Emergency officials in New York City, New Jersey, Boston and communities along the East Coast are rushing to prepare for an intense winter storm, forecast to arrive Sunday. The National Weather Service on Saturday increased its assessment of the potential severity of a storm that just days ago was anticipated to be relatively limited. The weather service said up to two feet of snow was possible as it issued blizzard warnings for New York City, Long Island, southern Connecticut and coastal communities in New Jersey and Delaware. The weather service said the storm could arrive quietly on Sunday with rainfall in some places before worsening, delivering up to two feet of snow before it ends on Monday.