• Adlerman, E. J., , K. K. Droegemeier, , and R. Davies-Jones, 1999: A numerical simulation of cyclinc mesocyclogenesis. J. Atmos. Sci., 56, 20452069, doi:10.1175/1520-0469(1999)056<2045:ANSOCM>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Atkins, N. T., , and M. St. Laurent, 2009a: Bow echo mesovortices. Part I: Processes that influence their damaging potential. Mon. Wea. Rev., 137, 14971513, doi:10.1175/2008MWR2649.1.

    • Search Google Scholar
    • Export Citation
  • Atkins, N. T., , and M. St. Laurent, 2009b: Bow echo mesovortices. Part II: Their genesis. Mon. Wea. Rev., 137, 15141532, doi:10.1175/2008MWR2650.1.

    • Search Google Scholar
    • Export Citation
  • Bryan, G. H., , and J. M. Fritsch, 2002: A benchmark simulation for moist nonhydrostatic numerical models. Mon. Wea. Rev., 130, 29172928, doi:10.1175/1520-0493(2002)130<2917:ABSFMN>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Calianese, E. J., , J. K. Jordan, , E. B. Curran, , A. R. Moller, , and G. Woodall, 2002: The Mayfest high-precipitation supercell of 5 May 1995: A case study. Preprints, 21st Conf. on Severe Local Storms, San Antonio, TX, Amer. Meteor. Soc., 105–108.

  • Dahl, J. M., , M. D. Parker, , and L. J. Wicker, 2012: Uncertainties in trajectory calculations with near-surface mesocyclones of simulated supercells. Mon. Wea. Rev., 140, 29592966, doi:10.1175/MWR-D-12-00131.1.

    • Search Google Scholar
    • Export Citation
  • Dial, G. L., , J. P. Racy, , and R. L. Thompson, 2010: Short-term convective mode evolution along synoptic boundaries. Wea. Forecasting, 25, 14301446, doi:10.1175/2010WAF2222315.1.

    • Search Google Scholar
    • Export Citation
  • Doswell, C. A., III, , and J. S. Evans, 2003: Proximity sounding analysis for derechos and supercells: An assessment of similarities and differences. Atmos. Res., 67–68, 117–133, doi:10.1016/S0169-8095(03)00047-4.

    • Search Google Scholar
    • Export Citation
  • Evans, J. S., , and C. A. Doswell, 2001: Examination of derecho environments using proximity soundings. Wea. Forecasting, 16, 329342, doi:10.1175/1520-0434(2001)016<0329:EODEUP>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Finley, C. A., , W. R. Cotton, , and R. A. Pielke, 2001: Numerical simulation of tornadogenesis in a high-precipitation supercell. Part I: Storm evolution and transition into a bow echo. J. Atmos. Sci., 58, 15971629, doi:10.1175/1520-0469(2001)058<1597:NSOTIA>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Fovell, R. G., , and Y. Ogura, 1988: Numerical simulation of a midlatitude squall line in two dimensions. J. Atmos. Sci., 45, 38463879, doi:10.1175/1520-0469(1988)045<3846:NSOAMS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • French, A. J., , and M. D. Parker, 2008: The initiation and evolution of multiple modes of convection within a meso-alpha-scale region. Wea. Forecasting, 23, 12211252, doi:10.1175/2008WAF2222136.1.

    • Search Google Scholar
    • Export Citation
  • French, A. J., , and M. D. Parker, 2010: The response of simulated nocturnal convective systems to a developing low-level jet. J. Atmos. Sci., 67, 33843408, doi:10.1175/2010JAS3329.1.

    • Search Google Scholar
    • Export Citation
  • French, A. J., , and M. D. Parker, 2012: Observations of mergers between squall lines and isolated supercell thunderstorms. Wea. Forecasting, 27, 255278, doi:10.1175/WAF-D-11-00058.1.

    • Search Google Scholar
    • Export Citation
  • Fujita, T. T., 1978: Manual of downburst identification for project NIMROD. SMRP Research Paper 117, University of Chicago, 104 pp. [NTIS N78-30771/1GI.]

  • Fujita, T. T., 1985: The downburst: Microburst and macroburst. SMRP Research Paper 210, University of Chicago, 122 pp. [NTIS PB-148880.]

  • Fujita, T. T., , and H. R. Byers, 1977: Spearhead echo and downbursts in the crash of an airliner. Mon. Wea. Rev., 105, 129146, doi:10.1175/1520-0493(1977)105<0129:SEADIT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Gallus, W. A., Jr., , N. A. Snook, , and E. V. Johnson, 2008: Spring and summer severe weather reports over the Midwest as a function of convective mode: A preliminary study. Wea. Forecasting, 23, 101113, doi:10.1175/2007WAF2006120.1.

