Lake-to-Lake Influence on Lake-Effect Snow Amounts in the Lake Michigan Snowbelt

The influence of an upwind lake on a lake-effect snow (LES) system occurring on a downwind lake is not well understood. Experienced operational forecasters have suggested that snowfall with the downwind LES would be enhanced; however this has not been examined quantitatively. This research seeks to compare snowfall amounts produced by LES from lake-to-lake (L2L) and single-lake events for the Lake Michigan Snowbelt. To examine snowfall throughout the Lake Michigan Snowbelt, daily SNODAS solid precipitation data were used for each LES day identified during the winters (October to March) of 2003/2004 – 2013/2014. LES days were divided into separate types using GOES visible satellite imagery: L2L Wind Parallel Bands (WPB), L2L Shore Parallel Bands (SPB), single-lake WPB, and single-lake SPB. A comparison of mean snowfall for L2L and single-lake LES across the 11 winters found L2L events produced more snowfall than single-lake events along the southeast shore of Lake Michigan and in the northwest lower peninsula of Michigan. Composited mean sea level pressure for L2L events had a large east-to-west gradient which produced strong, northerly surface winds, whereas single lake categories were dominated by high pressure and weak, westerly surface winds. The 850-hPa temperatures were 1–2°C cooler during L2L events but the surface temperatures were very similar across all categories, which could result in greater instability. The 2-m specific humidity composites showed that L2L events generally had more moisture available in over-lake regions. Both the findings from the snowfall analyses and atmospheric composite fields suggest that L2L events provide a more favorable environment for the development or enhancement of LES over the Lake Michigan Snowbelt. s suggest that L2L events provide a more favorable environment for the development or enhancement of LES over the Lake Michigan Snowbelt.