Lifted Index (LI) - Best 4 Layers

The lifted index (LI) is the temperature difference between an air parcel lifted adiabatically Tp(p) and the temperature of the environment Te(p) at a given pressure height in the troposphere (lowest layer where most weather occurs) of the atmosphere. When the value is positive, the atmosphere (at the respective height) is stable and when the value is negative, the atmosphere is unstable.

LI is generally scaled as follows:

LI 6 or Greater, Very Stable Conditions
LI Between 1 and 6 : Stable Conditions, Thunderstorms Not Likely
LI Between 0 and -2 : Slightly Unstable, Thunderstorms Possible, With Lifting Mechanism (i.e., cold front, daytime heating, ...)
LI Between -2 and -6 : Unstable, Thunderstorms Likely, Some Severe With Lifting Mechanism
LI Less Than -6: Very Unstable, Severe Thunderstorms Likely With Lifting Mechanism