According to the National Snow & Ice Data Center, blizzard prediction relies on modeling weather systems, as well as predicting temperatures. When a weather system moves through an area experiencing near- or sub-freezing temperatures, it can create the potential for anything from freezing rain to a full-fledged blizzard.
The heavy snowfall that blizzards create can be hard to predict in advance. A computer model might indicate a potentially wet weather system moving into an area, and it might indicate temperatures falling into a range that could produce significant amounts of snow. However, the exact timing of these weather events can mean the difference between feet of snow and a cold, wet rain.
In addition, a storm moving into an area that has already seen heavy snowfall can create a ground blizzard, as high winds blow loose snow and create dangerous conditions. For this reason, the National Weather Service issues weather watches well in advance of potentially dangerous winter storms, allowing the public to adjust their plans and take precautions. However, the systems that produce blizzards can be difficult to model and predict more than 24 hours in advance, especially in areas of the country that are not used to severe winter weather.