Unlike our last 2 big winter weather events which were all snow, this one will be more of a mix. That makes the forecast very difficult. Generally, an inch of rain converts to about 10 inches of snow. Once you start adding sleet and freezing rain into the equation with different ratios, the numbers get a lot harder to get a handle on. If you miss the timing or temperature by just a very tiny bit, it can make a large difference in the forecast.
The Saint Louis Metro area is under a Winter Weather Advisory through early Tuesday morning. These locations are looking at mostly snow with some sleet and light freezing rain mixed in. Snow accumulations of 1-3 inches are possible with about 1/4" of sleet and a light glazing of ice.
The Southern portion of our viewing area is under a Winter Storm Warning through early Tuesday. These locations are looking at mostly sleet and ice, with less snow. Significant ice and sleet accumulations are possible with up to a half inch of ice and/or up to an inch of sleet. Generally 1/4" of ice is enough to start to cause big problems with trees and power lines.