The High-Shear, Low-CAPE SHERB parameter and its evaluation

Keith D. SherburnDepartment of Marine, Earth, and Atmospheric Sciences

North Carolina State University

Research to Operations Webinar

October 24, 2014

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• 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, Low-

CAPE 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

For those attending SLS…

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• 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

Background

Typical Features• Cool

season/overnight• Strongly-forced• Low LCLs• Low-level instability• Low-level jet• QLCS or mini-

supercells• Spatially compact• Transient rotation• Little lightning

Credit Mike Strickler, WFO Raleigh

Clark (2009)Lane and Moore (2006)Davis and Parker (2014)

Sherburn and Parker (2014)

Credit Jason Davis

Supercell Mesocyclones (9 tor., 13 nontor.)

QLCS Mesovortices (17 tor., 12 nontor.)

Only vortices within 60 km of the radar

Statistically significant differences

No statistically significant differences

Differences mostly vanish aloft

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

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SHERB Parameter

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0

0.1

0.2

0.3

0.4

0.5

0.6

NR NP UM EGL SP LMV SA

MaximumTrueSkillStatistic

Region

Craven-BrooksEHISHERBS3SHERBESTPSCPV

Maximum TSS of Composite Parameters by Geographic Region

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SHERB Distributions

SHERBS3 Availability for Forecasters

• AWIPS-1 Volume Browser addition code & instructionshttps://collaborate.nws.noaa.gov/trac/nwsscp/wiki/AppsAwips/Sherb

(AWIPS-2 code under development)

• AWIPS-1 and AWIPS-2 GFE tool coding & instructionshttps://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/rapReal-time NAM – http://storms.meas.ncsu.edu/users/mdparker/namReal-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

• 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)

HSLC CSTAR Articles

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• 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

Acknowledgements

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• 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.

References

Contact Information

• Webinar Presenter – Keith Sherburn (kdsherbu@ncsu.edu)

• Principal Investigator– Dr. Matthew Parker (mdparker@ncsu.edu)

• NWS contributors– Jason Davis (BMX) jason.davis@noaa.gov– Justin Lane (GSP) Justin.Lane@noaa.gov– Jonathan Blaes (SOO RAH) jonathan.blaes@noaa.gov