Model output discussion - Into 2021

[Cuban Zebra]

13 minutes ago, fromey said:

I think a few need to stand down, put there toys back in the pram and read @carinthian post, watching the models at the moment is like watching a drunk person trying to pin the tail on a donkey. 
 

Spot on comment, but I think the donkey is drunk as well!

[Scott Ingham]

22 minutes ago, carinthian said:

Ok, I have an update from the team over here with specifics for the UK. Taking out any equation as regards to SSW in the conversation , I have a very interesting view on the models and forecast charts for the period 144t -240. Looks like a big difference now to evolve in that period between GFS and the UKMO . In their own view they still expect lower heights over Europe and a NEly flow into the British Isles with increasing snowfall for many,especially the Eastern side of Britain. This theory based on the East Atlantic high to enforce amplification towards the East Greenland Sea and to hold. Further outer range charts show the possible threat of a significant low to develop way out to the SW of Europe and move into the colder air mass but thats a low way off at the moment but is never the less being flagged. Should get a correction this evening from GFS/ECM run, they advise. So all in all very positive for you guys for early January cold spell to continue. Certainly better than the past few years.

C

I think tomorrow morning will see these corrections you speak of

[danm]

24 minutes ago, Tim Bland said:

My toys are in my hand and they are ready to be launched ECM and GFS are both snowless (apart from the odd flurry) for 50% of the UK , and by day 10 it’s turning milder,  so we don’t even have FI to hold onto.  Quite ironic that the SSW us potentially killed out chances for anything before last 3rd of winter.  Very disappointing for those hopeful of a snowy mid winter. I know some localised areas have seen a bit of snow but the map below is quite representative of the areas that look likely to miss out on proper snow

As we can see from this weeks snowfall in parts of the country, trying to forecast small troughs or showers this far out is always fruitless. We’ve learned this over the years - I wouldn’t rule out snow showing up anywhere at relatively short notice. 

[mushymanrob]

1 hour ago, Griff said:

 

Which is what @Catacol and Scott and many others have been saying for a while now. 

 

Sorry if ive repeated anything, theres been too many posts to wade through and ive other things to do including running my own site where ive reported on these developments since November.

[Snowy L]

The fact that it's not just the UK being affected but in fact the AO would go hugely positive on this morning's GFS should tell you it's not the SSW messing things up. The UK can get unlucky from SSWs, but northern blocking should still be there.

[BLAST FROM THE PAST]

15 minutes ago, carinthian said:

Hello Chris, no but I have access to a portal weather live briefing from a Central European Agency that provides detail snow forecasts for the resort. I use my past experience ( ex UK Met employee ) to discuss with the team of experts , which is very useful and always friendly.

Thanks for your interest.

 C

C

thanks for this regular input, very informative indeed no matter which way they point to.  Fascinating to hear what the professionals are seeing.  

The UKmo model in this situation is best to stick with currently as it only goes to t144 and if it sees mild it will show it.  It doesn’t yet.  I think if we are heading towards a GFS then tomorrow afternoon or Monday morning UKMO will show signs of that at t144.  Now it will be interesting tomorrow morning to see what it’s t120 shows compared to t144 this morning.

 

BFTP 

[Tim Bland]

13 minutes ago, danm said:

As we can see from this weeks snowfall in parts of the country, trying to forecast small troughs or showers this far out is always fruitless. We’ve learned this over the years - I wouldn’t rule out snow showing up anywhere at relatively short notice. 

I agree, there could be a light dusting for some and very locally enough for a snow ball but the disappointment comes at the prospect of seeing a prolonged widespread snowy spell in the heart of winter and I just don’t see that happening now. IF we were to get to the below position we are at least a week away from a cold setup , that takes us to February. 

[Tim Bland]

3 minutes ago, BLAST FROM THE PAST said:

C

thanks for this regular input, very informative indeed no matter which way they point to.  Fascinating to hear what the professionals are seeing.  

The UKmo model in this situation is best to stick with currently as it only goes to t144 and if it sees mild it will show it.  It doesn’t yet.  I think if we are heading towards a GFS then tomorrow afternoon or Monday morning UKMO will show signs of that at t144.  Now it will be interesting tomorrow morning to see what it’s t120 shows compared to t144 this morning.

 

BFTP 

GFS looks good at t144 and doesn’t show any signs of mild though Fred...

[danm]

1 minute ago, Tim Bland said:

I agree, there could be a light dusting for some and very locally enough for a snow ball but the disappointment comes at the prospect of seeing a prolonged widespread snowy spell in the heart of winter and I just don’t see that happening now. IF we were to get to the below position we are at least a week away from a cold setup , that takes us to February. 

