[Model Output Discussion - Spring Has Sprung]

@mountain shadow Yes, seems to be the theme through the entire winter..despite another SSW ongoing, no strong evidence of northerly blocking in the NWP output other than throwing out a few outside the reliable timeframe..  In fact, as you say, the opposite seems to be the case once within the reliable with the Iberian ridge having more influence and resulting in well above average temps, not helped by warmer than normal SSTs in the North Atlantic.  I had thought this current SSW may prove otherwise and perhaps it still will towards month end but no sign yet of any increased ensemble members heading in that direction post day 10. The trend, if anything, is less towards northerly blocking so other factors must be at play still.

[Model Output Discussion - Spring Has Sprung]

@Mike Poole Will be interesting to see if this SSW does indeed produce GH blocking and a cold period for the UK. However, looking at the NWP output, it’s a familiar story with some tantalising cold in FI on some ensemble members only for the complete opposite to be the reality in near time! Wouldn’t surprise me if we end up with an early plume of warmth courtesy of the familiar euro/iberian heights which we just can’t shake off for long. Or, just more rain! GFS ensembles this morning look more unsettled to me which I was surprised about.

[Model Output Discussion - Spring Has Sprung]

@Mike Poole

Your last para sums it all up perfectly, dire!! A winter that held such promise but didn’t just disappoint but went majorly bust on many fronts!!  I never thought we’d end up with one of the warmest Febs on record.

And yes, yet again the strat forecasts are trending in the wrong direction today. 

Worn down by this winter is an understatement.

 

[Model Output Discussion - Spring Has Sprung]

@Blessed Weather

Yes, I’ve been following these SSW charts all week and this morning’s update is not a positive trend. Some talk on twitter about a possible double dip SSW but that does not seem to be reflected within these charts. I’m no expert in this area so defer to those more knowledgeable. I think we are all hanging in the last chance saloon because of this potential SSW…

[Model Output Discussion - Spring Has Sprung]

@Kasim Awan I think we could well see a CET in excess of 7C in the absence of a significant cold spell (which seems likely) and continued very mild days/nights (also likely!) given the current output. We are already at 7.8C. I have to remind myself we are in February and not April !

[Model Output Discussion - Spring Has Sprung]

Very poor set of 12z ensembles from GFS. Mild pretty much throughout and on that basis we are on course for an exceptionally mild CET and could well be near the top for warmth. Hay ho, good riddance winter 23/24.

[Model Output Discussion - Spring Has Sprung]

@nick sussex, yes the only thing keeping me hanging in there is the potential SSW forecast. It’s all still jam tomorrow and it’s wearing to see the continued mild/exceptional mild output being pushed in the short term output. The CET for this month is likely to be very mild even if we do scrape some colder temps towards the end.  It’s been a painful season of model watching that’s for sure.

[Model Output Discussion - Spring Has Sprung]

@bluearmy things seem to be trending in the wrong direction. You are hinting this could be a response to the SSW? 

[Model Output Discussion - Spring Has Sprung]

I’m more interested in the potential for more sustained cold synoptics for the second half of Feb. A transient snow event this week is of little interest. GFS 12z operational has totally flipped and we end up in a mild south westerly next week with quite a powerful stream of lows running to the north and north west of the UK. That’s quite a change and would be difficult to shift! UKMO/GEM/GFS looking similar at 120hrs and to my untrained eye those synoptics don’t look great for cold thereafter although GEM does go on to build a continental feed albeit underwhelming.

i appreciate that these are just one set of deterministic runs so we await the ensembles but the potential for cold to develop during second half of February seems to be waning despite the favourable background signals being discussed.   In fact, I wouldn’t be surprised to end up with more of the same, exceptional mild temps on face value of this evenings output, next week has that possibility (again!)

This winter is a bust for my locale and I’ve pretty much given up on anything materialising now. 

