National Hurricane Center updates are taking effect starting this hurricane season, with a new version of the forecast cone designed to depict land-based tropical storm and hurricane alerts in addition to the coastal alerts that appeared in prior versions.
What changes when the National Hurricane Center adds inland alerts to the cone?
The revised forecast cone now includes a depiction of land-based tropical storm and hurricane alerts across the United States, Hawaii, Puerto Rico, and the U. S. Virgin Islands. The new cone replaces an earlier version that only depicted coastal tropical storm and hurricane alerts. The stated aim of adding inland alerts is to further communicate wind risk during tropical events.
In practical terms, the updated graphic can show more alerts along a storm track, including alerts away from the coast. The change is illustrated using Hurricane Milton’s forecasted track, where more alerts appear inland, and Hurricane Lane, where inclusion of a Hurricane Watch in the cone is used to emphasize that hurricane-force winds can be likely even if the center of the storm is well to the west of Hawaii.
Alongside the added inland alerts, the legend is also changing to simplify how overlapping alerts appear. Areas with multiple alerts in effect—specifically places under a Hurricane Watch and a Tropical Storm Warning—will display as a dashed area to reduce the number of stacked layers on the map.
What happens when outlook symbols change for near-zero development systems?
A separate update affects the seven-day tropical weather outlook. In previous years, systems with a low chance (less than 30%) of development were shown as a yellow X. That same symbol also included systems with a near 0% chance of development in both the two-day and seven-day outlook.
Beginning this season, systems that are not expected to develop (near 0%) will be shown as a gray X. The gray X also applies to systems where development chances have fallen to near 0% and/or are being highlighted to communicate a significant rainfall or flooding threat.
One exception is spelled out for mixed time-horizon expectations: if a system has a near 0% chance of development in two days but a greater chance in seven days, it will be displayed as a yellow X.
What to watch as the new graphics roll into this hurricane season
The updated cone and outlook symbols arrive at the start of the hurricane season referenced in the provided context, which begins on May 1 (ET). With the cone now depicting inland alerts, readers should expect the map to surface more advisory areas away from the coast during active storms, alongside the new dashed-area treatment for locations where multiple alerts overlap.
At the same time, the switch from a yellow X to a gray X for near-zero development systems is intended to distinguish between low-probability development and cases where development is not expected, while still allowing certain systems to be highlighted for rainfall and flooding risk even when formation chances are near zero.
National Hurricane Center users who rely on the cone and seven-day outlook graphics should look for these visual changes as storms develop through the season.
