CAPE (Convective Available Potential Energy) Index reflects the presence in the atmosphere of a certain amount of energy that can be used for convection.
In other words, it is an indicator of atmospheric instability, which can lead to showers, thunderstorms, and squalls. That's why, many athletes and sailors, fearing these and other extreme weather phenomena, check CAPE before going to sea.
The index is measured in J/kg (joules/kilogram):
Now you can find this extremely useful professional feature in Windy.app version 9.4 for iOS (and Android before). To do so:
1. Open your favorite spot or the nearest to your current location.
2. Choose Sail, Air or Expert Weather Profile by an icon righ to weather forecast models:
3. Find CAPE Index in the weather parameters on the left of the screen:
4. You can also add CAPE to your custom weather profile, using Customization feature: