November 15th, By Climate Central Arctic air begins to race across the relatively milder water of the Great Lakes every fall, generating lake effect snow.
SLR values in the Great Lakes range from about 8: Lake effect snow is almost always less dense than synoptic-origin snowfall. Snow in the southern Great Lakes region is typically heavier than in the north because colder temperatures in the north prevent the air from holding as much moisture, hence the snow is less dense.
Only one-quarter of SLR values indicate high-density snows over the Great Lakes region, so snow is most often average to light density.
The 25th left50th centerand 75th right percentile SLR values during Source: Baxter, Graves, and Moore Figure 5: Baxter, Graves, and Moore There is considerable variability in the seasonality of snow density particularly downwind of the Great Lakes Figure 5. When the lakes are not frozen over and their waters are warmer than the air above them convective updrafts can occur.
The additional moisture from the lakes in the updraft enhances snow crystal formation leading to more dense snowfalls. The ability of the lakes to increase snow densities is dampened once the waters are frozen over, which typically occurs throughout December, January, and February.
Information about average winter weather combined with snow density information is useful for describing when there is greatest potential for damaging conditions. Most snowstorms occur in December and January, which coincides when snow densities are lightest, so the greatest snow depths can be expected during these months.
Snow densities are typically lightest near the lakes but snow depths are greatest in the lake-effect zones. Snowstorms in the southern portion of the Great Lakes during early winter pose a greater threat for dense snow, although typically snow depths are less. Intense Snowstorms Figure 6: The amount of snow cm expected in a snowstorm at least once every 5 years Source: The amount of snow cm expected in a snowstorm at least once in every 10 years Source: Changnon The lake-effect zones, which have been identified as regions receiving the most annual average snowfall, are also where the heaviest snowstorms are experienced.
A heavy snowstorm, as defined by Changnonis an event when Weather station data were used to identify where heavy snowstorms occurred in the United States between The structure of the lake-effect zones is not as apparent in the maps of heavy snowstorms, because there are less data points compare the dots representing weather stations in Figures 6 and 7 to those in Figure 3a.
However, regions around the lakes upwind and downwind receive the heaviest snowstorms in the region.Lake-Effect Snowfall (formation) develops after extratropical cyclone (Alberta Clipper) passed over region and its cold front is well east of Great Lakes cold air . With that said, recent research has suggested that lake effect snow totals along Lake Superior and Lake Michigan have increased from to (Kunkel et.
al ). Due to the known quality issues with snow data, this research applied strict data standards for weather station snow data. Lake-effect snowfall is a large contributor to yearly precipitation in the Great Lakes region, affecting the water budget as well as local economies.
Air temperature is. Snow (including snow storms, snow cover, snow depth, and snow density) is a complicated variable in the Great Lakes region due to the influence of the lakes on local climate.
Great Lakes snow can be partitioned into two main categories - lake-effect snow and non-lake-effect snow. Nov 19, · A study that used oxygen isotopes to distinguish local lake-effect snow from snow formed outside the region showed a sharp increase in lake-effect .
This study examines records of snowfall from several lake-effect and non-lake-effect sites throughout most of the twentieth century in order to 1) determine whether differences in snowfall trends exist between these settings and 2) offer possible linkages between lake-effect snow trends and records of air temperature, water temperature, and ice cover.