As we found out, from that “fun” end to the work/school week last week, winter weather can come in many forms. Whether it’s snow, sleet, or freezing rain, it sure can cause quite a headache! So, why do we get snow and not sleet, or freezing rain and not snow? You’re about to find out!
It all starts high above the surface! Precipitation starts fairly high up, in a cold layer, where it is frozen in the form of snow. As it makes its way towards the surface: it can stay frozen as snow, all the way to the surface, as long as the surface is below freezing; it can melt and remain in the form of rain all the way to the surface, as long as the surface is above freezing; or, when the surface is below freezing, it can pass though various cold and warm layers, at various levels, and fall as freezing rain or sleet!
The type of precipitation, other than snow or rain, that the precipitation falls as then depends on the depth of the cold and warm layers it falls through before reaching the surface. If it starts in the cold layer, moves through a shallow warm layer, and then falls through a deep cold layer, it will melt briefly, before refreezing through the cold layer, and falling as sleet at the surface. However, if it is reversed, and the precipitation moves through a deep warm layer, and then falls through a shallow cold layer, the precipitation will completely melt through the warm layer and then move through the cold layer, near the surface, and fall as freezing rain, which falls as rain, but freezes on contact as it hits the sub-freezing surface.
All types of winter weather can be hazardous, but freezing rain is particularly dangerous, because, as it freezes on contact, even the smallest amount of accumulation, can create turn roads and sidewalks into sheets of ice, or create black ice on roadways, making travel extremely difficult and incredibly dangerous, since most cars have little to no grip or traction on ice.
Stay safe this winter!
-Forecaster Maggie Warren