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Brief Arctic blast on the way!

Posted at 6:27 PM, Dec 28, 2014

WEST MICHIGAN — Ready for colder temps? They’re on the way this week…but only briefly. Average/normal highs for this time of year have us in the low 30s, but we’ll struggle to reach the low 20s on Tuesday and Wednesday as Michigan gets brushed with a brief blast of Arctic air.

Strange how the weather can be in the Great Lakes. Grand Rapids tallied almost 32 inches of snow in the month of November…making it the snowiest (November) on record. Thus far this month of December, it has turned out to be the LEAST snowiest December on record. We’ll have to wait until we officially finish the month on Wednesday to see if that distinction holds.

While we would normally be forecasting an appreciable amount of lake-effect snow with this type of a cold air outbreak, there are three reasons why we will NOT see heavy lake-effect snow this week. First, this is shallow cold air. It does not encompass much of the atmosphere above the surface. Second, it is a dry air mass. Without much moisture it’s difficult to squeeze moisture from it in the first place. Third, our forecast models are showing a temperature inversion at about 3,000 feet. That means the atmosphere is actually warmer aloft, which creates (a sort of) cap/lid. It doesn’t allow the clouds, lift, and moisture to billow up to higher levels and deliver heavy snow.

The image attached to this story is a snapshot from one of our computer forecast models valid on Wednesday morning. The colors represent the air mass at around 5,000 feet above the surface. Note the colder tones (pink/deeper purples) over Michigan. In fact, the temperature just above the surface will be around -20 degrees Celsius. That equals -4 Fahrenheit, which will translate to only upper teens to near 20 at the surface. Throw in a stiff wind and we’ll see wind chills in the single digits!

Frankly, we’ll finish 2014 on a quiet note weather wise with the exception of some light lake-effect snow showers that may total a couple inches west of U.S. 131. Get the complete West Michigan forecast at www.fox17online.com/weather.