500mb Geopotential Heights Favour Cold For US & UK

There is a war going on with the models with wild swings for particularly the UK from extreme cold to mild conditions late next week. The reason for the wild swings is clear, the NAO/AO index is rapidly changing and heading into the tank. Remember that the NAO is currently positive and there is excellent agreement that it will go deeply negative within the next 7 days. The models struggle with this massive hemispheric-scale energy tranfer and so they’re flipping wildly. Computer models aren’t particularly reliable, especially when it comes to predicting conditions once a huge change takes place. It can be ok once that alteration in the height field has taken place but during that transition they have a tough time and for those who buy into individual model runs without having faith in their own ideas, will get tossed and turned too. I am not in the business of slagging other forecasters off.

There are those who clearly know what they are looking for and other who go soley by models. I have laid out my ideas in front of you and will continue to stand by those ideas.

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I stated this yesterday. I MAY BE WRONG with all this, but, you’ve got to at least credit me for the fact that what I’ve said all along, without ANY CHANGE SINCE SEPTEMBER and for this very time period, has at the very least showed up on models. I did expect this flopping back and forth but I believe once the smoke clears and the block takes up position nearer to Greenland and it spreads out over top of Scandinavia, we shall have a clearer picture at what may be ahead for us from mid-month through to Christmas.

Just as I thought, Europe is now grabbing headlines for snow chaos and building cold. This was alluded to well before modelling showed this and interestingly, following the snows yesterday, temperatures this morning dipped well below -10C across the interior Netherlands. The cold air as explained is moving across once the snow is laid down.

USA

As for the US, like many here in the UK, there are folks asking, will the snow and cold ever come, will it be just like last year. Well, blizzard warnings are out across parts of the Dakotas and there is a smorgisboard of winter weather warnings, advisories and all sorts across the Northern Tier and down the spine of the Rockies.

Arctic air will feed a system which will bring the nasty weather tonight, look out once the system clears as it will get darn cold. Think this weekend is cold across the the Northern Tier, the upcoming week looks to bring the first 20 below zero readings to parts of the Dakotas, Minnesota and perhaps other areas. More snows will following other southbound waves of arctic air and the week after the upcoming, looks colder. May see single digits all the way to Texas, near 40 below readings across parts of the Northern Plains and I wouldn’t be surprised to see a night or two where Minneapolis struggles to hit 0 and lows fall below -10. Chicago may see a few days with highs struggling to hit 10 and lows which push 0.

Here is the latest 500mb Geopotential height anomalies that you may find of interest.

Tuesday (72 hrs)

Courtesy/Owned by Weatherbell Models

Note the trough diving into the heart of the Lower 48 and the deep trough over the heart of Europe. Cold NW upper flow for the UK.

By Friday (144 hrs) note the ridge now in the eastern US and the low heights drapped across the N. Atlantic extending east through the UK and into Europe while a strong blocking high is drapped over top, extending from Greenland across the top of Scandinavia and into western Russia. This setup would support the Europe cold pushing somewhere further west and towards the UK with positive heights further south over eastern Europe.

Courtesy/Owned by Weatherbell Models

By Saturday (168 hrs) we have a very strong block extending from Greenland to Russia with very low thicknesses and cold air drapped across the N. Atlantic extending east through the UK where a low height core resides, extending across Europe.

Check out the punch of brutal arctic air diving into the West, this will deepen a trough which could be coast to coast! Wow.

Finally by Tuesday 18 Dec (240 hrs) a trough is positioned over the UK with arctic air within. The eastern of Europe has warmed with ridging. This would be the setup which, once much of the UK was snow covered, may experience a bitter cold spell which may not be unlike those numbers seen in Dec 2010. That is IF this was to occur and yes, it’s a big if I know.

Take a look at the US, notice the the Siberian connection feeding already brutal air over western Canada that is driving straight into a very deep and expanding western trough. The UK and US would be dealing with major cold between Dec 15-20 if this chart came true.

By the way, notice the blocking extending from eastern Canada all the way to the strongest positive which is from a monster ridge extending from the eastern Med up to arctic NW Russia, punching into the arctic sea. This would be a cold and snow lovers dream.

Courtesy/Owned by Weatherbell Models

Like I say, may may be seriously barking up the wrong tree with all this.
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