Editorial Type:
Article
Article Type:
Research Article

A Sensitivity Study of Hodograph-Based Methods for Estimating Supercell Motion

Hamish A. Ramsay Cooperative Institute for Mesoscale Meteorological Studies, and School of Meteorology, University of Oklahoma, Norman, Oklahoma

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Charles A. Doswell III Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma, Norman, Oklahoma

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Print Publication:
01 Dec 2005
DOI:
https://doi.org/10.1175/WAF889.1
Page(s):
954–970
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Abstract

Four supercell motion forecast algorithms are investigated with respect to their hodograph-analysis parameters. Another method derived from the data presented herein, the so-called offset method, is used to develop a baseline standard for the aforementioned schemes, using the observed storm motions and the mean wind. It is not a forecast scheme, as it is based on knowing the observed storm motions. This work explores the sensitivity of these algorithms to their arbitrary parameters by systematically varying those parameters, using a dataset of 394 right-moving supercells, and associated proximity soundings. The parameters used in these algorithms to define the layer depths for advection and/or propagation of supercells have not been shown to be optimum for this purpose. These arbitrary parameters compose the top and bottom levels of the mean wind layer, and a deviation vector from the mean wind defined through that layer. Two of the most recently developed algorithms have also implemented the vertical wind shear vector over an arbitrary layer depth. It has been found that, among other results, the scheme using both mean wind and vertical wind shear is more sensitive to the depth of the mean wind layer than it is to the depth of the vertical wind shear layer. It has also been shown that, when using the simplest schemes, the most accurate forecasts, on average, are obtained by using deep mean wind layers (i.e., greater than 0–10 km). Indeed, all the forecast schemes show a strong tendency for the u component of the predicted storm motion to be regulated by the depth of the mean wind layer. The υ component of the prediction storm motion, on the other hand, appears to be controlled by the deviation vector from the layer-mean wind. Although the schemes using vertical shear are shown to perform somewhat better on average than schemes based on the mean wind alone, there are times in which they also result in large forecast errors. The results demonstrate the inherent difficulty in using an observed hodograph to predict supercell motion.

Corresponding author address: Hamish A. Ramsay, CIMMS, University of Oklahoma, Sarkeys Energy Center, Rm. 1011, 100 E. Boyd St., Norman, OK 73019-1011. Email: hramsay@rossby.metr.ou.edu

Abstract

Four supercell motion forecast algorithms are investigated with respect to their hodograph-analysis parameters. Another method derived from the data presented herein, the so-called offset method, is used to develop a baseline standard for the aforementioned schemes, using the observed storm motions and the mean wind. It is not a forecast scheme, as it is based on knowing the observed storm motions. This work explores the sensitivity of these algorithms to their arbitrary parameters by systematically varying those parameters, using a dataset of 394 right-moving supercells, and associated proximity soundings. The parameters used in these algorithms to define the layer depths for advection and/or propagation of supercells have not been shown to be optimum for this purpose. These arbitrary parameters compose the top and bottom levels of the mean wind layer, and a deviation vector from the mean wind defined through that layer. Two of the most recently developed algorithms have also implemented the vertical wind shear vector over an arbitrary layer depth. It has been found that, among other results, the scheme using both mean wind and vertical wind shear is more sensitive to the depth of the mean wind layer than it is to the depth of the vertical wind shear layer. It has also been shown that, when using the simplest schemes, the most accurate forecasts, on average, are obtained by using deep mean wind layers (i.e., greater than 0–10 km). Indeed, all the forecast schemes show a strong tendency for the u component of the predicted storm motion to be regulated by the depth of the mean wind layer. The υ component of the prediction storm motion, on the other hand, appears to be controlled by the deviation vector from the layer-mean wind. Although the schemes using vertical shear are shown to perform somewhat better on average than schemes based on the mean wind alone, there are times in which they also result in large forecast errors. The results demonstrate the inherent difficulty in using an observed hodograph to predict supercell motion.

Corresponding author address: Hamish A. Ramsay, CIMMS, University of Oklahoma, Sarkeys Energy Center, Rm. 1011, 100 E. Boyd St., Norman, OK 73019-1011. Email: hramsay@rossby.metr.ou.edu

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  • Achtemeier, G. L., 1969: Some observations of splitting thunderstorms over Iowa on August 25–26, 1965. Preprints, Sixth Conf. on Severe Local Storms, Chicago, IL, Amer. Meteor. Soc., 89–94.

