Meteorologists Alyssa Andrews and Tucker Antico explain the weather science behind the Plainfield, Indiana fire at a Walmart distribution center. The smoke could be seen on radar and visible satellite this Wednesday on what would otherwise be a very clear day.
You may think of radar as something we only see precipitation on. However, the pulses sent out from radar sites can pick up other particles in the air. Sometimes, we can even see flocks of birds migrating. Certainly not only rain! This time, it was thick smoke.
Another way to see that smoke traveling north from the southerly breeze: the Correlation Coefficient! Notice the blue spike towards Kokomo. We usually use this radar tool in a storm capable of producing a tornado as a way to track debris. This radar image below can show us where particles are different than the air around it (debris particles from smoke).
You may have been able to see some of this smoke around your house, miles and miles away from were the fire originated. As the warm air rises, winds change direction with height high above the surface. That can allow the smoke to appear wrapped around the horizon, and correlate with winds shifting more southwesterly aloft (vs the stronger south breeze at the surface).
Luckily, this was a warm, clear day. Warm surface temperatures were in the low 70s this afternoon. Warm air at the surface is less dense than cool air high in the sky. This warm (buoyant) surface air wants to rise. Along with it, it took the smoke directly up in the sky, rather than spreading out at the surface.
That’s a good thing when we’re talking about air quality. The issue, however, may come in the overnight hours when temperatures at the surface drop down and cool off. A low level inversion may occur, which causes temperatures to actually warm with height, rather than cool off. If that happens, it could act as a cap in the atmosphere, not allowing the smoky air to rise up, and away from the air we breathe.