    • Search Google Scholar
    • Export Citation
  • Goodman, S. J., , and K. R. Knupp, 1993: Tornadogenesis via squall line and supercell interaction: The November 15, 1989, Huntsville, Alabama, tornado. The Tornado: Its Structure, Dynamics, Prediction, and Hazards,Geophys. Monogr., Vol. 79, Amer. Geophys. Union, 183199, doi:10.1029/GM079p0183.

  • Grim, J. A., , R. A. Rauber, , G. M. McFarquhar, , B. F. Jewett, , and D. P. Jorgensen, 2009: Development and forcing of the rear inflow jet in a rapidly developing and decaying squall line during BAMEX. Mon. Wea. Rev., 137, 12061229, doi:10.1175/2008MWR2503.1.

    • Search Google Scholar
    • Export Citation
  • Houston, A. L., , and R. B. Wilhelmson, 2011: The dependence of storm longevity on the pattern of deep convection initiation in a low-shear environment. Mon. Wea. Rev., 139, 31253138, doi:10.1175/MWR-D-10-05036.1.

    • Search Google Scholar
    • Export Citation
  • Houston, A. L., , and R. B. Wilhelmson, 2012: The impact of airmass boundaries on the propagation of deep convection: A modeling-based study in a high-CAPE, low-shear environment. Mon. Wea. Rev., 140, 167183, doi:10.1175/MWR-D-10-05033.1.

    • Search Google Scholar
    • Export Citation
  • James, R. P., , J. M. Fritsch, , and P. M. Markowski, 2005: Environmental distinctions between cellular and slabular convective lines. Mon. Wea. Rev., 133, 26692691, doi:10.1175/MWR3002.1.

    • Search Google Scholar
    • Export Citation
  • James, R. P., , P. M. Markowski, , and J. M. Fritsch, 2006: Bow echo sensitivity to ambient moisture and cold pool strength. Mon. Wea. Rev., 134, 950964, doi:10.1175/MWR3109.1.

    • Search Google Scholar
    • Export Citation
  • Jewett, B. F., , and R. B. Wilhelmson, 2006: The role of forcing in cell morphology and evolution within midlatitude squall lines. Mon. Wea. Rev., 134, 37142734, doi:10.1175/MWR3164.1.

    • Search Google Scholar
    • Export Citation
  • Klimowski, B. A., , M. R. Hjelmfelt, , and M. J. Bunkers, 2004: Radar observations of the early evolution of bow echoes. Wea. Forecasting, 19, 727734, doi:10.1175/1520-0434(2004)019<0727:ROOTEE>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Kogan, Y. L., , and A. Shapiro, 1996: The simulation of a convective cloud in a 3D model with explicit microphysics. Part II: Dynamical and microphysical aspects of cloud merger. J. Atmos. Sci., 53, 25252545, doi:10.1175/1520-0469(1996)053<2525:TSOACC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Lafore, J.-P., , and M. W. Moncrieff, 1989: A numerical investigation of the organization and interaction of the convective and stratiform regions of tropical squall lines. J. Atmos. Sci., 46, 521544.

    • Search Google Scholar
    • Export Citation
  • Letkewicz, C. E., , A. J. French, , and M. D. Parker, 2013: Base-state substitution: An idealized modeling technique for approximating environmental variability. Mon. Wea. Rev., 141, 30623086, doi:10.1175/MWR-D-12-00200.1.

    • Search Google Scholar
    • Export Citation
  • Mahoney, K. M., , and G. M. Lackmann, 2011: The sensitivity of momentum transport and severe surface winds to environmental moisture in idealized simulations of a mesoscale convective system. Mon. Wea. Rev., 139, 13521369, doi:10.1175/2010MWR3468.1.

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

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

  • Moller, A. R., , C. A. Doswell III, , M. P. Foster, , and G. R. Woodall, 1994: The operational recognition of supercell thunderstorm environments and storm structures. Wea. Forecasting, 9, 327347, doi:10.1175/1520-0434(1994)009<0327:TOROST>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Przybylinski, R. H., 1995: The bow echo: Observations, numerical simulations, and severe weather detection methods. Wea. Forecasting, 10, 203218, doi:10.1175/1520-0434(1995)010<0203:TBEONS>2.0.CO;2.

    • 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, doi:10.1175/1520-0434(1998)013<1148:ABCOSD>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Richardson, Y. P., , K. K. Droegemeier, , and R. P. Davies-Jones, 2007: The influence of horizontal environmental variability on numerically simulated convective storms. Part I: Variations in vertical shear. Mon. Wea. Rev., 135, 34293455, doi:10.1175/MWR3463.1.

