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12 UTC 500 mb May 7, 1995

12 UTC 500 mb May 7, 1995. 12 UTC 700 mb May 7, 1995. 12 UTC SFC May 7, 1995. 18 UTC SFC May 7, 1995. Radar Composite 7 May 1995 VORTEX. Convective Systems: Squall lines and Bow Echoes. ASP Colloquium 2006. Morris Weisman (NCAR/MMM). Houze et al. (BAMS, 1989).

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12 UTC 500 mb May 7, 1995

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  1. 12 UTC 500 mb May 7, 1995

  2. 12 UTC 700 mb May 7, 1995

  3. 12 UTC SFC May 7, 1995

  4. 18 UTC SFC May 7, 1995

  5. Radar Composite 7 May 1995 VORTEX

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

  7. Houze et al. (BAMS, 1989)

  8. Johnson and Hamilton (1988)

  9. Squall Line Environments:

  10. Houze et al. (BAMS, 1989)

  11. Biggerstaff and Houze (1991)

  12. Johnson and Hamilton (1988)

  13. Newton 1966

  14. Houze and Hobbs (1982)

  15. Leary and Houze (1979)

  16. Tropical Squall Lines: (Zipser, 1977) Severe Mid-Latitude Squall Lines: (Newton, 1963) Frontal Squall Lines: (Carbone, 1982)

  17. Symmetric, 2-D Squall Line

  18. Basic Equations: 2D Squall Line ⁄ *Also, no vortex tilting or stretching -- Or, more simply, consider the 2D horizontal vorticity equation: where

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

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

  21. Mature System: C/∆u > 1

  22. RKW (1988)

  23. RKW (1988)

  24. Mature System: C/∆u > 1

  25. Rear-Inflow Jets: *Strength of Rear-Inflow Jet is proportional to CAPE

  26. Lafore and Moncrieff (1989)

  27. RKW Theory: all other things being equal (e.g., same external forcing), squall line strength/longevity is “optimized” when the circulation associated with the system-generated cold pool remains “in balance” with the circulation associated with the low-level vertical wind shear. Issue: Squall-lines are observed to be strong and long-lived for a wider range of environments than suggested by the models (e.g., weaker shears, deeper shears,….). So, what is the utility of RKW theory?

  28. Thorpe et al. (1982) (2D) Squall Lines steadiest when shear confined to low-levels!

  29. Fovell (1988) (2D)

  30. Weisman et al. (1988) (3D)

  31. Weisman et al. (1988) (3D)

  32. Weisman et al. (1988) (3D)

  33. Weisman and Rotunno (2004)

  34. Weisman and Rotunno (2004)

  35. Weisman and Rotunno (2004)

  36. Weisman and Rotunno (2004)

  37. Weisman and Rotunno (2004)

  38. Weisman and Rotunno (2004)

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