“A meteorologically mind-boggling combination of ingredients  coming together: one of the largest expanses of tropical storm (gale) force winds on record with a tropical or subtropical cyclone in the Atlantic or for that matter anywhere else in the world; a track of the center making a sharp left turn in direction of movement toward New Jersey in a way that is unprecedented in the historical database, as it gets blocked from moving out to sea by a pattern that includes an exceptionally strong ridge of high pressure aloft near Greenland; a “warm-core” tropical cyclone embedded within a larger, nor’easter-like circulation; and eventually tropical moisture and arctic air combining to produce heavy snow in interior high elevations. This is an extraordinary situation, and I am not prone to hyperbole.” [Stu Ostro]
Being fueled in part by “ocean temperatures along the Northeast U.S. coast  about 5°F above average,” so “there will be an unusually large amount of water vapor available to make heavy rain” [former Hurricane Hunter Jeff Masters]
Also being driven by a high pressure blocking pattern near Greenland “forecast to be three standard deviations from the average” [Climate Central and CWG]And what's causing that high pressure blocking pattern near Greenland that is driving the storm toward the eastern U.S. instead of it remaining out at sea? A scientist at Rutgers who does work on the impact of the loss of Arctic sea ice says it is consistent with the fallout from this summer's record low sea ice:
The jet stream pattern — particularly the strongly negative NAO [North Atlantic Oscillation] and associated blocking — that has been in place for the last 2 weeks and is projected to be with us into next week is exactly the sort of highly amplified (i.e., wavy) pattern that I’d expect to see more of in response to ice loss and enhanced Arctic warming. Blocking happens naturally, of course, but it’s very possible that this block may have been boosted in intensity and/or duration by the record-breaking ice loss this summer. Late-season hurricanes are not unheard of either, but Sandy just happened to come along during this anomalous jet-stream pattern, as well as during an autumn with record-breaking warm sea-surface temperatures off the US east coast. It could very well be that general warming along with high sea-surface temperatures have lengthened the tropical storm season, making it more likely that a Sandy could form, travel so far north, and have an opportunity to interact with a deep jet-stream trough associated with the strong block, which is steering it westward into the mid-Atlantic. While it’s impossible to say how this scenario might have unfolded if sea-ice had been as extensive as it was in the 1980s, the situation at hand is completely consistent with what I’d expect to see happen more often as a result of unabated warming and especially the amplification of that warming in the Arctic.
I haven’t read the entire Noren paper yet, but it does not surprise me that severe flooding in the northeast could be linked with periods of negative AO [Arctic Oscillation]. When the AO is negative, the jet stream tends to be wavier, just like the situation we’re in now, which favors slow-moving weather systems that can cause floods. Losing ice, reducing the poleward temperature gradient, and warming the entire climate system should contribute to increasing the likelihood of condusive to anomalous storms.There's much more at his post to take in on this "warming-driven monster" that is asserting itself with a vengeance in the last week of the U.S. campaign. Maybe more attention to the global elephant in the room would have been warranted.
P.S. It goes without saying that our government, of course, is not doing any better in addressing the challenge.