6. Roll or Arcus Cloud

11. Supercell Thunderstorms

28. Storm split 1 Storm Split 2 Storm split 3

29. Squall Lines

37. Bow Echos

41. Often Associated with Strong Straight Line Winds Known as “Derechos” • Can reach 100-150 mph • http://www.youtube.com/watch?v=EGJmOeDEBtw • Great Derecho Website: http://www.spc.noaa.gov/misc/AbtDerechos/derechofacts.htm

42. Climatology (Events over 1980-2001

43. High Resolution Numerical Prediction of Convection

44. Explicit Convective Prediction • Requires high resolution (4km or less grid spacing) • Requires high-resolution analysis of current situation, using radar, surface observations and all other assets. • NCAR (WRF model) and CAPS (Oklahoma, ARPS model) are two leading efforts.

45. 10 km WRF forecast domain 4 km WRF forecast domain Bow Echo and Mesoscale Convective Vortex Experiment (BAMEX) Using the WRF Model Goal: Study the lifecycles of mesoscale convective vortices and bow echoes in and around the St. Louis MO area Field program conducted 20 May – 6 July 2003

46. Real-time WRF 4 km BAMEX Forecast Initialized 00 UTC 9 June 03 Reflectivity forecast Composite NEXRAD Radar

47. Real-time WRF 4 km BAMEX Forecast Valid 6/10/03 12Z 4 km BAMEX forecast 36 h Reflectivity 4 km BAMEX forecast 12 h Reflectivity Composite NEXRAD Radar

48. 27h WRF BAMEX Forecast Valid 6/10/03 03Z 4 km Max Reflectivity 10 km Max Reflectivity

49. 30h WRF BAMEX Forecast Valid 6/10/03 06Z 4 km Max Reflectivity 10 km Max Reflectivity

50. Real-time WRF 4 km BAMEX Forecast Initialized 00 UTC 10 June 03 Reflectivity forecast Composite NEXRAD Radar