Most of RI and SE MA is under a Winter Storm Warning for the quick-hitting burst of snow that is likely to bring several inches to Southern New England in a relatively short period of time Saturday afternoon and night. The areas shaded in pink are under a Winter Storm Warning, which generally means that 6 or more inches of snow is imminent. The areas shaded in purple are under a Winter Weather Advisory for less snow as a result of lighter precipitation or some mixing with rain.
The National Weather Service also offers snow probability forecasts for a given amount. The odds of at least 1″ are near certain for most of the area. The odds of 4″ are also quite high. In the areas that are expected to be hardest hit, the NWS is estimating a nearly 50/50 shot of 8″ of snow, and a 1 in 4 chance of a foot.
Overall, I think the odds projected by the NWS are decent. The only thing I would consider is slightly lower odds of reaching 8″ of snow. If the storm travels just a bit quicker than expected, or if the snow isn’t quite as heavy as forecast, than most of the ares will come up shy of 8″. I’d be in the 25-35% range for 8″ totals in the hardest hit areas.