  • Beebe, R. G., 1958: An instability line development as observed by the tornado research airplane. J. Meteor., 15 , 278–282.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Bowman, A. W., and Azzalini A. , 1997: Applied Smoothing Techniques for Data Analysis: The Kernel Approach with S-Plus Illustrations. Oxford University Press, 193 pp.

    • Search Google Scholar
    • Export Citation

  • Brooks, H. E., and Doswell C. A. III, 1996: A comparison of measures-oriented and distributions-oriented approaches to forecast verification. Wea. Forecasting, 11 , 288–303.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Brooks, H. E., Doswell C. A. III, and Cooper J. , 1994: On the environments of tornadic and nontornadic mesocyclones. Wea. Forecasting, 9 , 606–618.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Brown, R. A., 1993: A compositing approach for preserving significant features in atmospheric profiles. Mon. Wea. Rev., 121 , 874–880.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Browning, K. A., 1964: Airflow and precipitation trajectories within severe local storms which travel to the right of the winds. J. Atmos. Sci., 21 , 634–639.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Browning, K. A., 1965a: The evolution of tornadic storms. J. Atmos. Sci., 22 , 664–668.

  • Browning, K. A., 1965b: Some inferences about the updraft within a severe local storm. J. Atmos. Sci., 22 , 669–677.

  • Bunkers, M. J., Klimowski B. A. , Zeitler J. W. , Thompson R. L. , and Weisman M. L. , 2000: Predicting supercell motion using a new hodograph technique. Wea. Forecasting, 15 , 61–79.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Colquhoun, J. R., 1980: A method of estimating the velocity of a severe thunderstorm using the vertical wind profile in the storm’s environment. Preprints, Eighth Conf. on Weather Forecasting and Analysis, Denver, CO, Amer. Meteor. Soc., 316–323.

  • Darkow, G. L., 1969: An analysis of over sixty tornado proximity soundings. Preprints, Sixth Conf. on Severe Local Storms, Chicago, IL, Amer. Meteor. Soc., 218–221.

  • Davies, J. M., 1998: On supercell motion in weaker wind environments. Preprints, 19th Conf. on Severe Local Storms, Minneapolis, MN, Amer. Meteor. Soc., 685–688.

  • Davies, J. M., and Johns R. H. , 1993: Some wind and instability parameters associated with strong and violent tornadoes. Part I: Wind shear and helicity. The Tornado: Its Structure, Dynamics, Prediction, and Hazards, Geophys. Monogr., No. 79, Amer. Geophys. Union, 573–582.

    • Crossref
    • Export Citation

  • Davies-Jones, R. P., 1984: Streamwise vorticity: The origin of updraft rotation in supercell storms. J. Atmos. Sci., 41 , 2991–3006.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • desJardins, M. L., Brill K. F. , and Schotz S. S. , 1991: GEMPAK 5. Part I—GEMPAK 5 programmer’s guide. National Aeronautics and Space Administration, 176 pp. [Available from Scientific and Technical Information Division, Goddard Space Flight Center, Greenbelt, MD 20771.].

  • Doswell C. A. III, , and Burgess D. W. , 1993: Tornadoes and tornadic storms: A review of conceptual models. The Tornado: Its Structure, Dynamics, Prediction, and Hazards, Geophys. Monogr., No. 79, Amer. Geophys. Union, 161–182.

  • Droegemeier, K. K., Lazarus S. M. , and Davies-Jones R. , 1993: The influence of helicity on numerically simulated convective storms. Mon. Wea. Rev., 121 , 2005–2029.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Evans, J. S., and Doswell C. A. III, 2001: Examination of derecho environments using proximity soundings. Wea. Forecasting, 16 , 329–342.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Fankhauser, J. C., 1971: Thunderstorm environment interactions determined from aircraft and radar observations. Mon. Wea. Rev., 99 , 171–192.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Guyer, J. L., 2002: A case of supercell intensification along a preexisting boundary—Clay County Nebraska tornado of 22 September 2001. Preprints, 21st Conf. on Severe Local Storms, San Antonio, TX, Amer. Meteor. Soc., 579–581.

  • Hart, J. A., and Korotky W. , 1991: The SHARP workstation v1.30 users guide. NOAA/National Weather Service, 30 pp.

  • Maddox, R. A., 1976: An evaluation of tornado proximity wind and stability data. Mon. Wea. Rev., 104 , 133–142.

