Welcome to my 14th Europe winter forecast. In this forecast, the conclusions drawn for the 90-day meteorological winter period will be based on the climate drivers currently at play. I’ll look at the current AMO & PDO state, El Nino, IOD, MJO, QBO, Solar. What could each driver mean individually and collectively?

Another important factor to consider is the level of warmth in our oceans, atmosphere and on land. Record warmth continues to increase and this will most certainly shift the parameters, possibly altering the influences of the above climate drivers.

Current global sea surface temperature.

Year-to-date temperature anomaly land & sea

Of course, pinpointing any specific pattern several weeks or months ahead is near impossible but we can provide potential trends and likelihoods.

I THINK IT’S SAFE TO SAY, BASED ON THE BELOW CLIMATE DRIVERS DISCUSSION, THE SITUATION WE FIND OURSELVES IN THIS YEAR IS WITHIN CHARTERED TERRITORY AND WILL MAKE FOR A VERY INTERESTING WINTER AHEAD WITH DRIVERS COMPETING AND CONTRADICTING EACH OTHER. THERE APPEARS TO BE A REAL BATTLE GOING ON BOTH WITHIN THE OCEANS AND ATMOSPHERE

+/- Phases of Arctic Oscillation/North Atlantic Oscillation

• SOLAR CYCLE 25

We’re well underway with solar cycle 25. 2012 is the comparable year to this. Stronger than cycle 24 but weaker than 23, cycle 25 appears to have observed it’s first of likely two peaks. There’s some debate as to whether we could see solar maximum and a second peak earlier than what would be considered normal (next year). Or it may well come in 2025, more fitting within the traditional 11-year cycle.

Incidentally, when comparing this cycle to the previous and comparable year being 2012, back then we were at the tail end of a cold period between 2009 and 2013. The current sunspot activity and strength released to space (in my opinion) leads to a 50/50 in terms of cold or warm winter. This is purely in isolation of only the current solar state and not taking into account the warmer planet, ENSO etc etc.

More on the solar cycle in the Conclusion section below!

• WARM AMO

The warm or positive phase of the Atlantic Multidecadal Oscillation continues.

While the Atlantic continues within a record-breaking warm period, there has been a slight cooling shown up over recent weeks down to increased jet stream strength and generally stormier conditions extending from North America towards Europe.

This could resemble a slight tripole (warm-cold-warm) which has been known to aid Greenland blocking (-NAO).

Latest North Atlantic SST’s

 

An overall warm AMO tends to support greater frequency of a -NAO as does a tripole.

• EL NINO/PDO, IOD & MJO

Following a 3-year La Nina, El Nino in firmly in control for the winter ahead.

I’ve been closely monitoring the development of this year’s El Nino. It’s arguably still strengthening. That strengthening possibly aided by the most recent WWB (Westerly wind burst), triggered by a recent, more active MJO pulse transiting the Pacific which is helping push additional warm waters east.

There is TWO important question to ask… how strong is the El Nino and where is the warmest waters positioned?

Here are the regions. The important areas are region 1.2 and 3.4.

Current status as of 27 Nov, 2023

Niño 4        1.5ºC
Niño 3.4    2.1ºC
Niño 3       2.3ºC
Niño 1+2   2.0ºC

Region 3.4 is where El Nino is measured and status determined. Note BOTH 1.2 and 3.4 are over 2C above normal. That means we have a STRONG El Nino.

Here’s the temperature trend in recent weeks.

Note the slight rise in region 1.2 in the past week or so. This shows that we have a strong El Nino which may be yet to yet peak. That’s important.

In simple terms, a strong EAST based El Nino (waters warmest compared to average further east) is likely to enhance convection further east over the equatorial Pacific. This could help strengthen jet stream winds further north helping drive warm ocean air across both North America and Europe.

However, have the warmest waters further west (Nino 3.4) and you focus enhanced convection more over the central Pacific. By doing so, you have a greater chance of weakening the zonal westerlies, therefore increasing the chance for high latitude blocking. If only it was that simple right?

While the ocean may be uniformly VERY WARM central and east Pacific…

MEI (Multivariate ENSO Indix) Doesn’t See a Strong El Nino!

While the two most important Nino regions (1.2 and 3.4) may be over 2C above normal (strong El Nino), the MEI which measures ocean to atmosphere response, strongly suggests that the atmosphere isn’t properly coupled with the ocean for it being a STRONG El Nino.

