National Hurricane Center Experimental Tropical Cyclone Forecast Cone Graphic
During the 2026 hurricane season, NHC will issue an experimental version of the cone graphic that uses a different methodology to create the error cone. Since 2007, the operational NHC Tropical Cyclone Cone Graphic has been formed by enclosing the area swept out by a set of circles anchored at each forecast point that are based on the 67th percentile of the NHC absolute track errors over the previous five years. The error cone in the 2026 experimental graphic will be constructed using ellipses instead of circles to account for both the speed (along-track) and directional (cross-track) error components of the forecast.
The along-track (speed) error is determined by calculating the distance that the tropical cyclone center is either ahead of or behind the NHC track forecast. The cross-track (directional) error is determined by calculating how far the tropical cyclone center deviates to the left or right of the NHC track forecast. To form the experimental cone, an ellipse is anchored at each forecast point (12, 24, 36, 48, 60, 72, 96, and 120 hours), where the axes of each ellipse are based on the 90th percentile of the NHC along- and cross-track errors from the previous five years. The experimental cone is formed by smoothly connecting the area swept out by these ellipses. Since the center of a tropical cyclone would be expected to remain within each ellipse 90% of the time, the experimental cone represents the likely track area of the center of a tropical cyclone.
The experimental cone will be available on hurricanes.gov with each NHC advisory or special advisory. The experimental cone will be issued in addition to the operational cone. The NWS is soliciting comments on the experimental version of the cone graphic through November 30, 2026. Please provide feedback through the NWS survey at: https://www.surveymonkey.com/r/ProposedChangestotheTropicalCycloneConeGraphics_2026
Experimental Cone Graphic (Atlantic)
Operational (Red Dashed Line) vs. Experimental (White Shaded Area) Cone Comparison
Experimental Cone Graphic (Pacific)
Operational (Red Dashed Line) vs. Experimental (White Shaded Area) Cone Comparison
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