Model output discussion - Jan 3rd onwards

[Battleground Snow]

2 minutes ago, WINTRY WALES said:

Has there ever been periods where the US and us in the UK are in a cold (very cold) , snowy weather for lengthy periods of time??

Yes, attached. Probably more rare in recent times.

[Chesil View]

1 minute ago, WINTRY WALES said:

Has there ever been periods where the US and us in the UK are in a cold (very cold) , snowy period for lengthy periods??

yes plenty lots of the wintry spells of the 70's and 80's saw  deep cold and snow in both the US and the UK.

[IDO]

The ecm ens 12z suggests the op is a statistical outlier as early as d6-7:

The above is for London and keeps the mean around 1-2c below-average to average post d4. Models are struggling with the finer detail within the bigger picture and so the ecm op is probably one to be wary of as for specifics on the ground.

[Cymro]

1 minute ago, WINTRY WALES said:

Has there ever been periods where the US and us in the UK are in a cold (very cold) , snowy period for lengthy periods??

Perhaps someone with deeper knowledge than myself can contribute here but correct me if I'm wrong, but December 2010 saw large snowstorms or North Easters in the USA at the same time as our record breaking cold weather. It is therefor incorrect to state that we are in the Cooker when the USA goes into the freezer. 

Likewise the USA is a large landmass and the British Isles are not so you could have frigid cold weather in the North Eastern States and mild in the central and western states. It's true that a cold USA can fire up the Jetstream keeping us milder than average, but it can also be, as is often the case here, due to strong northern blocking and heights in Greenland. 

So you can't simply state that American Cold = Western European Warmth. 

[Matt H]

23 minutes ago, syed2878 said:

 Fantastic and excellent post again tomorrow thank you it is refreshing to get a unbiased view for once in this forum I think there’s too many hopecasting 

The post from Tamara is brilliant but I don’t like the way you’ve just casually dismissed the posts from everyone else. There have been many excellent contributions from a range of individuals recently about the way forward (not from me of course) and it’s unfair to accuse them of hopecasting just because you disagree with them.

Also I think you’re confusing hopecasting with people just enjoying some of the model runs that deliver a colder set up as well.

[mb018538]

2 minutes ago, IDO said:

The ecm ens 12z suggests the op is a statistical outlier as early as d6-7:

The above is for London and keeps the mean around 1-2c below-average to average post d4. Models are struggling with the finer detail within the bigger picture and so the ecm op is probably one to be wary of as for specifics on the ground.

Outlier, but the general trend isn’t particularly cold either way (for now). I know a lot of people don’t have patience around here, but it might be wise to have some in the coming week or two. The deck is being reshuffled, and we’re waiting to see where the cards fall. Nina or SSW effects to drive the weather? Too early too tell.

[Earthshine]

Trending milder.  However, it's anyone's guess what will happen in the final 3rd of the month.  In my opinion (not particularly backed-up by anything, just a gut-feeling), I think we will see the impacts of the current SSW in around 2 weeks time (so around 20th or so).

[Windysun1]

12 minutes ago, WINTRY WALES said:

Has there ever been periods where the US and us in the UK are in a cold (very cold) , snowy weather for lengthy periods of time??

1947 i believe

[sebastiaan1973]

A colder cluster at the end of the plume of the north east of the Netherlands. A good sign

[johnholmes]

Unusual for me to post a NOAA 500 mb anomaly at this time of day but it needs to be assessed along with all other model outputs. Sure kicks a hole in my morning prediction, but no matter, its happened before and will again.

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

It keeps its idea of trough-ridges again on its 6-10 day chart, about the same depth/height and similar position, then goes on to do almost the same in its 8-14 day chart.

Normally this pair of charts from NOAA is about the nearest we get to an accurate idea of what the 500 mb contours are going to be in the 6-14 day period from issue, so 12-20 th Jamuary. I wonder, if it is correct, what any single day at 500 mb will actually look like and the weather at the surface for the UK?

