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
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 2 For those attending SLS…
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 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
11 SHERB Parameter
12 Maximum TSS of Composite Parameters by Geographic Region
13 SHERB Distributions
SHERBS3 Availability for Forecasters AWIPS-1 Volume Browser addition code & instructions (AWIPS-2 code under development) AWIPS-1 and AWIPS-2 GFE tool coding & instructions Real-time SHERB plots from NC State Real-time RAP – Real-time NAM – Real-time GFS – SPC SHERB mesoscale analysis plots Nationwide SHERBS3 – Nationwide SHERBE – 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”
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
CSTAR Program NOAA Grant NA10NWS AMS/NOAA NWS Graduate Fellowship AMS/NASA Earth Science Graduate Fellowship Program NSF Grant AGS WFO Collaborators Storm Prediction Center Acknowledgements 19
Clark, M. R., 2009: The southern England tornadoes of 30 December Atmos. Res., 93, 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 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 20
Contact Information Webinar Presenter –Keith Sherburn Principal Investigator –Dr. Matthew Parker NWS contributors –Jason Davis (BMX) –Justin Lane (GSP) –Jonathan Blaes (SOO RAH)