It’s been a while since we’ve done some Meteorology 101, so let’s have some fun!
First of all, to get a BIG snow we need:
1) A well developed low pressure center passing to our south or southeast.
2) This has to happen with cold air in place.
We are going to get the first part. It’s the second part that may lag behind keeping us from getting a big snow, but still allowing some flurries and snow showers.
The maps above are from a computer model called the GFS. The top panels are forecasts of the surface isobars for 6am Wednesday and 6am Thursday. The bottom panels are the corresponding forecast of the precipitation for the 6 hours ending at 6am Wednesday and Thursday. The bottom panels also have a black line that is the forecast of the freezing line for 850 millibars (or about 5,000 ft.). This is often (but not always) where the rain/snow transition is.
In the top panels, you can see our Gulf Low bringing us copious amounts of rain on Wednesday when that black freezing line at 5,000 ft. is well to our northwest (we’re on the above freezing side). By Thursday morning, the low is well past us, and the black line has pushed to the Smokey Mountains (now we’re on below freezing side). If you are one hoping for that big snow, unfortunately the colder air comes in after the low has passed us. However, there still will be enough leftover moisture (along with an upper level disturbance) to cause some snow flurries late Wednesday night through Thursday morning. If the two could have been more in sync, we could have seen 3″ or more. This is something we will be watching for as we head through winter. For now, enjoy some flurries if we get them. The chances increase the farther east you are in Middle Tennessee.



