[Model Output Discussion - Spring Has Sprung]

Some really excellent posts on here this afternoon especially @Tamara& @Catacol. Thank you! Such interesting analysis and it will be interesting to see how events unfold during February. 
@Dennis, please keep posting. I too really enjoy reading these!

 

 

 

[Model Output Discussion - Spring Has Sprung]

Heights remaining stubbornly persistent throughout the 6z ensembles to our south and south west up until roughly the 10 day point when there are signs of this retreating west which allows some attempts at a northerly flow and lowering of heights to our east. Too far out for any confidence and the cold patterns that do follow don’t inspire hugely as those heights are never too far away from creeping back towards the UK. At least there are hints of a pattern change towards the end of the 10 day period, just about whether that gains momentum or fizzles out.  Personally, my confidence is pretty low for February now having read the mixed analysis on here the last few days.

[Model Output Discussion - Spring Has Sprung]

I thought the overnight ECM ensembles had taken a step back with less cold members in the latter stages compared to yesterday’s 12z.  More members inclined to extend high 850’s which suggest an extension of heights to our south over Europe and maintaining mild to very mild temperatures.  Not what I was hoping to see.  GFS shows a bit more interest especially the control run which has a cold northerly in the latter stages thanks to a high pressure centred to the west of the UK and extending north.

[Model Output Discussion - Spring Has Sprung]

2 hours ago, Singularity said:

Some here seem to view a strong Iberian high as a driver of weather patterns - but this is not so, it’s a response to drivers. In this case the forcing leads to attempts to establish a high over N Europe which are countered by the AO being too positive (likely related to the unusual stratospheric events - who’d have rationally bet on that one?), meaning that in a sense, amplification becomes trapped over S Europe.

Due to the MJO & AAM setup, further attempts to shift the high N are likely in the coming weeks (which can happen abruptly even with a strong Euro high). Signs are the first of those in 6 days time will likely fall short & boost the high over C/S Europe instead. Then, however, we are seeing the models tend to raise polar heights as we head into Feb. That improves the chances of the next attempt being successful, regardless of how current modelling paints the picture (they’re not actually that reliable for week 2+, it’s just easier to predict +NAO because it happens way more often than -NAO in N Atlantic climatology).

Emphasis on chance here. As Tamara has said many times over the years, there’s no magic bullet for HLB patterns. As I’ve said before, the most likely outcome isn’t always what happens. With this in mind I’ve found forecast model watching a lot less stressful.

Very interesting and helpful analysis, thank you.  So, it comes down to whether we can remove that strong AO signal in order for heights to build sufficiently north. Background signals are there and as you have highlighted there are some tentative signs in the latter stages of output but all too far away to be taken seriously at this point. At present, it does seem as if it’s rinse and repeat up until end of first week of Feb. All a bit underwhelming…

[Model Output Discussion - Cold spell ending - what next?]

5 minutes ago, mountain shadow said:

Did we really get Greenland blocking last week? Maybe for a day, possibly two, I would hardly call it sustained.

As for next month, the Met Office remain confident so they maybe have access to something we don't.

Do they remain confident? I think we all know how quickly their longer term forecasts can change and if they are seeing the same background signals change as we are at the moment, I would expect their forecast to be updated.  We shall see..

[Model Output Discussion - Cold spell ending - what next?]

Yes, the background signals for a cold February have been diminishing over the last few days. I think I’m more confident of believing that we are looking at an early taste of Spring in the next 10 days or so than anything wintry especially with those strong heights persisting over central/southern Europe giving the potential for a long fetch south or southwesterly wind.  February hasn’t felt like an especially wintry month for some considerable time. 

[Model Output Discussion - Cold spell ending - what next?]

