A sailor? You need a CAPE Index


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):

  • <0 J/kg — stable state: no Cumulus or Cumulonimbus clouds, heavy rainfall, thunderstorms, etc.;
  • 0-1000 J/kg — slight instability: if there is enough moisture in the air, there are Cumulus clouds (Cu), Cumulonimbus clouds (Cb), light rainfall, thunderstorms are possible);
  • 1000-2500 J/kg — moderate instability: Cumulonimbus clouds (Cb) with heavy rains, thunderstorms;
  • 2500-3500 J/kg — high instability: thunderstorms, sometimes heavy, hail, squalls;
  • ≥ 3500 J/kg — very high instability: heavy and very heavy thunderstorms, tornados.

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:


Read more about Cape Index

Read about 14 other ways of Windy.app customization

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