SAVANNAH, Ga. (WSAV) — It has been cold across the Southeast over the past few days, and this cold air will persist through the end of the workweek. With temperatures 10 to 20 degrees below average and a storm system on the way, portions of the Southeast may experience a wintry mess. A major question with this storm is which areas will experience only rain and which areas will see a wintry mix of snow. The latest model guidance shows better agreement as to where this rain and snow line will set up. For us in the Coastal Empire and Lowcountry though, we will likely see all rain. The further north you go into Georgia and South Carolina, things start to change, especially in the Appalachian Mountains. To snow or not to snow: End of this week compared to 2018 snowstorm So what needs to happen for different precipitation types to form? Let's start with rain. Up in the clouds, the air is below 32 degrees, which is cold enough to have frozen water drops or snow. As these flakes fall and encounter a warm layer of air that is above 32 degrees, the snow melts into a raindrop. With this warm layer of air extending to the surface, anything that falls out of the clouds will reach the ground as rain. Now let's talk sleet, which is another form of frozen precipitation. We once again start in the clouds with temperatures below 32 degrees. As the precipitation falls, we reach a thin layer of warm air in the middle of our column. With temperatures briefly above 32 degrees, the snow crystal will start to melt before re-entering another cold layer. As the partially melted snowflake falls back into this cold layer of air, it will re-freeze forming small ice pellets. These ice pellets can be dangerous on the roads as they create very slick conditions and interfere with your tires. When driving through sleet, it is best to drive slowly and keep enough space between yourself and the car in front of you. Next, we have freezing rain, which can cause black ice on our roadways. As precipitation falls out of the clouds as snow, we once again interact with a warm layer of air that is much thicker than when we are dealing with sleet. Upon reaching this layer, snow will melt into raindrops and remain a raindrop down to the ground. As we get near the ground, however, we encounter another cold layer of air, except this one is very shallow, sometimes only extending a few hundred feet above the surface, which is not enough time for the rain to re-freeze. As these raindrops hit the surface, they freeze on contact which glazes our homes, roads, and even vegetation in a thin layer of ice. This is the kind of precipitation that can be the most dangerous because on the roadways, this ice is hard to see and if drivers are not cautious, it can lead to accidents and big time travel impacts. Finally, we have snow, which here in the Coastal Empire and Lowcountry is pretty hard to come by. This type of precipitation is far less complicated than sleet or freezing rain. For snow to fall, you need a cold layer of air below 32 degrees to extend all the way down to the surface. If this happens, snow can remain frozen while traveling down to the surface and start to accumulate.