Storm Prediction Center Definition: SCP
A higher number corresponds to higher values of three key ingredients for supercells: 1) directional shear, 2) speed shear, and 3) instability.
Storm Prediction Center Definition: STP
A higher number corresponds to higher values of four key ingredients for significant (EF2+) tornadoes: 1) directional shear, 2) speed shear, 3) instability, and 4) low cloud bases.
The values above represent the ensemble mean of daily (~6 a.m. to ~6 a.m.) sums of SCP and STP values for grids in the United States.
Larger numbers (darker colors) represent larger areal coverage non-zero SCP values.
Smaller numbers (lighter colors) represent smaller areal coverage of non-zero SCP values.
A lower number for a day does not mean zero risk, as the risk could be regional or localized in nature.