Model output discussion - into 2018

[nick sussex]

I think the issue is just the painfully slow process for the low to fill and sink away.

And the lack of energy heading se.  A weaker low has a better chance not this bloated bowling ball.

 

[SMU]

4 minutes ago, stewfox said:

 

12 Z    144                                                                              6z 144

   

12z 168                                                                        6z 168

 

Looks worse to my untrained eye what am i missing ?

All 3 of the 12s UKMO / GFS / GEM are a bit saggy on the eastern end of the block-

subsequently the cold is mixed out from the SE - not the best of runs considering the level playing field set up from the 00zeds especially the UKMO

More runs needed.

[Cheshire Freeze]

12 minutes ago, northwestsnow said:

Although i disagree with Karyo- i think the ukmo 144 is better than GFS,and more potential!

GFS144

UKMO144

Absolutely nothing wrong with that UKMO run going forward. Think there will be just enough residual heights left to the N upon the next low coming in to make things interesting. The GFS however at that time frame is nowhere near as good. 

[carinthian]

12 minutes ago, carinthian said:

The UKMO has the Low sinking SW like the GEM run. The exact source of air mass cannot yet be determined but GEM seems the best to tap into some lower temps. Still some time for the high to develop and colder uppers to get established,crucially into Scandi land.

C

Good grief, lots of doom and gloom on the other thread about the GFS run about sinking Scandinavian high and a crap mild January to take hold. Its not even formed yet and charts post 240t hardly verify anyway. One thing for sure plenty of rain about this coming week and even snow on the hills up north even before any sort of Easterly arrives. ECM will lift your spirits tonight !

 C

Edited December 31, 2017 by carinthian

[northwestsnow]

3 minutes ago, CreweCold said:

Absolutely nothing wrong with that UKMO run going forward. Think there will be just enough residual heights left to the N upon the next low coming in to make things interesting. The GFS however at that time frame is nowhere near as good. 

I think there are crucial differences between ukmo and gfs Crewe- seems me and thee are the only ones - as you say, the difference to our north is noticeable!

Edited December 31, 2017 by northwestsnow

[Dancerwithwings]

There are differences between the big three including the GEM at 144h, but who cares at least it's not Atlantic driven and things are changing/evolving on every run.

Lets see what the ECM brings us next   

Edited December 31, 2017 by Dancerwithwings

[swfc]

Im struggling to see the problem regarding the gfs 6Z and oz.there is a rise in pressure towards Scandinavia back end of next week

It brings in a slack easterly with average 850s then looking at the models the northern arm of the jet pushes threw.barring details "if it happens" not much else to say really. If you're looking for snow and biting cold its not there . looking nw may bring in 850s cold enough for wintry conditions

 

[Daniel*]

I like UKMO a lot at 144 I wouldn’t call it poor in the slightest okay a slower evolution than we may have hoped but it looks set to get there it’s better than GFS no doubt. 

[nick sussex]

Any phasing of energy between the upstream trough and the limpet one near the UK before enough energy has slipped se will pull the limpet back north again .

Thats why it’s key that low heights develop further to the se , low heights to the sw of the UK is asking for trouble.

As Steve says too much sag to the east of the high , the high needs to be aligned ne/sw not nw/se.

 

[Polar Maritime]

Which leaves a week for minor adjustments expected at this range, Interesting model watching over the coming days.. Hope everyone enjoys there NYE whatever plans you may have.

Edited December 31, 2017 by Polar Maritime

[Jason M]

21 minutes ago, northwestsnow said:

Agreed.

12Zs are tripe.

Would imagine a sharp u-turn from Exeter tomorrow, cant help but feel whatever can go wrong does go wrong.

This time its the limpet low...

Must admit that I was surprised by the phrase 'very cold' as its just not supported in what we are seeing. I accept of course that they have more data and expertise but if we were missing something here i'd have expected to see some movement in the 12z suites. Lets see what the GEFS and ECM throw out. Personally I think the GFS opp has been well represented in recent GEFS suites so isn't a great surprise. The 'notable cold' option has always been in the minority (maybe 15-25%).

Maybe we just read too much into the wording of METO updates.  

 

[bobbydog]

on a positive note, if we're going to have to play the 'long game', the 12z pushes the PV over our side of the hemisphere. something we want to see for a major pattern change.

