Operational Use of Profiler Data and Satellite Imagery to Evaluate the NMC Numerical Models in Predicting Heavy Snow

Abstract

Near real-time wind profiler data from Stapleton International Airport at Denver, Colorado were used to confirm the existence of a midtropospheric closed low and vorticity maximum which were initially detected in satellite imagery over the High Plains of the United States. The initial development of the winter storm occurred between the conventional upper-air rawinsonde sites and differed, in several important aspects, from the guidance indicated by the three National Meteorological Center (NMC) operational numerical models: the nested grid (NGM), the limited-area fine-mesh (LFM), and the spectral in the aviation forecast run (AVN). Comparisons were made between hourly changes in the profiler winds, GOES satellite imagery and the location of heavy snow and the expected area of heavy snow derived by applying synoptic-climatological techniques to the three numerical models? initial and predicted positions of the vorticity maximum. The NGM forecast trends appeared to relate best to the changes in satellite imagery features, profiler winds, and surface observations. A feature in the satellite imagery near the Colorado/Kansas border was identified as a center of maximum vorticity near the 500-mb level and likely associated with a closed circulation in the vicinity of the 700-mb level. The increase of north profiler winds with height corroborated the vertical development and strengthening of the storm in east Colorado and west Kansas. The forecast problems of timing, location, and maximum amount of heavy snow are discussed from an operational point of view.