Characteristics of Dendritic Growth Zones during Lake-Effect, Synoptic-Scale, and Lake-Enhanced Winter Storms

During the cold season (October–March) the Great Lakes region can be impacted by synoptic-scale, lake-effect and lake-enhanced snow events. Snowfall accumulation in the events can depend on the type of snow crystal. Forecast experience has shown that dendrites tend to be favored with environmental temperatures between -12 and -18°C [the dendritic growth zone (DGZ)]. These dendrites can produce larger accumulation rates than other types of snow crystals in large part due to their geometry. . Understanding DGZ characteristics can aid forecasters in wintertime snowfall accumulation forecasts. This presentation will focus on the Buffalo region to determine similarities and differences in DGZs among synoptic-scale, lake-effect, and lake-enhanced snow events.

A five-year (2010–2015) cold-season climatology of soundings from Buffalo was gathered for each time when snowfall occurred within a 167-km radius of the Buffalo sounding location. A total of 653 sounding times were identified, with.300 associated with synoptic-scale snow snow, 297 with lake-effect snow, and 56 with lake-enhanced snow. DGZs in lake-effect soundings tend to feature the coolest temperatures and highest supersaturation rates, potentially indicating more rapid crystal growth. Lake-effect soundings also feature DGZs closest to the surface. Thus, dendrites that form during lake-effect snow events generally have a smaller distance to fall and potentially change growth characteristics than with other types of snow events. Further, lake-effect DGZs are associated with the lowest mixing ratio values, a result of the cold continental airmasses that are typically associated with lake-effect snow events. Finally, DGZ depth can vary but is often around 1000 m across all types of snow events.