IOP2 produced over 100 cm of snow on the western slope of the Tug Hill Plateau in 24 h. During the event significant vacillations in lake-effect morphology were observed. Organized long-lake-axis parallel (LLAP) bands centered over the transect produced the highest precipitation rates and accumulations at both lowland and upland sites, but also the lowest orographic ratios (i.e., the ratio of upland to lowland liquid precipitation equivalent). Rimed crystals and graupel were frequently observed at both sites during LLAP periods. Broad coverage periods, featuring less-organized convective coverage made up of distinct individual cells, produced lower precipitation rates at both sites but higher orographic ratios as cellular convection produced over the lake transitioned to a more stratiform mode with greater coverage and more persistent precipitation over the Tug Hill Plateau. Mixed mode periods, which consisted of broad coverage concomitant with an organized LLAP band, also exhibited broadening and a convective-to-stratiform transition. During these periods there were low orographic ratios between the upland and lowland site when the band was centered over the transect and high orographic ratios when the band was to the north or south of the transect.
Climatologically, organized bands account for 10% of lake-effect hours over Lake Ontario with broad coverage and mixed mode making up the majority of the remainder. Accordingly, this study suggests that the Tug Hill Plateau precipitation maximum may be largely due to the broadening of precipitation coverage and frequency over the uplands rather than the invigoration of LLAP bands over the Tug Hill Plateau.