A recent spatial, temporal, and meteorological climatology of thundersnow across the contiguous United States

A 20-winter climatology was conducted across the contiguous United States apart from Florida using automated weather stations. Results yielded several thousand reports with multiple reports sometimes accounting for one case. Cases were split up into categories based upon the setting in which the thundersnow occurred. Categories that were used were cyclone, orographic, lake effect, and coastal cyclone. These categories were then analyzed and compared to identify spatial and temporal patterns. Regionally, hotspots were found in the Great Plains to the Upper Midwest, Colorado, the East Coast, and areas adjacent to the Great Lakes. Temporally, occurrences peaked in the months of February, March, and April, with frequency varying by thundersnow type. Diurnal patterns were relatively uniform, though a slight increase was noted during the late afternoon and evening hours. Typically, prevailing winds were out of the north, except in lake effect and orographic cases, with mean speeds between 10-15 knots. Most cases exhibited a preference toward light snow falling at time of report with moderate and heavy snow splitting up the remaining half of cases. Mean temperatures were just below freezing throughout each case with dew point temperatures a couple degrees colder than the respective air temperature. Mean thermodynamic profiles for different cases showed a distinct inversion layer in the lower levels with the most unstable air parcel originating near the top of the inversion layer around 730 hPa. Very little, if any MU CAPE, was present in a lot of soundings with lake effect thundersnow demonstrating the most MU CAPE. Furthermore, snowfall was assessed to analyze where the deepest snowfall accumulations occurred. Results showed that there was no indication of the heaviest snow associated with reports of thundersnow, but rather heavy snow accumulations usually occurred within a snowstorm with varying distances. Lastly, a case study of widespread thundersnow reports supported previous findings: elevated convection within winter storms is driven by strong frontogenetic forcing, a deep moist layer with wind shear, and occasionally, negative equivalent potential vorticity.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Soil, Environmental and Atmospheric Sciences

Grantor dc:publisher

University of Missouri--Columbia

Year dc:date.issued

2025

Author dc:creator

• Simmons, Noah

Advisor dc:contributor.advisor

• Fox, Neil

Language dc:language.iso

eng, English

DOI

https://doi.org/10.32469/10355/109771

OAI identifier oai:identifier

oai:mospace.umsystem.edu:10355/109771