First Alert Weather In-Depth: What is above your head really counts
ROCHESTER, N.Y. – It is always a big challenge to forecast the weather in the winter and specifically trying to discern the type of precipitation – especially when it comes to a warm front. Think of the choices. There could be snow, sleet, freezing rain or maybe just all rain.
Currently, Western New York has a warm front or a quasi-stationary front in the neighborhood and the type of precipitation is highly dependent on where this front is located. A three-dimensional view of the atmosphere shows that the warm air will rise up over the top of that cold air. In meteorology we call this “overrunning.” This happens when the warm air is in motion aloft and rises above the colder, more dense air mass at the surface.
If you can imagine this three-dimensional view of the atmosphere, then we can apply this to what is going on above your head just a few thousand feet in the atmosphere. This is commonly thought of as the atmospheric column of the air. If the column is completely warm the precipitation may come down as just rain. However, get a little wedge of cold air (below freezing) at the surface that rain will freeze on contact with the surface. But if that wedge of cold air is a little bit thicker, then it has a better chance of falling as sleet. If the column is entirely cold it has an excellent chance of being all snow. And maybe a lot of snow of snow! Typically we will see each of these examples at some point in the winter season.