[Scott Ingham]

29 minutes ago, syed2878 said:

 And yet scott the update from Exeter if you look or read it today doesn’t really be any good news to be honest more south-westerly in the extended forecast the colder for the north that tell me to an extent that this SSW would not be favourable for us here I hope I am wrong and we get to see the effects of the SSW in the model output soon. 

Less goos news the further south you are snowtastic the further north.

Very cold air from scandi bumping into low pressure moving up from the South. 

Id take that for long range considering were talking a couple of hundred miles from snow and rain and models cant work that boundary out at t-48

[MATTWOLVES 3]

There is spread in those eps tonight...the mean perhaps shows signs of wanting to go colder later...and a fair amount of those runs are quite cold..I can see this being a brief mild spell,with adjustments being made over the next few days as the cards get re delt.

[IDO]

Just now, mb018538 said:

Outlier, but the general trend isn’t particularly cold either way (for now). I know a lot of people don’t have patience around here, but it might be wise to have some in the coming week or two. The deck is being reshuffled, and we’re waiting to see where the cards fall. Nina or SSW effects to drive the weather? Too early too tell.

Agree, this has been well signposted as a transitional period whilst we await for the main action (hopefully), but the tendency for models to overdo the warming of the uppers is an interesting feature and to note for when it may matter in a better synoptic?

My interest in weather is more statistically based, on the models, their bias and trying to second guess them, so I am coming from a different direction to many on here!

 

[Scott Ingham]

5 minutes ago, johnholmes said:

Unusual for me to post a NOAA 500 mb anomaly at this time of day but it needs to be assessed along with all other model outputs. Sure kicks a hole in my morning prediction, but no matter, its happened before and will again.

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

It keeps its idea of trough-ridges again on its 6-10 day chart, about the same depth/height and similar position, then goes on to do almost the same in its 8-14 day chart.

Normally this pair of charts from NOAA is about the nearest we get to an accurate idea of what the 500 mb contours are going to be in the 6-14 day period from issue, so 12-20 th Jamuary. I wonder, if it is correct, what any single day at 500 mb will actually look like and the weather at the surface for the UK?

If someone put a gun to your head and asked you to hazard a guess?

@mushymanrob

Edited January 6, 2021 by Scott Ingham

[feb1991blizzard]

5 minutes ago, Scott Ingham said:

If someone put a gun to your head and asked you to hazard a guess?

@mushymanrob

mixture of dry and showery days with heaviest PPN in Northern UK, Dryer than average South. Perhaps some wintriness East coast if pattern amplifies a little.

Edited January 6, 2021 by feb1991blizzard

[TSNWK]

3 minutes ago, johnholmes said:

Unusual for me to post a NOAA 500 mb anomaly at this time of day but it needs to be assessed along with all other model outputs. Sure kicks a hole in my morning prediction, but no matter, its happened before and will again.

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

It keeps its idea of trough-ridges again on its 6-10 day chart, about the same depth/height and similar position, then goes on to do almost the same in its 8-14 day chart.

Normally this pair of charts from NOAA is about the nearest we get to an accurate idea of what the 500 mb contours are going to be in the 6-14 day period from issue, so 12-20 th Jamuary. I wonder, if it is correct, what any single day at 500 mb will actually look like and the weather at the surface for the UK?

Thanks for this John.. if I recall part of your morning prediction was indicating no real sign of any deep cold.. I guess we can leave it like that for now...

[Griff]

5 minutes ago, MATTWOLVES said:

There is spread in those eps tonight...the mean perhaps shows signs of wanting to go colder later...and a fair amount of those runs are quite cold..I can see this being a brief mild spell,with adjustments being made over the next few days as the cards get re delt.

There have been hints across the various GFS runs and occasional ecm (unfairly in my opinion dubbed "phantoms") in the last few days... 

Certainly all to play for, for better or for worse. I love it! 

[mushymanrob]

9 minutes ago, johnholmes said:

Unusual for me to post a NOAA 500 mb anomaly at this time of day but it needs to be assessed along with all other model outputs. Sure kicks a hole in my morning prediction, but no matter, its happened before and will again.

