Deep Layer Shear

A measure of wind shear from the mid-levels of the atmosphere to the surface layer. Deep layer shear above a specific level (35knots) often leads to mid-level mesocyclones associated with supercell thunderstorms. (Wind Shear) Variation in wind speed and/or direction over a short distance. Shear usually refers to vertical wind shear, i.e., the change in wind with height, but the term also is used in Doppler radar to describe changes in radial velocity over short horizontal distances.