Bersallis III from orbit.
Bersallis III is a planet within Federation space and, until 2369, home to a Federation colony.
The planet is subject to violent firestorms every seven years. The firestorms form when solar flare radiation from the planet's sun reacts with high energy plasma present in the planet's atmosphere. While the next firestorm was expected for 2370, in 2369 one unusally large and fast-moving firestorm overwhelmed the colony's defenses established for that purpose. The USS Enterprise (NCC-1701-D) was dispatched to the planet to evacuate the colonists before the firestorm destroyed the colony.
The surface of Bersallis III during a firestorm.
Lieutenant Commander Nella Daren led an away team to the surface to establish a barrier using thermal deflector units, a technique she was familiar with through previous experience. The mission was ultimately successful and the 643 colonists were evacuated but eight members of the away team were lost. (TNG: "Lessons")