Tropical Cyclone Wind Speed Probabilities Products

Contents

1. Overview
2. Description of the tropical cyclone wind speed probabilities text product
3. Description of the tropical cyclone wind speed probabilities graphical products
4. Description of the tropical cyclone NDFD wind speed probabilities products
5. Potential advantages as compared to previous products
6. Method for computing the wind speed probabilities

1. Overview

The tropical cyclone surface wind speed probabilities text and graphical products issued by the Tropical Prediction Center/National Hurricane Center (TPC/NHC) became operational at the start of the 2006 hurricane seasons in the Atlantic and eastern North Pacific basins. The underlying techniques were developed by researchers at NOAA and Colorado State University, while the products themselves were developed by the Technical Support Branch (TSB) at TPC/NHC.

The tropical cyclone surface wind speed probabilities products provide probabilities of sustained (1-minute average) surface (10-meter altitude) wind speeds of at least 34 kt (39 mph, tropical storm force), 50 kt (58 mph), and 64 kt (74 mph, hurricane force) at individual locations in the Atlantic and eastern North Pacific basins. The probabilities are based on errors during recent years in the official track and intensity forecasts issued by the TPC/NHC. Variability in tropical cyclone size (wind radii) is also incorporated.

One separate wind speed probabilities text product is issued with each advisory package for each active tropical cyclone in the Atlantic and eastern North Pacific basins. Each text product contains probabilities for all three wind speed thresholds. The text products are available at about the same time as the other advisory package text products. Also, TPC/NHC issues a set of storm-centered graphical wind speed probabilities products with each advisory package for each active tropical cyclone in the Atlantic and eastern North Pacific basins. The wind speed probabilities graphics could take about 30 to 45 minutes longer than the corresponding text product to update following the issuance of the official forecast, especially since the text products are often sent several minutes before the advisory release deadline. This delay occurs because the storm-centered graphics display probabilities resulting from all active tropical cyclones in the applicable basin, whereas each probabilities text product applies to only one tropical cyclone. The processing of the graphics must wait until after the advisory release deadline (e.g., 11:00 PM EDT) to ensure that the forecasts for all active tropical cyclones have been sent.

The product description documents for both the probabilistic text and graphical products are available at http://products.weather.gov/viewliste.php in PDF format*.

Next:  Description of the tropical cyclone wind speed probabilities text product