Forecasting winter precipitation types in Mid-Missouri

Forecasting wintry weather in Mid-Missouri can be tricky, because we’re located in the mid-latitudes, meaning the freezing line tends to wobble right over us.

This can present several forecasting challenges, especially when trying to forecast winter precipitation days out from an event.

Temperatures play a huge role in winter forecasting. We look at temperatures through the entire atmosphere because they determine the type of precipitation we see.

We also look at the amount of moisture in the atmosphere, because even if air is saturated above the ground, dry air in the lower and middle levels of the atmosphere could evaporate precipitation before it reaches the ground.

Last, we look at the track and speed of the storm system. If it’s moving to our north and quickly, we may get less snow than if it were moving at a slower speed. Typically, if storms track just to our south with Gulf moisture, we tend to pick up more snow.

When storms originate to our northwest, specifically over Canada, and drop south, they tend to move more quickly, bringing less snow and a high snow to liquid ratio.

In Mid-Missouri, we can experience all types of wintry weather. When the entire atmosphere above us is below freezing, or 32 degrees, we will see snowfall.

Sometimes, a warmer layer of air develops just above the surface of the atmosphere where temperatures exceed 32 degrees, even though temperatures at the ground may be colder. This is called an inversion.

When this layer or short or not very dense, snow falling in the upper part of the atmosphere falls through this short layer and melts slightly before refreezing just above the surface. This is called sleet.

Finally, when the layer of warm air is thicker but temperatures are at or freezing at the ground, snow falls into this layer and warms enough to become rain. The rain reaches the ground and solidifies on contact with the ground or objects at the surface to form ice. This is known as freezing rain.

When temperatures are above 32 all the way through the atmosphere and at the ground, we see rain.