Validation of radar-estimated upslope snowfall in Southeastern Wyoming

Radar reflectivities combined with a reflectivity-to-snowrate (Z-S) parameterization are needed to take full advantage of the spatial and temporal resolution of data coming from the Weather Surveillance Radar (WSR) network. This work focuses on the Z-S relationship for upslope snowstorms impacting the eastern slope of the Laramie Mountain Range west of Cheyenne, Wyoming. Direct measurements of surface snowfall will be made using the Hotplate Precipitation Sensor (Yankee Environmental Systems) in locus with the lowest elevation scan of the Cheyenne WSR. By confining studies to winter upslope storms, and through the use of a fast-response precipitation sensor, it is our intent to validate, and if necessary refine, the Z-S relationship for the Cheyenne WSR and the S-estimations it provides. In addition to the WSR and the precipitation sensor, we anticipate that a few of the investigated storms will be probed by the Wyoming King Air aircraft. Of relevance to the Z-S correlation will be the remotely-sensed fields of radar reflectivity acquired by the cloud radar operated onboard the King Air. Since the cloud radar is capable of much finer spatial resolution than the WSR, the reflectivity fields coming from the former will be used to test the assumption of uniformity within the sample volume of the WSR. In the event that this assumption is validated, confidence in the accuracy of the derived Z-S relationship will be reinforced. Our project is scheduled for January and February 2006.