Model Output Discussion - Cold spell ending - what next?

[sebastiaan1973]

58 minutes ago, Met4Cast said:

What did previous look like a good chance of sustained high latitude blocking during February is rapidly fading. 

Despite an increasingly favourable MJO signal into the western Pacific, we’re missing a vital ingredient & that’ poleward propagating +AAM (westerly momentum). 

The arrow shows the previous “starting pistol” of +AAM anomalies propagating poleward through December & indeed into early January, this along with the MJO helped to support & sustain the recent blocking we’ve seen around the UK/over Greenland. 

Unfortunately, this time +AAM is increasingly glued to the equator & we’re not seeing this fluxing towards the pole, this helps (despite the MJO) to inflate the European ridge & indeed, a very strong signal for this within NWP through the remainder of January. A flat, mostly mild end to the month with low pressure systems deflected northwards, potentially stormy at times for Scotland. 

The reflective wave from the SSW hasn’t helped things either. So.. my hopes for something sustained in terms of cold/snow are rapidly fading. 

Okay ,thanks. What is need to turn it back as a good chance for high latiude anticyclone?  & don't you think we have to be careful by using these kind of 'forecast' because it not the first time, something went wrong. Like in for the end in december.  

[Penrith Snow]

10 minutes ago, Met4Cast said:

"Background signals" haven't failed, though. They only take you so far and micro details are important, shorter range changes are important. There have been several rounds of strat warming and it seems the most recent one "reflected" if you like, this helped to draw the Canadian PV eastwards towards Siberia which flattened out what previously should have been a more promising pattern for cold. 

Things change, forecasts evolve. Anyone expecting snow outside their front door or cold in a small area such as the UK purely based on teleconnections doesn't understand them, or is placing far too much emphasis on their ability to predict the micro pattern. Broadscale pattern they've done incredibly well this winter. 

Unfortunately, short-term prospects that simply cannot be forecasted at range (such as the SSW) can disrupt and change expectations. That doesn't make the teleconnections/background drivers useless.

Micro Pattern? Your joking, these are hemisphere wide pressure anomalies!

The Iberian Hign is 4 thousand miles wide at least while the polar vortex is strong, these are not 'micro' developments

Andy

[Gowon]

Just now, Penrith Snow said:

Micro Pattern? Your joking, these are hemisphere wide pressure anomalies!

The Iberian Hign is 4 thousand miles wide at least while the polar vortex is strong, these are not 'micro' developments

Andy

I think he's on about short waves 

5 minutes ago, Penrith Snow said:

Agreed,

However, the surprising thing is that tge MetO were taken in by all the cold signals as their MRF has been for colder than average conditions since early January and laughingly still is!

The MetO aren't known for cold ramping so some signals must have been clear, to me it demonstrates that all those teleconnections are useless as a forecasting tool, conditions over the next two weeks being the exact opposite to those predicted.

I would have had more success asking the Cat to point to the correct NH pressure anomaly for late January!

Andy

Has the Meto changed their forecast now for Feb?

[jules216]

1 minute ago, Met4Cast said:

Evidently you've not been reading the forum very much, then. 

Highlighting potential based on the evidence available isn't "ramping". Things didn't evolve as expected and it's important to know why & what changed. Simply saying "well that didn't happen ah well lets move on" doesn't teach you anything, it doesn't provide any context as to why. 

The teleconnections produced the Greenland blocking & two week colder spell we've just seen across the UK, this was well advertised weeks in advance, indeed, talks really started to pick up on this in early December! Goings on in the troposphere & changes have meant that the February period (still 2 weeks away, by the way) has evolved to show different weather patterns. 

What has "failed" there, precisely?

I agree that most of what was seen at the time as a forecaster tool was very useful. I name a few. 1. Falling GLAAM/AAM that enduced cold snap n.1 was well advertised as the low pressure systems started to fall deep on southern track in to central Europe. 2. A longish unfavorable pattern in December after MJO failed to reach phases 7-8-1 with enough amplitude. Again an attempt of cold air to be established at the turn of the year like in 2007 and 2015 that lasted about a week to 10 days for then the unfavorable pattern to re-emerge based on the SSW type.

