Probabilistic forecasting of ceiling and visibility at CONUS terminals: Development progress

The physical processes controlling ceiling and visibility (for example, the formation, evolution and motion of low cloud, precipitation, fog and haze) and the diverse seasonal, diurnal and geographic influences that modulate these controls yield a challenging forecast problem that is highly relevant to the overall efficiency of the NAS and the safety of general aviation.

This paper describes the status of current work toward a 1-12 hour ceiling and visibility (C&V) forecast guidance product. Development currently focuses on forecast capability at CONUS terminals in Chicago, Atlanta, Seattle, New York and other key cities where high traffic volume and frequent C&V events combine to yield costly impacts on the efficiency of traffic flow within the NAS. A more fully-developed product will provide forecast guidance at all METAR-equipped airports and will include forecast information in the regions between airports to support VFR flight planning and en-route avoidance of IFR conditions for general aviation.

We describe our approach toward probabilistic, observations-based statistical forecasting from 1 to 3 hours, and use verification results to illustrate the strengths and shortcomings of statistical forecast methods. Using the results of Bateman et al. (this conference), we discuss the outlook for use of CoSPA (extrapolation and NWP-based) storm forecasts to improve the performance of C&V forecasts from 1-6 hours. Finally, we examine verification results for operational resources such as LAMP, SREF and time-lagged ensembles of the RUC, and we outline a preliminary assessment of strategies for use of these resources toward a value-added 4-12 hour probabilistic forecast product.

This work is carried out by the National Ceiling and Visibility product development team under funding from the FAA's Aviation Weather Research Program.