Europe Winter 2017-18 Forecast

Today’s winter forecast is based on all current global atmospheric/oceanic drivers in place, their current status and model projection.

Here are the main factors taken into consideration for the upcoming 2017-18 winter for Europe.

Low Arctic Sea Ice/High Eurasia Snow Cover = negative Arctic/North Atlantic Oscillation?

Arctic sea ice as well as Eurasian snow cover continues to expand fast now that we’re into November. But how does these two players compare to normal?

A long term trend of below normal Arctic sea ice coverage continues but less extreme than previous years such as 2007 and 2012. Low Arctic sea ice winters favours above normal pressure over the arctic atmosphere. Another player favouring above normal heights over the Arctic is Eurasian snow cover. This October wound up above normal but not exceptionally and nowhere near as extensive as this time last year.

Via Judah Cohen

These two factors can also increase the possibility of a sudden stratospheric warming event. Something we’ve been teased with the last few winters but hasn’t come to fruition.

Both low sea ice and high Eurasia snow cover favours a -AO/NAO but there’s other factors like we’ve seen which can counteract. Last years super El Nino did that and brought both sides of the Atlantic a warm winter.

Weak La Nina

We’re on the cusp of a weak La Nina phase of the ENSO compared to strengthening El Nino at this time last year. Direct effects from La Nina on Europe isn’t clear within the scientific community but weak La Nina’s where coolest waters compared to normal are positioned over the central equatorial Pacific has been known to provide cooler weather to both the North-Central and Great Lakes region of the US/Canada as well as Western Europe.

Strong La Nina’s like El Nino’s are connected to warmer winters both sides of the Atlantic.

North Atlantic Sea Surface Temperature Profile

Current SSTA’s (sea surface temperature anomalies) show large cool extending out from the Davis Straits into the North Atlantic while warmth is positioned between North Carolina and Newfoundland as well as off France, Iberia and north of the British Isles.

Indeed this profile will change as we head into winter but two aspects of the above chart stands out, the ribbon of cool extending out from Central America associated with the oncoming La Nina and pool of cool in the North Atlantic. That pool of cool supports low pressure near Greenland (a +NAO) but warmth stacked up into the Arctic between Iceland and Norway supports high pressure which could lead to blocking so there’s conflict in potential outcome and perhaps a back and forth of both? Warmth off Iberia may also help enhance the Azores high too which can lead to milder and wetter southwest flows into Ireland and UK.

So, what has the greater feedback influence? Remember the SSTA profile can influence the atmosphere but likewise the atmosphere can influence the ocean but essentially it’s not one but all factors which need to play their role in order to get the result we’re expecting.

Spring Pattern so far

Warm and wet has been the story really since late summer through now. The cooler, drier of recent years coupled with weak to strong El Ninos were followed by warm and wet or warm and dry winters. I believe there’s correlation between ‘wet’ autumns and cooler winters. How much, I don’t know. Yopu can’t single out a particular factor and base the forecast on this. The closest factor toi doing so would be a strong ENSO of either warm or cold which can over ride other influences.

Solar Cycle 24, a weakening trend since 1980

Since the front end of winter 2010-11, our winters have warmed, likely due to the rise in and peaking of solar cycle 24 around 2014-15 and continued due to the Super El Nino of last winter. Now that we’ve crested the maximum and descending towards the next minimum and to the levels of 2009, we increase our chances of colder times ahead. However the run up to the expected solar minimum around 2020 can be complex and isn’t clear cut but I believe intense cold shots within relatively mild winters are on the increase over the next few years prior to the minimum. Once we get to the minimum I expect another 2009-10 winter.

The Forecast

Based on all the factors above and taking into consideration the expected changes of these factors as we go from summer to winter, e.g. shifting of warm and cool waters in Atlantic, strengthening/weaking or shift in La Nina, weakening solar cycle 24, I believe another milder than normal winter is likely.

The reason I have come to this conclusion is that I fear the La Nina may be stronger and or coolest waters are positioned near to South America. The Atlantic SSTA profile favours a North Atlantic trough which keeps the westerlies active. The low arctic sea ice and above normal Eurasian snow in recent years has failed to drive a -AO/NAO winter but with no El Nino, there’s greater chances of -AO/NAO episodes of cold into North America and indeed Europe.

A colder winter than last by far with greater fluctuation between a zonal and blocked pattern so greater likelihood of cold and snowy periods within an overall mild, westerly driven pattern.

While impossible to determine a month never mind 3 months out what each individual month may bring, I do believe our earth’s cooling trend coming off last years Super El Nino provides us with greater chance of cold and the fact that the solar cycle is on the decline, cold spells of greater intensity is more likely.

Each of the three winter months ahead could see cold spells but frequent and prolonged periods are unlikely. Perhaps 7 day spells of cold with opportunity for snow and lying snow supporting the coldest nights in the last 5 years could occur 3 to 4 times this winter.

Though cold prior to Christmas is a real possibility I believe the back end to winter (15 January onwards) is most likely to bring the toughest cold to Britain and Ireland but like I say, this winter is likely to be colder than last but overall another slightly milder than normal season overall.

Rest of Europe

Looks like eastern Europe and Scandinavia could be in for some major cold this winter but not without unusually mild periods as Atlantic air penetrates deep into the continent.

I agree in part with the below CFSv2 monthlies but I think it’s a more fluid setup than the below.

December

Credit: Tropical Tidbits

January

Credit: Tropical Tidbits

Credit: Tropical Tidbits

2 metre temp anomaly for Europe December through February

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Here’s the Jamstec Dec through Feb 17-18… Interesting cold UK, warm UK. Model seeing more Scandinavia blocking?? More snow here now compared to recent years!

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