Legend. Convective clouds = grey lines with values in %. Soaring-Index = values in color (in deg Kelvin) Some critical values for the Soaring Index. 15-20: isolated showers, 20% risk for thunderstorms 20-25: occasionally showers, 20-40% risk for thunderstorms 25-30: frequent showers, 40-60% risk for thunderstorms. 30-35: 60-80% risk for thunderstorms. >35   :  >80% risk for thunderstorms.