What CAPE can tell you
CAPE is expressed in joules per kilogram, written J/kg. Larger values can support stronger rising motion if storms develop. The scale represents potential energy, not the number of storms or the distance to the nearest lightning strike.
Read the forecast time carefully and compare the pattern over several frames. A broad area of instability is useful context, but it is not a boundary within which thunder is certain and outside which it is impossible.
Storms need more than instability
Thunderstorm development also depends on moisture and a mechanism that lifts the air. Other atmospheric conditions influence whether storms organise and how they move. A high CAPE value can occur without a thunderstorm developing at a particular place.
Compare the outlook with precipitation forecasts, available recent imagery and official warnings. A radar return describes precipitation; it should not be presented as a lightning detection unless the provider explicitly supplies that separate observation.
Use the outlook before you leave
For summer outdoor plans, check the forecast again close to departure and keep an alternative plan for a changing situation. Thunderstorms can be very local, and the map cannot establish a safe distance from every developing cell. If thunder is heard, seek suitable shelter and follow the advice of your national weather service. Do not wait for a colour on this map to confirm what you hear.
Questions about this map
Is this a thunderstorm radar or a live lightning map?
No. The initial layer is modelled CAPE. It shows atmospheric potential, not the time and location of observed lightning strikes.
Does low CAPE mean there is no thunderstorm risk?
No single parameter can rule out every situation. Use the full weather picture and official warnings rather than a fixed threshold on this map.