The Real-time Verification System (RTVS), developed by NOAA-ESRL/GSD's Aviation Branch, is principally focused on supporting and advancing verification activities within the FAA's Aviation Weather Research Program (AWRP). RTVS provides performance metrics for new forecast algorithms that are being transitioned into National Weather Service (NWS) operations, and gives direct feedback to forecasters and decision-makers alike. Increasingly, the system is being utilized to supply information to individual users of aviation-related weather forecasts. One example of such user-based verification is a new lead-time metric that has been developed for assessing skill in forecasting the onset of Instrument Flight Rules events (IFR events). The method utilized by RTVS compares the onset from observed IFR events with the onset from NWS-issued Terminal Aerodrome Forecasts (TAFs). A database of these events has been developed, consisting of 3.2 million TAFs, covering a 3-year time period, at over 600 individual airports.

An important by-product of this database development is a web-based verification tool that provides users a simple interrogation mechanism for comparing TAF weather elements, and observed weather conditions obtained from routine and special surface weather reports (METARs). The main purpose in gathering statistics on such a large number of events-- over 1 million TAF IFR events are analyzed-- is to highlight the capability of forecasts that have such a profound impact on strategic planning of air travel throughout the United Sates. The approach used to associate forecast and observed IFR events is event focused, and yields results that are stratified by station, region, weather scenario, forecast issuance hour, and other TAF attributes.

TAFs provide a concise statement on expected weather conditions at commercial and military airports throughout the world. They constitute the official forecast of aviation activity at FAA facilities. Routine TAFs are issued 4 times daily for forecast periods extending out to 24 hours. Amended and corrected TAFs are issued throughout the day as needed. These human-generated forecasts are utilized by all airports in the National Plan of Integrated Airport Systems (NPIAS). They are an important strategic aid to major users of the National Aviation System (NAS), including large air carriers, air taxi/commuters, general aviation, and military aircraft (FAA 2007).

This talk will focus on verification methods used to create the extensive database of forecast and observed IFR events, along with a short demonstration of the web tool that is used to interrogate the database and to retrieve statistical results. We will also present findings from our analysis of these results, with an emphasis on how this information can be utilized by the NWS to ascertain relative strengths and weaknesses of the overall TAF forecasting system.