If you want a cold outcome post SSW you need Ural blocking like 2020/21 for long lasting cold impacts. Also the pattern at onset was wrong this year. Like Sebastian wrote well its better to have European Blocking then Greenland blocking at onset. We had the reversed and now we are seing what it means. Its up to anybody to try and learn more from all kind of resources - outcomes not just focus on desired outcome. I ve learned that many years ago.

[syed2878]

20 minutes ago, Met4Cast said:

"Background signals" haven't failed, though. They only take you so far and micro details are important, shorter range changes are important. There have been several rounds of strat warming and it seems the most recent one "reflected" if you like, this helped to draw the Canadian PV eastwards towards Siberia which flattened out what previously should have been a more promising pattern for cold. 

Things change, forecasts evolve. Anyone expecting snow outside their front door or cold in a small area such as the UK purely based on teleconnections doesn't understand them, or is placing far too much emphasis on their ability to predict the micro pattern. Broadscale pattern they've done incredibly well this winter. 

Unfortunately, short-term prospects that simply cannot be forecasted at range (such as the SSW) can disrupt and change expectations. That doesn't make the teleconnections/background drivers useless.

The background drivers (GSDM, MJO etc) should be used as diagnostics of possible broadscale patterns and to provide context to NWP modelling, they cannot be used to say "London will see snow in 2 weeks". Forecasts constantly evolve and unfortunately on this occasion, unforecastable consequences have disrupted expectations. It's not about being right or wrong, it's about analysing the situation based on the evidence you have available and forming a conclusion, when the evidence changes or shifts so must too the formed conclusion, that's just the nature of this game.

 In a way, the background signals and telly connections did fail for somewhere like the UK. They are pretty much useless if I may say 

[AO-]

One just has to take a look at the last chart of the GFS06 to know that this one is not the savior. Maybe the EPS is better. Next... 

[Froze were the Days]

14 minutes ago, Penrith Snow said:

Agreed,

However, the surprising thing is that tge MetO were taken in by all the cold signals as their MRF has been for colder than average conditions since early January and laughingly still is!

The MetO aren't known for cold ramping so some signals must have been clear, to me it demonstrates that all those teleconnections are useless as a forecasting tool, conditions over the next two weeks being the exact opposite to those predicted.

I would have had more success asking the Cat to point to the correct NH pressure anomaly for late January!

Andy

Agree!...MetO were also wrong in 2018/19 predicting cold blocked conditions in late January into February which never materialised. 

As for teleconnections in these times of global warming...

[jules216]

10 minutes ago, Penrith Snow said:

Agreed,

However, the surprising thing is that tge MetO were taken in by all the cold signals as their MRF has been for colder than average conditions since early January and laughingly still is!

The MetO aren't known for cold ramping so some signals must have been clear, to me it demonstrates that all those teleconnections are useless as a forecasting tool, conditions over the next two weeks being the exact opposite to those predicted.

I would have had more success asking the Cat to point to the correct NH pressure anomaly for late January!

Andy

 I somehow don't know what the problem is in UK and seemingly UKMO with getting things wrong. Often we were making jokes with other friends here that also do regular seasonal analysis like example being well advertised UK warmth in July 2023 which we just never saw in our analysis at the time to last. Also past 3 years we are laughing when UKMO bring their spring seasonal maps out in February which bring +3 anomalies yet we knew that in May we will have -7C and devastating frost with better snow chances at Easter then Christmas. The most peculiar thing is that when I attempted to make jokes about this on twitter there were actual profesionals that jumped on me defending those UKMO maps saying its a "microscale diference" well yes the blocking is 2000km to north west and from +3 is -1 anomaly etc. 

[Met4Cast]

Just now, jules216 said:

I agree that most of what was seen at the time as a forecaster tool was very useful. I name a few. 1. Falling GLAAM/AAM that enduced cold snap n.1 was well advertised as the low pressure systems started to fall deep on southern track in to central Europe. 2. A longish unfavorable pattern in December after MJO failed to reach phases 7-8-1 with enough amplitude. Again an attempt of cold air to be established at the turn of the year like in 2007 and 2015 that lasted about a week to 10 days for then the unfavorable pattern to re-emerge based on the SSW type.

