National Hurricane Center Makes Changes to Tropical Weather Reporting

Hurricane season will be here before you know it and the National Hurricane Center (NHC) has made a few changes to how it will disseminate important information in the months ahead. Here is what you need to know about these changes.

Earlier Notice of Potential Tropical Events Part of NHC Changes

The Atlantic Hurricane Season kicks off on June 1. The NHC recently announced changes in how it will relay information about upcoming tropical weather events. The major change is that the agency will give an earlier notice on potential tropical activity coming to life.

For example, these advisories may now be issued up to 72 hours prior to the anticipated arrival of tropical-storm-force winds or the corresponding storm surge. These earlier notices will come regardless of the presence of a tropical storm, hurricane, or storm surge watch. This means that the new warnings will be independent of other advisories.

In the past, the advisories were issued no more than 48 hours prior to the when the storm was expected to usher in damaging wind or water hazards. While the longer heads-up is good for preparation, it also means that people will likely be in the cone of uncertainty for longer periods of time.

The new advisories will still come with the tag of "potential tropical cyclones." Advisories with this designation have not yet met the more stringent definition of a defined feature.

The NHC notched a banner year in its forecasting models over the 2024 certainty. Heading into the 2025 season, these predictive cones will be between 2% and 6% smaller in size. The better forecasting models over the last few seasons are helping to make these cones more precise. Diving into the specific numbers, the radii measurements for the ring that predicts where a tropical storm or hurricane eye will land in five days will decrease from an estimation of 220 miles to 213 miles in the upcoming season.

Going back to the 2003 season when the cone of uncertainty was initially pushed to five days, the radii are now over 100 miles smaller. These more exact forecasting models help experts to provide better estimates about where and when a tropical event will impact land.

This is a good time to note that some of the most dangerous impacts of a tropical weather event often happen well outside the defined cone of uncertainty. This means that effects such as storm surge, high winds, rip currents, flooding, and tornadoes are limited to the area within the cone.

It is expected that the cone will continue to shrink every year as the technology associated with storm forecasting improves. But this does not mean that the tropical weather events themselves are getting smaller or less dangerous. The cone of uncertainty is only designed to track the center of the storm and not its actual field of impact.