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Alan F. Srock and Lance F. Bosart Dept. of Atmospheric and Environmental Sciences

MCS Organization and Development Along Land/Lake-Induced Thermodynamic Boundaries near Lake Superior. Alan F. Srock and Lance F. Bosart Dept. of Atmospheric and Environmental Sciences University at Albany/SUNY, Albany, NY 12 th Northeast Regional Operational Workshop CESTM, Albany, NY

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Alan F. Srock and Lance F. Bosart Dept. of Atmospheric and Environmental Sciences

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  1. MCS Organization and Development Along Land/Lake-Induced Thermodynamic Boundaries near Lake Superior Alan F. Srock and Lance F. Bosart Dept. of Atmospheric and Environmental Sciences University at Albany/SUNY, Albany, NY 12th Northeast Regional Operational Workshop CESTM, Albany, NY 3-5 November 2010 Supported by NSF Grant #ATM-0646907

  2. Motivation • Intense, warm-season convection often depends on the location of low-level boundaries • Natural thermodynamic boundaries often occur near the Great Lakes • Big question: How can boundaries near the Great Lakes affect the formation and evolution of MCSs?

  3. Lake Breeze Example Return Flow 400-2000 m Adapted from Keen and Lyons (1978) LB Inflow 100-1000 m (water)

  4. Climatology Results n=70

  5. Climatology Results n=70

  6. Case Study: 30 July 2006 0000 UTC 30 July – 0600 UTC 31 July 2006 Blue Dots: Wind Reports Green Dots: Hail Reports

  7. Precipitation Comparison mm 6-h Eta forecast precipitation (mm) ending 0900 UTC from 0000 UTC 30 July 2006 run 1-h total precipitation (mm) from Stage IV data ending 0800 UTC 30 July 2006

  8. Precipitation Comparison W E mm 6-h Eta forecast precipitation (mm) ending 0900 UTC from 0000 UTC 30 July 2006 run 1-h total precipitation (mm) from Stage IV data ending 0800 UTC 30 July 2006

  9. 0900 UTC 29 July 0915 UTC 29 July IR Contours every 3 ºC 21 ºC contour

  10. IR 1200 UTC 29 July 1215 UTC 29 July Contours every 3 ºC 21 ºC contour

  11. IR 1500 UTC 29 July 1515 UTC 29 July Contours every 3 ºC 21 ºC contour

  12. IR 1800 UTC 29 July 1815 UTC 29 July Contours every 3 ºC 21 ºC contour

  13. IR 2100 UTC 29 July 2115 UTC 29 July Contours every 3 ºC 21 ºC contour

  14. IR 0000 UTC 30 July 0015 UTC 30 July Contours every 3 ºC 21 ºC contour

  15. IR 0300 UTC 30 July 0315 UTC 30 July Contours every 3 ºC 21 ºC contour

  16. IR 0600 UTC 30 July 0615 UTC 30 July Contours every 3 ºC 21 ºC contour

  17. IR 0900 UTC 30 July 0915 UTC 30 July Contours every 3 ºC 21 ºC contour

  18. IR 1200 UTC 30 July 1215 UTC 30 July Contours every 3 ºC 21 ºC contour

  19. 250 hPa ‒ 0000 UTC 30 July 20–km RUC m s −1 Height (m), Wind Speed (m s −1), and Winds (m s −1)

  20. 250 hPa ‒ 0000 UTC 30 July 20–km RUC m s −1 Height (m), Wind Speed (m s −1), and Winds (m s −1)

  21. 850 hPa ‒ 1200 UTC 29 July 20–km RUC K Height (m), Wind (m s−1), θe (K), and θ (K)

  22. 850 hPa ‒ 0000 UTC 30 July 20–km RUC K Height (m), Wind (m s−1), θe (K), and θ (K)

  23. MPX ‒ 0000 UTC 30 July Red – observed Blue – RUC20

  24. 850 hPa ‒ 0600 UTC 30 July 20–km RUC K Height (m), Wind (m s−1), θe (K), and θ (K)

  25. 850 hPa ‒ 1200 UTC 30 July 20–km RUC K Height (m), Wind (m s−1), θe (K), and θ (K)