That chart is from 18th Jan. Yes there is some support for a brief flattening of the pattern and small warm up mid month but as others have said, this is more likely to be a short term blip. Time will tell ofcourse, but we still have plenty to look forward to, including possible snow chances next week. 

[Methuselah]

53 minutes ago, Tim Bland said:

My toys are in my hand and they are ready to be launched ECM and GFS are both snowless (apart from the odd flurry) for 50% of the UK , and by day 10 it’s turning milder,  so we don’t even have FI to hold onto.  Quite ironic that the SSW us potentially killed out chances for anything before last 3rd of winter.  Very disappointing for those hopeful of a snowy mid winter. I know some localised areas have seen a bit of snow but the map below is quite representative of the areas that look likely to miss out on proper snow

I'm sure glad I've given up with those daft Day 10 Accumulation charts, Tim. I've also given up the hyperbolic steroids!

And, what's with all the 'optimistic/pessimistic' malarkey? Never once, in all my nearly 64 years, have I thought the weather depends on the way I feel...

Edited January 2, 2021 by General Cluster

[Weathizard]

7 minutes ago, Tim Bland said:

I agree, there could be a light dusting for some and very locally enough for a snow ball but the disappointment comes at the prospect of seeing a prolonged widespread snowy spell in the heart of winter and I just don’t see that happening now. IF we were to get to the below position we are at least a week away from a cold setup , that takes us to February. 

It’s a day 15 chart... if actuality looks anything like that I will eat my hat.

This is one of those occasions where stepping back and viewing anything the models show with a pinch of salt is needed, either way, otherwise we will end up driving ourselves up the wall.

It’s worth remembering how all model have a propensity for moving blocks too fast and the Atlantic blocking only starts waning as the models become more unreliable.

[MJB]

33 minutes ago, MATTWOLVES said:

SSW underway...yet some are getting anxious about this mornings runs again! We have a lot to look forward too..significant cold during final 3rd of the month would put in the Heart of winter..not the end like 2018..I think some are getting frustrated that they have yet to see falling snow,while others have already experienced it...let's face it how often does snow fall countrywide!  For the 3rd time this week,I'm witnessing falling snow...have a little patience...im sure many others will get there fix soon..Like I've said take all model output currently with a pinch of salt..there's alot going on.

Ultimately its the UKMO that remains rock solid and consistent,while the others flap about..

Hi Matt - I really enjoy your posts BUT no one ( including the pro's) can say with any confidence about cold at the end of the month .

We can't confirm what's going on in 144hrs so in 21 days is impossible , especially when we are relying on an SSW 

No dig , just my thoughts 

[swfc]

5 minutes ago, General Cluster said:

I'm sure glad I've given up with those daft Day 10 Accumulation charts, Tim. I've also given up the hyperbolic steroids!

And, what's with all the 'optimistic/pessimistic' malarkey? Never once, in all my nearly 64 years, have I thought the weather depends on the way I feel...

Happy New GC and yes given the current pandemic ete slightly irrelevent to most people in the busy real world. Enjoy anyway, whatever the weather brings

[Battleground Snow]

Ensembles show a less pronounced rise in temps towards the end compared to 00z. A few colder options in the scatter.

 

Edited January 2, 2021 by Battleground Snow

[johnholmes]

Just to add the Met O official comments on SSW (Sudden Stratospheric Warming) as I think it might help folk new to this forum and this phenomena and also add possibly cause a touch of reality to what and when surface events may occur once an SSW has occurred?

Sudden Stratospheric Warming

WWW.METOFFICE.GOV.UK

---

Sudden stratospheric warming describes an event when rapid warming occurs high up in the stratosphere. However, it can lead to changes in our weather at the surface.

 

[MATTWOLVES 3]

6 minutes ago, MJB said:

Hi Matt - I really enjoy your posts BUT no one ( including the pro's) can say with any confidence about cold at the end of the month .

We can't confirm what's going on in 144hrs so in 21 days is impossible , especially when we are relying on an SSW 

No dig , just my thoughts 

Yes mate I agree..every 2 in 3 SSW events deliver cold...thats something like 66% chance..nothing is 100%.. But something is different about this winter..The Northern Hemisphere looks primed.. But let's not forget even in significant cold and snow outbreaks,some parts of the UK will still miss out. Was also the case in 2018...Hopefully this one delivers more widespread..But yes take all model interpretation with much trepidation while major things get underway...there could be some wild output this time next week.

Edited January 2, 2021 by MATTWOLVES

[Matt H]

No need to panic everyone, the trusty NASA model is here to rescue us as it doesn’t flatten the pattern beyond t144.

I wish it was a good model sometimes.

