What do you think the Winter of 23 to 24 will be like?
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Here's an update on everything I usually look at in my winter posts.
This is how the current sea surface temperature anomalies stand across the globe.
Starting off with the most important and relevant to our locale, the North Atlantic Ocean continues to be in a largely warmer than average state though is a definite reduction from the marine heatwave it was experiencing back in the summer. Cooler anomalies have expanded but are still largely isolated. Some would say this almost has a tripole-esque distribution but not really in my opinion. For a tripole, you'd want to see a much stronger distribution of colder than average anomalies through the central portion of the North Atlantic going back to the eastern seaboard. This is just a general warm North Atlantic. A warm North Atlantic is less conducive to an enhanced jet stream without a baroclinic zone for intensification. However, any depressions that do form could hold an awful lot of moisture. The warm North Atlantic of course also modifies any colder airmasses coming from this direction.
Going over to the Pacific Ocean, the strong El Niño is very much in force. We are well into El Niño territory and the event has been officially designated recently by NOAA. During the summer, the event was strongly east focused over towards Peru but the east has seen a cooling since whilst retaining El Niño conditions. Meanwhile, the central portion has seen a strengthening to strong levels. HOWEVER, this is not a modoki El Niño as there isn't a strong enough contrast between the central and eastern portion. The warm anomalies are reasonably distributed rather than having a heavy focus on the central 3.4 region. Nonetheless, this is not your traditional strong El Niño. It's too complicated to get into the details that even I do not completely understand some of it but globally, this is a very strange situation. The simplest way of seeing that is the North Pacific in the SST anomalies which is still at odds and hasn't shown much change through the course of 2023 as the El Niño has developed. Any colder weather that does occur is more likely later in the winter during an El Niño.
The Indian Ocean Dipole (IOD) has been in a very positive phase this autumn. It is likely the second most positive IOD on record behind only that of 2019. The IOD has been said to have aided the development of the stubborn intense stratospheric polar vortex back during the winter of 2019-20 according to research. Papers available online on the matter.
Funnily enough, the stratospheric polar vortex is ongoing through a record-breaking state for the time of year. Could this be related to the IOD? No way to tell at this point in time. The GFS is forecasting a drop in the zonal winds but remaining on the strong side whilst there's a huge split at the end between average and record-breaking again in early December.
As I mention in the stratosphere watch thread, record-breaking zonal winds aren't necessarily a terrible sign for down the line as this allows a "breeding ground" if you like for planetary wave activity to occur whilst a weak stratosphere will hinder any wave activity. However, I do wonder about the anomalous positive IOD which has always been the one big negative going into this winter. Would this allow further record-breaking SPV conditions to occur for a prolonged period of time and eventually surface weather would feel the effects?
The last of the C3S seasonal model updates before the winter begins. This is the breakdown they show - as with all long range, NOT TO BE TAKEN AS GOSPEL. This is purely for speculation.
December shows a strong signal for a very unsettled, zonal month with a lot of low pressure in northern Europe. Some polar maritime cold snaps couldn't be ruled out with such a scenario as the low pressure looks to be somewhat NW-SE aligned but main thing is very unsettled.
January is more interesting but still a signal for an unsettled month. The low pressure is more towards the east of the country but no particular strong signal for any blocking in the North Atlantic. Perhaps a rather changeable month.
February shows a massive blocking signal near Greenland/Iceland with low pressure over Europe but note nothing particularly low signalled for Iberia. A cold month would be probable given the blocking but maybe not as wintry as you'd think.
This is a classic El Niño signature indicated by the C3S suite of models for the winter but I echo to not take these or anything I say seriously.
Photography site - https://www.sryanbruenphoto.com/
Weather photo portfolio - https://sryanbruen.myportfolio.com/weather-1
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Didn't anticipate doing an update for winter so soon after the last one on Sunday but the recent modelling output has me thinking and we need to talk.
Originally going into this winter, I had written it off way in advance for a few reasons. One, it was getting tiresome of the number of close shaves we had over the years. Two, the expected strength of the El Niño ongoing in the equatorial Pacific and the Indian Ocean Dipole. The combination of these two seemed to be curtains based on history but I guess there's the big red flag in my original thoughts. The old rule with the weather that we always must remember is nothing is guaranteed. Normally this means things changing to something we don't want it to but on rare occasions, it can happen the other way round unexpectedly. 2023 has been unprecedented in many regards... the current state of average global temperatures, the marine heatwave in the North Atlantic back in the summer are just two examples. Maybe the phrase "expect the unexpected" has some merit eh?
