Extreme Blocking High over Europe Discussion

[Ridingtime]

Hi everyone,

 

Recently many of the models have continuously shown a very extreme blocking high forming in the Arctic region over NE Europe and West Russia. You can see it here in the latest 0z Euro:

 

 

From my experience tracking weather living in Israel, I have never seen a block this strong and in this location and want some help understanding it's possible implications, especially for winter weather here.

 

It is clear that the models are all having a hard time forecasting what it will do for southern regions of Europe and Israel. Some show an extreme cold outbreak occurring as south as Turkey but then moving west across Europe beneath the block, only to then get pulled back into the ridge, likely thanks to a strong 960mb (!) low also being forecasted off the UK coast. Other solutions have shown a cold air trough digging south enough to give Israel snow thanks to the block. Some solutions show weak troughs that miss Israel all together. In short, there is still a lot of variance, likely because we are still 7 days out, but also because the block itself is so unusual in strength and location.

 

I'd love to hear some points from anyone else. Especially:

 

1) What has happened before when other blocks like this formed in this region? Usually during the winter we can Scandinavian highs or blocks over the UK but again rarely a block in this region.

 

2) What is the implication of a block this strong? It literally goes off the charts in most of the model runs

 

3) Is this block connected to any known indices. I thought it may be connected to the AO but I'm seeing that the AO forecasts aren't really being impacted by this block and keeping the AO mostly positive.

 

4) Would it be fair to say that a block in this magnitude would send cold air more south than being forecasted, increasing the chances Israel would get this cold?

 

Thanks in advance for your input and Happy Holidays to all!

[CAPE]

I like that those positive height anomalies are shifting more into the NAO domain on the latest runs of both the GFS and Euro. Would be a pretty darn impressive (and welcome) west-based block as advertised if those heights do in fact build over Greenland, and stick for a while.

[nzucker]

When that Kara high pressure forms a ridge bridge with the increasing heights over western North America and Alaska, the AO index will start to fall.

The block could cause unprecedented cold weather in North Africa and the Middle East.

[nzucker]

Athens looks to get very cold with 850s around -10C at 78hrs on 0Z GFS..Parts of northern Turkey are -15C with the -20C contour about 200mis northeast from the Black Sea. Many areas in the eastern Mediterranean and along Black Sea could have near record cold.

Edit: 0z GFS shows very heavy snow in northern Turkey as -17C@850mb crosses the warm Black Sea. I don't know how common this is, but can the Black Sea generate lake effect type bands?

I know the Adriatic Sea can give Italy's Appennini Mountains very heavy snowfall on NE winds, but those are pretty high elevations. This would be colder to the east along the Black Sea. The mountains around Sochi will get quite cold, but can anyone get Black Sea effect?

[Ridingtime]

Right now, models are showing a very insane amount of cold in Turkey, across the Black Sea, and those regions of Europe. However, the cold is basically grazing Israel and not going deep enough to give us a seriously good snow storm. The cold essentially gets cut off and then lingers but doesn't go south where I'd want it. However, I'm hoping over the next few days we start to see the block building more in a way where it pushes the cold more south.

 

Regardless, this is a massive Scandinavian block, and one that will definitely alter the weather pattern that we've been having up until now across the hemisphere where the polar jet has been too strong and keeping away the real cold air. I wouldn't be surprised if its effects eventually reach the northeast too.

[Rjay]

Athens looks to get very cold with 850s around -10C at 78hrs on 0Z GFS..Parts of northern Turkey are -15C with the -20C contour about 200mis northeast from the Black Sea. Many areas in the eastern Mediterranean and along Black Sea could have near record cold.

Edit: 0z GFS shows very heavy snow in northern Turkey as -17C@850mb crosses the warm Black Sea. I don't know how common this is, but can the Black Sea generate lake effect type bands?

I know the Adriatic Sea can give Italy's Appennini Mountains very heavy snowfall on NE winds, but those are pretty high elevations. This would be colder to the east along the Black Sea. The mountains around Sochi will get quite cold, but can anyone get Black Sea effect?

Yes the Back Sea can help generate "LES".