In all my years I have never done a preflight briefing of weather enroute. We look at what is shown and take off knowing what to expect. They must have encountered some icing and their pitot tubes froze up. That alone apparently took the airplane down for some reason. There is no evidence of their deviation 12 miles left of course not being adequate.
Using the fact they crashed is silly. If they iced up 40 miles off course probably wouldn't have made any difference. Hopefully the final report will clarify everything but right now we have zilch info.