Storm-Relative Velocity - the wind velocity minus storm motion. The wind at a given location may be the combination of the environmental flow plus winds due to a thunderstorm.
Storm-relative - Measured relative to a moving thunderstorm, usually referring to winds, wind shear, or helicity.
Storm-scale - Referring to weather systems with sizes on the order of individual thunderstorms. See synoptic scale, mesoscale.
It is related directly to storm-relative helicity in the lowest 2 km (SRH, in m2/s2) and CAPE (in j/kg) as follows: EHI = (CAPE x SRH)/160,000. Thus, higher values indicate unstable conditions and/or strong vertical shear.
In a storm-relative reference frame, the idealized signature is symmetric about the radar viewing direction with marked azimuthal shear across the core region between peak Doppler velocity values of opposite sign.
SRH: An acronym for Storm-relative Helicity.
Stability Index: The overall stability or instability of a sounding is sometimes conveniently expressed in the form of a single numerical value.
An index that incorporates vertical shear and instability, designed for the purpose of forecasting supercell thunderstorms. It is related directly to storm-relative helicity in the lowest 2 km (SRH, in mē/sē) and CAPE (in J/kg) as follows: ...
Such storms often exhibit higher severe / tornadic incidences due to the increased storm-relative shear encountered by such a storm's movement. Sometimes the "RIGHT SPLIT" of a splitting storm becomes the RIGHT TURNING STORM.
It is important to know that storm-relative winds are critical rather than absolute winds. Therefore, one must figure storm motion into the complex relationships concerning thunderstorm and vertical wind shear interactions.
 See also: Thunder, Wind, Storm, Shear, Supercell
  
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