Lightning potential
Thunderstorms Lightning Potential Index LPI
Lightning potential is a calculated indication of how favourable cloud conditions are for electrical discharges. It is not a measurement of lightning that has already occurred.
How a cloud becomes charged
Ice particles, graupel and supercooled droplets collide inside a thunderstorm cloud. These interactions can separate electric charge. Updraughts and downdraughts distribute the particles, allowing large electrical differences to build. Lightning discharges part of that imbalance.
What the model calculates
The Lightning Potential Index (LPI) combines information about updraughts and water or ice particles in clouds. The model product used here reports it in joules per kilogram (J/kg). Larger values indicate conditions more favourable for lightning activity.
Neither a flash count nor a percentage
- 10 J/kg does not mean ten flashes.
- A maximum does not identify a certain strike location.
- Values from different methods are not automatically comparable.
Observations matter for the immediate situation
A cell may move differently, develop later or fail to form. Lightning networks report detected discharges, while radar shows precipitation development. Both complement model charts. If thunder is audible, a low model value is not an all-clear: shelter and current official warnings matter.