NEW YORK—A dangerous winter storm brought significant snowfall, strong thunderstorms, and blustery winds to the northeastern U.S. on a holiday Monday. A foot or more of snow fell in parts of New York state, Ohio, and Pennsylvania Sunday night through Monday morning, and tens of thousands of customers in the region were without power. Forecasters in Buffalo, New York, said the snow was falling fast, dumping almost 17 inches by 10 a.m. The city advised people not to travel if they didn’t need to on this Martin Luther King Jr. Day, while some surrounding towns instituted a travel ban. “WOW! (Latest) snow measurement at 1 AM was 4.6 inches in the last hour at the Buffalo Airport!” the National Weather Service in Buffalo tweeted overnight. “And tack on another 4 inches in the last hour ending at 2 AM! Total so far since late Sun evening—10.2 inches.” The weather service …