Abstract
Lake-effect snow (LES) storms pose numerous hazards, including extreme snowfall and blizzard conditions, and insight into the large-scale precursor conditions associated with LES can aid local forecasters and potentially allow risks to be mitigated. In this study, a synoptic climatology of severe LES events over Lakes Erie and Ontario was created using an updated methodology based on previous studies with similar research objectives. Principal component analysis (PCA) coupled with cluster analysis (CA) was performed on a case set of LES events from a study domain encompassing both lakes, grouping LES events with similar spatial characteristics into the primary composite structures for LES. Synoptic scale composites were constructed for each cluster using the North American Regional Reanalysis (NARR). Additionally, one case from each cluster was simulated using the Weather Research and Forecast (WRF) model to analyze mesoscale conditions associated with each of the clusters. Three synoptic setups were identified that consisted of discrepancies, mostly in the surface fields, from a common pattern previously identified as being conducive to LES, which features a dipole and upper-level low pressure anomaly located near the Hudson Bay. Mesoscale conditions associated with each composite support differing LES impacts constrained to individual lakes or a combination of both.
Highlights
Beginning in late October and early November, continental polar air masses that traverse the Laurentian Great Lakes destabilize via pronounced vertical surface heat and moisture fluxes as lake surface temperatures exceed that of the ambient air
The climatology was constructed based on a set of 88 unique lake-effect snow (LES) events that impacted nearshore regions off Lake Erie, Lake Ontario, or both
Reanalysis fields for the LES events, based on the unrotated Principal component analysis (PCA) methodology blended with a kmeans cluster analysis
Summary
Beginning in late October and early November, continental polar air masses that traverse the Laurentian Great Lakes destabilize via pronounced vertical surface heat and moisture fluxes as lake surface temperatures exceed that of the ambient air. Air mass modification ensues and results in vigorous convection and the formation of narrow snow bands that range between 5–50 km in width and 50–200 km in length [1,2,3], known as lake-effect snow (LES). LES contributes up to 55% of annual snowfall in affected regions and can result in extreme snowfall accumulations from single events (occasionally in excess of 50 in) [4,5,6,7]. LES can cause numerous hazards including limited visibility, blizzard-like conditions, and substantial recreational and economic damage (e.g., power outages and city shutdowns) to major population centers such as Buffalo (population 1.1 million) and Cleveland (population 2 million) [8]. The purpose of this paper was to employ objective methods to obtain updated synoptic-scale patterns associated with LES off the two eastern Great Lakes, Lakes Erie and Ontario
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