Characterizing the Vertical Slope and Maintenance Mechanisms of Mesoscale Snow Bands in Mid-latitude Winter Storms

Mesoscale snow bands are frequently responsible for dumping large amounts of snow over a relatively small region and pose a considerable forecasting challenge. The recently concluded NASA Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) field campaign observed several instances of mesoscale snow bands during January and February of 2020, 2022, and 2023. These snow bands were sampled by a combination of airborne (NASA ER-2 and P-3) and ground-based remote sensing and in-situ instruments.

Along-band cross sections of these snow bands reveal that many of them are vertically sloped. A combined analysis of the reflectivity and wind retrievals from the ER-2 radars for the banding features observed on 5 February 2020 suggests these sloped features could be explained by vertical wind shear layers deforming a series of fall streaks into bands that extend hundreds of kilometers. Furthermore, the actual positioning of the banding features appears to coincide with regions of slantwise instability aloft in HRRR analysis fields. The present study will focus on extending our analysis to include additional cases and understanding the triggers and support mechanisms for these features using a combination of radar data, in-situ aircraft measurements, and numerical modeling.