Skew-T Parameters and Convective Indices
Instability
- Convective available potential energy (CAPE)
- Convective available potential energy (CAPE)
- Convective inhibition (CIN)
- Convective inhibition (CIN)
- Lifted index (LI)
- Lifted index (LI)
- Showalter stability index (SSI)
- Showalter stability index (SSI)
- Total Totals index (TT)
- Total Totals index (TT)
Vertical Wind Shear
Vertical wind shear is a very important parameter to evaluate when assessing the potential for severe thunderstorms as well as forecasting the storm type, evolution, and movement. As the magnitude of the 0-6 km shear increases, the storm characteristics evolve from short-lived ordinary cells to multi-cell, with supercells favored for shears > 25 m/s.
In environments favorable to severe storm development, wind shear vectors commonly turn clockwise, depicting veering of the winds over the lowest couple of kilometers. For cases of strong shear magnitude, a clockwise-turning hodograph favors a more sustained, long-lived storm with a cyclonically rotating updraft.
For a complete description of how to use a hodograph in diagnosis of severe thunderstorms, see the module: Using Hodographs.
For more on wind shear and convective storms, see the module: Shear and Convective Storms .
Combinations of Instability and Wind Shear