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Historical lake-effect snowfall trends for the Ontario snowbelt

Lakes modulate the regional climate through influencing the local energy and hydrological budget, which can produce lake effect snowfall (LES). The leeward shores of the Laurentian Great Lakes are susceptible to LES during the cold season when cold and dry continental air masses advect over long axes of relatively warm water bodies. This advection drives the exchange of moisture and energy fluxes from the lake surface to the lower planetary boundary layer (PBL), inducing instability and the development of LES.

During lake effect season, it is extremely dangerous for motorists traversing busy highways along the snowbelt region, such has highway 400 that connects Southern Ontario to the Cottage Country region, because the highly localized nature of LES can produce snowsqualls amidst patches of clearer sky leaving motorists in blinding and whiteout conditions. Despite LES impacts over the Canadian snowbelt region of the Great Lakes Basin (GLB), many LES studies were limited to the United States, with minimal climatological analyses on the Ontario snowbelt.

Current research investigated spatiotemporal trends in total monthly snowfall during the cold season from 1982 to 2013 using observational gridded datasets. Results show significant decreases in snowfall and precipitation along the Ontario snowbelt of Lake Superior, Lake Huron and Georgian Bay. Additional spatiotemporal trends of surface-atmosphere predictor LES variables indicate significantwarming in LST, significant decrease in ice cover fraction, and a robust increase in instability parameters such as omega, and vertical temperature gradient. While the behavioural trends of these variables are believed to enhance LES by increasing evaporation into the lower PBL, there are other complex processes involved such as inefficient moisture recycling and increase moisture storage from warmer air masses that inhibits the development of LES in these region.

Spatiotemporal snowfall trends (cm) over 32 years (1982 – 2013) of total monthly snowfall, November, December, January, February, and March (a)-(e) respectively, and the corresponding areas of significant decrease at the 90% confidence level (f)-(j)

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