    • Search Google Scholar
    • Export Citation
  • Rotunno, R., , J. B. Klemp, , and M. L. Weisman, 1988: A theory for strong, long-lived squall lines. J. Atmos. Sci., 45, 463485, doi:10.1175/1520-0469(1988)045<0463:ATFSLL>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Sabones, M., , E. M. Agee, , and M. Akridge, 1996: The Pulaski county and West Lafayette, Indiana, tornadoes, 26–27 April 1994: A case of supercell (mesocyclone) and squall line bow-echo interaction. Preprints, 18th Conf. on Severe Local Storms, San Francisco, CA, Amer. Meteor. Soc., 746–750.

  • Sieveking, J. E., , and R. W. Przybylinski, 2004: The interaction of a HP supercell thunderstorm and bow echo to produce a prolonged severe wind event in east central Missouri. 22nd Conf. on Severe Local Storms, Hyannis, MA, Amer. Meteor. Soc., 7A.5. [Available online at https://ams.confex.com/ams/11aram22sls/webprogram/Paper81818.html.]

  • Skamarock, W. C., , M. L. Weisman, , and J. B. Klemp, 1994: Three-dimensional evolution of simulated long-lived squall lines. J. Atmos. Sci., 51, 25632584, doi:10.1175/1520-0469(1994)051<2563:TDEOSL>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Smith, B. T., , R. L. Thompson, , J. S. Grams, , C. Broyles, , and H. E. Brooks, 2012: Convective modes for significant severe thunderstorms in the contiguous United States. Part I: Storm classification and climatology. Wea. Forecasting, 27, 11141135, doi:10.1175/WAF-D-11-00115.1.

    • Search Google Scholar
    • Export Citation
  • Smull, B. F., , and R. A. Houze Jr., 1987: Rear inflow in squall lines with trailing stratiform precipitation. Mon. Wea. Rev., 115, 28692889, doi:10.1175/1520-0493(1987)115<2869:RIISLW>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Thompson, R. L., , B. T. Smith, , J. S. Grams, , A. R. Dean, , and C. Broyles, 2012: Convective modes for significant severe thunderstorms in the contiguous United States. Part II: Storm supercell and QLCS tornado environments. Wea. Forecasting, 27, 11361154, doi:10.1175/WAF-D-11-00116.1.

    • Search Google Scholar
    • Export Citation
  • Trapp, R. J., , and M. L. Weisman, 2003: Low-level mesovortices within squall lines and bow echoes. Part II: Their genesis and implications. Mon. Wea. Rev., 131, 28042823, doi:10.1175/1520-0493(2003)131<2804:LMWSLA>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Trapp, R. J., , S. A. Tessendorf, , E. S. Godfrey, , and H. E. Brooks, 2005: Tornadoes from squall lines and bow echoes. Part I: Climatological distribution. Wea. Forecasting, 20, 2334, doi:10.1175/WAF-835.1.

    • Search Google Scholar
    • Export Citation
  • Wakimoto, R. M., 2001: Convectively driven high wind events. Severe Convective Storms, Meteor. Monogr., No. 50, Amer. Meteor. Soc., 255–298.

  • Wakimoto, R. M., , H. V. Murphey, , C. A. Davis, , and N. T. Atkins, 2006: High winds generated by bow echoes. Part II: The relationship between the mesovortices and damaging straight-line winds. Mon. Wea. Rev., 134, 28132829, doi:10.1175/MWR3216.1.

    • Search Google Scholar
    • Export Citation
  • Weisman, M. L., 1993: The genesis of severe, long-lived bow echoes. J. Atmos. Sci., 50, 645670, doi:10.1175/1520-0469(1993)050<0645:TGOSLL>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • 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, doi:10.1175/1520-0493(1982)110<0504:TDONSC>2.0.CO;2.

    • 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, doi:10.1175/1520-0493(1984)112<2479:TSACON>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Weisman, M. L., , and C. A. Davis, 1998: Mechanisms for the generation of mesoscale vortices within quasi-linear convective systems. J. Atmos. Sci., 55, 26032622, doi:10.1175/1520-0469(1998)055<2603:MFTGOM>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Weisman, M. L., , J. B. Klemp, , and R. Rotunno, 1988: Structure and evolution of numerically simulated squall lines. J. Atmos. Sci., 45, 19902013, doi:10.1175/1520-0469(1988)045<1990:SAEONS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Westcott, N. E., 1994: Merging of convective clouds: Cloud initiation, bridging, and subsequent growth. Mon. Wea. Rev., 122, 780790, doi:10.1175/1520-0493(1994)122<0780:MOCCCI>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Wheatley, D. M., , R. J. Trapp, , and N. T. Atkins, 2006: Radar and damage analysis of severe bow echoes observed during BAMEX. Mon. Wea. Rev., 134, 791806, doi:10.1175/MWR3100.1.

