Insider Blog: How a power plant “created” its own snow to share with Wisconsin communities

The National Weather Service in Milwaukee confirmed it on Twitter today; a power plant in Portage, Wisconsin unintentionally gave the atmosphere just what it needed to make snow this morning.

Baffling at first, this unexpected snow band turned out to be the result of something not that unusual. 

To understand how industrial exhaust can result in snow, we first need to understand a key variable to this equation; temperature inversions. 

On an average sunny day, you can typically expect the atmosphere to look like this, warm at the surface and cooling with height. 

However, there are times where the surface temperature is cooler than the atmosphere above it. This is usually the case when we have a low, overcast sky. This prevents air from rising and traps particles and moisture near the surface. 

That was the case this morning over Portage, Wisconsin. Visible satellite shows that blanket of low clouds overhead; a sign of a temperature inversion. 

The added moisture from the power plant's steam was trapped by the inversion, keeping it stuck in already cold and saturated air. 

This provided the right moisture and temperature conditions for efficient snow production, creating a band of snowfall that blew downwind. 

It also created an interesting spectacle on radar that couldn't otherwise be explained.