Other Instabilities » CSI Favorable Conditions

Simple 2-dimensional CSI theory assumes geostrophic flow with unidirectional shear and variations occurring only in the direction normal to the geostrophic shear or thermal wind vector. One can qualitatively use an observed or model-derived sounding, in combination with surface and upper air analyses, to infer environments potentially favorable for CSI, given the following:
- Conditions at or near saturation
- Strong, preferably unidirectional, vertical wind shear
- Weak conditional stability, usually a sounding slope close to moist adiabatic
- An environment favorable for lift
- Weak inertial stability, generally on the anticyclonic shear side of an upper-level jet
If the above conditions are met, the environment may be favorable for formation of precipitation bands oriented parallel to the thermal wind or thickness lines. In this case, you may wish to further evaluate the potential for CSI by analyzing cross sections.