If you want a cold outcome post SSW you need Ural blocking like 2020/21 for long lasting cold impacts. Also the pattern at onset was wrong this year. Like Sebastian wrote well its better to have European Blocking then Greenland blocking at onset. We had the reversed and now we are seing what it means. Its up to anybody to try and learn more from all kind of resources - outcomes not just focus on desired outcome. I ve learned that many years ago.

Your last sentence absolutely nailed it. 

By nature this thread is very "outcome" focused, i.e wanting cold and many trying to find evidence to fit with that desired outcome. Rather, that's the wrong way around. You should form conclusions based on the evidence at hand. But, many of us in here want to see cold/snow so naturally the thread skews the way that it does. 

Unfortunately the issue with that is when things do "go wrong" many throw the toys out of the pram and target those that attempt to distance themselves from chasing "desired outcomes" and instead, like yourself, try to forecast based on the most likely outcomes based on the evidence at hand. 

The GSDM isn't perfect, teleconnections aren't perfect, modelling isn't perfect. When forecasting, particularly at range you do have to make some assumptions & educated guesses on how things may evolve & what that could lead to in terms of broadscale patterns & indeed more local, regional detail. My point is, just because things are skewed/favour blocked & subsequently cold outcomes it doesn't mean something wont change or the forecast wont evolve. 

Some things simply cannot be forecasted at long-range, you can have all the favourable teleconnections in the world pointing towards blocked/cold outcomes but if something in the shorter timescale (i.e in this case a SSW) occurs, the entire forecast can shift. That doesn't mean the "teleconnections" are rubbish, it doesn't mean they've "failed", it just means something else has occurred which has shifted the pattern and sometimes that shift can be substantial. 

In terms of the cold spell just gone - It was clear the Atlantic would attempt to return, this was well sign posted and HLB was expected to relax, I posted this on January 11th:

Quote

 

The 20th-25th January still looks like the broader period for less cold weather to begin moving in across the UK, albeit with a lot of uncertainty. This in itself could bring significant snowfall risks but before that, cold next week with the risk of snow for some.

Ensemble spread for the above mentioned period is large with some members keeping the cold until later in that period, it may take a few attempts but there's certainly a signal there now for less cold air to push into the UK as blocking to the NW begins to relax. 

 

This return to Atlantic weather wasn't a sudden shock. Granted, the snowy breakdown didn't happen but the evolution has gone mostly as expected. There had been some musings/hope that ridges of high pressure would hold up to the north of the UK keeping the UK within the colder air but a strong Canadian vortex shifting east into the Atlantic put that to bed. 

So, when people say "the forecast has gone wrong" etc I'm really not sure what they're talking about.

[MATTWOLVES 3]

Gang..before the thread descends into a debate over who got it wrong and the fact the obituaries are coming in already and before February as even started...i would like to say firstly.

1.GFS is shambolic..one run there is no pv left as its in tatters..now the current run a couple of hours later has a strong PV sat over Greenland. Viewing it at range should come with a Health warning.

2. Talk of mjo failing is a tad premature as this as not occurred yet,and could still go favourable in the days ahead.

3.The met still go with the colder theme next month and I don't feel they will be changing the write up today.

4. Do background drivers that hold promise mean we will be getting the holy grail of winter sypnotics? No they do not..This cold snap started as a couple of cold days the other week before warming up by the weekend and then going cold again for 5 days last week! So about 7 or 8 cold days..and tbh nothing special away from the far North!

5.The cold snap around early December was equally as good on the back of no forcing and positive drivers whatsoever.

6. We have now entered the unknown.the Twilight Zone if you may,which means other new little variables are entering the equation and possibly squandering positive drivers..Next year we could be looking at awful teleconnections but other little variables may crop up and put us in a better position than this year!

7. Yes I do think there's some who will talk the talk and big up how good things look this winter,and when it all goes wrong they will quickly disappear till next year and give no insight in to why they think it went wrong! If I make a forecast and get it wrong I will hold my hands up and basically go again.. if you give me criticism I can take it and I will be ready to roll again.Hey even the best pros get it wrong and I feel this is gonna set a theme of many many more getting it wrong as we move further down the line.