Climate Prediction Center - 6-10 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

It keeps its idea of trough-ridges again on its 6-10 day chart, about the same depth/height and similar position, then goes on to do almost the same in its 8-14 day chart.

Normally this pair of charts from NOAA is about the nearest we get to an accurate idea of what the 500 mb contours are going to be in the 6-14 day period from issue, so 12-20 th Jamuary. I wonder, if it is correct, what any single day at 500 mb will actually look like and the weather at the surface for the UK?

Never ignore the voice of experience just because it might not say what you want them to say. 

Edited January 6, 2021 by mushymanrob

[Chesil View]

4 minutes ago, Scott Ingham said:

Less goos news the further south you are snowtastic the further north.

Very cold air from scandi bumping into low pressure moving up from the South. 

Id take that for long range considering were talking a couple of hundred miles from snow and rain and models cant work that boundary out at t-48

Quite e so Scott the modelling the Meto use at that range clearly sees the  UK as a possible battleground between cold and mild at that range probably along the lines of the gfs 06z earlier today. However that battleground could be any where from the Channel coast to the North of Scotland and more likely move between the two depending on the waxing and waning in strength of the competing forces.

If its anywhere near right it will make for some very interesting model watching and weather.

[mountain shadow]

4 minutes ago, TSNWK said:

Thanks for this John.. if I recall part of your morning prediction was indicating no real sign of any deep cold.. I guess we can leave it like that for now...

Yes. But he's saying this update means he doesn't really know now.

This update looks a lot more ridgy than the ops we've seen tonight.

Possible indications of upgrades to come?

[Scott Ingham]

6 minutes ago, TSNWK said:

Thanks for this John.. if I recall part of your morning prediction was indicating no real sign of any deep cold.. I guess we can leave it like that for now...

"Sure kicks a hole in my morning prediction. I think he means opposite

[stodge]

Evening all

First, thanks to everyone who enjoys my nightly ramblings on the medium to long term model output. I try to keep it light-headed and sometimes light-headed and while I enjoy snow, cold is where I'm at but when you see the writing on the wall for a cold spell, it merely starts the countdown to the next chase. Milder weather looks likely after the weekend and into next week but with interesting developments in the stratosphere could this be a blip before the cold returns? My money (and very nice money it is too) has been on an anticyclonic evolution but we need the HP somewhere interesting to draw in the frigid air rather than the benign and dull westerlies.

The route to very cold starts from very mild in my experience.

12Z GEM: T+120 takes us to Monday next week and the milder air is with us with a long ridge of HP from east of the Azores to south-western parts of the British isles. The LP which develops over Iceland is over Scandinavia delivering plenty of winter for them but the cold PM air flow looks like it will miss us and we have a benign drift from the WSW with a shallow but extensive Atlantic trough to the west and south west.  A shallow LP crosses the British isles but by T+180 there are signs of amplification with the Atlantic LP deepening and going nowhere allowing heights to rise in front of it meaning the HP over the north-west of Iberia ridging north over the British isles to weak heights forming to the north-east of Iceland. The mild or very mild regime very much in charge at this time.  Not much changes from there - the mild anticyclonic regime strengthen its grip with the HP moving slowly north and by T+240 extending a ridge to Iceland. A small LP extends east, then south-east into the northern North Sea and Scandinavia. Mild or very mild air (850s of +12) is briefly displaced from the north-west but any frigid air is well to the east at this time.

 

12Z GFS OP - a mild or very mild outlook from GEM which was the most bullish of the models last evening regarding the extent of the mild regime. On then to the Americans and the GFS OP - at T+120 some subtle differences from the GEM. The Atlantic is closer with a more progressive profile and the HP ridge weaker with the core further south. Cold air persists over southern England while milder air is spilling in from the west and north west.  The divergence intensifies as you might expect as we move on to T+180 - the HP is over or just to the south of the British isles with a slack or calm flow for many and a residual trough over Norway.  As we often see in these evolutions, it's colder in the south closest to the residual cold continental air and milder in the north and west. From there, the evolution is fascinating as the HP tries to build north to meet heights coming from the Pole - one lobe of LP gets through before, by T+240, the gap is closed. The air mass over the British Isles cools slightly with positive uppers confined to the far south-west.

