Tuesday, January 1, 2013

Could The Polar Vortex Collapse Like January 1985?

I have been calling for a polar vortex breakdown and possible collapse for a while now, and I now think it is time to introduce the possibility that January-February 2012 could resemble the infamous January 1985.

We'll start with a flashback to December 1984, image courtesy of weatheradvance.com. In December 1984, we saw strong high pressure to the north of Greenland, along with low pressure stretching across the Atlantic and low pressure in the Southwest. High pressure also prevailed across the Gulf of Alaska, and low pressure was present in the Bering Sea. I want you to keep an eye on that low pressure in the Southwest and high pressure in the GOA for our next image.

This is what the GFS Ensembles showed as of this morning's 12z run at initialization, also known as Hour 0 in the forecast. We see high pressure trying to squeeze into the Gulf of Alaska, low pressure in the Southwest and slight high pressure in the Pacific Northwest. Looking back at the first reanalysis image of December 1984 we find a similar small signal of a high pressure in the Pacific Northwest. Worth noting is the presence of strong high pressure across north Asia, in a very similar position to the one seen in the reanalysis image. Low pressure does not extend across the entire Atlantic, but let's not worry about that specific piece right now. We have now established a few good links to December 1984.

This reanalysis image, once again from weatheradvance.com, shows what the month of January 1985 was like as a whole. We saw high pressure dominating the northeast Pacific, low pressure in Asia, and a strong high pressure regime in the Arctic, which appears to have been a base for the exile of the polar vortex. Low pressure was found in the Plains and general North US as the polar vortex was displaced south.

Here's the strikingly scary part- the long range forecast from the GFS Ensembles closely resembles this reanalysis image. We see high pressure in both the northeast Pacific and north Atlantic. Low pressure is present in the Bering Sea and Eurasia. A triangle of high pressure systems from the Pacific, Atlantic and Arctic shows that we are once again looking at a potential exile of the polar vortex. Look closely at the US. Slight low pressure is forecasted in the North US in an eerily similar move to January 1985. The center of the polar vortex, placed west of Greenland and shown as several ovals, is in almost the exact same spot as the polar vortex in December 1985, once again shown as several ovals.

This is a perfect situation for the polar vortex to slip south- the atmosphere is practically rolling out the red carpet for the polar vortex to dip into the United States. With the triangle of high pressure barricading off Europe and the Pacific as possible exit points for the polar vortex, a lack of high pressure in North America is essentially a welcome mat. Low pressure does not go towards high pressure.

Let me set the record straight- I am not calling for another January 1985. What I AM saying is that signs are pointing to a SIMILAR set-up as January 1985. That in NO WAY means the polar vortex will once again slip south- it means the potential is there, but NOT CERTAIN.



Anonymous said...

Hey 'Drew, I was going through your older posts this morning (there isn't anything exciting weather-wise going on so I decided to delve into past weather events) when I noticed that you used to have some "secret formula" for determining how likely a model's forecast is to be correct. Could you elaborate on this?

Andrew said...

I'm afraid I don't remember this formula. If you have the link, could you comment with it?

Conor said...

I know this may be a crazy question to be asking on January 1, but is there anything right now that you can look at to get a hint at what kind of summer we'll be having in 2013? Even generalizations like "hotter than normal," etc.

Anonymous said...

Hi Andrew,

I have been following your posts regarding the upcoming ssw. What effect if any, will this have on the UK and Ireland?


Andrew said...

Conor: It's way too far out, but that drought in the Plains should amount to a hotter than normal summer.

Bridget: This is still a developing situation, so I cannot forecast the effects for anyone for at least another week. Sorry!

Anonymous said...

Sorry Andrew, here is the link for November 25th, 2010:
You mention it in two of your posts that day.

Andrew said...

Anonymous at 2:06: Interesting- I forget what I did to put that together.
You gave me an idea to make a new one- I'll have to tell others about it soon.

Anonymous said...

Andrew, If the polar vortex does collapse is their a lag time for the cold air to be drained into the United States? I"m from Maryland, the weather geek"s are already complaing that our winter is over. Tim Dantoni

Anonymous said...

Tim, I am from harford co. Md and interested in his answer to this question as well.

Andrew said...

There's a 2-4 week lag time, depending on how fast the cold air rushes down from the stratosphere. Sometimes it's 1-3 weeks.

Indndawg said...

Dear Lord pls let this happen

Indndawg said...

Christmas holidays 84 were very warm but weather man predicted a "strong front" to come thru on morning of 1/1/85.

It got cold and snowed a little in Tupelo MS...little did we know we would have 8-12" of ice pellets and snow before the warmup would happen in mid Feb 1985.

On Jan 22 or 23, I slept under 4 blankets and full clothing on. Never have felt cold like that in my 50 years

Art Vandelay said...

So now you are useing models from 28 years ago to determine our weather for this month?

Andrew said...

Art: It is called analog forecasting, using the past to predict the future. And they're not models, it's an observed chart and a forecast model from yesterday.

Anonymous said...

If it does set up like 1985
I will need Light therapy, & Prozac!Bring on the Summer!

Anonymous said...

Art-what does an architect know about polar weather anomolies? Or are you in the import/export business?