Precipitation Growth Processes in the Comma Head Region of an East Coast Winter Storm
On 7 February 2020, a rapidly deepening extratropical cyclone impacted the East Coast of the United States, leading to widespread impacts across many sectors of the economy. These large-scale impacts, along with the cyclone’s evolution, are consistent with a broader category of northeast extratropical cyclones referred to as “Nor’easters.” Despite the widespread impacts from Nor’easters, a multi-scale field campaign investigating disruptive winter storms along the U.S. East Coast has not been conducted in over 30 years. As such, scientists developed the Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) field campaign.
A primary goal of IMPACTS is to investigate precipitation processes occurring within East Coast winter storms. The 7 February research flight fulfilled this objective by targeting seven particle growth zones from cloud top to the melting layer to better understand how particles evolved through various temperature regimes. This winter storm was also stratified into two distinct regions: a stratiform region and a generating cell region. In previous studies, generating cells have been observed to create fluctuations in saturation conditions that further influence particle growth. That said, a comprehensive analysis of the influence of these dynamic substructures on specific temperature regimes has yet to be conducted. Thus, this study examines the influence of generating cells on both the microphysical characteristics of each particle growth layer and the physical mechanisms responsible for particle growth and evolution. Preliminary analysis determined that the generating cell region exhibited larger fluctuations in number concentration, mass, and supercooled liquid water than in the stratiform region. Furthermore, enhanced particle growth was observed in the generating cell region and was consistent with several particle growth mechanisms including aggregation, vapor depositional growth, and riming.
