Supercell Motion, Supercell Longevity, and Hodograph Resources
Supercell motion has remained an interesting topic since the 1940s when the documentation of these storms was in its infancy. The feature that sets supercells apart from ordinary thunderstorms is the presence of deep and persistent rotation (counterclockwise for right-moving storms and clockwise for left-moving storms, irrespective of hemisphere). This rotation induces a propagation component which is at right angles to the vertical wind shear (and not the mean wind). This sometimes can lead to a supercell motion that is at significant angles to the mean wind, and in a few instances, supercells have been observed to move "upstream" against the mean flow. As a result of these observations, and along with inspiration from the COMET module, "Anticipating Convective Storm Structure and Evolution," we began research in 1996 to further study the behavior of supercell motion, with a goal of being able to better predict supercell motion prior to storm formation. Our results support many of the previous theoretical and modeling studies, which indicate that supercell motion is primarily determined by advection plus rotationally induced propagation across the vertical wind shear. Studies by Ramsay and Doswell (2005) and Thomson et al. (2007) have supported our work. We also note that thermodynamics may play a noteworthy role in modulating supercell motion on occasion, and recent modeling work sheds some light on this topic (Kirkpatrick et al. 2007). After completing the above storm motion project, we looked at the vertical wind shear in environments of both right- and left-moving supercells (Bunkers 2002). We found that the bulk and total wind shear are similar for the two classes, but the absolute value of storm-relative helicity is larger for right-moving supercells, relative to the left-movers, across the United States.
Contact: If you have questions or comments about supercell motion, supercell longevity, or any of the other references listed on this page, please e-mail Matthew Bunkers, the Science and Operations Officer at the National Weather Service (NWS) in Rapid City, SD.
Bunkers, M. J., and M. A. Baxter, 2011: Radar tornadic debris signatures on 27 April 2011. Electronic J. Operational Meteor., 12 (7), 1–6.
* This is the inaugural issue of the "Images of Note" category for the National Weather Association (NWA) Electronic Journal of Operational Meteorology (EJOM).
Hodographs & 2005 Virtual Institute for Satellite Integration Training (VISIT) Teletraining
a) Hodograph (with SRH contours)
b) Hodograph (with storm-relative winds)
c) Hodograph (with 250-m spacing)
d) Supercell Motion Teletraining (includes audio playback version)
e) Predicting Supercell Motion in Operations (standalone PPT)
- Bunkers, M. J., 2002: Vertical wind shear associated with left-moving supercells. Wea. Forecasting, 17, 845–855.
- Bunkers, M. J., 2009: Comments on "Observational Analysis of the Predictability of Mesoscale Convective Systems." Wea. Forecasting, 24, 351–355.
- Bunkers, M. J., and J. W. Stoppkotte, 2007: Documentation of a rare tornadic left-moving supercell. Electronic J. Severe Storms Meteor., 2 (2), 1–22.
- Bunkers, M. J., D. R. Clabo, and J. W. Zeitler, 2009: Comments on "Structure and Formation Mechanism on the 24 May 2000 Supercell-Like Storm Developing in a Moist Environment over the Kanto Plain, Japan." Mon. Wea. Rev., 137, 2703–2712.
- * Corrigendum (8/26/2011): Although not our intention, there are a few places in the paper (e.g., p. 2704) where vertical vorticity and azimuthal shear were inadvertantly commingled. This is inappropriate because for solid body rotation the vertical vorticity equals twice the azimuthal shear; they are not equal to each other as implied on p. 2704. Thus, if vertical vorticity = 1 *10-2 s-1, then the azimuthal shear = 0.5 *10-2 s-1. Accordingly, the lower bounds of vertical vorticity in Table 1 should be 0.6–1.0 *10 -2 s-1. Nevertheless, the main conclusion that the Kanto Plain storm was a supercell remains valid.
- Bunkers, M. J., M. R. Hjelmfelt, and P. L. Smith, 2006a: An observational examination of long-lived supercells. Part I: Characteristics, evolution, and demise. Wea. Forecasting, 21, 673–688.
- Bunkers, M. J., J. S. Johnson, L. J. Czepyha, J. M. Grzywacz, B. A. Klimowski, and M. R. Hjelmfelt, 2006b: An observational examination of long-lived supercells. Part II: Environmental conditions and forecasting. Wea. Forecasting, 21, 689–714.
- Bunkers, M. J., B. A. Klimowski, J. W. Zeitler, R. L. Thompson, and M. L. Weisman, 2000: Predicting supercell motion using a new hodograph technique. Wea. Forecasting, 15, 61–79.
- Bunkers, M. J., D. R. Clabo, and J. W. Zeitler, 2009: Comments on "Structure and Formation Mechanism on the 24 May 2000 Supercell-Like Storm Developing in a Moist Environment over the Kanto Plain, Japan." Mon. Wea. Rev., submitted.
- Klimowski, B. A., and M. J. Bunkers, 2002: Comments on “Satellite observations of a severe supercell thunderstorm on 24 July 2000 made during the GOES-11 science test.” Wea. Forecasting, 17, 1111–1117.
- Klimowski, B. A., M. R. Hjelmfelt, M. J. Bunkers, D. Sedlacek, and L. R. Johnson, 1998: Hailstorm damage observed from the GOES-8 satellite: The 5-6 July 1996 Butte–Meade storm. Mon. Wea. Rev., 126, 831–834.
