Recent winters here on the Europe side of the pole has seen strong Atlantic influence thanks to a strong polar vortex positioned between Greenland and Scandinavia which has driven a strong westerly flow into Western Europe with low pressure firmly anchored near Iceland.

Why The Recent Warm, Wet, Stormy Winters And Why This Year Is Very Different

This has been the general setup since April 2013.

This PV position driving a strong zonal Atlantic jet stream makes it very difficult for high pressure to build west of Ireland and so the North Atlantic Oscillation has remained largely positive.

You can trace this pattern and PV position back to the North Pacific where waters south of Alaska have been exceptionally warm.

These waters have driven a cold North America pattern, increasing the temperature gradient between Caribbean and Quebec and this increases the strength of the Atlantic jet stream. That strong west wind aloft also cools the Atlantic beneath.

This autumn, we’ve seen the opposite with strong North Pacific jet stream, a huge cooling of the North Pacific due to upwelling and this has driven a warm North America pattern.

The Eurasia snow cover has been immense for late Oct/Nov likely down to record low arctic sea ice favouring arctic blocking and arctic warmth (-AO) and cold pattern for Siberia/N Kazakhstan, Mongolia, China.

The reason for strong North Pacific jet is likely down to a huge temperature gradient between SE Asia and bitterly cold Siberia.

This powerful zonal Pacific jet has enhanced the Aleutian low creating far stormier than normal conditions through the Gulf of Alaska.

The central North Atlantic remains cool but the jet stream has been quite strong recently but once it slows I expect to see warming here.

North America temp anomaly so far in November 2016

Less temperature gradient and the atmosphere’s ability to build heights further east over the Atlantic due to weaker jet is allowing waters to warm over the very areas of the Atlantic which have seen significant cooling.

Persistent Scandinavia blocking through October and now November has led to a cold Europe.

The polar vortex has been weak and remains so. Likely a direct result of record low arctic sea ice which tends to favour above normal surface pressure forcing a -AO. Our autumn has been cold and we’ve seen incredible early snow growth throughout Northern Eurasia thanks to the displacement of the PV over Siberia. This position supports favourable high latitude blocking on our side of the pole for the first time in 3-4 years, hence why we’re seeing more N/NE flow into the UK.

However, this year is different and long range models hold onto this weak, displaced PV.

This setup within the stratosphere has led to a persistently negative Arctic Oscillation and recent weeks has seen the negative North Atlantic Oscillation show up also.

Have you noticed the constant reformation of blocking high pressure west of Ireland, keeping our flow northerly or northeasterly?

What Has Winter’s First Month Got In Store?

Given the current state of the polar vortex, hemispheric pattern and shift in northern Pacific SSTA’s, a colder-than-normal pattern looks likely to continue. The weak PV remains displaced favouring a -AO/NAO December and continued NW/W/NE air flow into Western Europe with blocking out over the Atlantic west of Ireland extending up into Greenland and Iceland.

The current weakness and somewhat fluid nature of the PV and heat flux crossing central Asia towards the pole (reason for the displacement) could progress and mature towards the triggering of a sudden stratospheric warming event which could lead to a full blown Arctic/Siberian discharge into Europe or further splits in the PV which keeps a more modest cold pattern going with shots of more significant snow and cold.

In the last week, the PV has been over Greenland, hence the pullback of cold over Europe and Asia but it’s expected to swing back towards Siberia and therefore the cold should reload and return to Europe early December.

GFS Europe snow forecast through December 2.

ECMWF weeklies show a -NAO and cold pattern for Europe into the heart of December!

If there was to be a full blown SSWE, something we’ve not seen proper since January 2013, would likely occur mid or late December and so it’s full effects wouldn’t be felt until around Christmas or even early January.

FEATURED IMAGE CREDIT (TOP): ScotlandsMountains @steamingboots

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