Arctic air in July

Posted at 8:20 AM on July 16, 2009 by Paul Huttner (1 Comments)

Get ready for an arctic outbreak.

No we're not talking sub-zero air in July, but if the weather maps looked like this in January we would be. The jet stream and surface winds are blowing air directly from the Arctic Circle into Minnesota over the next 48 hours. The source region for Friday's air mass is the Arctic Ocean. When this happens in meteorology we call it "cross-polar flow." When it happens to you in July, you call the weatherman "names."

High temperatures Friday may be in the low 50s in northern Minnesota. We should make the September like 60s here in the south. The forecast high is around 67 degrees tomorrow in the metro. That's the average high for the last week in September!

The record low maximum temperature for Friday is 66 degrees set back in 1939. We have a shot at that record tomorrow. The only thing that may save us is the higher sun angle at this latitude compared to the Arctic. The increased solar energy will tend to modify the chilly air mass as it moves southward.

Take a look at some of the forecast highs for Friday.

-Twin Cities 67
-Brainerd 65
-Duluth 60
-International Falls 57
-Ely 56

These temperatures are a good 15 to 20 degrees below average. Campers could be dealing with frost in northeast Minnesota the next few mornings.

The weather will warm as we move into the weekend. Look for plenty of sun and highs getting close to 80 degrees again by Sunday in the metro.

I wouldn't go so far as to call this "the year without a summer" but signs are pointing to a cooler than average July to close the month. There are also indications that heat could return closer to August 1st. Weather patterns have a way of evening out. Keep that air conditioner tuned up. You may need it next month.

PH

Comments (1)

I've been hearing a lot about a wonky jetstream this year. Any theories on why it is so different?

Posted by Alex | July 17, 2009 6:51 PM

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