A Seasonal Analysis of Dendritic Growth Zones during Lake-Effect, Synoptic-Scale, and Lake-Enhanced Winter Storms

Dendritic ice crystals are known to have a substantial influence on snowfall accumulation. These ice crystals experience the most rapid growth within dendritic growth zones (DGZs), or the area of an atmospheric column from -12 to -18°C. This presentation will examine the seasonal characteristics of DGZs from five cold seasons (October–March) spanning 2010/2011 through 2014/2015. The Buffalo, NY region was chosen for this research since it routinely experiences lake-effect, lake-enhanced, and synoptic-scale snow storms.

During the time period studied, 653 soundings launched from Buffalo, NY (KBUF) occurred within two hours of measureable snowfall near Buffalo (i.e., within 100-km radius of the sounding location). Of these 653 soundings 297 occurred during a lake-effect snow event, 56 during a lake-enhanced snow event, and 300 during a synoptic-scale snow event. Lake-effect DGZs have bases consistently closest to the surface in each month of the cold season. During the peak months of the cold season (December, January), the DGZ base becomes closer to the surface in all types of snow events. Mean DGZ depth is greatest for lake-enhanced storms especially in the early months of the cold season. DGZ mixing ratio values are smallest in lake-effect storms and largest in synoptic-scale storms. Mixing ratios generally decrease for all storm types during middle of the cold season. Findings related to seasonal variability of DGZ characteristics show potential to aid in operational snowfall forecasting throughout the Great Lakes region and additional research results will be presented.