Weather Blog: Winter Precipitation Types And What You Need To Know

Winter in Oklahoma can bring rain, freezing rain, sleet and snow. It’s important to know which type of precipitation is expected and the impacts of each.

Forecasting winter weather can be tricky. Temperatures, at surface and aloft high in the sky, along with cloud depth and moisture availability in general determines which type of wintry precipitation we see at the surface.

Why are there different types of wintry precipitation?

Precipitation begins in the clouds as ice or snow. The temperature profile from the cloud to the surface will vary at different levels. As the snow from clouds fall, it will change depending on how warm or dry the layer it encounters. If the layer of air is warm enough, it would melt into rain (which happens in our warmer months). 

During the winter, the layer of warm air may not be thick enough or warm enough to completely melt the snow and we end up with different precipitation types. When ground temperatures dip below freezing, our wintry precipitation starts to give us trouble.

What is freezing rain and why is it so dangerous?

When temperatures at the surface are below freezing but there is a deep enough warm layer aloft to melt the snow before it reaches the surface, precipitation will fall as freezing rain. It’s raining but the rain will freeze on contact. It is the most dangerous kind of wintry precipitation. Roads can quickly become covered with a layer of ice, making them very slick and hazardous. Often it’s hard for drivers to see because it’s clear and leads to many crashes. Ice accumulation also weighs down power lines and tree limbs, causing power outages and tree damage.

What is sleet?

Sleet is essentially ice pellets that have refroze before making it to the surface. Temperatures at the surface are below freezing but the layer of warm air aloft is more shallow than with freezing rain. Snow partially melts within the warm layer aloft, then refreezes in the colder air before reaching the ground. Sleet, like freezing rain can make roads very slick. You can also sleet bounce off your car or the ground when it makes contact.

How do we get snow?

Snow, the holy grail of wintry precipitation requires temperatures from the cloud layer to the surface to be below freezing. There is a small caveat, if a very shallow layer of warm air is at the surface but the rest of the temperature is below freezing then there will probably not be enough time for the snowflake to melt. Thus, it could still be snowing while temperatures are above freezing at the surface! Snow can make roads slick and cause power outages. Heavier snow coupled with strong winds can greatly reduce visibility making travel even more difficult.

What should we do when winter precipitation is in the forecast?

It is very important be aware when winter weather could impact us. When we forecast wintry precipitation, know that roads could become slick and sometimes hazardous. We may also have power outages and depending on the severity of the winter storm, power outages can last for days or even weeks.