Climatological Characteristics and Orographic Enhancement of Lake-Effect Precipitation east of Lake Ontario and over the Tug Hill Plateau

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Sunday, 4 January 2015
Peter Gregory Veals, University of Utah, Salt Lake City, UT; and J. Steenburgh

Lake-effect snowstorms east of Lake Ontario are frequently intense and contribute to substantial seasonal accumulations, especially over the Tug Hill Plateau (hereafter Tug), which rises at a gentle 1.25% slope to ~500 m above lake level. Using a variety of datasets including radar imagery from the KTYX WSR-88D, this work examines the characteristics of lake-effect precipitation east of Lake Ontario over 13 cool seasons (16 September 2001 – 15 May 2014). During the study period, lake-effect days (LEDs) account for 61–76% (24–37%) of the mean cool-season snowfall (liquid precipitation equivalent) depending on location. Mean monthly lake-effect frequency and snowfall on LEDs peak from Dec–Jan. The highest lake-effect frequency and snowfall occur over the western and upper Tug, with an arm of relatively high frequency and snowfall extending to the southeast shore of Lake Ontario. To the east (lee), lake-effect frequency and snowfall decrease abruptly over the Black River Valley, although relatively high frequencies and snowfall extend downstream into the western Adirondack Mountains. Broad coverage and long-lake-axis-parallel (LLAP) bands dominate the lake-effect morphology throughout the region. There is no diurnal modulation of lake-effect frequency during the winter (December–Februrary), but weak modulation in the fall and spring, especially of LLAP bands. Collectively, these results illustrate the role that lake-effect precipitation plays in the cool-season hydroclimate east of Lake Ontario. The increase in lake-effect frequency and snowfall over the Tug suggest an inland/orographic intensification of many lake-effect systems, with evidence for shadowing in the lee.