Sunday, December 30, 2012

Polar Vortex Close To Collapse

As I have been emphasizing for days on end, the polar vortex is getting torn to shreds, and continues to look closer and closer to near-collapse with every model forecast. I will explain what is making it do so, and what it would take to make the vortex collapse.

These are two forecast images from the ECMWF model, with the top forecast showing the top layer of the stratosphere at 1 millibar, and the bottom forecast showing the lowest layer of the stratosphere at 100 millibars. Note how the 1 millibar layer shows high pressure covering the entire Arctic Circle, with the polar vortex now split into two vortices. This full split is much like cracking an egg- if you crack it into two, the yolk of the egg spills out. In this case, the cold air at the top of the stratosphere could flow down through the stratosphere, possibly even to the surface. As for the 100mb layer, high pressure is trying to build into the North Pole and attempting to split up the polar vortex, as seen in the 1mb layer. This is like partially cracking an egg- some yolk leaks out, but not all of it. Either way, it's progress.

This zonal wind forecast from the ECMWF, valid for 10 days out, shows very negative zonal wind anomalies in much of the stratosphere from 70N - 90N. These deep negative zonal anomalies signifies the creation of strong high pressure in the area, a.k.a. east winds. Sudden Stratospheric Warmings tend to initiate these different zonal wind values, and thus help to really hurt the polar vortex's strength. Seeing as how these easterly winds suddenly skyrocket in the entire stratosphere in the 10 day forecast, it's not all that far-fetched to continue to see severe damage inflicted upon the polar vortex at all levels.

These two graphs above show several things of importance. We'll start with the first set of image panels. The very top image shows an aqua-colored line of zonal winds at the 1 millibar level. We can see the sudden crash of the zonal winds at the 1mb layer, enhancing the forecast of zonal winds shown 3 images above this sentence. Let's now go to the bottom image of the first set of images. This shows EP-Flux, and essentially measures the strength at which warm air flows up into the stratosphere. The longer the arrow, the stronger the EP Flux and the more warm air wants to shoot into the stratosphere. Notice how it dies down again at the end of the forecast period, meaning the sudden stratospheric warming would stop.

The bottom set of images shows temperature forecasts. We want to pay attention to the first three images. They show the 10mb layer temperature for the first image, the 30mb temperature for the second image, and the 10mb/30mb temperature forecasts superimposed on each other. Now, we can see that both layers of the stratosphere warm nicely through the forecast period, a sign of the aforementioned sudden stratospheric warming (SSW). Even better for cold prospects (and polar vortex collapse pospects) later on is how this warming at the 10mb and 30mb layers does not crash back down to cold levels right after the warming, as is usually observed.

Some potential vorticity forecast images show a complete collapse of the vortex at what I assume to be the top of the stratosphere:

So all in all, the polar vortex is getting torn apart now, and will only get torn apart in the future even worse. A collapse of the vortex in the upper stratosphere appears likely, and it could only be a matter of time before the rest of the stratosphere starts experiencing big troubles as far as being able to maintain itself.

**Below info Updated at 2:30 PM**
The new 12z GFS forecast shows the polar vortex greatly displaced. Instead of being in the Arctic, it's all the way down in Japan! It appears another piece of the vortex may be off the coast of Europe. High pressure trapping the vortices south would theoretically deliver yet another crushing blow to the polar vortex, which I don't know will be able to recover fully in Jan-Feb.



armando said...

wow great news Andrew! This is going to be an exciting winter! Also I've seen this a few times about this possible storm next week from the 4-6, and the 12z euro model showed something very interesting. If you could get a chance could you put a post up on that potential storm? That would be great thanks for the updates as well!

Anonymous said...


blizzard 78 said...

what does that mean for usa

Cam Smith said...

How will this effect the weather in the North East?

Rod Houston said...

How will this affect the Midwest?

Anonymous said...

How will this affect the central plains??

Andrew said...

I cannot tell you what the weather will be like in your region, because this is still evolving.

ERN WX said...

Andrew, things seem to be coming together for the more back loaded winter that certain forecasters, like you and I, have been expecting. I-95 folks have had one dissapointment after another; however, LATE JAN./FEB. will offer at least one BIG ONE. ECMWF weeklies (I can't say much about them) do look good for the end of the month. Yes, next week will warm up, but blocking will return before the end of the month helping cold and snow potentials for the Ern half of the CONUS. One observation for fcstrs, is to account for the TOOOO far SE track with storms. That along with NO HIGH to the N and the OH Val Low staying strong too long enabled JUST enough warm air to get in and wreck a decent snow. Don't worry, you will get it. I hope I have posted something helpful. And as a side note, I have told OH Val. folks they would do well with snow. I am glad I am correct and you are getting snow. Stay tuned to The Weather Centre for EXCELLENT coverage!!!!!!!!!!!!!!