2002 supercell environment case studies

Below are several case analyses looking at supercell environments from 2002 regarding potential for supercell tornadoes compared to what actually occurred.  These are more detailed than cases I posted in 2001, using SPC parameter field depictions as well as RUC-2 model profiles at individual sites.

Each case deals with one or more specific supercells referenced on a radar image, giving some brief background on the general synoptic situation.   Environment analysis is then done using graphics saved from the SPC mesoanalysis page, as well as a RUC-2 model analysis profile near the specified supercell as an estimate of its inflow environment.  Assessment of each environment focuses on the following parameters:

• 0-1 km energy-helicity index (EHI) as an estimate of the shear-CAPE environment to support low-level mesocyclones, using 0-1 km SRH after Rasmussen 2001
• Boundary-layer to 6 km vector shear (BL-6 km shear) as an indicator of deep layer shear support, similar to Rasmessen and Blanchard 1998, and Weisman and Klemp 1982
• Lifting condensation level (LCL) height as an indicator of low-level humidity and possible RFD character, after Rasmussen and Blanchard 1998 and Markowski et al. 2002
• Other low-level thermodynamic parameters that may be important regarding whether a storm is "elevated" or surface-based:
          *  Convective inhibition (CIN) as a measure of strength of low-level stable layer (not as a tool concerning convective initiation), and
          *  Level of free convection (LFC) height as a measure of depth of low-level stable layer

These 5 parameters are assessed according to an estimate of relative support for significant supercell tornadoes from this table, developed from recent research and examination of databases associated with tornadic and nontornadic supercells:   
                                                                                          < click to enlarge table
0-3 km CAPE is noted on RUC-2 point profile depictions, but not specifically included in the parameter assessments because depictions of this parameter are not widely available, and recent real-time experience has sugggested CIN and LFC height to be less volatile when using model data and more relevant regarding low-level stability and tornadoes.

Hopefully the cases below will be useful as examples of assessing important environment characteristics together.  They've been helpful to me.   Enjoy...             

                                                                                                                                                                          -   Jon Davies 7/1/02  (jdavies1@cox.net)
Case studies:

• 4/17/02 tornadic and nontornadic supercell environments over Kansas, Oklahoma, and Iowa (several different supercells, including F3 tornado)
• 4/18/02 late night "elevated" nontornadic supercell in north central Kansas
• 4/28/02 LaPlata, Maryland tornadic supercell environment (F4 tornado, 3 dead)
• 5/1/02 "elevated" nontornadic supercell environment over Arkansas/Oklahoma (warm sector "elevated" profile)
• 6/23/02 tornadic and nontornadic supercell environments over South Dakota (including F3 tornado)

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