(COLORADO) — With afternoon showers and thunderstorms in the forecast, it’s a good time to talk about a smaller-scale weather feature that can have a big impact: the outflow boundary.

An outflow boundary forms when cooler air from a thunderstorm’s downdraft spreads out along the surface. As it moves, this cooler air acts like a mini cold front, colliding with warmer, more humid air nearby, which is necessary for thunderstorms. When that happens, the lift created by the collision of air masses can trigger new storms and sometimes even more intense than the original one.

These boundaries are something the FOX21 Storm Team closely monitors during active weather days. They’re often the reason storms pop up in areas that seemed quiet just an hour earlier, and sometimes models don’t pick up on them. 

So the next time you hear “outflow boundary” in a forecast, you’ll know it’s not just a technical term, it’s a clue that more storms could be on the way.