3D Characteristics of Snow Bands and Implications for Surface Snowfall in Northeast Winter Storms

Radar observations of winter storms often indicate horizontally elongated bands of locally enhanced reflectivity. Bands > 250 km long are known as primary bands and are typically strongly forced and associated with frontogenesis. In contrast, mesoscale multi-bands are groups of roughly parallel shorter bands that occur in a wide range of environments both with and without frontogenesis. Previous work indicates that there is probably more than one dominant physical process yielding the locally enhanced reflectivity in multi-bands. Additionally, wind shear and turbulence along the 3D trajectories of falling snow particles can disperse particles that were originally formed nearby in effect “smearing” a band detected at higher altitude in the cloud so that there is little to no evidence of the band just above the surface. We utilize data from NASA IMPACTS field campaign and the Stony Brook University Radar Observatory as well as the WSR-88D radar network and ASOS stations to investigate the range of 3D characteristics of snow bands and the probability that locally enhanced reflectivity features aloft yield locally enhanced snow rates at the surface. The results will have implications for how forecasters interpret radar data and quantitative precipitation estimates in snow storms.