HELENA — A recent prescribed burn of more than 300 acres to the southwest of the capital of Montana created a significant amount of smoke, startling some people. For years, fire mitigation has occurred in this area to prevent or slow a hypothetical wildfire that could burn into Helena.
Where there's fire, there's smoke. And sometimes a lot of it. After the prescribed burn, thick smoke settled in the downtown area, producing unhealthy air quality.
Some people questioned the decision to burn, and the weather conditions in which the burn was performed. The prescribed burn was very successful, with firefighters achieving their goal. The wind was fairly light, reducing the risk of the fire getting out of control. There was high pressure in place, creating calm atmospheric conditions. However, at night, high pressure causes sinking air. Air acts like a fluid, and drains down to the lowest point. The weather conditions forced smoke-filled air to sink down from behind Mount Helena, right into the downtown area. As the high pressure moved away, the atmosphere began to mix, the smoke dispersed, and the air quality improved.
While the wind was light enough for firefighters to control the fire, there was not enough wind to quickly carry and clear the smoke. weather conditions, the location of the burn, and the geography of the area created a brief, unpleasant period of smoke, but hopefully paid significant dividends in the long run.
