There's some good news I guess. Based on the 00z EPS, the extreme forecast index is okay for the AEMATT crowd.
This index essentially shows how unusual the EPS forecast is based on the last 20 years of the model climate in the 5 weeks centered on the date (the climate built by many model runs, not state of the climate according to the model). Values between 0.5 and 0.8 are unusual, above 0.8 very unusual or extreme. A value of 1 means that every EPS member is more extreme than the model climate.
The thing to keep in mind is that significant snowfall, even in the winter, is unusual. Most days it doesn't snow. But there is a signal for some significant impacts possible according to the EPS.
Also note that this index doesn't say how extreme. It could be a little more extreme than the model climate, or a lot more extreme. That's where the black lines come into play, that's the shift of tails (SOT). A value of 1 indicates that the 90th percentile of the forecast is one times the distance between the 90th and 99th percentile of the model climate. A value of 10 would be ten times. A SOT appears when at least 10% of EPS members are forecasting an event greater than the model climate extreme. Say the model climate extreme is 6 inches and the difference between the model climate 90th and 99th percentile is 1 inch, with a SOT value somewhere between 0 and 1 (call it 0.5) this 90th percentile forecast would be 6.5 inches.
Notice how the SOT values are higher and the EFI higher down around DC. That's because snow is more extreme in that area than New England, and more likely to be an extreme event based on forecasts.