Slight changes in temperatures from the surface up to a few thousand feet can change snow to rain or freezing rain. (Harris, 1959, Baxter, et al. 2005, Groisman et al. 2016). The type of precipitation has a significant impact on the general population, city government, and several industries. The impacts of snow and freezing rain include delays in travel, increased number of accidents, and closures of schools and businesses. City officials must make critical decisions on closing facilities and applying anti-icing materials to road surfaces. Beside lost revenue and productive due to closures, industries, like aviation sector, must relocate aircraft, delay or cancel operations and conduct costly de-icing procedures. The public, city official and industry look to the weather forecaster to predict the type of precipitation, timing of precipitation, and the amount of precipitation that will fall. A few degrees of temperature difference in the layer of air above the ground can make a significant difference in type and amount of precipitation that falls.
This presentation reports on a research project using standard upper air and surface data for 14 different snow events in San Antonio, Texas used to determine common features that can be used to help determine if the atmosphere is conducive to a measurable snowfall.