Diving Deeper Into The Dynamics Of Lake Effect Snow During The Recent Polar Vortex Visit

DISCUSSION: It is the heart of a true Arctic air intrusion and the only thing which most people are thinking about are the implications of the cold weather on how they will dress or what sort of social life they will likely plan during the extent of a given cold weather stint. However, there are several other atmospheric phenomena which can unfold during various parts of a cold air outbreak. One such example occurs when a very cold air mass moves over a relatively warmer lake, bay, or ocean surface. As this colder air moves over the warm body of water of some variable size, the cold air is modified and undergoes a reasonable degree of destabilization which sometimes leads to the development of shallower convection in the form of lake effect snow (i.e., when the shallower ocean, bay, or lake-driven convection is sufficiently organized).

This Winter-time atmospheric phenomenon is most common during the Winter-time months across various parts of North America and Europe if there is a sufficiently low amount of lake, sea, or ocean-based ice coverage present. The reason for why minimal ice coverage is a critical factor involved with lake effect snow is a result of the fact that substantial ice coverage will prevent the essential surface fluxing (i.e., the process of warmer water vapor being released from the warmer water body surface) from occurring. In the case of this past week across the full extent of Lake Ontario (and even Lake Erie for the most part), this was very far from the situation at hand. More specifically, as the heart of the coldest air associated with the brief visit from the “Polar Vortex” circulation moved over and across the Great Lakes region (and particularly across the extents of Lake Erie and Lake Ontario), this triggered a substantial lake response off Lake Erie and a truly prolific response off Lake Ontario.

In the brief animated gif attached above (courtesy of Meteorologist Tom Niziol from The Weather Channel in Atlanta, Georgia), you can clearly see how the full extent of Lake Ontario exhibited a classic long-lake axis parallel (LLAP) response to the severely cold air mass traversing across the full extent of the lake (Steiger et al. 2013). As a result of this incredibly efficient lake response, this allowed a truly EPIC lake effect snow band to develop and maintain itself over a long period of time with relatively minimal movement from a north-to-south perspective. In addition, in the latter part of this gif, you can also see this recent lake effect snow band from a three-dimensional perspective near the peak of its existence. Note how you can also see the clear gradual intensification of the shallowed lake-based convective cells which developed (per the growing blue-colored “puff-shaped” figures which were moving towards the eastern shoreline of Lake Ontario back on 31 January. Furthermore, you can also see how the blue-colored cells darkened somewhat as they approached the eastern shoreline which indicated that further intensification of the lake effect convection was occurring in earnest (i.e., leading to heavier snowfall occurring along and just east of Lake Ontario’s easternmost sections).

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References: Steiger, S., Schrom, R., Stamm, A., Ruth, D., Jaszka, K., Kress, T., Rathbun, B., Frame, J., Wurman, J. and Kosiba, K. (2013). Circulations, Bounded Weak Echo Regions, and Horizontal Vortices Observed within Long-Lake-Axis-Parallel–Lake-Effect Storms by the Doppler on Wheels*. Monthly Weather Review, 141(8), pp.2821-2840.

© 2019 Meteorologist Jordan Rabinowitz