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The High-Shear, Low-CAPE SHERB
parameter and its evaluation
Keith D. Sherburn
Department of Marine, Earth, and Atmospheric Sciences
North Carolina State University
Research to Operations Webinar
October 24, 2014
For those attending SLS…
• Tuesday posters, 3:00-4:15pm (Sessions 5 & 6):
– “Synoptic Influence on High Shear, Low CAPE Convective
Events”, Jessica R. King and M. D. Parker
– “On the usage of composite parameters in High-Shear, LowCAPE environments”, Keith D. Sherburn and M. D. Parker
• Wednesday, 4:45pm (Session 12B):
– “High-Shear, Low-CAPE environments: What we know and
where to go next”, Keith D. Sherburn and M. D. Parker
2
Background
• High-shear, low-CAPE (HSLC) environments: second
“key subclass” of severe weather (Schneider et al.
2006)
• Over half of significant or violent tornadoes (EF2+)
associated with HSLC
• Relatively high number of missed events and false
alarms
• Few operational or modeling studies
3
Typical
Features
• Cool
season/overnight
• Strongly-forced
• Low LCLs
• Low-level
instability
• Low-level jet
• QLCS or minisupercells
• Spatially compact
• Transient rotation
• Little lightning
Credit Mike Strickler, WFO Raleigh
Sherburn and Parker (2014)
ClarkDavis
Lane
(2009)
and Parker
Moore (2006)
and
(2014)
Credit Jason Davis
Supercell Mesocyclones (9 tor., 13 nontor.)
No
statistically
significant
differences
QLCS Mesovortices (17 tor., 12 nontor.)
Differences
mostly vanish
aloft
Statistically
significant
differences
Only vortices
within 60 km of
the radar
Davis and Parker (2014)
Statistically
significant
differences
Davis and Parker (2014)
Supercell Reflectivity Signatures
Davis and Parker (2014)
QLCS Reflectivity Signatures
Davis and Parker (2014)
Credit Jason Davis
SHERB Parameter
11
Maximum TSS of Composite Parameters by
Geographic Region
Maximum True Skill Statistic
0.6
0.5
0.4
Craven-Brooks
EHI
SHERBS3
SHERBE
STP
SCP
VGP
0.3
0.2
0.1
0
NR
NP
UM
EGL
SP
LMV
SA
Region
12
SHERB Distributions
13
SHERBS3 Availability for Forecasters
• AWIPS-1 Volume Browser addition code & instructions
https://collaborate.nws.noaa.gov/trac/nwsscp/wiki/AppsAwips/Sherb
(AWIPS-2 code under development)
• AWIPS-1 and AWIPS-2 GFE tool coding & instructions
https://collaborate.nws.noaa.gov/trac/nwsscp/wiki/Gfe/Smarttools/Sherb
• Real-time SHERB plots from NC State
Real-time RAP – http://storms.meas.ncsu.edu/users/mdparker/rap
Real-time NAM – http://storms.meas.ncsu.edu/users/mdparker/nam
Real-time GFS – http://storms.meas.ncsu.edu/users/mdparker/gfs
• SPC SHERB mesoscale analysis plots
Nationwide SHERBS3 – http://www.spc.noaa.gov/exper/mesoanalysis/s19/sherb3/sherb3.gif
Nationwide SHERBE – http://www.spc.noaa.gov/exper/mesoanalysis/s19/sherbe/sherbe.gif
• SHERB is expected to be added to Bufkit in an upcoming release
How not to use the SHERB
• To forecast convection
• Must be used with a confident forecast of convection
• All data points used to develop the SHERB were associated with either
severe or non-severe convection
• Therefore, cannot be used to forecast convection!
• Where convection is not
expected
• Values potentially above guidance
threshold where convection will
not occur
• In isolation
• Composite parameters (e.g., STP,
VGP) still exhibit skill, though
potentially at lower values than in
high-CAPE environments
Credit Jonathan Blaes
SHERB Feedback
• HSLC “One Stop Shop”
• http://www.meas.ncsu.edu/mdparker/sherb/index.html
SHERB Optimization
• Continuing to test different formulations of the SHERB
• Statistical and observational tests
• New combinations of parameters
• Operational tests
HSLC CSTAR Articles
• Davis and Parker (2014), “Radar Climatology of Tornadic
and Non-Tornadic Vortices in High-Shear, Low-CAPE
Environments in the Mid-Atlantic and Southeastern U.S.”
• Sherburn and Parker (2014), “Climatology and
Ingredients of Significant Severe Convection in High
Shear, Low CAPE Environments”
• Both in Weather and Forecasting (August 2014)
Acknowledgements
• CSTAR Program
• NOAA Grant NA10NWS4680007
• AMS/NOAA NWS Graduate Fellowship
• AMS/NASA Earth Science Graduate Fellowship Program
• NSF Grant AGS-1156123
• WFO Collaborators
• Storm Prediction Center
19
References
•
Clark, M. R., 2009: The southern England tornadoes of 30 December
2006. Atmos. Res., 93, 50-65.
•
Dean, A. R., and R. S. Schneider, 2008: Forecast challenges at the
NWS Storm Prediction Center relating to the frequency of favorable
severe storm environments. Preprints, 24th Conf. on Severe Local
Storms, Savannah, GA, Amer. Meteor. Soc., 9A.2.
•
Dean, A. R., and R. S. Schneider, 2012: An examination of tornado
environments, events, and impacts from 2003-2012. Preprints, 26th
Conf. on Severe Local Storms, Nashville, TN, Amer. Meteor. Soc., P60.
•
Lane, J. D., and P. D. Moore, 2006: Observations of a non-supercell
tornadic thunderstorm from terminal Doppler weather radar. 23rd Conf.
on Severe Local Storms, St. Louis, MO, Amer. Meteor. Soc., P4.5.
•
Schneider, R. S., A. R. Dean, S. J. Weiss, and P. D. Bothwell, 2006:
Analysis of estimated environments for 2004 and 2005 severe
convective storm reports. Preprints, 23rd Conf. on Severe Local
Storms, St. Louis, MO, Amer. Meteor. Soc., 3.5.
20
Contact Information
• Webinar Presenter
– Keith Sherburn ([email protected])
• Principal Investigator
– Dr. Matthew Parker ([email protected])
• NWS contributors
– Jason Davis (BMX) [email protected]
– Justin Lane (GSP) [email protected]
– Jonathan Blaes (SOO RAH) [email protected]
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