That would be a topography effect the storm has the structure of the hurricane. It can be explained like a wheel cocked more to the left to prevent torque from turning it to the right. The topography weakens the storm in a certain quadarant, and the excessive wind or energy is driven away from the island, thus moving the storm away. If anyone can explain this better- be my guest. JB did a map disco on it, and it seems to have been battle proven-so to speak.