12Z GFS Parallel - GFS OP very different to GEM and intriguing to say the least - I'll be fascinated to see where it goes further into FI. As for Parallel, it's also different as early as T+120 with the Atlantic trough phasing with the trough which is still over the Norwegian coast. The HP sends a weak ridge from the Azores over southern Britain. Still some -4 uppers over southern Britain at this time but it's getting a little milder further north. By T+180 it's looking like a complex and messy evolution. The HP is trying to build north through the British Isles while the Atlantic LP systems are going nowhere slowly far to the west and the trough remains over Scandinavia. By this time, colder air is restricted to northern and north-eastern parts of the British isles with milder air further south and west. The complexity continues from T+180 with heights to the far north becoming more evident pushing the trough to the south and aligning it negatively as the HP recedes so a more unsettled evolution by T+240.  Cooler air spilling east with frigid air (-20 uppers) over Finland.

12Z ECM - again, another very different evolution with the whole evening screaming confusion and uncertainty even as early as T+120. Once again, T+120 looks different - the Scandinavian LP is further south and close to the south western coast of Norway with a weak ridge extending south from Greenland. Mild W'ly winds over most of the British Isles with the HP centred west of Biscay. Moving on and while t looks briefly as though the Atlantic will take charge, by T+192, the HP is over Iberia and heights remain to the north with a ridge from the HP. It's generally mild over the British Isles at this time with a feed of cooler air into the north-west. By T+240, however, the Atlantic re-asserts with the trough aligned positively and a long-fetch SW'ly air flow. Milder air hasn't quite arrived but is approaching.

A disappointing end to the ECM but on a night of confusion in the models should I be surprised it's a case of "safety first"? Looking further ahead and with even more buckets of salt than usual, the T+312 and T+384 charts from the GFS OP and Parallel runs respectively.

As alike as two dissimilar things in a pod - one is mild and the other isn't.

Looking elsewhere, 12Z Control is completely different, mild for the most part but at the end of FI turning colder and stormy from the north with some very cold air moving in.

On to the 10 HPA charts and Control has another strong warming after mid month which further weakens the stratosphere. The FI warming is even more marked on the OP run but is much more muted on the Parallel.

Conclusion: There was a popular series on Radio4 called "I'm Sorry I Haven't A Clue" and that's where I am tonight. GEM is bullish about a mild evolution but GFS much less so and ECM somewhere in the middle. FI is probably T+96 onwards but a couple of thoughts.  The trend is for heights to try to push north from Iberia to link with heights coming south from the Pole. For now, the Atlantic seems to have too much energy to make it happen but the Atlantic is sluggish and propping up all this is both the weak PV and the frigid air to the east which is acting as a block in its own right. For now, the Scandinavian trough holds sway but it's possible we could see heights develop in time which would be fascinating. Those who argue the PV split/displacement is causing issues with the modelling have a point and it's difficult to be definite about the medium to longer term evolution tonight.

 

[Scott Ingham]

6 minutes ago, mushymanrob said:

Never ignore the voice of experience just because it might not say what you want them to say. 

Is he not saying theyve changed for the better tho mushy if you read his first line

[Scott Ingham]

10 minutes ago, feb1991blizzard said:

mixture of dry and showery days with heaviest PPN in Northern UK, Dryer than average South. Perhaps some wintriness East coast if pattern amplifies a little.

You think? 

Have you seen the 8-14?

Looks like signs of an omega block starting

[Scott Ingham]

7 minutes ago, Broadmayne blizzard said:

Quite e so Scott the modelling the Meto use at that range clearly sees the  UK as a possible battleground between cold and mild at that range probably along the lines of the gfs 06z earlier today. However that battleground could be any where from the Channel coast to the North of Scotland and more likely move between the two depending on the waxing and waning in strength of the competing forces.

If its anywhere near right it will make for some very interesting model watching and weather.

Yes!

My contact in the met mentioned as much yesterday morning.

They are 50/50 but if on the right side of cold it could get VERY interesting