The Polar Vortex: This is a term that was thrown out to the world this past winter. At first, you hear this and think of some awful snow-nado, right? Well the term came back this past week and with much debate. One thing about a debate of any nature is that you need to listen to both sides in order to make any progress.
Here's the skinny...Minneapolis reached a whopping high of 65 yesterday, and that's only the 84th time in the past 76 years where the high on a day in July was less than 70. Meanwhile, much cooler weather is forecast for a large portion of the country, including our area. As I'm writing this, most of our viewing area is struggling to hit the 80 degree mark after a four day streak of 90+ degree heat.
For some, this is the infamous Polar Vortex at work. For others, it's just an irregular pattern which features the jet stream moving further down south than usual without influence from the "PV". For many, Polar Vortex is still a foreign term.
One thing is for sure, as explained by this graphic. The Polar Vortex and Jet Stream are two completely different phenomena. The white whispy arrows represent the Polar Vortex, where as the large blue arrows represent the jet stream. The Polar Vortex is merely an large-scale, upper level circulation near the North Pole, which features very cold air and strong winds. This is NOTHING NEW! Yet for some reason, it was given a nifty name that would draw people's eyes and ears towards the TV.
The jet stream, is a wind maximum that separates warmer air in the south from cooler air to the north, and is on the edge of the vortex.
Here's a hypothetical scenario during the winter-time:
Every once in a while, a piece of the AbominableSnowmanPolarDeathMachine breaks off and moves southward, and the jet stream will move accordingly. As we saw in January, low temperatures were below zero on three difference occasions.
Here's what's going on this week:
The jet stream is moving further southward, in an unusual summer-time set up. (Its unusual southward dip doesn't appear to be due to a piece of the Polar Vortex taking a vacation down south. Rather, it looks as though this airmass is too warm at a certain level in the atmosphere to have polar origin.)
Regardless, cooler air comes into play north of a surface cold front as a result of the jet stream movement. So, is this movement a result of the Polar Vortex? And are we going to blame every jet stream intrusion on the Polar Vortex now? Some may say, "Who actually cares? Just tell us it's going to be cooler, and we'll move on."
Well if we're going to continue using this PV term, even though the phenomenon itself is nothing new, there needs to be some sort of criteria. We either base it off of geographic origin, or we base it off of the temperatures at a certain level in the atmosphere (since I've observed both arguments). For example, at such-and-such a level, the temperature needs to be below zero degrees for the disturbance to be considered polar. OR is it too harmful to the communication process to go using a word like "polar" in July?
That's where debate amongst meteorologists and feedback from viewers come into play. Before we go communicating this cool new catch phrase, we should come to a consensus on what criteria need to be met.
In a perfect world, we could just say "Hey it's going to be colder than normal, thanks to surface winds from the north and the jet stream moving south." But that would just be too easy, right?
---Meteorologist Chris Michaels---
Facebook: Chris Michaels WCYB