1. Environmental Features Discriminating Between High Shear/Low CAPE Severe Convection and Null Events Keith Sherburn Matthew Parker North Carolina State University 2012 Collaborative Science, Technology, and Applied Research Workshop 16 November 2012

2. Acknowledgements AMS/NOAA NWS Graduate Fellowship CSTAR Program NOAA Grant NA10NWS4680007 WFO Collaborators Storm Prediction Center Andy Dean Rich Thompson Convective Storms Group

3. INTRODUCTION What is high shear/low CAPE, and why do we care?

4. INTRODUCTION “High” shear  0-6 km layer  ≥ 35 knots (18 m/s) “Low” CAPE  Surface-based parcel  ≤ 500 J/kg HSLC

5. INTRODUCTION Tornadoes <= 500 J/kg MLCAPE Significant Tornadoes <= 500 J/kg MLCAPE Guyer and Dean (2010)

6. INTRODUCTION All HSLC Significant Reports from 2006-2011

7. INTRODUCTION Storm Prediction Center (SPC)

8. INTRODUCTION Research limited to last couple of decades Many unanswered questions:  Role of mesovortices?  Role of rear-inflow jet?  Influence of boundaries?  Vertical distribution of instability and moisture?  Compensation for overall lack of instability?  How can we improve the forecasting of these events?

9. DATA AND METHODS What we have and how we’re using it

10. DEVELOPMENT DATA Events subjectively determined by WFOs, but include majority of HSLC events in region SPC Relational Database (SFCOA; aka Mesoanalysis) “nearest neighbor” “HSLC Event” – Over half of reports for a CWA were HSLC One report per CWA per hour 80 significant reports

11. DEVELOPMENT DATA Nulls were warnings issued on a day in which no severe reports were received by the WFO issuing the warning SFCOA interpolated to latitude, longitude point 114 nulls

13. VERIFICATION DATA All significant severe reports across US from 2006-2011 All nulls, as defined previously, from Oct. 2006 through 2011 SFCOA nearest neighbor 2517 HSLC Significant Reports (275 CSTAR) 1316 HSLC Nulls (118 CSTAR)

15. METHODS Statistical analyses Skill scores – True Skill Statistic: – TSS = (ad-bc)/[(a+c)(b+d)] ~ POD – FA Rate – a: Hit, b: False Alarm, c: Miss, d: Correct Null Box-and-whisker plots

16. RESULTS What we’ve found so far

17. 1 RESULTS HSLC CONVECTION SIGNIFICANT EVENTS NULLS SIGNIFICANT TORNADOES SIGNIFICANT WINDS 2

18. 1 SEVERE HAZARDS IN ENVIRONMENTS WITH REDUCED BUOYANCY PARAMETER: SHERB = (0-3 km shear magnitude / 25 m s -1 ) * (0-3 km lapse rate / 5.2 K km -1 ) * (700-500 mb lapse rate / 5.8 K km -1 ) EFFECTIVE SHEAR VERSION: SHERBE = (Effective shear magnitude / 26 m s -1 ) * (0-3 km lapse rate / 5.2 K km -1 ) * (700-500 mb lapse rate / 5.8 K km -1 )

21. SHERBE SHERB STP SCP Craven-Brooks VGP EHI

22. SHERBE SHERB STP SCP Craven-Brooks VGP EHI

23. SHERBE SHERB STP SCP Craven-Brooks VGP EHI

24. SHERBE SHERB STP SCP Craven-Brooks VGP EHI

25. 1 2 3 456 7 8 9 10 11 30 S 63 N 95 S 72 N 374 S 134 N 300 S 96 N 76 S 68 N 18 S 23 N 4 S 39 N 19 S 38 N 414 S 201 N 876 S 417 N 306 S 168 N

26. 1 2 3 456 7 8 9 10 11 2 T 28 W 5 H 16 T 64 W 15 H 13 T 229 W 132 H 7 T 164 W 129 H 1 T 62 W 13 H 2 T 16 W 0 H 0 T 4 W 0 H 2 T 15 W 2 H 7 T 253 W 154 H 188 T 555 W 133 H 64 T 189 W 53 H

27. 1 2 3 456 7 8 9 10 11 SCP SHERBE SCP EHI SHERB Craven-Brooks/ EHI/SCP SHERB/EHI SHERBE SHERB

28. FUTURE WORK Where do we go from here?

29. FUTURE WORK IDEALIZED SIMULATIONS Hypothesis testing Bryan’s Cloud Model 1 (CM1) Using composite soundings COMPOSITE PARAMETERS Test real-time Evaluate differences by region Other formulations

30. storms.meas.ncsu.edu/users/mdparker/nam/

31. CONCLUSIONS

32. HSLC a forecast problem in SE/Mid-Atlantic Significant tornadoes need high shear, but what about CAPE? Our composite parameters show an improvement in skill over existing parameters for our CSTAR region

33. EXTRA SLIDES

35. SHERBE SHERB STP SCP Craven-Brooks VGP EHI 1 2 3 4 5 6 7 8 10 9 11

36. SHERBE SHERB STP SCP Craven-Brooks VGP EHI 1 2 3 4 5 6 7 8 10 9 11

38. 1 35 HSLC Significant Events 60 HSLC Nulls SHERB optimal: TSS = 0.257 @ 0.59 SHERBE optimal: TSS = 0.286 @ 0.77 Best composite parameter: SCP = 0.469 @ 1.25

39. 1 SHERB/E Component Optimal TSS: ESHR = 0.317 @ 37 kts S3MG = 0.360 @ 23.5 kts LLLR = 0.200 @ 3.3 K km -1 LR75 = 0.050 @ 4.8 K km -1 Max Individual TSS: M5CP = 0.489 @ 350 J kg -1 50 mb mixed-layer CAPE

