The Perfect Storm originated from a cold front that exited the east coast of the United States. On October 28, the front spawned an extratropical low to the east of Nova Scotia. Around that time, a ridge extended from the Appalachian Mountains northeastward to Greenland, with a strong high pressure center over eastern Canada. The blocking ridge forced the extratropical low to track toward the southeast and later to the west. Hurricane Grace was swept aloft by its cold front into the warm conveyor belt circulation of the deep cyclone on October 29, with the storm completely absorbing Grace by the next day. The cyclone significantly strengthened as a result of the temperature contrast between the cold air to the northwest, and the warmth and moisture from the remnants of Grace. The low-pressure system continued deepening as it drifted toward the United States. It had an unusual retrograde motion for a nor'easter, beginning a set of meteorological circumstances that occur only once every 50 to 100 years. Most nor'easters affect New England from the southwest.