I put the Thursday night/Friday storm for this week at about 40% right now.
The #### is this now? How big you thinking?
Tough answer. This past storm was pretty much a given at 5 days out. This storm is 4 days out and models are not agreeing at all. While this won't be a thread the needle type storm, this will definitely be something more in the middle.
Currently, the Euro is seeing this as something big. Big as in "slightly smaller than this past one." Right now, it is thinking this would be more of a New England storm, but we (the MA) could be included. It shows the southern energy moving ahead of the northern energy, which allows a bomb of a low pressure to ride up the coast. GFS and Canadian do not agree. They have the southern system moving just a little too slow which would send the low out to sea. The key here is that all of the models see a low developing, so the big question is "up the coast" or "out to sea." Right now, the Euro seems to have a better handle on the data. And while people love to say things like "King Euro!", that same king failed miserably with this past storm.
This storm will have a much higher bust ratio, especially for the MA. But that doesn't mean it won't happen. I say 40% because my eyes tell me it's a 50/50 chance, but my gut tells me that I shouldn't put too much faith in one model when the the other models do not agree.