40. 2 95 Significant Events 72 Nulls SHERB optimal: TSS = 0.208 @ 0.94 SHERBE optimal: TSS = 0.365 @ 0.83 Best composite parameter: SHERBE

41. 2 SHERB/E Component Optimal TSS: ESHR = 0.416 @ 44 kts S3MG = 0.190 @ 25.5 kts LLLR = 0.068 @ 4.8 K km -1 LR75 = 0.046 @ 7.3 K km -1 Max Individual TSS: ESHR

42. 3 374 Significant Events 134 Nulls SHERB optimal: TSS = 0.281 @ 0.71 SHERBE optimal: TSS = 0.286 @ 0.78 Best composite parameter: SCP = 0.360 @ 2.42

43. 3 SHERB/E Component Optimal TSS: ESHR = 0.320 @ 47 kts S3MG = 0.235 @ 35.5 kts LLLR = 0.057 @ 3.6 K km -1 LR75 = 0.253 @ 6.8 K km -1 Max Individual TSS: ESHR

44. 4 300 Significant Events 96 Nulls SHERB optimal: TSS = 0.278 @ 0.77 SHERBE optimal: TSS = 0.322 @ 0.94 Best composite parameter: EHI3M1* = 0.443 @ 0.95 *0-3 km SRH and 100 mb mixed CAPE

45. 4 SHERB/E Component Optimal TSS: ESHR = 0.364 @ 49 kts S3MG = 0.157 @ 29.5 kts LLLR = 0.069 @ 4.4 K km -1 LR75 = 0.147 @ 7.2 K km -1 Max Individual TSS: M1MX = 0.406 @ 11 g kg -1 100 mb mean mixing ratio

46. 5 76 Significant Events 68 Nulls SHERB optimal: TSS = 0.365 @ 1.22 SHERBE optimal: TSS = 0.183 @ 1.41 Best composite parameter: SHERB

47. 5 SHERB/E Component Optimal TSS: ESHR = 0.168 @ 38 kts S3MG = 0.195 @ 27 kts LLLR = 0.064 @ 6.7 K km -1 LR75 = 0.060 @ 6.3 K km -1 Max Individual TSS: S1MG = 0.310 @ 15 kts 0-1 km shear magnitude NLFH = 0.441 @ 3800 m Non-virtual LFC height (higher for events)

48. 6 18 Significant Events 23 Nulls SHERB optimal: TSS = 0.517 @ 1.10 SHERBE optimal: TSS = 0.101 @ 1.04 Best composite parameter: SHERB

49. 6 SHERB/E Component Optimal TSS: ESHR = 0.012 @ 57 kts S3MG = 0.493 @ 25 kts LLLR = 0.312 @ 6.4 K km -1 LR75 = 0.000 @ 5.3 K km -1 Max Individual TSS: MUCN = 0.639 @ -40 J kg -1 Most Unstable CIN S8MG = 0.693 @ 67 kts 0-8 km shear magnitude

50. 7 306 Significant Events 168 Nulls SHERB optimal: TSS = 0.471 @ 0.99 SHERBE optimal: TSS = 0.470 @ 1.05 Best composite parameter: SHERB

51. 7 SHERB/E Component Optimal TSS: ESHR = 0.381 @ 49 kts S3MG = 0.291 @ 39 kts LLLR = 0.204 @ 5.3 K km -1 LR75 = 0.282 @ 5.8 K km -1 Max Individual TSS: ESHR

52. 8 876 Significant Events 417 Nulls SHERB optimal: TSS = 0.352 @ 0.87 SHERBE optimal: TSS = 0.347 @ 0.95 Best composite parameter: SHERB

53. 8 SHERB/E Component Optimal TSS: ESHR = 0.298 @ 48 kts S3MG = 0.223 @ 35.5 kts LLLR = 0.264 @ 5.4 K km -1 LR75 = 0.111 @ 6.1 K km -1 Max Individual TSS: ESHR

54. 9 414 Significant Events 201 Nulls SHERB optimal: TSS = 0.195 @ 0.83 SHERBE optimal: TSS = 0.324 @ 0.81 Best composite parameter: SHERBE

55. 9 SHERB/E Component Optimal TSS: ESHR = 0.325 @ 44 kts S3MG = 0.144 @ 29.5 kts LLLR = 0.098 @ 3.9 K km -1 LR75 = 0.119 @ 6.1 K km -1 Max Individual TSS: ESHR

56. 10 19 Significant Events 38 Nulls SHERB optimal: TSS = 0.395 @ 1.36 SHERBE optimal: TSS = 0.105 @ 1.34 Best composite parameter: SHERB/EHI

57. 10 SHERB/E Component Optimal TSS: ESHR = 0.237 @ 46 kts S3MG = 0.474 @ 37.5 kts LLLR = 0.079 @ 9.1 K km -1 LR75 = 0.053 @ 8.5 K km -1 Max Individual TSS: SRH3 = 0.605 @ 200 m 2 s -2

58. 11 4 Significant Events 39 Nulls SHERB optimal: TSS = 0.083 @ 0.88 SHERBE optimal: TSS = 0.000 Best composite parameter: SCP = 0.250 @ 0.41 EHI = 0.250 @ 0.52/0.45 CBSS = 0.250 @ 10000

59. 11 SHERB/E Component Optimal TSS: ESHR = 0.122 @ 37 kts S3MG = 0.167 @ 28.5 kts LLLR = 0.077 @ 5.5 K km -1 LR75 = 0.154 @ 5.8 K km -1 Max Individual TSS: INPW = 0.769 @ 0.9” Precipitable water