Supercell Composite Parameter

A multiple ingredient, composite index that includes effective storm-relative helicity (ESRH, based on Bunkers right supercell motion), most unstable parcel CAPE (muCAPE) and convective inhibition (muCIN), and effective bulk wind difference (EBWD). Each ingredient is normalized to supercell "threshold" values, and larger values of SCP denote greater "overlap" in the three supercell ingredients. Only positive values of SCP are displayed, which correspond to environments favoring right-moving (cyclonic) supercells.

This index is formulated as follows:

SCP = (muCAPE / 1000 J kg-1) * (ESRH / 50 m2 s-2) * (EBWD / 20 m s-1) * (-40 J kg-1 / muCIN)

EBWD is divided by 20 m s-1 in the range of 10-20 m s-1. EBWD less than 10 m s-1is set to zero, and EBWD greater than 20 m s-1 is set to one. The muCIN term is based on work by Gropp and Davenport (2018), August issue of Weather and Forecasting, and it is set to 1.0 when muCIN is greater than -40 kg-1.

Additional information can be found here. (Please open this link in another browser window.)