Well, as a matter of fact, after scanning the rankings you've given in your poster, it is obviously that you prefer U Minnesota-Twin Cities and Yale, rather than Northwestern. The weather is the last thing should be considered, and I also accepted offer from UMTC as well as NWU, but I decide to choose UMTC. UMTC is more suitable for an individual who would like to be a research scientist in future. NWU is prestigous for its Mechanics. And if your interest is in Mechanics, OK,please go ahead. I know little about Yale in ME area. That is my view on these universities. Btw, I have ever been to these universities more than once and the weather in UMTC is not so bad as you imagined.