MIAMI — Subtropical Storm Nicole began strengthening on Tuesday as Florida’s eastern coast prepares for a possible tropical storm or Category 1 hurricane later this week. Overnight, the National Hurricane Center nudged its predicted track north toward Melbourne, but Nicole’s wind field is already nearly the size of the entire state, so its effects will be felt throughout Florida starting as early as Wednesday. In addition to the hurricane watches already issued along Florida’s east coast, the hurricane center early Tuesday upgraded the east coast’s tropical storm watch to a warning and issued …