Multiple Remote Sensor Observations of Supercooled Liquid Water in a Winter Storm at Beaver, Utah

Abstract

The temporal and spatial distribution of cloud liquid water in a winter storm from the 1983 Utah/NOAA Cooperative Weather Modification Program is characterized using remote sensing observations. The remote sensors, located at a mountain-base site near Beaver, Utah, consisted of a dual-channel microwave radiometer operated in an azimuthal scanning mode, and a polarization lidar and Ku-band radar both operated in the vertically pointing mode. The cloud system was associated with the passage of a weak cold front and produced only light snowfall across the barrier network of precipitation gages. Although the amounts of supercooled water detected radiometrically varied considerably during the storm, liquid water depths were consistently enhanced in the direction of the barrier. The spatial distribution of liquid water was observed to undergo a transition from a primarily orographic distribution to a more area-wide pattern immediately behind the front, and then became convective as the storm dissipated. A new method of analysis applied to the scanning microwave radiometer measurement appears promising for relating liquid water concentrations with the local topography. It is suggested that the near real-time availability of the measurements could lead to improvements in cloud seeding strategies.