[northwestsnow]

1 minute ago, bobbydog said:

on a positive note, if we're going to have to play the 'long game', the 12z pushes the PV over our side of the hemisphere. something we want to see for a major pattern change.

Haha Hope so Bobby, i'm sick to my back teeth of seeing blues and purples to our North west, winter after winter..

[snowray]

Much better control run from the GFS. All eyes on this evenings ECM.

 

Happy new year everyone.

[Mucka]

24 minutes ago, nick sussex said:

I think the issue is just the painfully slow process for the low to fill and sink away.

And the lack of energy heading se.  A weaker low has a better chance not this bloated bowling ball.

 

Although the Op output has not been that encouraging this afternoon, the GEFS are at least a little better..

They sink the low into Western/Central Europe, have a better orientation of high pressure to bring in cold uppers, and generally a stronger block than the 06z set.

As Steve says, there are no real trends emerging in the output as yet to determine which way this is going, just run to run variability.

I am still waiting for a few consecutive ensemble sets to point the way but at the moment it really is a case of more runs needed.

Edited December 31, 2017 by Mucka

[Frosty.]

Too much analysing / scrutinizing every op  run..have more faith in what the experts are saying, less stressful!..fingers crossed it all works out regarding another burst of wintry weather..more runs needed etc..!

[Paceyboy]

I like watching the development of eaterlies. We do not want to see the perfect easterly modelled at that range as it would just lead to disappointment on here (somebody on this forum said this but not sure who so I wont guess and take the credit from the person if I am wrong)

The interest in this evolution lies in its development and over the years in these scenarios low pressure placement and strength of high pressure over scandivia/NNE of us is what determines the depth of cold. Put it this way there is alot more to this scandi high than was modelled two days ago already. Now that we are reaching timescales of 144-200h where it resides currently, it will either sink and we will know it will sink or it can upgrade and strengthen heights.

Personally i cant really recall many instances, short time a decade - I know, when easterlies were just restricted to Scotland. On many if not most occasions everything moves south closer to the time, obviously we do not want this to the extreme as the high will sink.

If the cold hits us it could only be a 3 day event, currently shown on more favourable runs but the interest lies in potential upgrades or more of a drawn out battleground instead of short sharp cold snap that is over and will set us back another week until another chance arises.

Edited December 31, 2017 by Paceyboy

[Decemberof2010]

I will take pert 11 thank you

[Tamara]

Just relatively briefly from me simply to wish members a Happy New Year

For what little it is worth, I would repeat the mantra I always used to suggest, and advise keeping some powder back in terms of too much intra suite NWP analysis - with some way to go with this upcoming evolution.    Tropical forcing is coming back into being with the MJO heading into and programmed to head through the Indian Ocean and impacting AAM tendency upwards again. In simplest layperson terms, this sequence is pivotal to how much amplification flux there is downstream to create any meaningful chance of cold air advection from the NE in the further outlook.

But a reminder of that Phase 4 Global Wind Oscillation which shows the possible prize.

Its a case of can we properly get there and if so how long can it hold?   Failure returns the pattern back to similar to what we currently have with Canadian vortex domination and downstream cyclonic cold rain and wind (and occasional snow away from the south and chiefly at northern altitude).

To part with: Composites need careful reading between the lines in terms of interpretation as much as NWP interpretations of signals. But the GWO doesn't lie whatever phase it passes through.

Edited December 31, 2017 by Tamara

[snowray]

Big improvement with the GFS ensembles, some very cold members now turning up from D6 onwards.

 

London & Manchester.

Edited December 31, 2017 by snowray

[lassie23]

2 hours ago, Bring Back1962-63 said:

TIME FOR ANOTHER THOROUGH CROSS-MODEL ANALYSIS

With a “possible” easterly appearing in most of the model output for about one week away, I promised in my short post last night (on page 9) that I would produce one of my long reports focusing on Eurasian current and predicted upper and surface temperatures as well as snow cover analysis. I have already started on that and I will complete it either later this year or early next year (ie: either late this evening or early tomorrow morning)! I hope to provide a better idea of just how cold a potential easterly is likely to be.

