Atmospheric Stability API Parameters
Convective Available Potential Energy (CAPE) | Convective Inhibition (CIN) | Lifted Index | Thunderstorm Probability
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.
cape:JkgExamples
- Below is a chart containing CAPE values on the 18th of August 2017 when a severe thunderstorm hit Switzerland in the evening. One can clearly make out the increasing instability of the atmosphere.
-
Here you can find a two day forecast of the CAPE:
https://api.meteomatics.com/2024-04-24T00:00:00ZP2D:PT1H/cape:Jkg/47.412164,9.340652/html
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).
cin:JkgExamples
- Below is an image containing the CIN values over the US on September 20, 2021 at 15 UTC, while thunderstorms were passing over Wisconsin and off the Florida coast. The image was generated using https://api.meteomatics.com/2021-09-20T15:00:00Z/cin:Jkg/USA:0.05,0.05/html_map
-
Here you can find a two day forecast of CIN:
https://api.meteomatics.com/2024-04-24T00:00:00ZP2D:PT1H/cin:Jkg/47.412164,9.340652/html
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.
lifted_index:KExamples
- Below is a chart containing the lifted index values on the 18th of August, 2017, when a severe thunderstorm hit Switzerland in the evening. We observe the rapidly decreasing values around 18h when the storm formed.
-
Here you can find a two day forecast of the lifted index with the corresponding json file:
https://api.meteomatics.com/2024-04-24T00:00:00ZP2D:PT1H/lifted_index:K/47.412164,9.340652/json
Thunderstorm Probabilities
Gives the probability of a thunderstorm to occur.
prob_tstorm_<interval>:pAvailable intervals: 1h, 2h, 3h, 6h, 12h, 24h
Examples
- Show a thunderstorm probability forecast for the next two days:
-
Below is an image of the thunderstorm probabilities on June 28th at 15 UTC over Europe:
https://api.meteomatics.com/now/prob_tstorm_1h:p/70,-15_35,30:0.1,0.1/html -
https://api.meteomatics.com/now/prob_tstorm_12h:p/70,-15_35,30:15,15/json
{"version":"3.0","user":"api-test","dateGenerated":"2018-02-21T14:51:41Z","status":"OK","data": [{"parameter":"prob_tstorm_12h:p","coordinates": [{"lat":35,"lon":-15,"dates":[{"date":"2017-08-01T00:00:00Z","value":12.9}]}, {"lat":35,"lon":0,"dates":[{"date":"2017-08-01T00:00:00Z","value":44.2}]}, {"lat":35,"lon":15,"dates":[{"date":"2017-08-01T00:00:00Z","value":23.4}]}, {"lat":35,"lon":30,"dates":[{"date":"2017-08-01T00:00:00Z","value":86.4}]}, {"lat":50,"lon":-15,"dates":[{"date":"2017-08-01T00:00:00Z","value":16.1}]}, {"lat":50,"lon":0,"dates":[{"date":"2017-08-01T00:00:00Z","value":14.3}]}, {"lat":50,"lon":15,"dates":[{"date":"2017-08-01T00:00:00Z","value":22.2}]}, {"lat":50,"lon":30,"dates":[{"date":"2017-08-01T00:00:00Z","value":11.4}]}, {"lat":65,"lon":-15,"dates":[{"date":"2017-08-01T00:00:00Z","value":11.8}]}, {"lat":65,"lon":0,"dates":[{"date":"2017-08-01T00:00:00Z","value":13.6}]}, {"lat":65,"lon":15,"dates":[{"date":"2017-08-01T00:00:00Z","value":21.5}]}, {"lat":65,"lon":30,"dates":[{"date":"2017-08-01T00:00:00Z","value":17}]}]}]}