36 minutes ago, bluearmy said:

Exeter are calling a higher chance than usual of north or east winds as we head towards mid feb.  That likely places a block to our nw or north. not particularly specific but possibly reflects an agreement between glosea and ec46 clustering.  Whilst the scandi ridge option seemed to catch a few off guard with its appearance within 10 days on modelling earlier last week, the ens suites that pushed that ridge also failed to maintain it and sent lower heights across to scandi as week 2 progressed.  I think many here expected to see HLB showing by the end of jan. Some model runs are expanding a monster of a Siberian high end jan but it seems that the upstream tpv will see that off as far as it influencing w europe.  It seems that we have to go through the cycle of the tpv sending a chunk to scandi and then we wait to see where the wave break sets up the upper ridge that follows. 
 

the seasonals have been fairly bullish on height rises to the wetst or northwest in feb - my take is that many here haven’t seen any reason to dismiss that.  We just have to get through another transition of zonal flow which sadly is longer than many hope to see. 

But, haven’t the unexpected strat developments taken everyone by surprise this year including the experts? As per Catacol’s post above, this looks to be bouncing back to above average and could well override any trop led developments that would otherwise have led to cold developing in February.  Also, I have found that the longer term MetO updates sometimes take a little while to update probably because they are waiting for a more difinitive signal, ie waiting to see whether the strengthening strat does indeed become the dominant factor over the next week or so.  I guess we will have to wait and see on that one.

[Model Output Discussion - Cold spell ending - what next?]

21 minutes ago, damianslaw said:

Out to 10 days, ECM and GFS show a predominantly westerly airflow from Friday onwards, with a strong ridge to our south attempting to build north but thwarted by a very strong jet. We exchange a cold, in the north very cold week, for a nationwide very mild week, chalk and cheese conditions.

No clear signal how things may develop as enter February, but interesting to see GFS continues to show heights building into the UK which could herald a pattern change to blocked again.

Agreed. I was thinking the same. Attempts for the high to ridge north and also height rises towards Scandinavia but with the PV set up over Greenland and a strong jet, it’s difficult to see how any ridge won’t be flattened. North potentially unsettled and cooler with the south drier and relatively mild or perhaps very mild depending on wind direction.  If heights to the North East can establish perhaps things may become favourable but it looks tough against that strong jet.

[Model Output Discussion - Colder but how cold and for how long?]

1 hour ago, bluearmy said:

Heights into Greenland for more than a fleeting ridge at best look troublesome to me within the next 16 days. 
unless we see the Canadian vortex relaxing itself markedly across the end week 2 ens, then i think we could be looking towards week 4 approaching mid feb to get that to stick.  It really wouldn’t surprise me to see the nwp trying to repeat the last couple weeks with a mlb that eases north to Orkney ish latitude  and then retrogresses slowly. if upstream plays ball then we can then get a griceland high to follow. If split flow plays ball then we can possibly advect something notable around the south of an Orkney high. 

 

 

That would tie in with forecast of strat PV to return to above average (GEFS mean) following SSW underway today. That would be problematic for HLB especially if PV establishes Greenland?

[Model Output Discussion - Colder but how cold and for how long?]

2 hours ago, Catacol said:

For those looking further out, JMA monthly published yesterday for February.

UK, as usual on this one, at 10 o clock.

Otherwise the current situation is not what many on here would have hoped for. This GFS for tomorrow screams all kinds of wintry wonders:

but closer examination shows that much of central and southern UK is stuck in a col, neither fed by the strongest and coldest winds from the N and/or NE nor quite in line for the channel runner. There is a day or so to go for surprises to turn up, and as we speak Scotland is getting pasted....but the snow hungry majority in the south are left gasping. Feels like rolling a double 1 and damnably unfortunate.

Then comes week 2. 22-29 Jan approx was always flagged as a week of greatest concern because the impacts of lowering momentum would be greatest and the need to gave got a block cemented in a good place would be highest. But that double 1 effect may be about to land again. (is that like rolling 4 x 1s?!) The strat splits tomorrow

and the zonal mean is much below average, even close to a technical (if very short lived) SSW

- and we could be excused for thinking that there is little better context for ongoing northerly blocking. But look how steep the recovery is, and with little to no model disagreement. Back to average in a flash, and GFS largely puts the vortex back together again by the end of the weekend.