In the meantime, I want to "attempt" to assess whether this cold(er) interlude will be transient or longer lasting. I shall start with one of my cross-model analyses focusing on what appears to be the critical period around day 7. I shall use the 0z runs for most of the models and the 6z for those that produce these (they’re rolling out while I’m writing this part of my post but I'll be working on it for another 3 to 4 hours yet!).  As UKMO only goes up to D6 with its "full view" charts, I shall provide some additional focus on this model first of all:

UKMO T+144 Europe1 view   UKMO T+144 Europe2 view   UKMO T+144 "N. Hem." view   UKMO T+168 "SW Atlantic" view           

                                           

I shall make two general points here. Firstly, I have often said that when one is considering the broader pattern, it's essential to look upstream using the widest possible view charts available. The Northern Hemisphere view charts provides the whole Arctic profile and down to the middle latitudes and beyond. The Europe view charts come into their own for assessing the finer detail. On this occasion when we are looking north-east, I've also included the Europe 2 view chart as that goes further into Russia. It's amazing how these slightly different viewing angles can give quite a different impression. That leads me on to my second point, the restricted view chart for the south-western Atlantic which barely shows the UK. Yes, these T+168 charts have their uses but we must view them with extreme caution, especially when we are looking more to our north or east. I agree with @johnholmes - it's not one's eye sight that is being challenged (as per his slightly tongue in cheek comment) but rather one's imagination! It's fine to speculate but let's put this into its proper context and compare all the these charts now. The T+144s have that deep LP centred over the Irish Sea. During the previous 24 hours it has been drifting south-east and is slowly filling - I also show the D5 charts to demonstrate this (you'll need to move back and forth to compare the D5 and D6 charts for each view):

UKMO T+120 Europe1 view   UKMO T+120 Europe2 view   UKMO T+120 "N. Hem." view 

                          

Looking at the D5 Europe 1 view chart, the ridge of HP extends from Greenland towards Scandinavia and by D6 there "appears" to be a cut-off HP centred over and just to the north of Iceland. On the Europe 2 view chart, we can see that this HP is still part of a broader belt of HP extending from the Greenland region. This chart also shows that there is a strong area of HP over central and northern Russia which, at this stage, looks fairly stationery and showing signs of ridging south-westwards - how different that is from the Europe 1 view!. Now, if we move onto the northern hemisphere view charts, a lot more is revealed. At D5 the belt of HP to the north extends from western Scandinavia, through Greenland and all the way across to north-east Canada. The Russian HP is a vast area of HP which extends through all of southern and central Russia, northern and central Asia and through to northern China. This HP is little changed by D6 but it does appear that the two areas of HP are just about to link up through Scandinavia building through the weakening LP there. Perhaps very significantly, there is now another belt of HP ridging across the Arctic from the north-east Pacific and western Alaska. The PV is once again being disrupted and is not particularly strong. 

Right, let's bring in the other models for day 7 with times adjusted to show the charts for 0100 on January 7th (only northern hemisphere view from now on: 

         ECM  0z T+168                       GFS 6z T+162                        GEM  0z T+168                    NAVGEM 6z T+162     

                  

The ECM takes a rather different route by ridging the Azores HP north-eastwards into Scandinavia. The LP is weaker and further south and centred over north-west France with a fairly slack short fetch east-north-easterly pushing across the UK. At this stage it looks like the HP over Scandinavia is attempting to ridge further north-eastwards towards the large belt of HP over Russia/Asia. What catches my attention is the powerful renewed push of WAA and build of HP back into the Arctic from the Alaskan side. This could either be set to ridge across to the Russian HP or down through Greenland towards Iceland and might secure a stronger and more permanent block of HP towards Scandinavia. I'm not showing the later charts in this post but I will outline each model's evolution. ECM do take the latter route which does look very encouraging for coldies. The Arctic profile looks thoroughly disrupted again which, if this continues, could well lead to a greater chance of an extended cold spell (or one with only brief less cold interludes). Much still depends upon the strength of the PV and whether the stratosphere finally manages to couple properly with the troposphere - on this occasion this will NOT be good for coldies for at least the rest of January (please refer to my last few posts for the reasons). 

I know that the GFS 6z is a little different to its 0z run in the middle and extended periods. The 6z is pretty simiIar to the ECM 0z at D7 but the HP to our north is a little stronger and showing signs of ridging northwards into the Arctic, perhaps set to link up with the HP up there. The Russian HP is also slightly stronger and a little further north and looking set to ridge into the Arctic too. I like that "three-pronged" attack on the Arctic which "should" (depending on the factors that I just stated) be very encouraging further forward. I had a sneak preview of what the GFS operational runs has in mind and it almost gets to a great position, prolonging the Scandi HP for a while but then strengthens the PV considerably on our side of the Arctic (I'll look at the GEFS ensemble suite shortly).          

