The Influence of Orographic Features on Lake Effect Snow: A Case Study on the November 2022 Great Lakes Snowstorm

From November 16 to 20th 2022, the Buffalo-Niagara Falls metropolitan area and parts of northwest New York state were pummeled by an intense lake effect snowstorm, receiving over 80 inches of snow over the span of 4 days. Positioned downstream of two large lakes and with areas of elevated terrain, Buffalo and other regions of upstate New York are familiar with significant lake-effect snow events. However, in November 2022, Lake Ontario had the highest average surface temperature for mid-November within the last 27 years while Lake Erie had the second highest temperature. These high temperatures, combined with a surge of cold air aloft, created a largely unstable environment that caused snowfall rates as high as 3-6 inches per hour.

The intensity of the November 2022 event provided an opportunity to analyze how strong lake effect snowstorms in the Great Lakes Region are influenced by nearshore orographic features. Previous literature suggests that downwind terrain heights of 500 meters (such as those located in our study region) may not be tall enough to significantly impact lake effect snow storm dynamics. However, different lake effect snow modes (i.e. the shape of the storm) may play a substantial role in a storm’s precipitation distribution by influencing orographic ratios (the ratio of the precipitation in the highlands to the precipitation in the lowlands).

To examine how terrain impacted the distribution of precipitation during the November 2022 lake-effect snow event, we used the Weather Research and Forecasting Model (WRF) to model the storm under two scenarios: 1) a control scenario with 100% terrain and 2) an exploratory scenario in which all terrain is removed. For analysis, we focused on 4 cities based on elevation and storm path: Silver Creek, NY (218 m) and Holland, NY (493 m) for the Lake Erie sites and Watertown, NY (146 m) and Worth Center, NY (452 m) for the Lake Ontario sites.

Downwind of Lake Erie and Lake Ontario, the November 2022 lake effect snowstorm had fetch that was predominantly long-lake axis parallel, which led to a low orographic ratio since the winds forced convection to simply go around the terrain. However, later in the event, a wind shift changed the lake-effect snow to enter a broad coverage mode, which made the cross-barrier winds stronger and forced the convection to go over the terrain, leading to a higher orographic ratio. These two outcomes demonstrate that, despite the terrain heights of our study area not being theoretically not tall enough to significantly shape the storm, the terrain was still an influential factor for the region. Terrain features and lake effect storm mode don’t independently influence air flow and precipitation distribution — it is important to analyze the interactions between them by assessing the direction and strength of the predominant wind flow with respect to the terrain location and height.