In fact the MEI actually indicates an atmospheric reflection more of La Nina rather than El Nino. The below chart shows 2023 compared to the recent strong to super El Ninos.

Keep in mind, if you simply single out just El Nino (which if strong can overwelm the global pattern)… a strong ‘east’ based El Nino tends to bring warmer overall winters but the below doesn’t suggest the ocean is driving the atmosphere!

SOI Resembles A Not So Strong El Nino also!

Another indicator, like the MEI is the SOI (Southern Oscillation Index) which is another measurement (pressure between Darwin and Tahiti) of how the atmosphere is responding to the ocean. It too doesn’t fit the very warm central and eastern SST profile or what you would expect from the very warm SST profile.

So, the kiss of death ‘east’ based El Nino doesn’t appear to be showing within the atmosphere…

Here’s what’s most important regarding ‘type’ of El Nino…

Strong EAST based Walker Circulation

Modoki or CENTRAL based El Nino Walker Circulation

Interesting tweet from World Climate Service

https://twitter.com/WorldClimateSvc/status/1731709335351222489

Negative PDO?

Another oddity to the strange ocean-atmosphere coupling over the Pacific is the weakly negative or cold Pacific Decadal Oscillation signature. Let’s just say it’s rare to have a cold PDO during the warm phase of ENSO, La Nina’s tend to correlate to -PDO’s while El Nino is typically a positive or warm PDO.

The -PDO too could be working against the atmosphere properly responding to the ocean over the tropical Pacific.

The ONI value for Aug-Sep-Oct stands at 1.5C above average. Warmer than 2009’s 0.7C but cooler than 2015’s 2.2C and 1997’s 2.1C

Despite an ‘on the surface’ strong El Nino, why is the lack of atmospheric response so important?

We aren’t seeing the strong El Nino within the ocean respond to the atmosphere. Whether this is due to the wider warmer oceans globally or other factors, I don’t know.

It appears the atmosphere is more central or modoki than east and this could have more of a 2009-10 response to the Northern Hemisphere rather than 1997 or 2015. We may see something in between, however.

My slight issue with all this is a potential lag. In the past week, we’ve seen a slight uptick in warmth in region 1.2 and we know the atmosphere takes time to respond. Who’s to say we won’t see more of an east based response later December into January?

Most Positive IOD Since 2019

There’s often a strong link between El Nino and Indian Ocean Dipole (warm west/cool east). In fact a +IOD is pretty much a continuation of El Nino and the Walker Circulation in the Indian Ocean.

The IOD has been very strongly positive.

It appears to have peaked in it’s current positive phase. During the autumn, the cooling up against Sumatra and warming up against Africa made for the strongest + episode since 2019.

It’s long been considered that the strong +IOD event during autumn 2019 helped power up the polar vortex to record levels which in turn produced very mild conditions through the mid latitudes of the Northern Hemisphere during the mid and late winter of 2019-20.

However, there was no El Nino along with the record strong +IOD back in 2019.

I guess you could say a strong +IOD on it’s own tends to favour a stronger zonal Pacific/Atlantic jet stream, +AO/NAO, strong SPV pattern but throw in -QBO (discussed below) and El Nino and it has more of an opposite effect.

This is just personal speculation but I wonder if the +IOD, -PDO is fueling the more modoki or central El Nino-type walker circulation?

MJO

The Madden Julian Oscillation is a pulse of enhanced convection which circumnavigates the equator. The active phase enhances thunderstorm activity while there’s an inactive cell on the opposite side of the planet. The stronger this ‘active phase’, the more influence this may have on the pattern over the Northern Hemisphere.

Where El Nino and the Indian Ocean Dipole come into play, the MJO tends to become enhanced where oceans are warmest compared to average. Therefore, the active phase of the MJO tends to focus on central and east Pacific during strong east based Ninos whereas during modoki El Ninos, the focus of the MJO stays central or west with sinking in west and east Pacific. This provides a very different upper air pattern further north.

Here’s the CFSv2 projection of rainfall. Indicative of a central based Nino combined with +IOD.

Notice the focus of heaviest precip is over the central Pacific which correlates to phases 7, 8, perhaps 1.