I always knew in the back of my head to the idea of if you can get a blocking signal in an El Niño December, it can persist and get even more intense as the winter goes on. History confirms it if we look at specifically the years where December had a -NAO signature during an ongoing El Niño event (disregarding the strength) and subtract from years that didn't. It's an anomalously strong signal. 2009-10 was the most recent instance of this. That winter saw a blocking signal begin in mid-December 2009 via high pressure over the Urals and getting inflated by warm air advection in the North Atlantic, this then retrogressed westward setting up a cold spell. This spell had two phases - the first from the 16th December to Christmas Day which did bring snowfalls but accumulations were lacking over Ireland generally though was a very cold spell in terms of nights with Christmas morning being especially cold, getting down to -10/-11C in the Midlands (who'd have known only a year later, we'd see -18C rounded up in Mayo on Christmas morning again?) then the Atlantic broke through with freezing rain initially. We went into a milder but not overly so period for a few days before blocking got going to the north again and ushered in an easterly wind by the 30th and New Year's Eve. Initially this was heavy rain - original posters from back then will remember it as the infamous Wet Bulb Wednesday - before falling as snow off the Irish Sea on New Year's Eve. This would then culminate in the second phase or coldest spell of the winter - the first 10 days of January 2010. At the time it was classified as the most unbroken prolonged cold spell in Ireland since 1963 (officially) though did not break any records.
I gave that summary to show you what can evolve in such a scenario, it is far from the only one. Lots of the years do something similar, some more extreme than others. Whilst that was an idea I had in mind, I clearly was being very pessimistic and seen the strong El Niño forecasts saying well no chance of that.
So could we see similar for 2023-24? In theory yes. We could. However, times have changed and we live in very unknown territory which I guess is a bit of a cop out and something we've heard a lot but what else can I say?
Watch out for developments. My eyes are all pinned to the stratosphere at the moment more than anything with the exciting evolution of a possible rare Canadian warming (at least this century). The below is quoted directly from Judah Cohen's recent blog here. He mentions how Canadian warmings favour mild for the US and Canada whilst, depending on exactly how the stratospheric polar vortex (SPV) sets up, it can be a signal for below average temperatures across northern Europe.
No doubt some will bring up the fact November 1962, the November predating the big 1963 winter, had a Canadian warming event. Careful that is not the only example, far from. Another thing to note is how Canadian warmings can evolve into major sudden stratospheric warming events too where there's a reversal of the zonal winds in the upper stratosphere over the North Pole.
The autumn pattern and possibly the IOD (although that's just a theory based on what we've learned with 2019-20) are potential factors in why we've been seeing a record-breaking SPV for the time of year. Once the Ural blocking and Aleutian troughing get their act together, the stratosphere will be primed for disruption in my opinion.
In contrast, the Canadian ridging in the polar stratosphere forces the stratospheric PV closer and even into northern Eurasia. The lowering of geopotential heights across northern Eurasia and possibly coupled with easterly flow, results in below normal temperatures. I think that the below normal temperatures over Northern Europe might be overdone in Figure iv. A similar analysis was done in Cohen et al. 2021 Figure 1 (also middle or third cluster) and there the cold temperatures are mostly limited to Northern Asia. I think the closer and deeper into Europe the PV center eventually reaches, the colder the temperature response will be in Europe. But certainly, the potential is there for the cold period across Europe to persist and possibly deepen especially across Northern Europe.
Very exciting stuff all round if you're a coldie. Never thought I'd be saying this. However, keeping feet way on the ground for now as we've been done over too many times. Let's hope there's lots to talk about to come if nothing less 🙂
Photography site - https://www.sryanbruenphoto.com/
Weather photo portfolio - https://sryanbruen.myportfolio.com/weather-1
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The issue with answering this question is there is a lack of a definitive Canadian warming record or dataset unlike major sudden stratospheric warming events. There's a reasonable record that is applicable up to 2001 from the University of Berlin but this hasn't been updated.
Canadian warmings are simply an eastward displacement of the Aleutian high across Canada, typically during the months of November or December, leading to a modest increase in stratospheric temperature.
During a minor or major SSW, normally the warming starts over Siberia and goes counterclockwise over the top edges of the Arctic Circle. This displaces the stratospheric polar vortex to North America, North Atlantic or Europe. More often than not, this includes the high latitudes relevant to us to create blocking areas of high pressure and why PV displacements can actually create a more zonal flow for us though results vary wildly depending on the event.
As far as I'm able to tell, November 2009 did not contain a Canadian warming though it did have a significant minor stratospheric warming that would have serious implications down the line with a split of the stratospheric polar vortex occurring through December 2009 without a reversal (Vargin, 2013) which no doubt played a massive part in the blocking that would dominate the period from mid-December to mid-January 2009/10.
The most recent Canadian warming I am aware of is November 2016 which played its part in a record weak stratospheric polar vortex for the time of year and November 2016 was a blocked, cold month for northwestern Europe. Whatever happened to result in December 2016 being much milder though still dry is an unknown to me, probably an example of blocking not in the right position for us. As you can see, much of December was feeding off the effects of the record weak SPV through November. (Reminder that Northern Annular Mode is another name for Arctic Oscillation but is normally used for describing the AO from the top to the bottom of the atmosphere when discussing about stratospheric to tropospheric responses)
Photography site - https://www.sryanbruenphoto.com/
Weather photo portfolio - https://sryanbruen.myportfolio.com/weather-1
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