You may have heard the words "Alberta Clipper" mentioned a lot recently in relation to the weather.
These are low pressure centers that usually drop into the U.S. from Alberta, Canada, most often traveling through The Ohio Valley before turning northeastward. See first graphic.
They move fast, and are known in the Mid-West to bring a quick, short lived snow often in the 3" or less category.
For us farther to the south, it has only meant a few rain showers that end in snow flurries and snow showers when the cold air drops in behind the low.
That has been the general weather pattern for almost a month now.
So what's it take for Middle TN to get a big snow?
The answer: A Gulf low mixing with some arctic air.
Gulf lows bring plenty of moisture with them, and IF you can get the cold air in place to mix with that, a large 3-6" or greater snow can occur. That low also needs to pass to our south. See second graphic.
The problem in Middle TN is that often, the cold air is a little out of sync with the Gulf moisture causing the precip to begin as rain before changing to snow. That by its very nature makes it hard to predict accumulations.
If the moisture outruns the cold air, you don't get the big amounts.
BUT, when the cold air is already in place when the low moves our way, it's time to break out the snow sleds!
Unfortunately, I don't have this scenario in our 7 Day Forecast this week.
Another 2 Clippers will bring cold arctic air behind them, but only flurries and snow showers with the cold air.