Post on 25-Feb-2016
description
Environmental Features Discriminating Between High Shear/Low CAPE Severe
Convection and Null Events
Keith SherburnMatthew Parker
North Carolina State University
2012 Collaborative Science, Technology, and Applied Research Workshop
16 November 2012
Acknowledgements• AMS/NOAA NWS Graduate Fellowship• CSTAR Program• NOAA Grant NA10NWS4680007
• WFO Collaborators• Storm Prediction Center• Andy Dean• Rich Thompson
• Convective Storms Group
INTRODUCTIONWhat is high shear/low CAPE, and why do we care?
INTRODUCTION• “High” shear
0-6 km layer ≥ 35 knots (18 m/s)
• “Low” CAPE Surface-based parcel ≤ 500 J/kg
HSLC
INTRODUCTION• Tornadoes
<= 500 J/kg MLCAPE
• Significant Tornadoes <= 500 J/kg MLCAPE
Guyer and Dean (2010)
INTRODUCTION
All HSLC Significant Reports from 2006-2011
INTRODUCTION
Storm Prediction Center (SPC)
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?
DATA AND METHODSWhat we have and how we’re using it
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
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
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0
5
10
15
20
25
30
35
40
45
50
Annual Cycle of Reports and Nulls – Development Dataset
Nulls Significant Severe
Month
Perc
enta
ge
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)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0
5
10
15
20
25
30
35
U.S. Annual Cycle of Reports and Nulls - Verification Dataset
Reports % Nulls % Tornadoes % Wind % Hail %
Month
Perc
enta
ge
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
RESULTSWhat we’ve found so far
1
RESULTS
HSLC CONVECTIO
N
SIGNIFICANT EVENTS
NULLS
SIGNIFICANT TORNADOES
SIGNIFICANT WINDS
2
1SEVERE 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)
0 0.10.20.30.40.50.60.70.80.9 1 1.11.21.31.41.51.61.71.81.9 2 2.12.22.32.42.50
0.1
0.2
0.3
0.4
0.5
0.6
0.7
True Skill Statistic: Our Domain HSLC Significant Events vs. Nulls
Parameter Threshold Value
True
Ski
ll St
atis
tic
SHERBESHERBSTPSCPCraven-BrooksVGPEHI
0 0.10.20.30.40.50.60.70.80.9 1 1.11.21.31.41.51.61.71.81.9 2 2.12.22.32.42.50
0.1
0.2
0.3
0.4
0.5
0.6
0.7
True Skill Statistic: Our Domain HSLC Signif -icant Tornadoes vs. Nulls
Parameter Threshold Value
True
Ski
ll St
atis
tic
SHERBESHERBSTPSCPCraven-BrooksVGPEHI
0 0.10.20.30.40.50.60.70.80.9 1 1.11.21.31.41.51.61.71.81.9 2 2.12.22.32.42.50
0.1
0.2
0.3
0.4
0.5
0.6
0.7
True Skill Statistic: All US HSLC Signif -icant Events vs. Nulls
Parameter Threshold Value
True
Ski
ll St
atis
tic
SHERBESHERBSTPSCPCraven-BrooksVGPEHI
0 0.10.20.30.40.50.60.70.80.9 1 1.11.21.31.41.51.61.71.81.9 2 2.12.22.32.42.50
0.1
0.2
0.3
0.4
0.5
0.6
0.7
True Skill Statistic: All US HSLC Signif -icant Tornadoes vs. Nulls
Parameter Threshold Value
True
Ski
ll St
atis
tic
SHERBESHERBSTPSCPCraven-BrooksVGPEHI
123456
7891011
30 S63 N
95 S72 N
374 S134 N
300 S96 N
76 S68 N
18 S23 N
4 S39 N
19 S38 N
414 S201 N
876 S417 N
306 S168 N
123456
7891011
2 T28 W5 H
16 T64 W15 H
13 T229 W132 H
7 T164 W129 H
1 T62 W13 H
2 T16 W0 H
0 T4 W0 H 2 T
15 W2 H
7 T253 W154 H
188 T555 W133 H
64 T189 W53 H
123456
7891011
SCP
SHERBE
SCPEHISHERBSHERB
Craven-Brooks/EHI/SCP
SHERB/EHI
SHERBESHERB
SHERB
FUTURE WORKWhere do we go from here?
FUTURE WORKIDEALIZED
SIMULATIONS• Hypothesis testing• Bryan’s Cloud Model 1
(CM1)• Using composite soundings
COMPOSITE PARAMETERS• Test real-time• Evaluate differences
by region• Other formulations
storms.meas.ncsu.edu/users/mdparker/nam/
CONCLUSIONS
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
EXTRA SLIDES
1 2 3 4 5 6 7 8 9 10 11 US0
0.1
0.2
0.3
0.4
0.5
0.6
All HSLC: Optimal Composite Parameter Skill by Region
Region
True
Ski
ll St
atis
tic
SHERBESHERBSTPSCPCraven-BrooksVGPEHI
123456
7810 911
1 2 3 4 5 6 7 8 9 10 11 US0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
HSLC Tor: Optimal Composite Parameter Skill by Region
Region
True
Ski
ll St
atis
tic
SHERBESHERBSTPSCPCraven-BrooksVGPEHI
123456
7810 911
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
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
2• 95 Significant Events• 72 Nulls
• SHERB optimal:• TSS = 0.208 @ 0.94
• SHERBE optimal:• TSS = 0.365 @ 0.83
• Best composite parameter:• SHERBE
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
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
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
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
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
5• 76 Significant Events• 68 Nulls
• SHERB optimal:• TSS = 0.365 @ 1.22
• SHERBE optimal:• TSS = 0.183 @ 1.41
• Best composite parameter:• SHERB
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)
6• 18 Significant Events• 23 Nulls
• SHERB optimal:• TSS = 0.517 @ 1.10
• SHERBE optimal:• TSS = 0.101 @ 1.04
• Best composite parameter:• SHERB
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
7• 306 Significant Events• 168 Nulls
• SHERB optimal:• TSS = 0.471 @ 0.99
• SHERBE optimal:• TSS = 0.470 @ 1.05
• Best composite parameter:• SHERB
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
8• 876 Significant Events• 417 Nulls
• SHERB optimal:• TSS = 0.352 @ 0.87
• SHERBE optimal:• TSS = 0.347 @ 0.95
• Best composite parameter:• SHERB
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
9• 414 Significant Events• 201 Nulls
• SHERB optimal:• TSS = 0.195 @ 0.83
• SHERBE optimal:• TSS = 0.324 @ 0.81
• Best composite parameter:• SHERBE
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
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
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 m2s-2
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
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