Understanding the different types of winter precipitation

Winter storms are notorious for their dangerous wintry precipitation. Heavy snow, sleet, and ice can all have significant consequences on our everyday lives. This article will dive into the different types of wintry precipitation, how to differentiate them, and under what conditions they form.

Freezing rain is often the most dangerous kind of winter precipitation. This is because it does not freeze until it hits the ground, turning roads and other surfaces into a slippery ice sheet. It could also cause power outages and topple trees due to the ice's added weight on powerlines and branches.

Like freezing rain, sleet forms when liquid raindrops fall from a layer of warm air into a layer of freezing air that hugs the surface. However, in contrast to freezing rain, the freezing air layer is much thicker during a sleet event, allowing the raindrops to freeze into transparent ice pellets before reaching the ground.

Sleet is as dangerous as freezing rain as it tends to accumulate into a slushy or frozen layer on surfaces. Freezing rain and sleet can be tracked on the WeatherRadar and is highlighted by the area in pale orange.

This is the kind of precipitation that we all think of when dealing with a winter storm. In most cases, snow reaches the ground when the entire column of air between the cloud and ground is below freezing. Heavy snow occurs when there is a lot of moisture in the atmosphere, which is usually the case during the strongest storm systems.

Graupel is the least-known type of winter precipitation and is often mistaken with hail. Graupel is best described as soft, small pellets that form when supercooled water droplets (at a temperature below 0C) freeze onto a snow crystal—a process called riming. Unlike hail, which can grow several inches in diameter, the more brittle graupel is usually less than one-fifth of an inch in diameter.

Winter storms can also bring heavy rain, especially to areas south of the storm where temperatures tend to stay warmer. Rain will either start as a liquid drop or snow in the upper levels of the atmosphere and then reach the surface as liquid because temperatures on the ground are above freezing.