The days are getting shorter, temperatures are getting cooler and before we know it, snowflakes will begin showing up in the forecast.

Each winter, the terms sleet, rain, snow and freezing rain are used in our forecast quite frequently. These types of winter weather can cause hazardous conditions, but how do they form, and how are they different?

How do the different types of winter precipitation form?

During the winter season, precipitation starts in the clouds as snow due to the clouds being cold enough (below 32°F) for snowflakes to develop. As the snowflakes begins to fall, the temperature of the air between the cloud and the ground dictates what type of precipitation will reach the ground.

The formation of each type of winter precipitation depends of the temperature of the air between the cloud and the ground.

For snow to fall, the column of air between the cloud and the ground must be below 32°F.

If the column of air between the cloud and the ground is above 32°F, the snowflakes will melt into raindrops and will fall as rain.

The next type of winter precipitation is freezing rain. This type of winter precipitation occurs when snowflakes fall into a deep layer of warm air above 32°F. The above-freezing air causes the snowflakes to melt into raindrops. The raindrops then fall into a layer of air below 32°F just above the surface and are supercooled instead of re-freezing. Since the raindrops are supercooled, they instantly refreeze upon contact with anything that is at or below freezing, creating a glaze of ice on the ground, trees, power lines and other objects. Freezing rain is typically the most dangerous type of weather precipitation.

The final type of winter precipitation is sleet which forms when snowflakes fall into a shallow layer of warm air above 32°F. The above-freezing air causes the snowflakes to melt into raindrops. The raindrops will then fall into a layer of air below 32°F. The below-freezing air causes the raindrops to freeze into tiny ice pellets known as sleet before hitting the surface. Sleet is often confused with hail.

As we head through fall and head towards winter, it’s important to familiarize yourself with the different types of winter weather and to be prepared for when winter weather hits. You can always stay up to date with the forecast here.