Communicating Imperfect Hurricane Forecasts

The National Hurricane Center (NHC) issues 5-day (120-hour) forecasts for all tropical cyclones in the Atlantic and eastern North Pacific basins. These forecasts include deterministic position and intensity predictions at 12-hourly time steps out to 48 hours and at 24-hour time steps thereafter out to 120 hours. The historical errors in these forecasts are known and published by the NHC; for example, the five-year (2002-2006) mean forecast track errors range from 35 n mi at 12 h to 290 n mi at 120 h and the intensity errors range from 6 kt at 12 h to 22 kt at 120 h. Given these errors, the NHC issues a suite of products (an “advisory package”) to convey an appropriate amount of uncertainty, so that the forecasts can be responsibly utilized for risk communication, preparedness, and decision-making. NHC relies on broadcast meteorologists as partners in conveying these forecasts and their uncertainties to the public. The NHC has continued to refine operational products (both text and graphical) that are designed to help broadcast meteorologists and other partners and customers in communicating and dealing with the forecast uncertainties. These products include the 3-day and 5-day track forecast cone graphics, 34-, 50-, and 64-kt wind speed probability products (text and graphics), the probabilistic maximum wind speed forecast table, the tropical cyclone discussion, and experimental storm surge probability graphics. Knowledge and use of these products, some of which have recently been introduced or modified, are vital in understanding and communicating the uncertainties associated with a particular tropical cyclone forecast.

This presentation will discuss tropical cyclone forecast uncertainties and limitations. It will also provide specific examples of how NHC and other National Weather Service (NWS) products can be used to assist broadcast meteorologists in conveying forecast uncertainties and potential hazards to the public. We also hope to receive feedback on how these products are being utilized by broadcasters and on how the products could be enhanced to better serve the broadcast meteorology community.