Convective Forecast Verification Operational Impact Assessment Jennifer Mahoney, Mike Kay, Sean Madine, Joan Hart Forecast Systems Laboratory Barbara Brown National Center for Atmospheric Research 9-30-04

Background Verification techniques are strongly tied to the product definition and intended use of a forecast. Therefore, the verification problem becomes very difficult when the forecast is not clearly defined. Goals: Clarify the product definition and intended use of Collaborative Convective Forecast Product (CCFP). Demonstrate techniques for evaluating the operational impact of CCFP.

Verification of CCFP Product Definition (Meteorological) – Use – A region spanning at least 3,000 sq. miles and containing at a minimum, echoes of at least 40 dbZ composite reflectivity, covering at least 25% of the CCFP region, with tops at least 25,000 ft. Use – CCFP is a strategic tool used for developing a plan or framework for managing the impact of convective weather on the air traffic flow system (e.g., Baseball). Operational impact – CCFP region contains the convection as well as a measure of the possible impact of the convection on the flow of air traffic.

Convective Constrained Area (CCA) Raw Observations 30 June 2004 CCA-10 CCA-20

Operational Impact Coverage Field Flight handbook rules Raw observations CCFP product definition Operational Impact Coverage Field - Guidance for a CCFP 30 June 2004

Future Work Regionalize the operational impact coverage field by region, sector, and time of day. Incorporate echo top information into the convective constrained area. Evaluate flight track data to quantify the impact of convection on the flow of air traffic.

Conclusions CCFP should only be used as a tool for establishing a plan for managing the flow of air traffic. Verification methods can be developed for CCFP that incorporate the operational impact of convective weather on the flow of air traffic. There is no right answer. There are many ways to evaluate a forecast. All methods tell you something about the quality and usefulness of the forecast.

Acknowledgments Thanks to Tom Fahey Fred Johnson Jack May Dave Rodenhuis for numerous discussions and valuable in site.