A wildland fire event where the main fire crosses a fireline, containment line, or natural barrier, establishing itself on the unburned side. It usually occurs adjacent to the established line, unlike a spot fire which is ignited by flying embers further away. Crews must quickly flank and contain a slopover before it compromises the entire defensive strategy.
Heard on the job
We had a small slopover on Division Alpha, but the hand crew caught it before it hit the ridge.
Insider tip
Treat a slopover as an immediate threat to the line; if left unchecked, it renders the existing containment line useless.