S158A Lake-Effect Snowbands through the Mohawk River Valley

Sunday, 12 January 2020
Patrick McMillan, Hobart and William Smith Colleges, Geneva, NY; and A. Shaw, N. D. Metz, and N. F. Laird

Shore-parallel lake-effect snow bands commonly exist during the cold season over large inland water bodies. In the United States, this occurs most often over the Great Lakes. These lakes feature large long-axis distances with relatively warm water for cold air to travel over. Research had been previously conducted into the general synoptic-scale conditions that influence the organization and intensity of these bands. For example, the magnitude of the low-level instability, presence of a lake-to-lake connection, and direction of the low-level flow have all been found to be important in determining snowband characteristics. This purpose of this study is to examine the conditions that facilitate long-distance lake-effect snowbands that travel through the Mohawk River Valley.

A seven-year (2012/13 through 2018/19) cold-season (Oct–Mar) climatology was created for all shore-parallel snow bands off of Lake Ontario. A total of 375 shore-parallel lake-effect bands were discovered emanating from the southern and eastern shores of the lake, 81 of which travelled toward the Mohawk River Valley. Composites were created for those bands that travelled a long distance down the valley versus those that had a similar orientation but did not reach the valley. These composites revealed that the 850-hPa temperature was largely similar between the long and short band composites. However, a deeper trough at 500-hPa and tighter height gradient with stronger 850-hPa winds were present for the long distance bands. Furthermore, the pressure gradient at the surface for long distance bands was substantially stronger. These results suggest that low-level instability, utilizing 850-hPa temperature as a metric, is not as important as the dynamical synoptic-scale forcing for promoting longer-distance bands through the Mohawk River Valley.

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