Assessing Lead-time Errors and Spatial Displacement for the Onset and Cessation of Convective Weather Events within the Terminal Area from the NDFD Thunderstorm Forecast Product

Following the establishment of requirements set forth by the Traffic Flow Management Requirements Working Group (TRWG), an in-depth assessment has been conducted on the suitability of the National Digital Forecast Database (NDFD) convective weather forecast product in traffic flow planning. The assessment methodology includes the development of forecast accuracy measures relative to timing for the onset and cessation of convective weather within the terminal area, and it includes an assessment of aviation-specific concerns centered on the Northeast U.S. Methods and initial results to be presented cover two convective seasons (June-September 2010 and 2011), and they provide a measure of error in forecasting lead time to onset and cessation of convection, spatial displacement of forecasts relative to observations, and preliminary findings related to impacts along specific jetways.

The observation set used in this study comes from the Corridor Integrated Weather System (CIWS), where both vertically-integrated liquid (VIL) and echo top heights are utilized. Skill scores and performance measures are presented in the context of TWRG requirements for a terminal space within a 75-nmi radius of the Operational Evolution Partnership (OEP) 35 airports. These measures are used to baseline current forecasting capabilities and are provided prior to the implementation of forecast services that will support NextGen Mid-term Operational Capabilities (MOC). On-going efforts within this analysis framework provide for the inclusion of other deterministic and probabilistic forecast products.

This paper will describe the datasets used in the initial study, criteria for the identification of convective events within the terminal space, scoring considerations used for the experiment, and initial results. This paper will also address other techniques for assessing jetway impact, future work for assessing convective weather products in an aviation context, and development of an online tool for presenting error statistics for event timing and displacement.