8.And finally I feel the interest lies around mid month and beyond..Dont be foolhardy and write a whole month off...we have seen before that mother nature considers our predictions,laughs at them and goes on to do her own things!

To sum up i would say we are close to the last chance saloon.but everytime we give in hope or make a long range prediction we get it wrong! So this time when we expect nothing we will once again most likely be proven wrong again.

Don't give in hope,as in this world today hope is all we've got.

Take care you lot.

[Gowon]

8 minutes ago, MATTWOLVES 3 said:

Gang..before the thread descends into a debate over who got it wrong and the fact the obituaries are coming in already and before February as even started...i would like to say firstly.

1.GFS is shambolic..one run there is no pv left as its in tatters..now the current run a couple of hours later has a strong PV sat over Greenland. Viewing it at range should come with a Health warning.

2. Talk of mjo failing is a tad premature as this as not occurred yet,and could still go favourable in the days ahead.

3.The met still go with the colder theme next month and I don't feel they will be changing the write up today.

4. Do background drivers that hold promise mean we will be getting the holy grail of winter sypnotics? No they do not..This cold snap started as a couple of cold days the other week before warming up by the weekend and then going cold again for 5 days last week! So about 7 or 8 cold days..and tbh nothing special away from the far North!

5.The cold snap around early December was equally as good on the back of no forcing and positive drivers whatsoever.

6. We have now entered the unknown.the Twilight Zone if you may,which means other new little variables are entering the equation and possibly squandering positive drivers..Next year we could be looking at awful teleconnections but other little variables may crop up and put us in a better position than this year!

7. Yes I do think there's some who will talk the talk and big up how good things look this winter,and when it all goes wrong they will quickly disappear till next year and give no insight in to why they think it went wrong! If I make a forecast and get it wrong I will hold my hands up and basically go again.. if you give me criticism I can take it and I will be ready to roll again.Hey even the best pros get it wrong and I feel this is gonna set a theme of many many more getting it wrong as we move further down the line.

8.And finally I feel the interest lies around mid month and beyond..Dont be foolhardy and write a whole month off...we have seen before that mother nature considers our predictions,laughs at them and goes on to do her own things!

To sum up i would say we are close to the last chance saloon.but everytime we give in hope or make a long range prediction we get it wrong! So this time when we expect nothing we will once again most likely be proven wrong again.

Don't give in hope,as in this world today hope is all we've got.

Take care you lot.

I love your message at the end.

[MATTWOLVES 3]

Hey folks I viewed that 6z op run and thought no hope! Looks like the ens had other ideas.

All aboard the Feb express anyone??

Edited January 22 by MATTWOLVES 3

[johncam]

1 hour ago, Gowon said:

Back to where we started:

Yep , take a while from there to get anything wintry that lasts more than a day ot two.

[Battleground Snow]

I share the disappointment in the modelling at the moment, but it can always change at 10+ days away.

A slight positive today is the ecm seems to be resisting the urge to send the mjo into cod in phase 7, the 500mb anomaly is decent for February, although phase 8 is what we really want.

It seems to be taking an age to shift the tpv away from Greenland, which is eating up valuable winter days.

I would say a cold spell is still possible, but it's looking more  like mid February now, compared  to the monthly glosea / ecm which were advertising a totally blocked month for February a couple of weeks ago based on how strong the anomalies were

Edited January 22 by Battleground Snow

[Mike Poole]

2 minutes ago, Battleground Snow said:

I share the disappointment in the modelling at the moment, but it can always change at 10+ days away.

A slight positive today is the ecm seems to be resisting the urge to send the mjo into cod in phase 7, the 500mb anomaly is decent for February, although phase 8 is what we really want.

It seems to be taking an age to shift the tpv away from Greenland, which is eating up valuable winter days.

