2026/05/22 by Phillip Yeh, Brian A. Colle
Earth and Planetary Sciences · Environmental Science · #Tropical and Extratropical Cyclones Research #Meteorological Phenomena and Simulations #Climate variability and models
paper · doi:10.1175/mwr-d-25-0228.1
Abstract The comma heads of winter cyclones have a variety of precipitation structures ranging from cells to bands. Much of the previous research has explored the environmental conditions for larger (primary) snowbands in the cyclone comma head, with less work comparing the environments of the broader spectrum of snowband structures. This study looks at these environments for a full range of object sizes and shapes for cool-season cyclones over the northeast United States (NEUS) from 1996 to 2023. The ERA5 reanalysis is used to obtain the environmental parameters and cyclone tracks. Only a weak relationship exists between different object characteristics and parameters such as frontogenesis, stability, and vertical shear. A self-organizing map (SOM) approach was applied to specific regions of the cyclone comma head, and the analysis was separated into different cyclone track orientations over the NEUS. The environmental relationships are somewhat more robust using the SOM technique, such as stronger midlevel frontogenesis in regions with more prevalent large bands and greater low-level vertical shear in regions with more frequent amorphous objects; however, the environments are still not statistically different for each precipitation object type. Given this result and the large spread in environmental ingredients for each object type, it is hypothesized that the objects may have environmental differences that evolve from the development to mature stages. Significance Statement A broad spectrum of organized precipitation structures exists in winter storms leading to variations in snowfall in a storm, but the environment within winter storms is complex. This study attempts to identify the environments that favor different precipitation structures. Although regions with a higher frequency of large, band-like objects tend to coincide with stronger midlevel forcing for ascent, weak stability, and some weak low-level vertical shear, the results are not statistically significant. Thus, this motivates more research to better understand how the environment changes as objects grow during their life cycle.