    • Search Google Scholar
    • Export Citation
  • Wicker, L. J., , and R. B. Wilhelmson, 1995: Simulation and analysis of tornado development and decay within a three-dimensional supercell thunderstorm. J. Atmos. Sci., 52, 26752703, doi:10.1175/1520-0469(1995)052<2675:SAAOTD>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Wolf, P. L., 1998: WSR-88D radar depiction of supercell–bow echo interaction: Unexpected evolution of a large, tornadic “comma-shaped” supercell over eastern Oklahoma. Wea. Forecasting, 13, 492504, doi:10.1175/1520-0434(1998)013<0492:WRDOSB>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Wolf, R., , R. Przybylinski, , and P. Berg, 1996: Observations of a merging bowing segment and supercell. Preprints, 18th Conf. on Severe Local Storms, San Francisco, CA, Amer. Meteor. Soc., 740–745.

  • Xue, M., 2004: Tornadogenesis within a simulated supercell storm. 22nd Conf. on Severe Local Storms, Hyannis, MA, Amer. Meteor. Soc., 9.6. [Available online at https://ams.confex.com/ams/11aram22sls/techprogram/paper_81574.htm.]

  • Yang, M.-J., , and R. A. Houze Jr., 1995: Sensitivity of squall-line rear inflow to ice microphysics and environmental humidity. Mon. Wea. Rev., 123, 31753193, doi:10.1175/1520-0493(1995)123<3175:SOSLRI>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
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Numerical Simulations of Bow Echo Formation Following a Squall Line–Supercell Merger

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  • 1 Atmospheric and Environmental Sciences, South Dakota School of Mines and Technology, Rapid City, South Dakota
  • 2 Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina
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Abstract

Output from idealized numerical simulations is used to investigate the storm-scale processes responsible for squall-line evolution following a merger with an isolated supercell. A simulation including a squall line–supercell merger is compared to one using the same initial squall line and background environment without the merger. These simulations reveal that while bow echo formation is favored by the strongly sheared background environment, the merger produces a more compact bowing structure owing to a locally enhanced rear-inflow jet. The merger also represents a favored location for severe weather production relative to other portions of the squall line, with surface winds, vertical vorticity, and rainfall all being maximized in the vicinity of the merger.

An analysis of storm-scale processes reveals that the premerger squall line weakens as it encounters outflow from the preline supercell, and the supercell becomes the leading edge of the merged system. Subsequent localized strengthening of the cold pool and rear-inflow jet produce a compact, intense bow echo local to the merger, with a descending rear-inflow jet creating a broad swath of damaging surface winds. These features, common to severe bow echoes, are shown to be a direct result of the merger in the present simulations, and are diminished or absent in the no-merger simulation. Sensitivity tests reveal that mergers in a weaker vertical wind shear environment do not produce an enhanced bow echo structure, and only produce a localized region of marginally enhanced surface winds. Additional tests demonstrate that the details of postmerger evolution vary with merger location along the line.

Corresponding author address: Adam J. French, South Dakota School of Mines and Technology, 501 E. St. Joseph St., Rapid City, SD 57701. E-mail: adam.french@sdsmt.edu

Abstract

Output from idealized numerical simulations is used to investigate the storm-scale processes responsible for squall-line evolution following a merger with an isolated supercell. A simulation including a squall line–supercell merger is compared to one using the same initial squall line and background environment without the merger. These simulations reveal that while bow echo formation is favored by the strongly sheared background environment, the merger produces a more compact bowing structure owing to a locally enhanced rear-inflow jet. The merger also represents a favored location for severe weather production relative to other portions of the squall line, with surface winds, vertical vorticity, and rainfall all being maximized in the vicinity of the merger.

An analysis of storm-scale processes reveals that the premerger squall line weakens as it encounters outflow from the preline supercell, and the supercell becomes the leading edge of the merged system. Subsequent localized strengthening of the cold pool and rear-inflow jet produce a compact, intense bow echo local to the merger, with a descending rear-inflow jet creating a broad swath of damaging surface winds. These features, common to severe bow echoes, are shown to be a direct result of the merger in the present simulations, and are diminished or absent in the no-merger simulation. Sensitivity tests reveal that mergers in a weaker vertical wind shear environment do not produce an enhanced bow echo structure, and only produce a localized region of marginally enhanced surface winds. Additional tests demonstrate that the details of postmerger evolution vary with merger location along the line.

Corresponding author address: Adam J. French, South Dakota School of Mines and Technology, 501 E. St. Joseph St., Rapid City, SD 57701. E-mail: adam.french@sdsmt.edu
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