2. Parameters

Shear Assessment » Helicity Definition

Definition: Storm Relative Environmental Helicity (SREH)

Storm relative environmental helicity (SREH) provides an indication of an environment that favors the development of thunderstorms with rotating updrafts. High values of SREH (usually >150 m2/sec2) are usually associated with long-lived supercells with rotating updrafts, capable of producing tornadoes.

More technically, SREH is a measure of the streamwise vorticity within the inflow environment of a convective storm. What do we mean by that? Let's look at each piece of the definition.