The Evolution of Convective Storms Initiated by an Isolated Mountain Ridge

Brett Soderholm Department of Atmospheric and Oceanic Sciences, McGill University, Montréal, Québec, Canada

Search for other papers by Brett Soderholm in
Current site
Google Scholar
PubMed
Close
,
Bryn Ronalds Department of Atmospheric and Oceanic Sciences, McGill University, Montréal, Québec, Canada

Search for other papers by Bryn Ronalds in
Current site
Google Scholar
PubMed
Close
, and
Daniel J. Kirshbaum Department of Atmospheric and Oceanic Sciences, McGill University, Montréal, Québec, Canada

Search for other papers by Daniel J. Kirshbaum in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

The evolution of convective storms over the Black Hills, an isolated mountain ridge in South Dakota and Wyoming and a regional convection hotspot, is investigated using a 10-yr observational climatology and quasi-idealized numerical simulations. Radar-observed diurnally forced mountain-convection events are classified according to their maximum cell-track length and duration, which are quantified using an automated cell-tracking algorithm. Environmental conditions during these events are obtained from operational radiosonde and model-analysis data. These data suggest that mountain-forced convective cells generally struggle to survive in the convectively inhibited flow downwind of the Black Hills. Those cells that do survive downwind prefer environments with strong bulk vertical shear over the 0–6-km layer, which favors organized multicellular or supercellular convection. Under slightly weaker shear, the cells tend to dissipate rapidly as they propagate downwind. Relatively weak winds aloft, when coupled with low-level winds aligned with the long terrain axis, support longer-lived, quasi-stationary cells with flash-flooding potential. The weak winds favor slow cell propagation while the along-ridge flow limits the negative feedbacks of storm outflow on the elevated convergence over the ridge, allowing convection to repeatedly initiate in the same location. The storm evolution is relatively insensitive to the background thermodynamic profile, provided that sufficient moist instability exists to support deep convection. Convection-permitting numerical simulations reinforce that changes in the background wind profile alone can explain the observed variations in cell evolution. They also suggest that the longevity of convective cells downwind of the ridge is sensitive to terrain-induced modifications to the vertical wind shear.

Corresponding author address: Daniel J. Kirshbaum, Department of Atmospheric and Oceanic Sciences, McGill University, Room 945, Burnside Hall, 805 Sherbrooke St. West, Montréal, QC H3A 0B9, Canada. E-mail: daniel.kirshbaum@mcgill.ca

Abstract

The evolution of convective storms over the Black Hills, an isolated mountain ridge in South Dakota and Wyoming and a regional convection hotspot, is investigated using a 10-yr observational climatology and quasi-idealized numerical simulations. Radar-observed diurnally forced mountain-convection events are classified according to their maximum cell-track length and duration, which are quantified using an automated cell-tracking algorithm. Environmental conditions during these events are obtained from operational radiosonde and model-analysis data. These data suggest that mountain-forced convective cells generally struggle to survive in the convectively inhibited flow downwind of the Black Hills. Those cells that do survive downwind prefer environments with strong bulk vertical shear over the 0–6-km layer, which favors organized multicellular or supercellular convection. Under slightly weaker shear, the cells tend to dissipate rapidly as they propagate downwind. Relatively weak winds aloft, when coupled with low-level winds aligned with the long terrain axis, support longer-lived, quasi-stationary cells with flash-flooding potential. The weak winds favor slow cell propagation while the along-ridge flow limits the negative feedbacks of storm outflow on the elevated convergence over the ridge, allowing convection to repeatedly initiate in the same location. The storm evolution is relatively insensitive to the background thermodynamic profile, provided that sufficient moist instability exists to support deep convection. Convection-permitting numerical simulations reinforce that changes in the background wind profile alone can explain the observed variations in cell evolution. They also suggest that the longevity of convective cells downwind of the ridge is sensitive to terrain-induced modifications to the vertical wind shear.

Corresponding author address: Daniel J. Kirshbaum, Department of Atmospheric and Oceanic Sciences, McGill University, Room 945, Burnside Hall, 805 Sherbrooke St. West, Montréal, QC H3A 0B9, Canada. E-mail: daniel.kirshbaum@mcgill.ca
Save
  • Akaeda, K., J. Reisner, and D. Parsons, 1995: The role of mesoscale and topographically induced circulations in initiating a flash flood observed during the TAMEX project. Mon. Wea. Rev., 123, 17201739.

