The National Hurricane Center's Arrival of Tropical-Storm-Force Winds Product

The arrival of sustained tropical-storm-force winds is a critical threshold for coastal communities. Emergency managers need this information to determine when to begin and complete coastal evacuations, while the public needs to know when to prepare their homes or businesses and get supplies. Once sustained tropical-storm-force winds begin, such preparations usually become too dangerous or difficult.

Historically, most decision makers have inferred the arrival of tropical-storm-force winds from NHC products deterministically, without accounting for tropical cyclone track or size uncertainty. The risk in not factoring in these uncertainties is that communities may have less time to prepare if a tropical cyclone speeds up or increases in size beyond NHC’s initial forecasts. To better meet users’ needs, NHC has worked with social scientists and GIS experts to develop graphics depicting when tropical-storm-force winds from a tropical cyclone could arrive at individual locations. The social science testing has included one-on-one telephone interviews, focus groups, and online surveys with emergency managers and broadcast meteorologists, as well as an online survey with a representative sample of the general public, to gather opinions on the idea, content, and design of the product. Based on these data, NHC provided experimental versions of the product on the NHC website for all tropical cyclones in its area of responsibility during the 2017 season. User feedback from the 2017 experimental phase, as well as from the public surveys, will inform the implementation of an operational graphic and data dissemination beginning during the 2018 hurricane season.