Why so cold for so long?

Brr!  We here in the Stateline definitely felt the cold grip of winter enter the area this Veterans Day- the air temperature has plummeted from the 60’s Monday evening (Nov. 10) to the middle 30’s 24 hours later.

The air temperature trend from Nov. 10 to Nov. 11

The air temperature trend from Nov. 10 to Nov. 11

Get used to the 30’s, because we’ll be seeing them for a while, at least through next week.  So why will they hang around for so long?

First, let’s look at what brought the unwelcome Arctic air in.  And no, it’s not the Polar Vortex.

Former super-typhoon Nuri helped move warm air north, which pushed cold air south

Former super-typhoon Nuri helped move warm air north, which pushed cold air south

A former super-typhoon named Nuri (a typhoon is the same thing as a hurricane; different name because it formed in a different part of the world (Pacific vs Atlantic, in general terms)) moved into the Bering Sea.  On its move, the storm intensified.  A lot.  While the storm raged near Alaska, it caused some side effect to this that are affecting us now.  Nuri was able to rev up the jet stream nearby, pushing a ridge in the jet stream along the Pacific Coast northward.  This shoving of the ridge moved a lot of unseasonably warm air toward the North Pole.  That push of warm air north dislodged cold, Arctic air from the North Pole and sent to sliding down to us in the Midwest.

That’s what we felt Monday into Veterans Day on Tuesday was the very cold air finally reaching us.  Now, that air will stick around because the ridge is sort of coming back into play.

Broad high pressure on the West Coast makes life difficult in the Midwest

Broad high pressure on the West Coast makes life difficult in the Midwest

Forming Wednesday and lasting well into next week is a blocking pattern called an Omega Block.  We call these patterns blocking patterns because they do just that: block any changes to the weather pattern, resulting in consistent, persistent, stagnant weather for a long stretch of time.

In this case, the omega block (which looks like the Greek letter Omega) is cause by Nuri weakening, relaxing the jet stream near Alaska and causing a strong ridge to form on the West Coast.  That broad area of high pressure under the ridge means weather systems either have to travel all the way around it, or be strong enough to break the ridge down.  This results in the weather being very consistent for a while.

So in the end, the Arctic air that arrived for Veterans Day? It’s not going anywhere, anytime soon.  We’ll have highs in the 30’s and lows in the teens clear into next week!  Bundle up!

-Alex

 

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Posted under weather

This post was written by Alex Kirchner on November 11, 2014

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