I would say a cold spell is still possible, but it looking more  like mid February now, compared  to the monthly glosea / ecm which were advertising a totally blocked month for February a couple of weeks ago based on how strong the anomalies were

It is difficult to see from the monthly average plots that we see from the seasonals, whether GloSea6 was seeing a moderately blocked signal for the whole month of February or a very blocked signal for the second half only after a meh first half.  We have now to hope the latter…

[Don]

2 hours ago, Ali1977 said:

So everything was looking good for late Winter and now signals aren’t so good - well personally the long range signals are clearly worth toffee - so with that February is still very possibly going to be wintery - so far I’ve had no snow what so ever living on a pretty decent hill - sad times, so everything is crossed for Feb and early March. Mid March onwards , I’ll be ready for the heat

Even that CFS chart posted earlier today seems to now be pointing towards a mild March!  As soon as the models abruptly ended the recent cold spell, alarm bells started ringing for me ref to rest of winter!

Edited January 22 by Don

[bluearmy]

17 minutes ago, MATTWOLVES 3 said:

Hey folks I viewed that 6z op run and thought no hope! Looks like the ens had other ideas.

All aboard the Feb express anyone??

The pieces of the puzzle are there into week 3 matt but getting them to fall for our little part of nw europe is v tough  

[Duane S.]

22 hours ago, Duane S. said:

06z Op. Outlier or trendsetter?

 

Consistency it is not (although, Op aside, an improvement though)

[bluearmy]

16 minutes ago, Battleground Snow said:

I share the disappointment in the modelling at the moment, but it can always change at 10+ days away.

A slight positive today is the ecm seems to be resisting the urge to send the mjo into cod in phase 7, the 500mb anomaly is decent for February, although phase 8 is what we really want.

It seems to be taking an age to shift the tpv away from Greenland, which is eating up valuable winter days.

I would say a cold spell is still possible, but it's looking more  like mid February now, compared  to the monthly glosea / ecm which were advertising a totally blocked month for February a couple of weeks ago based on how strong the anomalies were

Joe b had a piece the other day illustrating a v warm sst anom that had appeared unexpectedly ne of Australia 

It could interfere with the expected movement of the MJO through its phases 

the ec today is more promising (the BC a little less so). Be interesting to see if the 46 picks that up later. 

[Gowon]

4 minutes ago, bluearmy said:

Joe b had a piece the other day illustrating a v warm sst anom that had appeared unexpectedly ne of Australia 

It could interfere with the expected movement of the MJO through its phases 

the ec today is more promising (the BC a little less so). Be interesting to see if the 46 picks that up later. 

What's the BC, blue?

[Battleground Snow]

2 minutes ago, Gowon said:

What's the BC, blue?

It's the bias correction, I purposely used the non biased corrected version, purely based on It seems to be more accurate at the moment, looking backwards on the previous wave, (doesn't mean it will be this time out though)

Which I know sounds counter intuitive.

Edited January 22 by Battleground Snow

[Cassivellaunus]

What sort of conditions will we be looking at early Feb given what I think is a Bartlett high encroaching? Does this tend to produce fog this time of year or clear skies

[StretfordEnd1996]

2 hours 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.

The MET aren't necessary on their own though when comparing their thoughts to the model output - i.e. ECMWF

CFS

[Eagle Eye]

With the rise GLAAM signal being poor for us specifically, the second GLAAM rising signal was delayed on the latest CFS. We're running out of time for February to be honest, especially the firs half. The Euro-Scandi high does look like becoming more of a ridge and we do get stuck with an expanded mild and zonal pattern almost irrespective of the US pattern. The second potential GLAAM rise toward mid Feb will be very important for any prospects for most of us later into Winter. 

Edited January 22 by Eagle Eye

[Don]

47 minutes ago, bluearmy said:

Joe b had a piece the other day illustrating a v warm sst anom that had appeared unexpectedly ne of Australia 

It could interfere with the expected movement of the MJO through its phases 

the ec today is more promising (the BC a little less so). Be interesting to see if the 46 picks that up later. 

All these unexpected interferences!  Seems like every thing that can go wrong, Is going wrong! 

8 minutes ago, Eagle Eye said:

With the rise GLAAM signal being poor for us specifically, the second GLAAM rising signal was delayed on the latest CFS. We're running out of time for February to be honest, especially the firs half. The Euro-Scandi high does look like becoming more of a ridge and we do get stuck with an expanded mild and zonal pattern almost irrespective of the US pattern. The second potential GLAAM rise toward mid Feb will be very important for any prospects for most of us later into Winter. 

Going by how things are currently going, it would be brave to bet against it being another bust?!