Skew-T Procedure
- Find the temperature (T) and dewpoint (Td) at 850 hPa
- From that T and Td, find the LCL
- From the LCL lift the parcel moist adiabatically to 500 hPa and find the parcel temperature (T′).
- Given the 500 hPa sounding temperature (T500), SSI is computed as follows:
SSI = T500 - T′