Orographic and thermodynamic processes influencing mixed-phase precipitation banding in an eastern United States winter storm

Mesoscale snowbands within the comma head of wintertime extratropical cyclones can cause major societal disruptions and are challenging to predict. Previous literature has suggested the importance of mid-level frontogenesis in primary snowband development northwest of the surface low. However, little is known about the coupled microphysical and thermodynamic processes within these primary snowbands. In this study we examine the 16–17 January 2022 winter storm, where complex terrain interacted with a near-freezing thermodynamic profile to support a heavy mixed-phase precipitation band over western New York. Microphysical observations for this case were obtained from the University of Illinois System for Characterizing and Measuring Precipitation (SCAMP), a multi-sensor suite of instruments deployed in Buffalo, NY. To further investigate the orographic and thermodynamic processes influencing the mixed precipitation band, output from a Weather Research and Forecasting (WRF) model simulation with 1 km grid spacing was analyzed. Simulated WRF vertical cross sections through the banded precipitation revealed mid-level ascent above persistent low-level subsidence. This low-level subsidence initially formed over the higher terrain southeast of Buffalo, NY in a stable layer with orographic gravity waves. Within this subsidence layer, adiabatic warming allowed for an isolated pocket of above-freezing temperatures to form, which then moved northwest toward the SCAMP site in Buffalo, NY. As the above-freezing layer developed, particle size and fall speed distributions from the SCAMP depicted melting snow as the predominant precipitation type. Overall, the orographic gravity waves and associated adiabatic warming promoted snow particle melting, and consequently, the intense snowfall rates observed within the primary snowband during this storm.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Atmospheric Sciences

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Jesmonth, Kaitlyn R.

Contributors dc:contributor

• Nesbitt, Stephen
• Rauber, Robert
• Steenburgh, Jim

• Snow
• Winter Storm
• Mesoscale Banding
• Microphysics
• Orographic Effects

Statement dc:rights

• Copyright 2025 Kaitlyn Jesmonth

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/129296

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F129296