[johnholmes]

5 minutes ago, johnholmes said:

Just to add the Met O official comments on SSW (Sudden Stratospheric Warming) as I think it might help folk new to this forum and this phenomena and also add possibly cause a touch of reality to what and when surface events may occur once an SSW has occurred?

Sudden Stratospheric Warming

WWW.METOFFICE.GOV.UK

---

Sudden stratospheric warming describes an event when rapid warming occurs high up in the stratosphere. However, it can lead to changes in our weather at the surface.

 

I feel that this is also relevant in the model thread from UK Met, fairly recently about the SSW

Opposing forces battle for winter supremacy

Posted on 30 December, 2020 by Met Office Press Office

The second half of December has seen dramatic swings between different weather patterns. Storm Bella brought strong winds and flooding, while the current flow of air from the north is bringing colder conditions with ice and some snow across the UK. With dramatic changes in weather over the last two weeks, what is the pattern for the first half of January?

We expect the northerly feel to continue into the new year, however, as we look further ahead there are currently conflicting meteorological signals. To gain an understanding of the longer-term outlook forecasters need to look at signals from around the globe.

Adam Scaife, Head of Met Office long-range prediction, said: “Our latest forecasts now show that a sudden stratospheric warming (SSW) is expected in the first week of January which will maintain the chances of colder weather throughout the coming month.

“During an SSW intense warming occurs high in the atmosphere at around 30km above the North Pole. This is accompanied by a complete reversal of the winds that circulate around the Arctic at high altitude and the mean wind direction switches from the usual strong winter westerlies to easterlies.

“The easterlies at high altitude then slowly burrow down towards the lower atmosphere where our weather occurs. This process increases the chances of colder weather right across Northern Europe for several weeks after the event first occurs high the stratosphere.”

Met Office Chief Meteorologist Paul Davies said: “It’s important to note that not all SSWs lead to colder-than-normal conditions over the UK and there are other global weather factors that can impact our winter weather. This year they include a La Nina.

“During La Nina the second half of the winter in the UK tends to be dominated by milder and wetter conditions which come from the Atlantic on an invigorated jet stream. In effect, we have two opposing forces for winter supremacy at play; the SSW and La Nina.

In the meantime, and consistent with a SSW in early January, our current 6-30 day forecast points to the  likelihood of the cold conditions experienced recently continuing through January.”

[johnholmes]

Just now, johnholmes said:

I feel that this is also relevant in the model thread from UK Met, fairly recently about the SSW

Opposing forces battle for winter supremacy

Posted on 30 December, 2020 by Met Office Press Office

The second half of December has seen dramatic swings between different weather patterns. Storm Bella brought strong winds and flooding, while the current flow of air from the north is bringing colder conditions with ice and some snow across the UK. With dramatic changes in weather over the last two weeks, what is the pattern for the first half of January?

We expect the northerly feel to continue into the new year, however, as we look further ahead there are currently conflicting meteorological signals. To gain an understanding of the longer-term outlook forecasters need to look at signals from around the globe.

Adam Scaife, Head of Met Office long-range prediction, said: “Our latest forecasts now show that a sudden stratospheric warming (SSW) is expected in the first week of January which will maintain the chances of colder weather throughout the coming month.

“During an SSW intense warming occurs high in the atmosphere at around 30km above the North Pole. This is accompanied by a complete reversal of the winds that circulate around the Arctic at high altitude and the mean wind direction switches from the usual strong winter westerlies to easterlies.

“The easterlies at high altitude then slowly burrow down towards the lower atmosphere where our weather occurs. This process increases the chances of colder weather right across Northern Europe for several weeks after the event first occurs high the stratosphere.”

Met Office Chief Meteorologist Paul Davies said: “It’s important to note that not all SSWs lead to colder-than-normal conditions over the UK and there are other global weather factors that can impact our winter weather. This year they include a La Nina.

“During La Nina the second half of the winter in the UK tends to be dominated by milder and wetter conditions which come from the Atlantic on an invigorated jet stream. In effect, we have two opposing forces for winter supremacy at play; the SSW and La Nina.

In the meantime, and consistent with a SSW in early January, our current 6-30 day forecast points to the  likelihood of the cold conditions experienced recently continuing through January.”

This seems to be UK Met's official stance on the time from an SSW to possibly affect European weather

The sudden stratospheric warming usually takes a few weeks to influence our weather at the surface, or into the next month.

[johnholmes]

Just now, johnholmes said:

This seems to be UK Met's official stance on the time from an SSW to possibly affect European weather

The sudden stratospheric warming usually takes a few weeks to influence our weather at the surface, or into the next month.

Just to add another item to the mix from my usual source, 500 mb anomaly charts!

