Forecasting lake‐/sea‐effect snowstorms, advancement, and challenges

Abstract

Lake-/sea-effect snow forms typically from late fall to winter when a cold air mass moves over the warmer, large water surface. The resulting intense snowfall has many societal impacts on communities living in downwind areas; hence, accurate forecasts of lake-/sea-effect snow are essential for safety and preparedness. Forecasting lake-/sea-effect snow is extremely challenging, but over the past decades the advancement of numerical forecast models and the expansion of observational networks have incrementally improved the forecasting capability. The recent advancement includes numerical forecast models with high spatiotemporal resolutions that allow simulating vigorous snowstorms at the kilometer-scale and the frequent inclusion of radar observations in the model. This combination of more accurate weather prediction models as well as ground-based and remotely sensed observations has aided operational forecasters to make better lake-/sea-effect snow forecasts. A remaining challenge is that many observations of precipitation, surface meteorology, evaporation, and heat supply from the water surface are still limited to being landbased and the information over the water, particularly offshore, remains a gap.This primer overviews the basic mechanisms for lake-/sea-effect snow formation, evolution of forecast techniques, and challenges to be addressed in the future.This article is categorized under: • Science of Water > Water Extremes • Science of Water > Water and Environmental Change • Science of Water > Methods K E Y W O R D S extreme weather, lake-effect snow, numerical model, sea-effect snow, weather forecast

How Could Future Climate Conditions Reshape a Devastating Lake‐Effect Snow Storm?

“…Depending on the location, other factors, such as a convergence due to land breezes or an uplift due to orographic effects, also play a role in the intensification of LES storms (Alcott & Steenburgh, 2013;Fujisaki-Manome et al, 2022;Umek & Gohm, 2016;Veals & Steenburgh, 2015). The world's largest unfrozen surface freshwater system, the Laurentian Great Lakes (Superior, Michigan, Huron, Erie, and Ontario), provides tremendous amounts of moisture that interact with the north-westerly cold dry air, often originating from the Canadian North (Fujisaki-Manome et al, 2022;Notaro et al, 2013;Wright et al, 2013). As such, LES storms play a significant role in shaping the regional Great Lakes climate, especially within the Great Lakes snowbelt, an area of high snowfall along the eastern and southern downwind shorelines.…”

“…Among the various extreme weather events, lake‐effect snow (LES) storm—a meteorological phenomenon characterized by heavy convective precipitation downwind of lakes in the form of snow—is a unique and critical coastal hazard (Ayon et al., 2020; Dewey, 1977; Fujisaki‐Manome et al., 2022; Notaro et al., 2013). LES storms are formed when a frigid dry air mass traverses over a substantial stretch of comparatively warmer water, triggering the development of a convective internal boundary layer (Figure 1a).…”

Impact of Cyclone‐Cyclone Interaction on Lake‐Effect Snowbands: A False Alarm

“…Accurate prediction of winter snowfall over the Great Lakes region is still challenging, especially for its locations and amount (Fujisaki‐Manome et al., 2022). Regarding winter weather forecasts in Ontario, Canada, OSPC received the public complaints mostly concerning false alarms in forecasting snowfall events, especially lake‐effect and/or lake‐enhanced snowfall.…”

“…Since the lake-effect precipitation associated with two or more cyclones occurs from time to time, the newly developed diagnostic method described in Cao et al (2019) is particularly appropriate to examine the effects of two or more cyclones and their interactions on lake-effect precipitation, with emphasis on severe precipitation having high impacts on society. Accurate prediction of winter snowfall over the Great Lakes region is still challenging, especially for its locations and amount (Fujisaki-Manome et al, 2022). Regarding winter weather forecasts in Ontario, Canada, OSPC received the public complaints mostly concerning false alarms in forecasting snowfall events, especially lake-effect and/or lake-enhanced snowfall.…”

Climatology of sea‐effect snow in Finland

“…Climate models to be able to resolve convective snowband cells should have a high horizontal resolution, 5 km or less. Given the small scale of these phenomena, forecasting the location, timing and intensity of sea‐effect snow is still challenging even for convection permitting weather forecast models (Fujisaki‐Manome et al ., 2022). Especially, heavy precipitation in output data of coarse (resolution typically > 25 km) climate models or reanalysis tend to be underestimated (Médus et al ., 2022).…”