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
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.)