Our last couple of winter storms have had a lot of people asking us one big question...Why is it raining at my house when the temperature is below 32 degrees?  It can be confusing, but hopefully this blog will help.  For the answers we have to look not only at what is going on at the surface, but also higher up in the atmosphere.  Lets start at the top and work our way down.  1. Within the clouds and just below, temperatures are cold enough for precipitation to start falling as snow.  That seems easy enough, but here comes the clincher... 2. Generally, the air cools as you go higher in elevation, but during freezing rain and sleet events this isn't the case.  In these situations, a layer of air-warmer than 32 degrees-moves in between the clouds and the cold air trapped at the surface.  As the snow falls through this layer it melts.  Now, you're likely to have rain or sleet, instead of snow.  3.  The final layer to take into account is at the surface.  In sleet and freezing rain situations there is a cold layer of air where we take our temperature measurements.  (This is below the warm layer).  The depth of the cold air plays a big role in what type of wintry weather we see.  If the layer is thick enough, sleet will likely be the precip type.  However, if the cold layer at the surface is very shallow, then the rain from layer 2 doesn't have enough time to freeze, before it hits the surface.  At this point, what looks like rain freezes on the cold surfaces and thus we get freezing rain.

(Graphic Source:  University of Illinois)

Hopefully this clears things up a little bit.  In the meantime...stay safe out there!

Meteorologist Kyle Mounce

WPSD NewsChannel 6