HIGHLIGHT: Investigating the “Time Of Wind Return” (TOWR) for Transient Terminal Convective Weather Events

Air traffic operations are significantly impacted when convective weather impacts an airport terminal. In addition to the immediate safety threats associated with thunderstorms (dangerous wind shear, lightning strikes, heavy rainfall, reduced ceilings and visibility), convectively-induced outflow winds (typically referred to as “gust fronts”) often result in drastic changes in wind speed and direction at the airport that require runway reconfigurations. Over the years, much research and development has been devoted to identifying and predicting gust front passage through airport terminal airspace. As a result, traffic managers and airport tower controllers have made great strides in mitigating the impacts of these initial storm-driven wind shifts in terminal airspace.

Significant challenges remain, however, in managing terminal airspace and airport surface operations when the terminal wind field is perturbed by convection. One of the most vexing challenges for traffic managers and tower controllers is trying to determine when the off-nominal wind conditions – and resultant changes and impacts to the air traffic operation – associated with transient convection will cease and the pre-impact wind regime will become re-established.

The Time Of Wind Return (TOWR) project is a foundational weather service analysis study of this “end of storm-induced wind shift” phenomenon, the potential impacts on airport operations, and the potential applications and benefits of TOWR forecast decision support. An historical assessment of TOWR events over a ten year period at core airports demonstrates the frequency and variability of this convective phenomenon across the National Airspace System (NAS). A combined analysis of these discrete weather events and corresponding airport traffic characteristics given TOWR conditions quantifies TOWR impacts on airport operations. A detailed benefit analysis will be provided to illustrate the potentially significant delay/cost savings for airport surface operations if traffic management decisions were supported by a TOWR predictor. Initial research into the technical feasibility of the predictability of the TOWR will be presented and the applicability of TOWR predictions to near and mid-term NextGen operations will be discussed.