By now you should have gotten wind of the European model this afternoon. There are big red flags on the European model with regards to a major snowstorm from New York City north and east. Even in areas in Eastern and Southeastern Pennsylvania the cuttoff line has suddenly become very sharp.
Big Red Flags On European Model Snowfall Forecast
Now this is a big change and a continuation of the southern trend this model has been on for the last 2 days. Why is the model doing this? Take a look at the upper air maps for the European GFS and Canadian side by side and it is actually very simple.