  26. CAPE/Shear ‒ 0000 UTC 30 July 20–km RUC J kg −1 CAPE (J kg−1) and 1000‒700 hPa Shear (m s−1)

  27. CAPE/Shear ‒ 0600 UTC 30 July 20–km RUC J kg −1 CAPE (J kg−1) and 1000‒700 hPa Shear (m s−1)

  28. CAPE/Shear ‒ 1200 UTC 30 July 20–km RUC J kg −1 CAPE (J kg−1) and 1000‒700 hPa Shear (m s−1)

  29. 850 hPa ‒ 0000 UTC 30 July 1º GFS Q ∙∆ Q-vec, Q-vec convergence, Height (dam), Temperature (ºC)

  30. 850 hPa ‒ 0600 UTC 30 July 1º GFS Q ∙∆ Q-vec, Q-vec convergence, Height (dam), Temperature (ºC)

  31. 850 hPa ‒ 1200 UTC 30 July 1º GFS Q ∙∆ Q-vec, Q-vec convergence, Height (dam), Temperature (ºC)

  32. Synoptic Overview • Large-scale conditions favorable for MCS formation, but eastern MCS did not develop until reaching lake boundary • Ample low-level moisture advected northeastward throughout the period, likely aided by evapotranspiration • Thermodynamic boundary persisted over the Northern Plains through the 30th, but not over Wisconsin

  33. 1500 UTC 29 July 2006 Surface Wind (kt), θ(K), Radar (dBZ)

  34. 0000 UTC 30 July 2006 Surface Wind (kt), θ(K), Radar (dBZ)

  35. 0600 UTC 30 July 2006 Surface Wind (kt), θ(K), Radar (dBZ)

  36. 0600 UTC 30 July 2006 Surface Wind (kt), θ(K), Radar (dBZ)

  37. EAU HYR ASX 45006 Temperature (oC) 29/06 29/12 29/18 30/00 30/06 30/12 Wind (kt)

  38. EAU HYR ASX 45006 Temperature (oC) 29/06 29/12 29/18 30/00 30/06 30/12 Wind (kt)

  39. Surface Conclusions • Two boundaries remained in the wake of the 29 July MCS over central WI: • Southern boundary weakened throughout the day on cold side of boundary • Northern near-shore boundary remained strong throughout, aided by natural land/lake temperature gradient • Eastern part of the next MCS (30 July) organized along northern near-shore boundary at SW edge of Lake Superior

  40. WRF Modeling Study • Simulations run to test effect of land/lake boundary on development of convection • Key details: • Initialized at 0000 UTC 30 July • 4 km horizontal grid spacing • Explicit convection

  41. 850 hPa ‒ 0600 UTC 30 July RUC WRF 6-h forecast K Height (m), Wind (m s−1), θe (K), and θ (K)

  42. 850 hPa ‒ 0900 UTC 30 July RUC WRF WRF 9-h forecast K Height (m), Wind (m s−1), θe (K), and θ (K)

  43. Surface ‒ 0300 UTC 30 July Observed WRF WRF 3-h forecast Surface Wind (kt), Reflectivity (dBZ), and θ (K)

  44. Surface ‒ 0600 UTC 30 July Observed WRF WRF 6-h forecast Surface Wind (kt), Reflectivity (dBZ), and θ (K)

  45. Surface ‒ 0900 UTC 30 July Observed WRF WRF 9-h forecast Surface Wind (kt), Reflectivity (dBZ), and θ (K)

  46. Surface ‒ 1200 UTC 30 July Observed WRF WRF 12-h forecast Surface Wind (kt), Reflectivity (dBZ), and θ (K)

  47. Modeling Conclusions • WRF simulation resolves key upper-level and synoptic-scale features well • Near-surface differences between simulation and observations led to differences in reflectivity/precipitation/MCS development • Better representation of lake-induced near-surface boundaries is likely important for improved forecast of MCS development

  48. Conclusions • Near-surface land/lake boundary helped to focus development of the eastern MCS on 30 July • Eastern MCS did not fully develop until low-level moisture reached near-surface land/lake boundary • Proper representation of near-surface land/lake boundaries important to improving forecasts of near-lake MCS development Email: srock@atmos.albany.edu

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