So far based on observations, the snow amounts in South Dakota seem to be following the Kuchera method. if that continues to be the trend with the storm, here are the model maps for the kuchera methods based off the NAM model. The GFS seems to be too low so far while the NAM seems to be to better with snow amounts. Just an observation to share. Something tells me that localization of the models will do best in this storm given the convective nature.
From the COD Meteorology Site.
Snowfall Accumulation (Kuchera Method)
Total Snowfall Accumulation
The snowfall amount is then calculated by multiplying ratio by the forecast QPF. The amount displayed is cumulative, starting at the beginning of the model run and accumulating throughout the entire forecast period.