Another Arctic air and lake effect snow event

WEST MICHIGAN — By no means is it unusual to see an occasional Arctic air outbreak and lake effect snow in West Michigan in the winter…and the one this week is not much different. That said, there are a few things to note…especially for you science buffs and weather geeks.

Sometimes these Arctic outbreaks can bring snow measured in feet, but not this time. While some isolated locations may see a three-day total from Wednesday to Friday around 10″ or so, many locations along/west of U.S. 131 will be in the 4″ to 8″ range. Why? Three mitigating factors!

First, sometimes meteorologists look at the the dedritic growth zone or DGZ. This is the location where snow crystals grow. When the DGZ is too low or below the cloud base (for the best snowflake) or crystal production, total snowfall is limited. Simply put…an optimum location might produce more snow. Click here for more on this.

Second, the column of air moving over Lake Michigan (while cold) is not necessarily saturated. A mediocre or semi-saturated air mass will limit snow production. Keep in mind the colder the air, the less moisture content to the snow itself. It becomes a drier, more powdery snow that becomes difficult to rack up huge totals.

Third, one of the biggest mitigating factors for heavy snow production and snowfall is the location of what meteorologists call the inversion. A temperature inversion is simply where the temperature increases with height…counter-intuitive I know. Temperature generally tends to decrease with height, but a temperature inversion is an area above the surface (at some point) where the temperature in our vertical atmosphere actually increases (or may stay the same). These inversions also help to limit or mitigate severe weather during our warm seasons by creating a “lid or cap” in the lower atmosphere or planetary boundary layer (PBL). It’s similar in the winter. Despite the fact that Arctic air and moisture could be in place, a temperature inversion at 5,000 feet or below will usually limit substantial snow accumulations. Meteorologists generally like to see no inversion or a higher inversion of 8,000 to 10,000 feet for the clouds and precipitation to build and bellow up. Click here for more. The image below shows graphically what an inversion may look like to help conceptualize the idea.

temperature_inversion

Our forecast calls for temperatures below normal through next week Monday before a bigger warm up arrives. Average highs for this time of year have us at about 31 degrees. Get the complete West Michigan forecast at www.fox17online.com/weather.

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