BUFFALO, N.Y. — The first big snowfall of the season is blanketing towns along Lake Erie in upstate New York and northwestern Pennsylvania in the middle of the hectic holiday travel and shopping weekend, while numbing cold and heavy snow could persist into next week and cause hazards in the Great Lakes, Plains and Midwest regions. The heavy snow has led to a state of emergency declaration in parts of New York and a disaster declaration in Pennsylvania, with officials warning of dangerous conditions for Thanksgiving travelers trying to return home. [time-brightcove not-tgx=”true”] “Travel will be extremely difficult and hazardous this weekend, especially in areas where multiple feet of snow may accumulate very quickly,” the National Weather Service said Saturday. Part of I-90 in Pennsylvania was closed Saturday, and as were westbound lanes of the New York Thruway heading toward Pennsylvania.