Wind Speed Probabilities for Tropical Systems affecting the Carolinas
PLEASE NOTE: Probabilities for a particular location and speed are provided only when the 120-hour (5-day) cumulative probability is at least 2.5%.
Click on map for particular location
The wind speed probability product is created for selected coastal and inland cities for each forecast issued by the National Hurricane Center. Each wind speed probability text product provides probabilities (in percent) for wind speeds of at least 34 kt (39 mph, tropical storm force), 50 kt (58 mph), or 64 kt (74 mph, hurricane force) at each listed location. Two types of probability values are produced in this text product: cumulative probabilities of occurrence, and individual probabilities of onset.
Cumulative probabilities are provided in this text product for the following time periods: 0-12 hours, 0-24 hours, 0-36 hours, 0-48 hours, 0-72 hours, 0-96 hours, and 0-120 hours. These cumulative probabilities indicate the overall chances that the stated wind speed will occur at each location during the period between hour 0 (the beginning of the forecast) and each listed forecast hour. In the graphical product the cumulative probabilities are show in green.
Individual period probabilities are provided for each of the following time intervals: 0-12 hours, 12-24 hours, 24-36 hours, 36-48 hours, 48-72 hours, 72-96 hours, and 96-120 hours. These individual period probabilities indicate the chances that the stated wind speed will start during each individual period at each location. Cumulative probabilities through each forecast time period are also just the sum of the individual period probabilities up to that time. In the graphical product the individual probabilities are shown in blue.
In other words, cumulative probabilities express the chance that a particular event will occur. The individual period probabilities give an idea of when the event is most likely to begin.
It is important for users to realize that probabilities that may seem relatively small may still be quite significant. The probabilities may indicate there is a chance that a damaging or even an extreme event may occur at your location. This may warrant making preparations to protect lives and property. Users are urged to consider the potentially immense cost (in terms of lives, property, etc.) of not preparing for an extreme event, even if the chances at an individual point are only perhaps 1 in 20 (5%) or 1 in 10 (10%) that the event will occur.