So - what's happening?

Factors leaning towards a cold and blocked outlook have had to work pretty hard to get our blocking pattern in place. Even with a favourable pulse of momentum, a good GWO orbit, and lagged impacts of an amplified MFO through the west pacific we have not quite got the block in place. Meanwhile, as soon as those signals fade into a period when it was well noted that things would get less automatically "good" for winter, we get a collapse of the pattern that is on the crazy side of fast. We go from the good chart at the top of this post to this within 4 days:

No obvious lag here for the flatter MJO phases!! And a reforming vortex has helped support an atlantic pattern in double quick time. It is almost as though the wax wane nature of the atmosphere has been placed on a hill. To get to a blocked phase we have to sprint up the hill on our bike, in first gear, legs pumping and burning once at the top. But then to return to the starting point it is an easy cruise downhill, hands off the handlebars, freewheeling.

Maybe this is CC in action. Or maybe it is just a reflection of some very poor luck for the coming week and the one after. I don't know. I guess in the end, other than to take the learning from it, I don't really care. It has never been easy to get snow to this country and 1988 to 2008 was a 20 year run of misery punctuated by a couple of good moments. Hunting those rare major snowfalls would be no fun at all if they came every year.....but it would be good if the fates could allow us 1 in 5!!

This winter is not done. I read some guff on this thread that I find annoying, folk announcing the default return of a period of westerlies as though there is something wise and significant in doing so. Saying the UK will usually have westerlies and that the best way of approaching UK winter weather forecasting is to say "westerly" each time because you will usually be correct is both lazy and daft. I don't put my money on Ronnie O'Sullivan to win the snooker each time "because he usually does." I do it because I analyse the context and decide it is the most likely outcome....and I might still put £10 on a young outsider with half a chance of making it based on analysis and form, as per Luke Littler in the Darts. If Ronnie is ill the week before Sheffield I probably don't back him at all, despite the past run of success!

And this is where we are right now. January 15, half way through winter. We had a decent start, a disappointing Xmas/NY and now sit in 4 days of frigid air but without widespread snow forecast. Bugger. Westerlies to return for a while. But the analysis doesn't change, and the weighted approach to appropriate forecasting remains. The next momentum cycle is underway, signalled by rising frictional torque as of a couple of days ago. The MJO will be back in the west pacific pretty quickly looking at model forecasts, and while the vortex returns to average it doesnt appear to launch itself into an above average phase. Read Tamara's work rather than mine on this - she expresses the technical aspects of wind flow much better than anyone else on here....but in essence we are set to have more wave action return, a meridional pattern embed and poleward flux that should bring blocking back to the table quite quickly. I haven't seen a seasonal do anything other than go with a negative AO for February and the combination of high momentum and a favourable MJO in a Nino year will bring things back. I had said 3-5 days of atlantic westerlies. That was based on the cold hanging on until Sunday as I had it down as a cold week....but it appears the cold is fading faster than we might reasonably have expected....so it pushes longer. I do think by the end of week 2, that's somewhere around 26/26/28 Jan, we will have a more favourable context back on the table....or at least sitting on the hot plate waiting to be served.

Winter hunting in the UK has never been easy. C'est la vie. But we continue to look, and search, and roll those dice despite the fact that 80-90% of the time they don't give us what we seek.

 

This is a superb post. Thank you for taking time to put this together in such an informed, clear and honest fashion. I always enjoy reading your analysis and your posts are always explained in easy to understand language despite the complexity of our weather. And you are always so humble especially when things don’t quite go to plan. We’ve been unlucky this time with snow chances frustratingly close this week for those south of the border. And the quick return of the westerlies is a bit of a kick in the proverbial too. But, I will keep returning to the models and the excellent posts written by the likes of you and hope that we get that next lucky roll of the dice into February.

[Model Output Discussion - Colder but how cold and for how long?]

4 minutes ago, stodge said:

Yes, the next pattern change to a westerly-based regime was and has been well signalled and those hoping for some continuation of the cold were really clutching at the flimmiest of straws.

