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Is There a “Tipping Point” between Simulated Nontornadic and Tornadic Supercells in VORTEX2 Environments?



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  • Journal Title:
    Monthly Weather Review
  • Personal Author:
  • NOAA Program & Office:
    OAR (Oceanic and Atmospheric Research)
  • Description:
    Previous work has suggested that the lower-tropospheric wind profile may partly determine whether supercells become tornadic. If tornadogenesis within the VORTEX2 composite environments is more sensitive to the lower-tropospheric winds than to either the upper-tropospheric winds or the thermodynamic profile, then systematically varying the lower-tropospheric wind profile might reveal a “tipping point” between nontornadic and tornadic supercells. As a test, simulated supercells are initiated in environments that have been gradually interpolated between the low-level wind profiles of the nontornadic and tornadic VORTEX2 supercell composites while also interchanging the upper-tropospheric winds and thermodynamic profile. Simulated supercells become tornadic when the low-level wind profile incorporates at least 40% of the structure from the tornadic VORTEX2 composite environment. Both the nontornadic and tornadic storms have similar outflow temperatures and availability of surface vertical vorticity near their updrafts. Most distinctly, a robust low-level mesocyclone and updraft immediately overlie the intensifying near-surface circulation in each of the tornadic supercells. The nontornadic supercells have low-level updrafts that are disorganized, with pockets of descent throughout the region where surface vertical vorticity resides. The lower-tropospheric wind profile drives these distinct configurations of the low-level mesocyclone and updraft, regardless of the VORTEX2 composite upper-tropospheric wind profile or thermodynamic profile. This study therefore supports a potentially useful, robust link between the probability of supercell tornadogenesis and the lower-tropospheric wind profile, with tornadogenesis more (less) likely when the orientation of horizontal vorticity in the lowest few hundred meters is streamwise (crosswise).
  • Keywords:
  • Source:
    Monthly Weather Review, 146(8), 2667-2693
  • DOI:
  • Document Type:
    Journal Article
  • Funding:
    Grant no. NA15OAR4590235
  • Rights Information:
    Other
  • Compliance:
    CHORUS
  • Main Document Checksum:
    urn:sha256:74aa7d5df8d928f538a231794c8ffcf518ea19d77e94d741313e8680b1951028
  • Download URL:
  • File Type:
    Filetype[PDF - 8.04 MB ]
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