The dryline is a common occurrence in West Texas during the spring months. Often, a synoptic-flow pattern exists that allows the dryline to develop/intensify during the morning, move eastward in the afternoon and then retreat back west in the evening. This usually occurs over a period of a few days in between the incursions of short-wave troughs into the region. As little large-scale forcing for upward motion is present, moist convection is usually limited by a strong capping inversion and only isolated thunderstorms may develop. However, even in the absence of thunderstorms the pattern of oscillation is still of interest to forecasters. Accurate forecasts of the dryline position will help forecasters predict the temperature, humidity, wind speed and wind direction and may contribute to increasing the accuracy of forecasts of fires and aerosol and particulate dispersion.

From 14 April to 18 April, 2002, under broad southwesterly upper-level flow, the dryline oscillated diurnally across the study region until a strong front moved through on 19 April. This paper investigates the evolution of this dryline utilizing the Pennsylvania State University-National Center for Atmospheric Research mesoscale model (MM5) and Atmet’s Regional Atmospheric Modeling System (RAMS). Results from the models are compared with high-resolution surface observations from the West Texas Mesonet.

Each model domain consists of a 45 by 45 18-km outer grid with a 46 by 46 6-km nested grid centered near Lubbock, TX. The models are initialized using the NCEP ETA 0-hour forecast dataset. The model-predicted dryline is compared to analyses obtained from 29 stations of the West Texas Mesonet. In addition, the effect of observational nudging using West Texas Mesonet data on the model predictions is investigated.