Phases of the MJO

What might this mean for W Europe? Blocking, especially January February according to the below graphic produced by Marco Petagna of the Met Office.

• QBO

The QBO or Quasi Biennial Oscillation. Put simply, the QBO is a belt of winds which blow either westerly or easterly within the stratosphere above the equator.

 

When blowing westerly, this can tend to promote strengthening of the mid latitude westerlies leading to the bottling of cold up over the arctic (+Arctic Oscillation) and (+ North Atlantic Oscillation), promoting mild conditions.

This year, we have a strongly easterly QBO which can (not always) provide frictional effects on the polar jet stream. If you think about it, if everything is moving easterly over the N Hem between equator and pole, there’s not much stopping the mild Pacific/Atlantic air masses from flooding North America and Europe, holding the arctic air within the source. But have a wind blowing in the opposite direction underneath and this is like throwing a stone against a moving bicycle tire, it’s going to at least attempt to slow it’s forward speed!

By slowing the jet stream winds, you increase the chance of warmer air from equator moving north and in turn colder arctic air moving south.

• WARM, WET AUTUMN FOLLOWING WARM, WET SUMMER (MOST -NAO SINCE SUMMER 2009)

Meteorologist Joe Bastardi of Weatherbell Analytics said years ago, where the heaviest rains fall during autumn, can be an indicator of where the cold wants to go down the road…

Also, the type of pattern during the summer and autumn can also signal where the winter pattern may be heading.

Summer 2023, while very warm throughout the hemisphere and NW Europe observed a very warm but wet July through November period, we did indeed see a similar upper air setup to 2009 which strongest -NAO since 2009 and very soggy late summer and autumn (also like 2009). Time will tell if the top sentence in this section has any validity in 2003-24.

• NORTHERN HEMISPHERE SNOW COVER/EARLY START TO WINTER

We’ve gotten off to a fast start to winter for all three major industrial centres. North America, Europe and East Asia courtesy of strong high latitude blocking (-AO/NAO).

 

This may be, in-part due to a slight weakening of the polar vortex back in October combined with a more active phase 8 into 1 of the MJO and healthy northern hemisphere snow cover.

Simply a pattern repeating? Strong -NAO summer breeds rain and low pressure but in late November into December, cold and snow!

Check out the AO tanking!

Change is on the way late week 1 into 2 of December as the MJO moves into phases 3 and 4. That’s WARMER phases for both North America and W Europe.

230 MPH Atlantic jet stream to fire up and throw some storms and moisture towards the UK between 7-20th December as MJO rotates through 4,5,6 but… then into 7-8 for Christmas??

• POLAR STRATOSPHERE

Probably one of the biggest drivers we look at with much anticipation each autumn and winter is the polar vortex.

As of late November, the polar stratospheric wind is at or near record strong levels with it’s core cooling to between -84 and -87C, some runs had it cool to -90C!

Old vs new ECMWF run for mean zonal winds.

Note the sharp deceleration of these winds into December.

The reason behind this weakening of the PV is likely down to ‘heat fluxes’ pushing from troposphere up into the lower stratosphere. The result is warming as winds begin slowing.

https://twitter.com/Superchri90/status/1729882020778754211

Intriguing…

ECMWF

Week 2 (4-11 Dec)

Week 3 (11-18 Dec)

Week 4 (18-25 Dec)

Warming causes the stratosphere to expand and troposphere to contract. This forces pressure to build at the surface underneath forcing a -AO and if in the right place, possibly a -NAO return following a return of the Atlantic pattern.

Conclusion

Even if we don’t see an eventual major SSW or Sudden Stratospheric Warming event from the anticipated December weakening, a weakening or minor warming still slows the mean zonal wind resulting in a less strong PV.

Combine the strat warming with ‘atypical El Nino, (anticipated) favourable MJO (for cold) and -QBO, there ‘should’ be plenty of opportunity for cold to be released south into the mid latitudes this winter. That’s despite a pull back of the cold week 2 of December.

For the early period of winter, I believe a ‘warm-east based El Nino’ and +IOD type pattern is likely during much of December. In other words with the MJO heading into the ‘warmer phases’ combined with some effects of the +IOD (possible reason for near record strong SPV currently) we’ll see an Atlantic dominated early winter.

