A Flow Constraint Technique for an Operationally Relevant Metric of Forecast Performance

Currently, the Forecast Impact and Quality Assessment Section (FIQAS) within NOAA/OAR’s Global Systems Division uses a technique known as the Flow Constraint Index (FCI) as an operationally relevant methodology to evaluate forecast performance, and it is also incorporated in the NWS-funded tool known as INSITE in a decision support context. FCI identifies airspace constraint due to weather for a given weather scenario as depicted in a convective forecast or observations. Understanding a product’s ability to identify airspace constraints can be considered a first-order, operationally-relevant measure of product skill. This technique has been extended to an approach known as the Flow Constraint Mitigation (FCM) technique, which is a more comprehensive view of a product in its ability to not only identify constraint, but to also accurately identify available airspace that would support rerouting solutions.

Leveraging traffic knowledge and graph theory concepts established via FCI, a proof-of-concept framework was built that identifies alternative route solutions around a given weather hazard (traffic flow obstruction). For a given flight path, the framework determines a set of alternative paths around an obstruction as a solution set for possible reroutes. Once a solution set of alternate routes is established, performance evaluation can occur by considering the solution sets determined based upon the forecast weather, as compared to the solutions determined by the observed weather. From this, one can establish a proxy for determining the cost of adjusting planned routes based upon the forecast weather scenario. Note that the FCM is not a full air-traffic simulation tool; the added complexity is not necessary for impact-based verification of convective forecasts. This presentation will provide motivation and background for the FCI and FCM techniques, an overview of the FCM, and a review of case studies where FCM was applied.