Presented by Al Fisher

1. 2009 StormsPart 2 ©2010 Fisher

3. Radar beam increases in size with distance from radar.

4. Radar takes 4-5 minutes to complete full scan when in storm/precip mode.

5. Reliable doppler wind data limited to about 60-70 nm.

7. Height of beam above ground vs distance from radar. Green 10nm Yellow 15nm Red 20nm

8. MDW TDWR 20nm 10nm

9. ORD TDWR 20nm 10nm

11. PROBLEM(s) OF THE DAY (POTD) ORGANIZED SEVERE STORMS INGREDIENTS-BASED APPROACH MOISTURE INSTABILITY (sources for convective) LIFT SHEAR

13. TornadicSupercell “Ingredients” Instability (varies, usually CAPE > 1000 J/Kg) Deep layer shear (0-6km) bulk shear > 35kt Low level shear (0-1km) SRH > 150 m2/s2 or pre-existing boundary) Relatively high RH values (in BL and aloft) Sfc Td depressions <12°F

15. Effective Bulk Shear (EBS)

16. Supercell Composite Parameter (SCP)

18. Showed boldly only after event started

19. Underscores STP as a DIAGNOSTICparameter

20. 0-6 km shear, 0-1 km SRH (400+), and MLLCL all favorable for STP ≥1

21. Primary shortcoming resulted from MLCAPE values less than 500 J/kg until 23z

35. Friday June 19, 2009 Naper Days

39. Pocket of 87 mph winds

46. July 24, 2009

50. ILX

51. ILX

52. Base Velocity 1700 ft

53. 3500 ft

54. LOT

56. Base Velocity

58. Aug. 9, 2009

59. DVN

61. DVN Base Velocity

62. DVN Storm Relative Velocity

63. DVN VAD Wind