Forecast Equation to Predict the Severity of Thunderstorm Events


Convective Available Potential Energy CAPE (J/kg)

Maximum Wind Speed in Sounding WMAX (kts)

Energy-Helicity Index EHI

Storm Speed SSPD (kts)

Storm-relative Helicity SRH (m2/s2)


  


S =
S > 3.5 : Non-Severe Event
2.5 < S < 3.5 : Minor Severe Event
1.5 < S < 2.5 : Major Severe Event
S < 1.5 : Tornadic Event

This index is calculated using the following equation:

      S = 4.943709 - 0.000777(CAPE) - 0.004005(WMAX) + 0.181217(EHI) - 0.026867(SSPD) - 0.006479(SRH)


Maglaras, G.J. and K.D. LaPenta, 1997: Development of a Forecast Equation to Predict the Severity of Thunderstorm Events in New York State. National Weather Digest, 21, 3-9.


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