  • Maddox, R. A., Hoxit L. R. , and Chappell C. F. , 1980: A study of tornadic thunderstorm interactions with thermal boundaries. Mon. Wea. Rev., 108 , 322–336.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Markowski, P. M., and Richardson Y. P. , 2004: Multiple-Doppler radar observations of vertical wind profile heterogeneity in convective boundary layers. Preprints. 22d Conf. on Severe Local Storms, Hyannis, MA, Amer. Meteor. Soc., CD-ROM, P13.1.

    • Search Google Scholar
    • Export Citation

  • Markowski, P. M., Straka J. M. , Rasmussen E. N. , and Blanchard D. O. , 1998: Variability of storm-relative helicity during VORTEX. Mon. Wea. Rev., 126 , 2959–2971.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Markowski, P. M., Hannon C. , Frame J. , Lancaster E. , Pietrycha A. , Edwards R. , and Thompson R. L. , 2003: Characteristics of vertical wind profiles near supercells obtained from the Rapid Update Cycle. Wea. Forecasting, 18 , 1262–1272.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Marwitz, J. D., 1972: The structure and motion of severe hailstorms. Part I: Supercell storms. J. Appl. Meteor., 11 , 166–179.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Moller, A. R., Doswell C. A. III, and Przybylinski R. , 1990: High-precipitation supercells: A conceptual model and documentation. Preprints, 16th Conf. on Severe Local Storms, Kananaskis Park, AB, Canada, Amer. Meteor. Soc., 52–57.

  • Monteverdi, J. P., Blier W. , Stumpf G. , Pi W. , and Anderson K. , 2001: First WSR-88D documentation of an anticyclonic supercell with anticyclonic tornadoes: The Sunnyvale–Los Altos, California, tornadoes of 4 May 1998. Mon. Wea. Rev., 129 , 2805–2814.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Rasmussen, E. N., and Blanchard D. O. , 1998: A baseline climatology of sounding-derived supercell and tornado forecast parameters. Wea. Forecasting, 13 , 1148–1164.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Rotunno, R., and Klemp J. B. , 1982: The influence of the shear-induced pressure gradient on thunderstorm motion. Mon. Wea. Rev., 110 , 136–151.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Rotunno, R., and Klemp J. B. , 1985: On the rotation and propagation of simulated supercell thunderstorms. J. Atmos. Sci., 42 , 271–292.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Sills, D. M., Wilson J. , Joe P. I. , Burgess D. W. , Webb R. M. , and Fox N. I. , 2004: The 3 November tornadic event during Sydney 2000: Storm evolution and the role of low-level boundaries. Wea. Forecasting, 19 , 22–42.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Stumpf, J., Witt A. , Mitchell D. E. , Spencer P. L. , Johnson J. T. , Eilts M. D. , Thomas K. W. , and Burgess D. W. , 1998: The National Severe Storms Laboratory Mesocyclone Detection Algorithm for the WSR-88D. Wea. Forecasting, 13 , 304–326.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Thompson, R. L., 1998: Eta Model storm-relative winds associated with tornadic and nontornadic supercells. Wea. Forecasting, 13 , 125–137.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Wand, M. P., and Jones M. C. , 1995: Kernel Smoothing. Statistics and Applied Probability Monogr. , No. 60, Chapman and Hall, 212 pp.

  • Weaver, J. F., 1979: Storm motion as related to boundary-layer convergence. Mon. Wea. Rev., 107 , 612–619.

  • Weisman, M. L., and Klemp J. B. , 1984: The structure and classification of numerically simulated convective storms in directionally varying wind shears. Mon. Wea. Rev., 112 , 2479–2498.

    • Crossref
    • Search Google Scholar
    • Export Citation

  • Weisman, M. L., Gilmore M. S. , and Wicker L. J. , 1998: The impact of convective storms on their local environment: What is an appropriate ambient sounding? Preprints. 19th Conf. on Severe Local Storms, Minneapolis, MN, Amer. Meteor. Soc., 238–688.

    • Search Google Scholar
    • Export Citation

  • Wilks, D. S., 1995: Statistical Methods in the Atmospheric Sciences. Academic Press, 467 pp.

  • Zehr, R. M., and Purdom J. F. W. , 1982: Examples of a wide variety of thunderstorm propagation mechanisms. Preprints. 12th Conf. on Severe Local Storms, San Antonio, TX, Amer. Meteor. Soc., 499–502.

    • Search Google Scholar
    • Export Citation
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