It takes a lot for snow to form. Many conditions have to be met before we'll see snow in the Brazos Valley. Then assuming we get snow, that doesn't mean that it's going to stick.
The first thing we need for any kind of precipitation is moisture. Without moisture, we won't see any precipitation of any kind. The first step in snow formation is the formation of a cloud. Snow forms in much the same way that rain does, except temperatures in the cloud are always below freezing. Tiny ice crystals in this cold cloud bump into each other and stick together, forming the snowflakes. In the case of rain, there may be cloud droplets instead of ice crystals, although we can see ice crystals that later melt and rain will still occur.
Of course we need cold temperatures for snow, and we need cold temperatures from the cloud all the way to the ground. If the air near the surface is too warm, the snow will melt before it reaches the ground and we'll get a cold rain. If a pocket of warm air exists between the cloud and the ground, snow will fall from the cloud, melt as it enters the warmer air, then refreeze before hitting the ground. This is how freezing rain is formed.
As exciting as it is to see the snow falling, that alone won't bring us snowmen, snowball fights or forts. The snow has to accumulate, commonly called sticking. In order for this to occur, the ground has to be cold enough so that the snow won't melt when it hits the ground. Grass and exposed structures like bridges will cool first, while roads remain warmer. This is why you'll begin to see snow piling up in your lawn before your street or driveway.
What should happen in the Brazos Valley?
Models indicate the temperature profiles look cold enough in both the surface and higher up in the atmosphere for snow. Temperatures remain below freezing from the surface upward. The big question is will enough moisture move in before the disturbance does. As of Thursday evening, it looks like enough moisture will make its way into the area for some light snowfall. Accumulation is tricky as well. The first snow that falls will not stick. The ground's simply too warm. But with falling temperatures throughout the day, some of the later snow may hold on for awhile.
Regardless of the snow/ no snow issue, it will be cold. Winter weather advisories, winter storm watches and a freeze warning have been issued for parts of the Brazos Valley. Make sure your pets are taken care of. Either bring them inside or make sure they have a nice warm shelter. Your plants need to be protected as well. Move the most sensitive plants indoors, and cover your other plants with cloth rather than plastic which cuts off the air supply to the plant. Any exposed pipes should also be covered. And don't forget to take care of yourself either! Dress warmly, in layers. Dig out your hats and mittens from the back of the closet, you'll need them!