United States landfalling hurricane probability webpage

The United States landfalling hurricane probability webpage has been developed to provide coastal residents, emergency managers and other interested parties the probability of being affected by a tropical cyclone in a given year. These probabilities are based upon the climatological probability of landfall from 1900-2004 for the Gulf Coast and the southeastern United States. For the northeast United States and mid-Atlantic regions, probabilities are based upon landfalls from 1851-2004 due to the greater population density in this part of the country during the latter part of the 19th century.

Probabilities of being affected by a tropical storm, hurricane and major hurricane have been specified for eleven regions from Brownsville, Texas to Eastport, Maine, where the eleven regions have been created based upon frequency of landfall during the 20th century. These eleven regions have been subdivided into 55 subregions based upon coastal population density, and probabilities have also been specified for 205 coastal and near-coastal counties. Climatological probabilities are adjusted by Colorado State University seasonal hurricane forecasts, with higher probabilities specified when an above-average season is expected. In addition to probabilities of storms actually affecting a location, probabilities of a storm in the vicinity of a region, subregion or county are also provided, due to the inherent uncertainty in prediction of hurricane tracks and intensities. Lastly, 50-year probabilities of being affected by tropical cyclones are provided. This is due to the fact that although in any one year, the probability of being affected by a hurricane is quite low, over 50 years, these probabilities become quite significant. Decisions for future construction should be based upon these longer-term probabilities.

The United States landfalling hurricane probability webpage went live on June 1, 2004 at http://www.e-transit.org/hurricane. In its first year of operation, it received approximately 500,000 hits. Future updates to the webpage are planned and include monthly landfall probabilities and the ability for the user to be able to obtain probabilities for shorter time periods that they specify (i.e., daily, weekly).