My concern with regards to a cold pattern is two or three-fold. We are expected to see ‘Canadian stratospheric warming in December. This ISN’T the most favourable for cold in Western Europe even with a blocking high over Greenland. The jet tends to be southward displaced yes but too strong to not undercut and simply run underneath into the UK and Ireland. This suggests possibly a cool but wet December but late December could get interesting.

Mid to late winter (January/February) will really be determined by what response the atmosphere has over the Pacific and even Indian Ocean coupled with polar vortex. We may still be yet to see a peaking of Nino despite a likely sharp weakening of the IOD.

The strat warming and atmospheric response over Pacific is pleasing from a cold perspective. Models too see increased blocking beyond New Year. Blocking on many of the below models show an increased blocking within the high lats and Greenland in January, further strengthening February and March.

Mild option can’t be ignored!

I slightly fear December 2015/Winter 2013-14 & 2019-20

While I’m going for the ‘back and forth’ type winter in 2023-24 with mix of warm and cold, one cannot rule out the Atlantic dominated winter or high pressure ‘too close’.

Due to the strong El Nino and uncertainties regarding whether it’s east or central based as well as whether it’s peaked or not, December 2015 comes to mind.

Also, winter 2013-14 is there too, possibly due to the type of strat warming we’re likely to see in December. Canadian Strat warming’s can fuel arctic outbreaks into North America but in turn drive a strong Atlantic jet straight at the UK & Ireland. Great for North America, not so for Western Europe.

While a +IOD in itself may have helped fuel the near record strong polar vortex in early 2020, the El Nino and east QBO likely offset’s this and according to Richard Traut’s research on the combo of an El Nino and -QBO, there is a greater chance at seeing an SSW, likely beyond New Year.

Long Range Models

Dec-Feb 500mb geopotential height anomaly

Meteo France

Met Office

JMA

ECMWF

ECCC

DWD

Multimodel

THE FORECAST

Based on everything discussed above…

I believe the Overall Winter 2023-24 (Dec-Feb) shall come out AVERAGE TO SLIGHTLY ABOVE AVERAGE For Temperature, Wetter Especially Southern Europe, Drier Northern Europe!

Breakdown…

December

While blocking should continue over Greenland and Arctic, the Atlantic for the most part should continue to dominate Western Europe through at least through mid-month bringing milder than average temperatures after a cold start.

Colder conditions shall prevail over Scandinavia and the eastern continent with potential significant snowfall for Alps into Balkans, Romania, Turkey, Ukraine etc.

There’s a question mark with regards to the run-up to Christmas and New Year. I suspect the MJO may attempt at a return towards phase 7, eventually shifting into 8 and 1. This increases a return to colder for UK and Ireland and so I wouldn’t be surprised to see moderate chances of some snow, especially for Scotland.

Overall, Average to Slightly ABOVE Average temperatures for UK/Ire, Colder for Scandinavia and east Europe, warmer Iberia, France. Wetter for southern UK/Ireland, Drier Northern and this goes for Europe (dry north/wet south)

January

January has the potential to see an increased snow and cold threat for Western Europe as blocking may strengthen either up over Greenland or Scandinavia in response to both MJO and strat warming.

I am going to suggest a moderate January cold spell. The cold may start as early as Dec 20th or as late as Jan 2-4th and may last 10-16 days before a pull back during the 2nd half of the month. The Atlantic is likely to return with warmer, wetter weather.

There’s also a growing possibility that January sees strong to major warming of the stratosphere early/mid January. The potential impacts of this if it was to occur would come towards the end of the month and more likely early February.

Overall, average to below average temperatures with cold first half followed by milder 2nd half.

February

I believe February has the greatest potential for a prolonged, severe cold and snowy spell for much of Europe. The high latitude blocking should peak as is often the case during El Nino winters coinciding with a -QBO and possible SSW.

If all things come together, we could see one of if not coldest February’s since 2010.

Overall, a cold and potentially snowy February with firmly below average temperatures, above average snowfall

The cold may ease late February but come back to bring possibly one of the coldest March’s to the UK and Ireland since 2013.

This winter really could go either way. By that I mean the cold spells which I anticipate happening could be stronger and longer, equally how long and strong the periods of warmth are will ultimately determine whether this overall winter was cold, average or mild for the Dec through Feb period.

The timing of these milder vs colder spells is near impossible to determine. Therefore cold vs warm could be out by a week or so.

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