Winter storms have a significant impact on airline and airport operations, including safety and airport efficiency. Snowfall intensity (liquid-equivalent snowfall) is a crucial parameter that needs to be measured and reported accurately at the airport site. The current method of determining snowfall intensity (S-, S, S+) is based on National Weather Service (NWS) observations of visibility, and can be misleading under conditions of high liquid-equivalent snowfall rates and high visibility. The accurate, quantitative measurement of winter precipitation (snow, sleet, freezing rain) continues to be a challenge to meteorologists and to meteorological instrumentation.

In recent years, improvements in the technology of the weighing-type gauge have led to improved winter precipitation measurements, to the point where the gauges are now able to record snowfall liquid-equivalent accumulations with a resolution of .01 to .001 of an inch, and a time resolution on the order of a minute. This improved technology has led to the potential of using these gauges in an operational setting to produce real-time estimates of snowfall accumulations and precipitation rates.

In spite of the improved real-time performance of snowgauges, problems with accuracy still remain. These include the problem of snow sticking to the inside surfaces of the gauge opening and not being recorded until a later time when the surface warms sufficiently to allow the accumulated snow and ice to fall into the catchment reservoir; and the persistent problem of wind and its effect on catchment efficiency.

In order to evaluate the performance of meteorological instrumentation used to measure real-time liquid-equivalent precipitation, the Research Applications Program (RAP) at NCAR has developed (with FAA funding) a winter test facility near Boulder, Colorado. The facility consists of several different types of precipitation/snow gauges, wind shields and various visibility and present weather sensors. Manual measurements of snowfall liquid-equivalent accumulation are made every 15 minutes to provide a measure of ground truth. The over 80 inches of annual snow and the variety of precipitation types and meteorological conditions make it an ideal winter test facility.