The Cone of Uncertainty: What it is and How to Interpret it

The Cone of Uncertainty, officially named the Tropical Cyclone Track Forecast Cone, is a graphic issued by the National Hurricane Center once a region of interest becomes a tropical storm. The area within the cone of uncertainty encapsulates the forecasted track of the center of tropical system. Additionally, the cone of uncertainty includes the likely error in the forecast track. This error is calculated using the errors in prediction of years past. The graphic also includes select watches, warnings and advisories when systems near coastlines. 

Technology is evolving rapidly and as it does, forecasting accuracy will increase. There will always be uncertainty in forecasting tropical systems. The cone of uncertainty may narrow as technology evolves, however there will still be an element of error especially with longer lead times for forecasting. 

How to Interpret the Cone

The correct way to interpret the forecast cone is to interpret the cone as all of the possible tracks of the storm. Even the outermost edges of the cone are possible tracks that the system could take. Keep in mind that systems can span hundreds of miles across. Because of this the cone does not encapsulate all of the areas likely to be impacted. An example that is closer to home is the storm track of Hurricane Ian. Ian tracked along the right edge of one of the early cones of uncertainty. Cayo Costa and Fort Myers were never excluded from the cone of uncertainty. 

Always make sure that you are taking heed to directives from local officials. Additionally, be sure to pay attention to watches, warnings and advisories as tropical systems approach. As landfall approaches, the cone will narrow because it is only reflective of the center of the track of the system. This is why the watches, warnings and advisories are issued. Pay the most attention to active watches, warnings and advisories.