An Updated Synoptic Climatology of Lake Erie and Lake Ontario Heavy Lake-Effect Snow Events

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.

Structure and Evolution of Non-Lake-Effect Snow Producing Alberta Clippers

“…[20]) form during LES events. This was observed in [35] and [36] who found that, for a PBL thermodynamic profile conducive to LES formation, subtle variations in the surface dipole structure driven by deviations in the synoptic scale pattern led to varying LES snow band types and impacts.…”

“…Additionally, as the clipper propagates and matures, an anticyclone will typically build in its wake which creates a pressure dipole and tight isobaric gradient between the two pressure systems. As [35,36] note, in addition to strong flow, this dipole has also been linked with LES off the Great Lakes.…”

“…), warm and moisten the PBL above the lake surface which results convective updraft formation and the eventual development of elongated snow bands over the lake surface that stretch inland into the lake's lee [18,[20][21][22][23][24][25]. While the mesoscale conditions linked with LES have been extensively investigated [26][27][28][29][30][31][32][33][34], studies characterizing the synoptic environments associated with LES remain limited, though contemporary studies are beginning to integrate updated analysis techniques to identify synoptic-scale structures underlying LES [35,36]. In our study, we will focus specifically on the role of the cyclone track (the Alberta Clipper (hereafter clipper)) that is most responsible for LES, and which synoptic conditions and processes associated with clippers are most influential to LES formation.…”

“…Previous studies have outlined the following conditions as typical for a synoptic environment comprising Great Lakes LES [35,36,[44][45][46]:…”

“…Finally, Section 4 summarizes the results and discusses future work. [35] highlighting the evolution of the common dipole structure present during a LES event off the eastern Great Lakes (Lakes Erie and Ontario).…”