    • Search Google Scholar
    • Export Citation
  • Banta, R. M., 1984: Daytime boundary-layer evolution over mountainous terrain. Part I: Observations of the dry circulations. Mon. Wea. Rev., 112, 340356.

    • Search Google Scholar
    • Export Citation
  • Banta, R. M., 1990: Atmospheric Processes over Complex Terrain. Meteor. Monogr., No. 45, Amer. Meteor. Soc., 323 pp.

  • Banta, R. M., and C. B. Schaaf, 1987: Thunderstorm genesis zones in the Colorado Rocky Mountains as determined by traceback of geosynchronous satellite images. Mon. Wea. Rev., 115, 463476.

    • Search Google Scholar
    • Export Citation
  • Bougeault, P., and Coauthors, 2001: The MAP special observing period. Bull. Amer. Meteor. Soc., 82, 433462.

  • Bryan, G. H., and J. M. Fritsch, 2002: A benchmark simulation for moist nonhydrostatic models. Mon. Wea. Rev., 130, 29172928.

  • 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, 6179.

    • Search Google Scholar
    • Export Citation
  • 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, 673688.

    • Search Google Scholar
    • Export Citation
  • Bunkers, M. J., J. S. Johnson, L. J. Czephya, 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, 689714.

    • Search Google Scholar
    • Export Citation
  • Chu, C.-M., and Y.-L. Lin, 2000: Effects of orography on the generation and propagation of mesoscale convective systems in a two-dimensional conditionally unstable flow. J. Atmos. Sci., 57, 38173837.

    • Search Google Scholar
    • Export Citation
  • Damiani, R., and Coauthors, 2008: The cumulus, photogrammetric, in situ, and Doppler observations experiment of 2006. Bull. Amer. Meteor. Soc., 89, 5773.

    • Search Google Scholar
    • Export Citation
  • Davies-Jones, R., 1984: Streamwise vorticity: The origin of updraft rotation in supercell storms. J. Atmos. Sci., 41, 29913006.

  • Demko, J. C., and B. Geerts, 2010: A numerical study of the evolving convective boundary layer and orographic circulation around the Santa Catalina Mountains in Arizona. Part II: Interaction with deep convection. Mon. Wea. Rev., 138, 36033622.

    • Search Google Scholar
    • Export Citation
  • Dixon, M., and G. Weiner, 1993: TITAN: Thunderstorm Identification, Tracking, Analyzing and Nowcasting—A radar-based methodology. J. Atmos. Oceanic Technol., 10, 785797.

    • Search Google Scholar
    • Export Citation
  • Doswell, C. A. I., 2001: Severe convective storms—An overview. Severe Convective Storms, Meteor. Monogr., No. 50, Amer. Meteor. Soc., 1–26.

  • Ducrocq, V., O. Nuissier, D. Ricard, C. Lebeaupin, and T. Thouvenin, 2008: A numerical study of three catastrophic precipitating events over southern France. II: Mesoscale triggering and stationarity factors. Quart. J. Roy. Meteor. Soc., 134, 131145.

    • Search Google Scholar
    • Export Citation
  • Geerts, B., Q. Miao, and J. C. Demko, 2008: Pressure perturbations and upslope flow over a heated, isolated mountain. Mon. Wea. Rev., 136, 42724288.

    • Search Google Scholar
    • Export Citation
  • Houze, R. A., 1993: Cloud Dynamics.Academic Press, 573 pp.

  • Houze, R. A., W. Schmid, R. G. Fovell, and H.-H. Schiesser, 1993: Hailstorms in Switzerland: Left movers, right movers, and false hooks. Mon. Wea. Rev., 121, 33453370.

    • Search Google Scholar
    • Export Citation
  • Johnson, J. T., P. L. MacKeen, A. Witt, E. D. Mitchell, G. J. Stumpf, M. D. Eilts, and K. W. Thomas, 1998: The storm cell identification and tracking algorithm: An enhanced WSR-88D algorithm. Wea. Forecasting, 13, 263276.

