Steps to Improve Ceiling and Visibility Forecasts for Aviation

Delays to the U.S. air carrier system cost billions of dollars every year. The majority of these delays are weather related, mostly due to thunderstorms and low ceilings and visibilities. Recognizing that the impact of weather on the air carrier system can be mitigated by improved terminal forecasts, the NWS has put a high priority on improving its service to the aviation community. Among the goals documented in "Vision 2005": the National Weather Service Strategic Plan for Weather, Water and Climate Services, 2000 - 2005, are: "ensure local airport warnings for established criteria have a probability of detection of at least .80 and a false alarm rate of .40 or less (2005)"; and "reduce the false alarm rate by 50 percent and increase the probability of detection by 50 percent for critical ceiling (200 feet) and visibility (1/4 mile) forecasts as contained in aviation terminal forecasts (2005)". While much effort has been given to improving forecasts of thunderstorms, the forecasting of low ceilings and visibilities has historically received relatively little attention. This is reflected in the verification scores in terminal forecasts which have remained essentially unchanged over the last two decades. This paper will focus on the steps necessary for the NWS to achieve its ambitious goals of improved ceiling and visibility forecasts, including: (1) improve our understanding of low cloud and fog processes; (2) improve mesoscale numerical models for low cloud forecasting; (3) improve the utilization of satellite data; (4) develop a system of algorithms similar to the "System for Convection Analysis and Nowcasting (SCAN) that will integrate all information required for forecasting ceilings and visibility; (5) improve use of climatological data in the aviation forecast process; (6) initiate an intensive program to educate all NWS field meteorologists in the forecasting of low clouds and fog; (7) provide more focus on aviation forecasting in the NWS offices and offer incentives for improved performance.