2. >20NM <15NM >20NM All Storms Composite produces stormtable & detail picture Data level <15NM Stormlab

3. Terminal Doppler Radar ORD & MDW

4. Server choice

5. For Storm Rel Velocity only…Use the Composite storm table for the storm motion to enter. Either use table value for particular storm if looks good, or average several storm motions to arrive at a value to enter. TOR warning also an option, look at code at bottom of warning. Do this first before clicking on SRV.

6. Enter position/spotter data

7. 2 ways to “sample” the warning polygon

11. Clicking on radar site opens window, shows current watches and warnings Loop control buttons

12. Naperville shows at 4X, road numbers at 8X .

13. Interwarn

15. Stormlab/Interwarn computer configuration 1 PC 2 PC 3 PC * * * Interwarn * * * Composite Reflectivity+Table * * * SPC Mesoanalysis * * * Precipitation * * * VAD Winds L 2 L 2 * Storm Relative Velocity L 2 L 2 * Velocity L 2 L 2 * Reflectivity #1 #2 #3 #1 #2 #1

17. .96 Degree Beam Resolution If R = 60 NM 120 NM 180 NM 240 NM D = 1 NM 2 NM 3 NM 4 NM D D = Beam Width Radar resolution with respect to beam width / range

18. The Zero Isodop “Problem” When the wind velocity is parallel to the radial, the full component of the wind is measured When the radial is perpendicular to the the wind, the radar displays zero velocity - This “zero zone” is called the “Zero Isodop”. What percentage of actual wind will the radar detect? 0 0 = 100% - Parallel 15 0 = 97% 30 0 = 87% 45 0 = 71% 60 0 = 50% 75 0 = 26% 90 0 = 0% - Perpendicular

19. Azimuth Resolution Considerations Weak inbound, weak outbound Rotation too small to be resolved Stronger inbound than outbound Strong inbound, strong outbound Azimuth 3 Azimuth 2 Azimuth 1 Enlarged image along a radial. Individual “blocks” represent one sample volume. This graphically shows the radar resolution. Rotational couplet identification can be affected by azimuth resolution. As the diagram shows, the closer a rotation is to the radar the more likely it will be identified correctly. If the rotation is smaller than the 1 0 beam width (possible at long ranges) then the rotation will be diluted or averaged by all the velocities in that sample volume. This may cause the couplet to go unidentified until it gets closer to the radar.

20. Line of tstms moving thru ne IL

21. Base velocity locates gust front

22. Lake breeze in precip mode, how it would look if a gustfront coming out of a tstm or shower.

23. Lake breeze on base velocity

24. Bowing squall line

25. Bowing line with Base velocity, inbound winds 50-64 kts

26. Bowing line on Composite. Note storm motions 45-60 kts

27. Bowing squall line over N IL

28. Composite view, note cell motion of 45 & 52 kts

29. Base velocity, > 55 kts inbound with stronger cells

30. VAD winds, note 50-60 kts noted 3-6,000 feet as line is within 20 nm of radar

31. Reflectivity Book end vortex forms and Inflow jet intensifies Derecho Aug 4, 2008

33. Base Velocity Gustfront

34. Reflectivity

35. Storm Relative Motion Tornadic circulation 2 EF1 tornadoes

36. Storm Relative Motion Tornadic circulation EF2 tornado

37. IA tornado: Mesocyclone & hail symbols, along with pathcast.

38. IA tornado: Strong inflow and updraft area notch (9,000 ft)

39. IA tornado: B ounded W eak E cho R egion Extremely strong updraft (16,000 ft)

40. GA… Nothing special on .5 reflectivity

41. .5 SRM shows very strong rotation

42. Note red triangle ( T ornado V ortex S ignature) + Meso value of 12

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

44. Joliet tornado 4/20/04 .5° and 3.4° 1800 ft 300 ft

45. Joliet tornado: .5° and 3.4° 300 ft 1800 ft

46. Example of level 2 Base Velocity detail. Microburst of 62+ knots which unroofed apartment complex in Carol Stream April 2007. 1400 ft

47. One hour rainfall

48. 3 Hour Rainfall

51. Tornadogenesis: Three ingredients Development of a persistent, rotating updraft 1 Ingestion of enhanced SRH (occasionally, large-scale SRH is sufficient) and development of strong low-level rotation 2 Development of a downdraft partially embedded in the rotation that aids in the transport of rotation to the ground, followed by focusing of that rotation through convergence if the downdraft reaches the ground with some very uncommon properties 3

52. Tornadogenesis in a Nutshell

53. L Forward Flank Downdraft Inflow RFD June 7, 2008

54. L Forward Flank Downdraft Inflow RFD

55. L “ Old” Tornado Becomes Rain-wrapped

56. L L

57. TDWR WSR-88D Left over old hook “ eye” New hook developing

60. Allan Fisher [email_address] 630-355-2628