Assessment of Wind Shear Forecast Performance and Implications on Wind Compression Impacts

Winds that change direction and/or speed with altitude, or wind shear, in critical airspace regions and in the presence of sufficient air traffic demand can result in wind compression constraints – where this wind shear, if not planned for, can result in the loss of required separation between aircraft (at worst) or excessive airborne vectoring, holding, or diversions (at best). Unanticipated wind compression can result in increased impacts and delays that cascade across the National Airspace System (NAS). Air Traffic Management (ATM) decision-makers currently seek to mitigate wind compression impacts by evaluating wind observations and weather model forecasts, but these efforts lack critical and explicit awareness of key objectively-identified and operationally-relevant wind shear thresholds and historical forecast performance which could otherwise enhance capabilities to proactively manage these constraints. Most wind compression events are therefore managed reactively by ATM, typically only after associated spacing impacts have begun, resulting often in a more difficult and challenging air traffic operation with increased disruptions and delay. This underscores the need for timely and reliable prediction of compression-conducive wind shear onset, duration, and severity.

This paper addresses these operational wind shear forecast needs by assessing the performance and utility of two weather forecast models with contrasting spatial and temporal resolutions in predicting the magnitude and timing of wind shear events at key Core airports, leveraging objectively-identified airport-specific wind shear thresholds. Isolation of these wind shear thresholds at each focus airport from distributions of historical wind shear during operationally impactful wind compression events and their potential operational applications beyond this weather forecast analysis will be described. The relationship between these wind shear thresholds and air traffic responses to these wind shear environments will also be evaluated (a) to initially characterize the overall wind compression severity and (b) to understand the potential operational implications and opportunities associated with thresholded wind shear timing and magnitude forecast performance. Opportunities to extend this analysis to identify existing gaps, shortfalls, and ATM needs in wind shear forecasts will also be discussed.