Nowcasts and Short-Range (0-2 Hour) Forecasts of Thunderstorms and Severe Convective Weather for Use in Air Traffic Control

摘要

Since 1971, weather radars with automatic signal digitizing capability have been undergoing operational testing and evaluation as part of the Digitized Radar Experiment (D/RADEX) of the National Weather Service. The data generated by these radars have been used to develop automated techniques for monitoring and predicting thunderstorms and severe local convective weather at or near air terminals. Digital radar data, archived over a period of six years, have been used in conjunction with a sophisticated technique to identify and track each important echo within the radar umbrella. Parameters based on reflectivities, echo tops, and the estimated vertically-integrated liquid-water (VIL) have been computed for each echo and statistically related to the reported severe weather occurrences. The derived relationship can be used to estimate the probability of a given cell being associated with severe weather. In the predictive part of the effort, the objective is to forecast the locations and intensity of convective weather activity for periods of up to 1 hour. We have derived statistical equations relating various radar-based parameters to subsequently observed radar reflectivity values. The parameters used involve observed and extrapolated patterns of reflectivities, echo tops, and VIL. The system movement vector used for extrapolating the radar fields is objectively determined by binary matching of successive observations of reflectivity patterns. (Author)