A powerful weather system is battering the tri-state area with heavy rain and strong winds Saturday as a fast-moving storm blankets northern New England with snow.A flood watch went into effect Saturday morning for the New York City metro area through central and southern New Jersey. The storm could dump up to 4 inches of rain on parts of the region.The heaviest rainfall is expected in the afternoon and early evening, and minor flooding in low-lying areas such as roads and yards is possible.Isolated flooding late Saturday and into Sunday is also expected.The New York City area is also…