Low-Level Mesoscale and Cloud-Scale Interactions Promoting Deep Convection Initiation

Details

• Journal Title:
  Monthly Weather Review
• Personal Author:
  Marquis, James N. ; Varble, Adam C. ; Robinson, Paul ; Nelson, T. Connor ; Friedrich, Katja
• NOAA Program & Office:
  NWS (National Weather Service) ; CIRA (Cooperative Institute for Research in the Atmosphere)
• Description:
  Data from scanning radars, radiosondes, and vertical profilers deployed during three field campaigns are analyzed to study interactions between cloud-scale updrafts associated with initiating deep moist convection and the surrounding environment. Three cases are analyzed in which the radar networks permitted dual-Doppler wind retrievals in clear air preceding and during the onset of surface precipitation. These observations capture the evolution of (i) the mesoscale and boundary layer flow, and (ii) low-level updrafts associated with deep moist convection initiation (CI) events yielding sustained or short-lived precipitating storms. The elimination of convective inhibition did not distinguish between sustained and unsustained CI events, though the vertical distribution of convective available potential energy may have played a role. The clearest signal differentiating the initiation of sustained versus unsustained precipitating deep convection was the depth of the low-level horizontal wind convergence associated with the mesoscale flow feature triggering CI, a sharp surface wind shift boundary, or orographic upslope flow. The depth of the boundary layer relative to the height of the LFC failed to be a consistent indicator of CI potential. Widths of the earliest detectable low-level updrafts associated with sustained precipitating deep convection were ~3–5 km, larger than updrafts associated with surrounding boundary layer turbulence (~1–3 km wide). It is hypothesized that updrafts of this larger size are important for initiating cells to survive the destructive effects of buoyancy dilution via entrainment.
• Keywords:
  Atmospheric Science
• Source:
  Monthly Weather Review, 149(8), 2473-2495
• DOI:
  https://doi.org/10.1175/mwr-d-20-0391.1
• ISSN:
  0027-0644 ; 1520-0493
• Format:
  PDF
• Publisher:
  American Meteorological Society
• Document Type:
  Journal Article
• Rights Information:
  Other
• Compliance:
  Library
• Main Document Checksum:
  urn:sha256:3b49be5e48d2fb9fb8c7ba7709fe793f745a04bcdd67c88a795c6643dedda6ae
• Download URL:
  https://repository.library.noaa.gov/view/noaa/53988/noaa_53988_DS1.pdf
• File Type:
  [PDF - 13.27 MB ]