and the SPC will have a chance to experiment with using such forecasting input. This gives those individuals an opportunity to have input on how such models will be implemented in the future, based on their experiences. A continuing problem with introduction of new technology is that forecasters often have so little experience with the new systems that they have no chance to influence the acquisition and evolution of the new technological tools until very late in the game. By being involved with VORTEX, the participating forecasters (and their associated agencies) have a real chance to affect the implementation of new forecasting techniques and technology.
Similar benefits accrue for the participating forecasters (and, their associated agencies within the NWS) as a result of interacting with the principal scientific investigators. This is especially important for the OUN NOC by virtue of their combined research-operations mission. By their involvement, contact by the NWS with the leading scientists in the area gives the NWS an opportunity to (a) learn about what the research community is doing in this topic area, and (b) offer their insights about what problems the NWS is encountering. This experiment is an ideal venue for encouraging research-operations interaction that can only benefit all of the agencies involved.
Finally, the new knowledge we hope to gain through VORTEX tornado dynamics studies should enable structural engineers to establish improved design standards to mitigate tornado damage.
Moreover, the statements of objectives in such field programs have tended toward vague generalities (sometimes referred to as " motherhood" ) such as " to document" , or " to observe" , or " to understand" some phenomenon. Objectives of this sort cannot help but be met during the project, of course, but they offer little or no basis for judging the outcome of the effort. Projects done this way are little more than " fishing expeditions" with no real focus. In VORTEX, we focus tightly on what we believe to be key scientific questions that can be refuted with observations of the sort we expect to obtain during the field effort (i.e., testable hypotheses). We cast our objectives in the form of refutable hypotheses because validating them in any other form would require an infinite number of cases. We make specific statements about what sorts of data we need to obtain to evaluate our hypotheses, and have even stated what outcomes would suffice to refute the hypotheses.
By virtue of this tight focus on testable hypotheses, we can achieve our objectives with relatively limited resources. Most of the major field programs of recent vintage, both past and planned, have required substantial, multi-million dollar investments, mostly because of the diversity of objectives and the desire to make observations on scales covering a range of several orders of magnitude. It is the attempt to include multiple scales that makes these programs so expensive. Rather than having a host of diverse objectives covering many scales of motion, our principal investigators all agree that we are seeking observations within and near tornadic storms. Hence, we will not have the conflict between some investigators trying to get in close proximity to a single convective storm at the same time that other investigators want to spread our observation platforms along a mesoscale structure hundreds of kilometers in extent.
Finally, we are intending to rely heavily on new operational observation tools, with only limited dependence on special observation platforms. In fact, we believe it is essential to accomplish our research objectives if the investment in these new observing systems is to bear operational fruit (little or no research investment in data from these systems has been made). Although we are seeking answers to basic scientific questions, there are immediate operational implications from the results of this experiment. Our relatively modest investments are in mobile observing systems, designed to give us as many cases to work with as possible. Field programs in the past tied to fixed observing networks have not given scientists the number of cases needed to validate (or, more properly, to invalidate) key scientific hypotheses; thus, the tendency for " motherhood" objectives. A handful of particularly well-sampled cases have tended to dominate scientific thinking about studied phenomena, which invariably yields a biased view of the events. Our program, by covering two years, should yield a representative sample of events (say, on the order of 30 or so), including null cases (where supercell thunderstorms and/or tornadoes did not develop) which are essential for comparison purposes. Relying heavily on operational data sets means that the majority of the observational systems will be running 24 h per day, 7 days per week, so we can obtain at least some new data (recall that the operational systems like the WSR-88D radars, the Oklahoma Mesonetwork, the ARM-CART platforms, and the Profiler Demonstration Network still will be relatively new observing systems, even in 1995) for " surprise" events, to help in the predictive aspects of the tornado problem. Moreover, studies based in operational observations will translate easily into operational advances and improved forecasts and warnings.
In VORTEX, the primary goal of the mobile sensing facility is to support the gathering of data to further understanding of tornadoes and tornadogenesis. However, the type of storm that will be studied is also the subject of several testable hypotheses put forth by storm electrification researchers at NSSL and university collaborators under the direction of Dr. David Rust. Since the data required to test these hypotheses can be gathered in a manner which does not interfere with but, instead, enhances the tornado experiment, the storm electrification objectives will be pursued as an adjunct experiment to the tornado program.
Other adjunct experiments include a set of forecasting experiments in which operational tornado and storm forecasts will be made in terms of areal probability distributions ( " Forecasting in VORTEX" ), and an experiment designed to enhance the operational capabilities of the WSR-88D radars ( " Observing Systems and Supporting Data Sets" ). Finally, a major collaborative experiment in numerical analysis and forecasting is being conducted by the Center for Analysis and Prediction of Storms (CAPS) at the University of Oklahoma ( " Analysis and Modeling" ).
The experiment will be held in the southern and central Plains states ( see map ) from about 32 to 38 degrees north latitude and 96 to 102 degrees west longitude. This region generally is ideal for observing tornadoes and tornadic storms because of their relative frequency, the relative flatness of the terrain, a suitable road network, and the generally good visibility. The entire region is under the coverage of WSR-88D Doppler radars with archival capabilities, and a significant portion of the region is covered by the relatively dense Oklahoma Mesonet.
It is sometimes argued that the tornadic storms in this region are too exhaustively studied compared to those in other regions. However, the hypotheses we are testing in this experiment have never been evaluated in any region, and we would argue that the principals of physics governing storm behavior are universal. Further, VORTEX is designed to study processes in tornadic storms, while previous studies have concentrated largely on " snapshot" documentation of morphology. Once we gain an understanding of the basic processes of tornadogenesis and of tornado dynamics, then the new knowledge can be tested for universality by observing storms in other regions, if regions can be found with adequate visibility and road networks.
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