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Environmental Features Discriminating Between High Shear/Low CAPE Severe Convection and Null Events

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. Acknowledgements.

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Environmental Features Discriminating Between High Shear/Low CAPE Severe Convection and Null Events

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

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

  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

  12. 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)

  13. 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

  14. What we’ve found so far RESULTS

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

  16. 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)

  17. SHERBE SHERB STP SCP Craven-Brooks VGP EHI

  18. SHERBE SHERB STP SCP Craven-Brooks VGP EHI

  19. SHERBE SHERB STP SCP Craven-Brooks VGP EHI

  20. SHERBE SHERB STP SCP Craven-Brooks VGP EHI

  21. 18 S 23 N 76 S 68 N 300 S 96 N 374 S 134 N 95 S 72 N 6 5 4 3 1 2 30 S 63 N 11 9 10 8 7 4 S 39 N 306 S 168 N 19 S 38 N 876 S 417 N 414 S 201 N

  22. 2 T 16 W 0 H 1 T 62 W 13 H 7 T 164 W 129 H 13 T 229 W 132 H 16 T 64 W 15 H 6 5 4 3 1 2 2 T 28 W 5 H 11 9 10 8 7 0 T 4 W 0 H 64 T 189 W 53 H 2 T 15 W 2 H 188 T 555 W 133 H 7 T 253 W 154 H

  23. SHERB SHERB EHI SCP SHERBE 6 5 4 3 1 2 SCP 11 9 10 8 7 Craven-Brooks/ EHI/SCP SHERB SHERB/EHI SHERB SHERBE

  24. Where do we go from here? Future work

  25. 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

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

  27. CONCLUSIONS

  28. CONCLUSIONS • 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

  29. EXTRA SLIDES

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

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

  32. 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 1

  33. 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 1

  34. 95 Significant Events • 72 Nulls • SHERB optimal: • TSS = 0.208 @ 0.94 • SHERBE optimal: • TSS = 0.365 @ 0.83 • Best composite parameter: • SHERBE 2

  35. 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 2

  36. 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 3

  37. 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 3

  38. 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 4

  39. 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 4

  40. 76 Significant Events • 68 Nulls • SHERB optimal: • TSS = 0.365 @ 1.22 • SHERBE optimal: • TSS = 0.183 @ 1.41 • Best composite parameter: • SHERB 5

  41. 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) 5

  42. 18 Significant Events • 23 Nulls • SHERB optimal: • TSS = 0.517 @ 1.10 • SHERBE optimal: • TSS = 0.101 @ 1.04 • Best composite parameter: • SHERB 6

  43. 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 6

  44. 306 Significant Events • 168 Nulls • SHERB optimal: • TSS = 0.471 @ 0.99 • SHERBE optimal: • TSS = 0.470 @ 1.05 • Best composite parameter: • SHERB 7

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