 

I don’t think a continuation of the cold was necessarily expected but neither are the exceptionally mild charts currently being shown in the model output. What many were thinking is that the breakdown would not be as abrupt and would potentially offer a slower and possibly snowier transition to less cold conditions.

[Model Output Discussion - Colder but how cold and for how long?]

I don’t think I was quite expecting such an exceptionally mild looking set of charts to appear in the model output as is currently showing for next week. And there is nothing indicating at the moment that won’t be for an extended period, ie 10 days + (waxing and waning a bit). I take note and value those more knowledgeable members who are confident of a more blocked and cold pattern re-emerging end Jan into Feb. I do hope we get something of more note than this upcoming week before winter is out.  At the moment, I’m looking at these charts and thinking they look all too familiar (not favourable to coldies) despite the favourable background signals that many have been discussing.

Still, we should enjoy the short lived cold spell this week and the break from all that rain and some will no doubt be posting some wonderful winter photos that many of us will, sadly,  have to enjoy vicariously.

[Model Output Discussion - Colder but how cold and for how long?]

Model fatigue definitely creeping in for me. On reflection, nothing much has changed, cold this week, more mobile the following week and then potential for more blocking to arise thereafter. But, it’s all been rather underwhelming to be honest especially next week. I expect it’s because the snow potential is very limited other than favoured locations and perhaps the far south with a degree of luck. I am also surprised and disappointed about the speed of the breakdown next weekend and the lack of battleground potential. And, we can’t rule out the prospect of some exceptionally mild weather the following week with those all too familiar Iberian heights showing in a number of the model outputs.  I hope some get lucky this week out of this setup but overall it has been rather deflating and it feels like many have already moved on to the next chase..

[Model Output Discussion - Into 2024]

The trend to colder is clearly there in all models from early next week. What is less clear is how far north any milder incursions will push. What does seem evident to me is that uncertainty has increased a notch today regards next week and this is evident tonight in the GEFS ensembles. I think to discount the GFS isn’t sensible, the trend is for more energy to be thrown up against the cold, maybe it has overestimated this but maybe not.  I don’t think there is much clarity this evening. We just need to wait and see how this unfolds each day. It does seem as if it will be a high risk high reward scenario with some people getting very lucky and others very disappointed. The UK is in the boundary zone as usual, big differences for us living here but very small margins on a global scale.  Having lived on the south coast during my childhood, can’t tell you how many times I’ve watched rain tumbling down outside only to watch how feet of snow have fallen midlands northwards..seems like it’s that kind of scenario setting up next week.

[Yorkshire and E England regional discussion]

1 hour ago, reef said:

A bit of a poor effort here. Its stopped now and this is what we ended up with.

We need a good northerly...

I share your pain ! Curse of the east coast. North Norfolk the same, been snowing heavily this morning but absolutely nothing has stuck! Those at elevation and away from east coast have certainly benefited. Unless we get deep cold uppers and low dew points, just impossible to get a decent snow event. Sadly, northerlies are just not potent enough these days. Can’t remember when one delivered here. Easterlies off a frigid continent are our best scenario.  Hay ho…at least I got to see falling snow. I was doubtful of that a couple of days ago.

[Model Output Discussion - A cold start to Spring?]

4 hours ago, Catacol said:

After my gloomy posts of yesterday some better news for the short term. ECM is an upgrade for the second half of the week - this chart is at least a snowmaker for a day.

Mmm..I’m still feeling gloomy but very much from an imby perspective. I thought yesterday I might see a snowflake if lucky but even that is now looking very unlikely. Convective snow showers from the North Sea looking to stay offshore even in the north east where the met office have warnings out. We look to miss out on upcoming events further south and north too! Once upon a time a cold artic plunge from the north/north east would have put my location in a favoured spot but not to be this year..looking very good for many parts though as you highlight and hopefully your locale too being that bit more west and north.