The only current one is NOAA EC-GFS have not been issued this morning and the last two days they showed just the predicted contour lines (no bad thing in itself as far as I am concerned!)

Anyway this is the ltest NOAA 6-10 day and further out 8-14.

The 6-10, has returned to its meridional pattern, which it seemed to be less keen on for a couple of days. However, the 8-14 is sort of 50:50, meridional in the west of the chart but nor really in the eastern half. Like all models it is having difficulty in predicting more than a week to 10 days ahead. In my view it is the most reliable indicator we have free access to what the upper air pattern is likely to be in the 6-10 day time frame. That is 6-10 days from last evening.

Worth a look, and it perhaps fits with UK Met predictions.

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

 

 

[Tim Bland]

28 minutes ago, General Cluster said:

I'm sure glad I've given up with those daft Day 10 Accumulation charts, Tim. I've also given up the hyperbolic steroids!

And, what's with all the 'optimistic/pessimistic' malarkey? Never once, in all my nearly 64 years, have I thought the weather depends on the way I feel...

Haha yes, I need to give up on day 5+ I think never mind day 10! I think most on here are passionate about the weather and that’s why they invest so much time in it as a hobby. Watching and waiting for a cold spell for it to vanish is akin to a trainspotter driving miles to see a train only to find out it is cancelled, I’m just honest about how I feel I’m going to stay more opened minded though. It’s just the weather

[feb1991blizzard]

Chart of the day - still definitely holding hope for late January.

[Cuban Zebra]

34 minutes ago, Battleground Snow said:

Ensembles show a less pronounced rise in temps towards the end compared to 00z. A few colder options in the scatter.

 

As the pieces start to fall into place in the next 24-48 hours we’ll see this improve and steadily head downwards!

[chionomaniac]

I have had a good look at the strat charts this morning and there appears to be a lot of guesswork as to how the SSW may affect the trop.  All indications to me are that we have a good propagating event already in the early days after the SSW.

One would expect normally a flushing down of westerly winds to the trop and therefore an increase in a flatter trop pattern for a while. But to me this is just not happening. This is the picture as of yesterday:

We have the weakened residual positive u winds at the top to middle strat about to be crushed by the developing SSW. What is of particular interest here, is the fact that prior to the SSW, the middle to lower strat positive u winds are either very weak, or on the case of the troposphere, none existent. These (strong) lower strat winds would normally act as a barrier to propagation, or will be flushed down trop wards as the SSW takes hold. But as they are not present the SSW can propagate right down to the trop almost ‘unopposed’.

So by day10 we have this:

The whole polar field from strat top to trop bottom almost one complete negative anomaly. Not only is it likely that the quick propagation of the SSW will continue to deliver a more meridional NH trop pattern, but where cold is transported south to mid latitude areas the cold will likely be severe and long lasting. The effects of this SSW are likely to be felt for some time yet, probably til spring.

What we can’t be sure of yet is how we are likely to be affected, though early indications suggest a continuation of the winter pattern we have seen so far. But with cold reinforcements added in for good measure.

 

edit - just to explain that u winds are mean zonal mean winds at any given latitude and height.ie where when travelling around the earth at say 60°N and 10hPA height, the net winds are positive (westerly) or negative (easterly)

Edited January 2, 2021 by chionomaniac

[Catacol]

3 minutes ago, chionomaniac said:

I have had a good look at the strat charts this morning and there appears to be a lot of guesswork as to how the SSW may affect the trop.  All indications to me are that we have a good propagating event already in the early days after the SSW.

One would expect normally a flushing down of westerly winds to the trop and therefore an increase in a flatter trop pattern for a while. But to me this is just not happening. This is the picture as of yesterday:

We have the weakened residual positive u winds at the top to middle strat about to be crushed by the developing SSW. What is of particular interest here, is the fact that prior to the SSW, the middle to lower strat positive u winds are either very weak, or on the case of the troposphere, none existent. These (strong) lower strat winds would normally act as a barrier to propagation, or will be flushed down trop wards as the SSW takes hold. But as they are not present the SSW can propagate right down to the trop almost ‘unopposed’.

So by day10 we have this:

The whole polar field from strat top to trop bottom almost one complete negative anomaly. Not only is it likely that the quick propagation of the SSW will continue to deliver a more meridional NH trop pattern, but where cold is transported south to mid latitude areas the cold will likely be severe and long lasting. The effects of this SSW are likely to be felt for some time yet, probably til spring.

What we can’t be sure of yet is how we are likely to be affected, though early indications suggest a continuation of the winter pattern we have seen so far. But with cold reinforcements added in for good measure.

Excellent analysis Ed. Model runs are going to become very erratic I think as they try and get a handle on a fast moving and complex situation. Wow...a lot has happened in the last 10-14 days!