Craven SigSvr Parameter
The simple product of 100mb MLCAPE and 0-6km magnitude of the vector difference (m/s; often referred to as "deep layer shear") accounts for the compensation between instability and shear magnitude. Using a database of about 60,000 soundings, the majority of significant severe events (2+ inch hail, 65+ knot winds, F2+ tornadoes) occur when the product exceeds 20,000 m3/s3.
The index is formulated as follows:
C = (MLCAPE J kg-1) * (SHR6 m s-1)
For example, a 0-6-km shear of 20 m s-1 (40 knots) and CAPE of 3000 J kg-1 results in a Craven SigSvr index of 60,000. Units are scaled to the nearest 1000 on the web plot.
Craven, J. P., and H. E. Brooks, 2004: Baseline climatology of sounding derived parameters associated with deeep moist convection. Natl. Wea. Digest, 28, 13-24.