Question

Sounding plotted on skew-T diagram

This sounding comes from the vicinity of a mesoscale convective system in north Texas on 6 May 2003.

Determine the Showalter stability index (SSI). Enter your answer in the text box below, then click Done.

SSI =   

Answer: -3
From the dewpoint and temperature at 850 hPa, find the LCL. From the LCL, follow a saturation adiabat up to 500 hPa.

The temperature where the saturation adiabat crosses the 500 hPa isobar = T′ = -7°C.

The temperature of the environment at 500 hPa = T500 = -10°C.

SSI = T500 - T' = -10 -(-7) = -3
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