WeatherWhys for November 17,2016 from accuweather.com

Hurricane Lenny spent its entire lifespan traveling in a west-to-east fashion from the central Caribbean to the Atlantic, which was unprecedented in the history of tropical record-keeping. Tropical systems are typically guided westward from the Atlantic to the Caribbean by high pressure, then may curve to the northeast if they encounter a dip in the jet stream over North America. In Lenny's case, a large dip in the jet stream was in place over the western Atlantic and put the hurricane on its eastward track.