- Klimowski, B. A., M. J. Bunkers, M. R. Hjelmfelt, and J. N. Covert, 2003: Severe convective windstorms over the northern high plains of the United States. Wea. Forecasting, 18, 502–519.
- Klimowski, B. A., M. R., Hjelmfelt, and M. J. Bunkers, 2004: Radar observations of the early evolution of bow echoes. Wea. Forecasting, 19, 727–734.
- Lindsey, D. T., and M. J. Bunkers, 2005: Observations of a severe, left-moving supercell on 4 May 2003. Wea. Forecasting, 20, 15–22.
- Zeitler, J. W., and M. J. Bunkers, 2005: Operational forecasting of supercell motion: Review and case studies using multiple datasets. Natl. Wea. Dig., 29 (1), 81–97.
- Bunkers, M. J., 1996a: Examination of the preconvective environment associated with a severe nontornadic supercell: Variations in CAPE and SREH. Preprints, 18th Conf. on Severe Local Storms, San Francisco, CA, Amer. Meteor. Soc., 703–707.
- Bunkers, M. J., 1996b: On the use of the WSR-88D during situations of rapidly developing severe thunderstorms. NOAA/NWS WFO
Rapid City, SD , Internal Report, 6 p.
- Bunkers, M. J., 2002: A new convective sounding analysis program for AWIPS. Preprints, 18th International Conference on Interactive Information and Processing Systems (IIPS), Orlando, FL, Amer. Meteor. Soc., 209–210.
- Bunkers, M. J., 2010: How midlevel horizontal humidity gradients affect simulated storm morphology. Preprints, 25th Conf. on Severe Local Storms, Denver, CO, Amer. Meteor. Soc., P7.1.
- Bunkers, M. J., and J. W. Zeitler, 2000: On the nature of highly deviant supercell motion. Preprints, 20th Conf. on Severe Local Storms, Orlando, FL, Amer. Meteor. Soc., 236–239.
- Bunkers, M. J., B. A. Klimowski, J. W. Zeitler, R. L. Thompson, and M. L. Weisman, 1998: Predicting supercell motion using hodograph techniques. Preprints, 19th Conf. on Severe Local Storms, Minneapolis, MN, Amer. Meteor. Soc., 611–614.
- Bunkers, M. J., B. A. Klimowski, and J. W. Zeitler, 2002: The importance of parcel choice and the measure of vertical wind shear in evaluating the convective environment. Preprints, 21st Conf. on Severe Local Storms, San Antonio, TX, Amer. Meteor. Soc., 379–382.
- Bunkers, M. J., J. S. Johnson, J. M. Grzywacz, L. J. Czepyha, and B. A. Klimowski, 2002: A preliminary investigation of supercell longevity. Preprints, 21st Conf. on Severe Local Storms, San Antonio, TX, Amer. Meteor. Soc., 655–658.
- Hintz, D. L., and M. J. Bunkers, 1995: Examination of an apparent landspout in the eastern Black Hills of western South Dakota. NOAA/NWS CR Tech. Attach. 95-08, 11 pp. [Available from NWS Central Region, 601 E. 12th St., Rm 1836, Kansas City, MO 64106-2897.]
- Lindsey, D. T., and M. J. Bunkers, 2004: On the motion and interaction between left-moving and right-moving supercells on 4 May 2003. 22nd Conf. on Severe Local Storms, Hyannis, MA, Amer. Meteor. Soc., CD-ROM, 12.2.
- Yu, X., M. A. Magsig, and M. J. Bunkers, 2002: Enhancements to a new convective sounding analysis program for AWIPS. Preprints, 21st Conf. on Severe Local Storms, San Antonio, TX, Amer. Meteor. Soc., J77–J80.
- Zeitler, J. W., and M. J. Bunkers, 2002: Anticipating and monitoring supercell motion for severe weather operations. Preprints, 21st Conf. on Severe Local Storms, San Antonio, TX, Amer. Meteor. Soc., J61–J64.
- 2010 -- Vortex Arches in Supercells: WSR-88D Observations (14th Annual Northern Plains Convective Workshop, Sioux Falls, SD)...available upon request
- 2008 -- Some Applications of Indices to Forecasting (12th Annual Great Divide Workshop, Billings, MT)
- 2008 -- Sounding Analysis and Research Tools: What is used at Rapid City? (12th Annual Northern Plains Weather Workshop, Bismarck, ND)...Download toolkit here.
- 2007 -- Presentation on Updrafts, Spectrum Width, and Hail (32nd NWA Annual Meeting, Reno, NV)
- 2006 -- An Observational Assessment of Off-Hodograph Deviations for use in Operational Supercell Forecasting Methods (23rd Conf. SLS, St. Louis, MO)
- 2006 -- Examples of Supercell Motion and Supercell Longevity From a Forecasting Perspective (10th Severe Storms and Doppler Radar Conference, Des Moines, IA)
- 2005 -- A Study of Supercell Longevity across the U. S. High Plains (9th High Plains Conference, North Platte, NE)
- 2004 -- Merging Storms & Tornadogenesis (8th Northern Plains Weather Workshop, Sioux Falls, SD)
- 2002 -- A Preliminary Investigation of Supercell Longevity (6th High Plains Conference, Dodge City, KS)
- 2001 -- A Preliminary Convective Climatology of Central United States Radiosonde Data (5th High Plains Conference, North Platte, NE)
- 1999 -- Predicting Supercell Motion Using Hodograph Techniques [Revised 2002; developed for COMET webcast]
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