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Convective Systems: Squall lines and Bow Echoes

Convective Systems: Squall lines and Bow Echoes . ASP Colloquium 2006. Morris Weisman (NCAR/MMM). Radar Composite 7 May 1995 VORTEX. Radar Composite 26 May 1997. Radar Composite 11 June 2001. Squall Line Environments:. Bow Echoes: Fujita 1978. Bow Echoes: Fujita 1978.

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Convective Systems: Squall lines and Bow Echoes

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  1. Convective Systems: Squall lines and Bow Echoes ASP Colloquium 2006 Morris Weisman (NCAR/MMM)

  2. Radar Composite 7 May 1995 VORTEX

  3. Radar Composite 26 May 1997

  4. Radar Composite 11 June 2001

  5. Squall Line Environments:

  6. Bow Echoes: Fujita 1978

  7. Bow Echoes: Fujita 1978

  8. 5 May 1996 18:48 GMT

  9. 5 May 1996 18:48 GMT

  10. 15 July 1995 Tree Blow Down in Adirondacks, 8 killed

  11. Symmetric, 2-D Squall Line

  12. Asymmetric Squall Line

  13. Houze et al. (BAMS, 1989)

  14. Houze et al. (BAMS, 1989)

  15. Surface Pressure Fields:

  16. So, how well do numerical models reproduce this observed spectrum?? Comet Web Modules: htpp://meted.ucar.edu/topics_convective.php • Convective Storm Matrix • MCS Matrix

  17. Symmetric, 2-D Squall Line

  18. RKW Theory Rotunno et al. (JAS, 1988) C/∆u > 1 “Optimal”condition for cold pool lifting C/∆u = 1 C/∆u < 1

  19. Early System Evolution “Optimal” C/∆u << 1 C/∆u ~ 1

  20. Mature System: C/∆u > 1

  21. Strength of Rear-Inflow Jet is proportional to CAPE

  22. 20 ms-1 shear, no Coriolis forcing

  23. How can we systematically produce the observed line-end vortex pattern?

  24. Line-end vortex mechanisms: Early Phase:

  25. Line-end vortex mechanisms: Mature Phase:

  26. Role of Line-End Vortices Focuses and Intensifies Rear-Inflow Jet

  27. Asymmetric Squall Line

  28. 20 ms-1 shear, Coriolis forcing

  29. Coriolis Effects:

  30. Symmetric-to-asymmetric evolution represents a generic property of finite-length squall lines in the presence of Coriolis forcing.

  31. IR Satellite from 27-28 May, 1998

  32. Radar Composite 28 May 1998

  33. X Upscale Growth of Convection Chris Davis (NCAR/MMM) Bow echoes 0540 UTC 10 June, 2003 MCV 0600 UTC 10 June, 2003 MCSs 11 June, 2003

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