A Climatology of Cool-Season Precipitation Objects in the Comma Head of an Extratropical Cyclone

Extratropical cyclones have precipitation structures within the comma head ranging from cells to banded precipitation. Much of the previous research in the comma head has focused on the larger primary (single) snowbands, with little investigation of the broader spectrum of snowband structures. An updated precipitation band climatology within the cyclone comma head is necessary to understand the variety of structures that exist, which will help with model validation and field study investigations. Composite radar over the Northeast United States and adjacent coastal waters from 1996 to 2023 is used to quantify the distribution of precipitation objects in terms of length, aspect ratio, and area in a cyclone-relative framework. Additionally, cyclone cases were further separated by both track orientation and deepening rate. There is a broad distribution of precipitation object sizes, thus no clear separation between primary and multibands defined in previous studies. Band-like objects most frequently occur north and northwest of the surface cyclone center, while more cellular objects are favored east and south of the center. Larger structures and more band-like objects are more common in rapidly deepening cyclones, and these structures tend to be oriented in a southwest-to-northeast direction. Storms with a more west-to-east track favor band-like objects to the north-northeast and oriented in a west-to-east direction. Using the results from this climatology, a new conceptual model of precipitation objects in the cyclone comma head is presented.