    • Search Google Scholar
    • Export Citation
  • Kirshbaum, D. J., 2011: Cloud-resolving simulations of deep convection over a heated mountain. J. Atmos. Sci., 68, 361378.

  • Kirshbaum, D. J., 2013: On thermally forced circulations over heated terrain. J. Atmos. Sci., 70, 16901709.

  • Kuo, J.-T., and H. D. Orville, 1973: A radar climatology of summertime convective clouds in the Black Hills. J. Appl. Meteor., 12, 359368.

    • Search Google Scholar
    • Export Citation
  • Landel, G., J. A. Smith, M. L. Baeck, M. Steiner, and F. L. Ogden, 1999: Radar studies of heavy convective rainfall in mountainous terrain. J. Geophys. Res., 104 (D24), 31 45131 465.

    • Search Google Scholar
    • Export Citation
  • Maddox, R. A., L. R. Hoxit, C. F. Chappell, and F. R. Caraceña, 1978: Comparison of meteorological aspects of the Big Thompson and Rapid City flash floods. Mon. Wea. Rev., 106, 375389.

    • Search Google Scholar
    • Export Citation
  • Markowski, P., and Y. Richardson, 2010: Mesoscale Meteorology in Midlatitudes.Wiley, 430 pp.

  • Markowski, P., and N. Dotzek, 2011: A numerical study of the effects of orography on supercells. Atmos. Res., 100, 457478.

  • McCaul, E. W., and C. Cohen, 2002: The impact on simulated storm structure and intensity of variations in the mixed layer and moist layer depths. Mon. Wea. Rev., 130, 17221748.

    • Search Google Scholar
    • Export Citation
  • Miglietta, M. M., and R. Rotunno, 2009: Numerical simulations of conditionally unstable flows over a mountain ridge. J. Atmos. Sci., 66, 18651885.

    • Search Google Scholar
    • Export Citation
  • Miglietta, M. M., and R. Rotunno, 2012: Application of theory to simulations of observed cases of orographically forced convective rainfall. Mon. Wea. Rev., 140, 30393053.

    • Search Google Scholar
    • Export Citation
  • Nair, U. S., M. R. Hjelmfelt, and R. A. Pielke, 1997: Numerical simulations of the 9–10 June 1972 Black Hills storm using CSU RAMS. Mon. Wea. Rev., 125, 17531766.

    • Search Google Scholar
    • Export Citation
  • Petersen, W. A., and Coauthors, 1999: Mesoscale and radar observations of the Fort Collins flash flood of 28 July 1997. Bull. Amer. Meteor. Soc., 80, 191216.

    • Search Google Scholar
    • Export Citation
  • Rasmussen, E. N., and D. O. Blanchard, 1998: A baseline climatology of sounding-derived supercell and tornado forecast parameters. Wea. Forecasting, 13, 11481164.

    • Search Google Scholar
    • Export Citation
  • Smith, R. B., and Coauthors, 2012: Orographic precipitation in the tropics: The Dominica Experiment. Bull. Amer. Meteor. Soc., 93, 15671579.

    • Search Google Scholar
    • Export Citation
  • Soderholm, B., 2013: The evolution of convective storms initiated by an isolated mountain range. M.S. thesis, Department of Atmospheric and Oceanic Sciences, McGill University, Montréal, Quebec, Canada, 91 pp.

  • Weisman, M. L., and J. B. Klemp, 1982: The dependence of numerically simulated convective storms on vertical wind shear and buoyancy. Mon. Wea. Rev., 110, 504520.

    • Search Google Scholar
    • Export Citation
  • Weisman, M. L., and J. B. Klemp, 1984: The structure and classification of numerically simulated convective storms in directionally varying wind shears. Mon. Wea. Rev., 112, 24792498.

    • Search Google Scholar
    • Export Citation
  • Wulfmeyer, V., and Coauthors, 2008: The convective and orographically induced precipitation study: A research and development project of the World Weather Research Program for improving quantitative precipitation forecasting in low-mountain regions. Bull. Amer. Meteor. Soc., 89, 14771486.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 796 238 13
PDF Downloads 632 233 16