Coldest air of the season…by far!

November 9, 2013 0 Comments

It’s about that time where every new week as we head deeper into fall becomes the coldest of the season.  This upcoming week is significant for a couple of reasons.  The image below is a surface weather analysis map that meteorologists look at to try and pinpoint the forecast.  Notice the big blue “H” over the Upper Midwest.  If you’ve watched weather reports you know it stands for high pressure.  You also know that relatively nice weather is associated with these systems.  Calmer winds, clearer skies, all of the above.  That “H” symbolizes a new airmass.  We’ve been cool, but now we will be really cool.  That number 1045 is the pressure in millibars.  You may be used to hearing pressure measured in inches of mercury or in PSI like when you fill up your tires.  Anyway, to understand what this means, you have to know a little bit about pressure. (Sorry in advance for the novel)  Just like when it gets cold outside for humans, we’re slow, don;t want to move, and huddle close for warmth.  Air molecules do the same.   The closer those air molecules are packed together, the higher the pressure will be.  I’ll stop rambling and just say even fore the Upper Midwest in November this airmass is an unseasonably cold one.  This is more indicative of the middle of Winter.

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Now it won;t be as cold as if this airmass was coming in the middle of Winter.  Why?  Because we don;t have snow on the ground yet.  That is a reason why we won’t break any records.  If there was snow on the ground, we would likely be flirting with record low temperatures..which are at or below 0 degrees this time of the year.  That snow pack acts as a refrigerator on clear and calm nights to cool things down very efficiently.  With that said…temperatures will be running 15-20 degrees below 0 come Monday and Tuesday.  Here’s a look at where this air is coming from.  We have to look way up north in Canada.  Afternoon temps were in the single digits to teens up there.  Now this airmass will modify on it’s journey south so it won’t be as cold, but still.

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Afternoon temps were in the single digits to teens up there.  Now this airmass will modify on it’s journey south so it won’t be as cold, but still.

 

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We may get a little light snow with the passage of the Arctic cold front that delivers the cold air, but nothing major in terms of snow for the next couple of days.

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