As the Nation’s most recent snowstorm continues to move northward across eastern Canada, west and west-southwest winds have moved into the eastern Great Lakes region (Fig. 1 and Fig. 2). Winds blowing from this direction have the longest over-lake trajectories and are, hence, better able to pick up more heat and moisture from the lakes. It’s easy to see this in the pre-sunrise radar image on Jan. 7 2014 from Buffalo, NY (Fig. 3). Two snow bands, in the middle of Lakes Erie and Ontario, are running down the length of the lake, parallel to the west-southwest winds. Infrared satellite imagery shows the lake effect snow band pattern, as well (Fig. 4). With Buffalo and Watertown (both in NY) at the receiving end of these wind-focused snow bands, it’s not surprising that both areas are under various winter weather warnings (Fig. 5).
Along with the addition of heat and moisture to the arctic air mass on the air mass’ passage over the Lakes, uplift in Tug Hill Plateau (near Watertown) and convergence of winds along and near the eastern shoreline of the lakes all add to the localized heavy snowfall potential.
As is typical with such patterns, snowfall variability will be huge. Some areas are expected to receive upwards of three feet of snow in the next day and a half (Fig. 6). Other areas nearby may receive a few inches or less. This variation can occur over just a few miles.
In addition to snowfall variability, visibilities will be highly variable both in time and in space. In some places, near zero visibilities can be expected (especially along I-90), while in nearby locales, the sun may be shining and visibilities may be unlimited. Depending upon how the winds vary over time, the heavy snow band may reposition itself, moving from one area to a nearby area. Sun may replace blizzard conditions (and vice versa) within moments. The pattern can even transition several times in succession over relatively short time periods.
Whiteout conditions, road blockages and closures due to blowing and drifting snow and very low visibilities are all on the menu for the next two days across areas shown in Fig. 6. Visibilities may also be impacted by bright sunlight reflecting off snow and/or ice-covered ground.
© 2014 H. Michael Mogil