Tactical 0-2 Hour Convective Weather Forecasts for FAA

Thunderstorms account for a significant fraction of air traffic delays in the US, resulting in enormous annual economic losses. In response, the FAA Convective Weather Product Development Team has developed an automated tactical (0-2 hr time frame) convective weather forecast product for use in the Integrated Terminal Weather System (ITWS) and the Corridor Integrated Weather System (CIWS).

The Convective Weather Forecast (CWF) algorithm is a multi-scale storm tracking algorithm that takes into account measured storm growth and decay trends and underlying models of how convection behaves. CWF is designed to track the envelope motion of large scale storms and the cell motion of smaller, isolated cell regions. It computes growing and decaying trends of precipitation (radar-based estimate of vertically integrated liquid water) over different time scales to make estimates of future storm strength and areal coverage. A significant aspect of this system is its categorization of weather type (line, stratiform, small or large isolated cell, etc.), used in applying the correct track vectors, growth and decay trends and storm evolution models to the forecast, and ultimately in predicting the impact of the forecasted weather on air traffic capacity.

The Convective Weather Forecast product is displayed in a separate window on the ITWS or CIWS Situation Display, and consists of an animated loop forecast of selectable length. The “fuzzy” deterministic forecast will be displayed in three levels, signifying areas of low, moderate and high probability that level 3 or greater precipitation will be present at those locations in the future. These forecast precipitation maps provide an easily understood graphical representation of the future weather, requiring no further interpretation.

This paper will motivate the FAA need for the 0-2 hr automated tactical forecast capability, describe the CWF algorithm, provide examples of the forecast features, and provide statistics on the algorithm performance. It will also briefly describe future work and further applications of the CWF technology.

This work was sponsored by the Federal Aviation Administration under Air Force Contract No. F19628-00-C-0002. Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the U.S. Government.