Statistical Analysis of the Existence of Thundersnow and Snow-to-Liquid Ratios

Currently, snow-to-liquid ratio (SLR) values are determined by daily observations, from weather observers, from Cooperative Summary of the Day (COOP) stations. These data are a summary of what occurred in the previous 24 hours or from a sum of four 6 hour observations. Previous studies have shown that heavily rimmed particles or compact particle habits (i.e needles, bullets) have lower SLR values; while large aggregates (i.e. dendrites) have higher SLR values. A combination of these particles can accumulate at COOP stations within a 24 hour period and may not be representative for processes on smaller time scales within large, fast-moving systems. However, one possible phenomena that has not been examined would be the existence of lightning in snowstorms (thundersnow) and the possible connections with SLR. The occurrence of thundersnow indicates the presence of supercooled liquid water and is a fundamental parameter for ice crystal and aggregate growth. Connections between the existence of thundersnow and daily SLR would provide forecasters a rough approximation of what SLR could be on the storm timescale environment if thundersnow does occur. The use of the Geostationary Lightning Mapper (GLM) on GOES-R along with surface observations from COOP stations will be utilized to analyze the possible connections between SLR and the existence of thundersnow. This presentation will highlight results for several heavy-banded snowfall cases from the 2017-2018 winter and provide a potential proof of concept for snowfall cases for the 2018-2019 winter.