Atmospheric Stability API Parameters

Convective Available Potential Energy (CAPE) | Convective Inhibition (CIN) | Lifted Index | Thunderstorm Probability

| Thunderstorm Height

Convective Available Potential Energy (CAPE)

The convective available potential energy (given in joules per kilogram air) is the amount of energy a parcel of air would have if lifted a certain distance vertically through the atmosphere. Any value greater than 0 J/kg indicates instability and an increasing probability of thunderstorms and hail.



Convective Inhibition (CIN)

The convective inhibition (given in joules per kilogram air) is the amount of energy required to lift the parcel to the level of free convection (LFC). While high values (150 J/kg and above) of CIN suppress thunderstorm development, lower CIN values suggest favorable thunderstorm development conditions (i.e. when CIN is 30 J/kg or less).



Lifted Index

The lifted index (given in Kelvin) is the difference between the temperature of the environment and that of an air parcel lifted adiabatically to a given pressure height in the troposphere, usually 500 hPa. The atmosphere at the given height is stable for positive values of the lifted index and unstable for negative values. When the value falls below -2, thunderstorms are anticipated. and for lower values, especially those below -6, severe weather is expected.



Thunderstorm Probabilities

Gives the probability of a thunderstorm to occur.


Available intervals: 1h, 2h, 3h, 6h, 12h, 24h


  • Show a thunderstorm probability forecast for the next two days: Prob tstorm
  • Below is an image of the thunderstorm probabilities on June 28th at 15 UTC over Europe:,-15_35,30:0.1,0.1/html Probability tstorm


Thunderstorm Height

Gives the height of a thunderstorm during the requested interval. A value is returned only if a thunderstorm occurence is likely. If m or ft are queried as a unit then the value above sea level is returned.
If the likelihood is none, a value of -666 is returned. In case no data is available, a value of -999 is reutrned.


Available intervals: 1h, 2h, 3h, 6h, 12h, 24h

Available units: m, ft, FL, hPa