Hawaii hasn't experiences a major hurricane in over two decades. Now, the island state is threatened by two: Iselle and Julio. The MODIS image below shows Iselle on the left and Julio on the right.
Both are expected to weaken to tropical storms by the time they reach Hawaii, but Iselle is projected to directly impact the big island. Infrared Satellite is shown below with the projected hurricane path.
Source: Weather Underground
How do meteorologists make the cone of uncertainty? It's a combination of several different weather models. Each model gives a different solution.