Key Factors

• Current Global state (ocean & land temperature anomaly)

On a global scale, our oceans are about as warm as any time since at least the beginning of the satellite era. Note the level of widespread warmth particularly from equator to arctic.

CDAS temperature anomaly for land and ocean YEAR-TO-DATE!

Despite the warmth, we of course have to be mindful of fluctuations of warm and cold on both land and ocean but the above is current.

The -PDO (Pacific Decadal Oscillation) signal (a likely La Nina hangover) has weakened considerably in the past month while +AMO (Atlantic Multidecadal Oscillation) remains record warm and has been for quite some time now.

We are seeing some subtle changes in the Atlantic SST profile after rapid heating occurred back in late spring/early summer. This rapid warming of the ocean surface to record warm levels was courtesy (in part at least) of unusually strong and persistent high pressure from April through June. Thanks to a flip in the 500mb pattern from above to below normal heights, so ‘some’ of that heat weakened in intensity (though remains warm).

During later August and through September, tropical cyclone activity increased (despite an El Nino) and this aided further cooling within the subtropical North Atlantic. We shall see if the more recent 200-mph zonal Atlantic jet stream manages to further remove some heat and help create a tripole (North Atlantic SST profile of warm-cold-warm).

The below SSTA difference in just the past week suggests that the above might be true but is it temporary?

• Past summer upper air pattern (lot’s of blocking)

It was a mixed summer 2023 with regards to the AO.

But likely the most -NAO since 2009.

• Record Warm September & Very Wet Period July through October

Back last winter I made the statement that the UK/Ireland/W Europe should see a large-scale and long term shift from dry to wet. This occurring during the summer. This, due to the transition from La Nina to El Nino, happened!

Rainfall has been on the increase especially early to mid autumn as cold begins to expand and slip south meeting warm subtropical air which strengthens the jet stream.

Persistent blocking near both Greenland and Europe along with active storm track, albeit displaced to the south. This storm track lifting out of the warmer source region has played an important role along with warm SST’s has helped transport more moisture into Ireland and UK. Throw in the resistance from blocking highs which slow or stall fronts and the result is more rain for longer over one particular area. Made worse further if the flow meets hills which further enhance rainfall.

• El Nino

The SST profile of the equatorial Pacific continues to reflect a moderate to strong El Nino.

As of early November…

Nino region 1.2

Nino region 3.4

As you can see, we continue to see a decrease in the warm anomaly in region 1.2 (east) while the region 3.4 warms (central). However, the warmth remains firm in both 1.2 and 2.4.

Other indicators such as the MEI (Multivariate ENSO Index) more modoki rather than east.

The SOI suggests weakening El Nino base state (atmospheric reflection).

• Positive IOD + El Nino

The last time we had a +IOD was the record strong episode in 2019 but this didn’t coincide with El Nino.

Past years with both +IOD and El Nino was 1963, 1972, 1982, 1997, 2015 & 2018 according to Jason Nicholls.

• QBO (easterly)

The east QBO continues to strengthen. This can help create a weaker jet stream and help high latitude blocking (-AO)

https://twitter.com/richardtraut/status/1720173624588410906

• Healthy Gain in Northern Hemisphere snow cover

• Solar Cycle 25

Solar cycle 25 appears to be more active than predicted as can be seen below but remains at weak to moderate levels. The sharp increase in sunspot numbers we observed earlier this year may have seen the first of likely 2 peaks as sunspot activity has significantly reduced of late. These lulls can be normal prior to double maximums and a renewed surge in activity is likely prior to a possible early maximum occurring perhaps as early as next year. We shall see! Cycle 25 is more active than 24 but weaker than 23 and Richard Traut states cycle 25 is comparable to 16, also evident in the below chart.

• Potential Stratospheric Warming in December?

The ECM mean zonal winds and PV strengthens through the 1st half of November but a possible deceleration early/mid-December.

I have to say some of the most recent runs have slightly backed away from the strong anomalous warmth.

Latest run (it’s pushing back the time frame)

It’s worth keeping in mind that the below is just ONE of many model solutions so caution is advised with regards to buying into this solution.

The ECM has consistently shown a strong warming from Siberia towards the pole in early December… Strong strat warm/major SSW. Even if it does occur and it’s a big if, there’s still a 30% chance NO cold makes it to W Europe and like we saw in 2013, the major strat warming which did take place favoured North America, not Europe.

CONCLUSION

If the El Nino reflects more of a modoki rather than east response to the atmosphere then we should see a phase 8-1-2 MJO. This favours a less strong, less flat jet with greater chance for blocking to build northwards into the higher lats.

However, force more convection within the equatorial Pacific towards S America (east based nino response) and you strengthen the zonal jet across E Pacific-North America-Atlantic which then floods the continents with mild oceanic air. Therefore bottling any arctic air up within the source (+AO), examples of this 1997 and 2015 stand out.

However, have a central based El Nino coupled with -QBO you have a greater chance of not only blocking but weaker stratospheric PV and increased chance for an SSW (ECM model already shows this for December). Modoki Ninos combined with -QBO’s in the (1-2 yrs) prior to solar maximum, tend to favour -AO/NAO winters.

An east based Nino response STILL needs consideration and if it were to happen, this could overwhelm all other competing drivers…

With all of the above considered and taking into account the strong +AMO, there’s also greater chance for blocking over the Atlantic also (-NAO).

From what I can see, we had an neutral ENSO/+IOD but -QBO back in late 2017 and during the backside of that winter we of course witnessed a major SSW in mid-Feb which resulted in the ‘Beast from the East’.

Interesting tweets with regards to the +IOD in relation to strenghening the polar vortex…

https://twitter.com/MeteoMark/status/1719067147941363750

Wet October-Blocky Cold Winter follows?

Where it rains heavy in autumn can sometimes show where the trough wants to go down the road. That was a statement Joe Bastardi made several years ago. When looking at some notably wet October and Novembers from the past, major winter cold did indeed follow. Oct 2000 I believe was wettest on record. 2000-2001 saw some significant wintry periods. The floods of November 2009 was followed by you know what. Record rains in 2020 was followed by notable cold spells, especially February 2021.

October 2023 was eastern Scotland’s wettest on record, UK’s 6th wettest.

Wild card??

I actually included this very volcano in my summer forecast as we observed an eruption back in the spring.

https://twitter.com/KulakPiotr/status/1719109087932141949

Here’s some interesting research from Richard Traut.

“When ENSO is moderate, the chance of an SSW is 77%. 13 of the last 17 moderate Nino winters have seen an SSW. There’s a 64% chance of an SSW occurring when there’s enhanced Siberia snow cover. East QBO’s give a 90% chance of an SSW based on the last 20 moderate Ninos. 

So based on all the above, there’s a 77-80% chance of an SSW happening in winter 2023-24″

I stated, given it relatively high latitude position, could this have a ‘high latitude blocking influence’ this summer?

Coincidence or not, we did indeed see a very blocky summer with south displaced jet, especially later summer and early autumn… Could this new eruption enhance any blocking opportunity this winter? Recall what happened in 2010 in Iceland??

….

When it comes to warm or cold winters, there’s extremely fine margins, the difference between 09-10 and 2019-20 isn’t much. 1, 2 or even 3 seemingly perfect teleconnections doesn’t guarentee anything when it comes to the atmosphere and I know 2 things, 2009-10 is a rare event and increasingly harder to come by.

It has to be said, given the warmer planet, I believe it is harder to get that cold overall winter but I suspect there’s plenty of room for spells of cold in 2023-24. At this time, the greatest chance comes AFTER New Year!