The GEM shows slightly greater amplification with most of the HPs slightly stronger too. The LP is further south (over Spain) and the flow is more north-easterly. I really like how it evolves after D7. It builds and strengthens the Scandi HP with the flow veering more to a south-easterly (probably dry by then). There looks to be a classic battle zone forming shortly after D10 with an Atlantic LP trying to make inroads from the west. Whether this breaks down the block is not certain but "if" GEM is anywhere near close to the correct solution, the whole Arctic profile at D10, suggests that the main block will quickly re-establish with a return to cold conditions. It looks like the Scandi HP will build right through the Arctic. Coldies, "if" this occurred, we would all be delighted with outcome over the next few weeks!  (CAUTION: we cannot count on anything at this stage and the models are only just beginning to get a handle on this possible new evolution).

The NAVGEM also shows a quite strong HP to our north. The LP to our south may either be good or bad news. It would be close enough to produce precipitation (remember that I'm dealing with the temperature profiles in this evening's post, so I'll leave it to others to hunt for any possible snowfall) but it's possible that the flow around the LP could push some milder air into the flow from the south. The LP either needs to take on more of a negative tilt or slide away south-eastwards. Looking into the latter part of this run, NAVGEM build quite a strong HP over Scandi with an east-south-easterly flow over us. The position with the possible milder incursion from the south or any CAA from the east is still not fully resolved. This may only delay the arrival of more significant cold as the Arctic profile again looks primed for something even more interesting for coldies on this particular run. Not least because HP over the Pole is building steadily southwards and looks set to link with the Scandi HP forming a strong block. This is only one run and only at D7/8 (T+180).

 JMA Dec 30th 12z T+180       GEFS Control 6z T+162          GEFS Mean 6z T+162         GEFS  6z T+162 Ens Panel

                   

The JMA run is from yesterday's 12z. Again it has HP to our north-north-east but a little weaker at this stage. The LP is now to the east of us and we are under a fairly slack north-easterly flow.  The JMA does go on to develop a Scandi HP which then weakens to produce a battle zone and possibly a snowy breakdown before milder air arrives from the Atlantic. Once again, this is not all bad news, as this run also builds HP right through the Arctic and any less cold interlude would probably be pretty brief.

The GEFS control run is quite similar to the GFS operational run at T+162 on a macro scale but there are slight differences around the UK. The HP to our north is slightly further east into Scandinavia. The weak LP is over southern England rather than just to the south (possibly similar problems as for the NAVGEM, depending on how marginal any colder air is). By D10, the control run is even more progressive than the operational run in pushing the block away eastwards and replacing it with another Polar Maritime west-north-westerly flow. Then the control backs the flow even more quickly to south of west by D12. By D16 both runs end with a pretty mobile pattern but the control once again has a Polar Maritime west-north-westerly flow and the Operational a milder west-south-westerly flow. The control run does end up with far more WAA pumping back into the Arctic.           

The GEFS mean can be misleading as it averages out all 20 of the ensembles, plus the control run and the GFS operational run and needs to be examined with caution. The mean does show up all the areas of HP surprisingly well at D7.  There's a Scandi HP of sorts and an Arctic HP close to the Pole and further HP from Alaska ridging towards an even stronger Russian HP. The mean does also suggest a return to an Atlantic flow towards the end of this run but pretty strong HP is maintained right across the Arctic. This should provide us with an interesting set of ensemble members!

The GEFS  6z Panel with the ensemble suite at T+162 does indeed show a fascinating spread of almost entirely cold(er) patterns (or in the process of turning colder). Of the 20 members, 14 show a Scandi HP of sorts (some well developed). 5 show an Arctic HP to our north. Just one is less progressive with the Azores HP ridging north-eastwards across the UK and towards Scandinavia. 8 show an easterly of sorts (none are long fetch at this stage). 4 have north-easterlies, 1 south-easterly, 5 are cyclonic with the LP right over us , 1 has a col over us and 1 HP right over us.

By the end of the GEFS run we have a real ensemble mixture, probably a little more typical of the unreliable period. Some of these clusters overlap. There are still 5 Scandi HPs of sorts but "no" proper easterlies at that stage. 5 more have HP close to us or to the north. 2 have us under a cold cyclonic flow. There are 5 north-westerlies with cold Polar Maritime air over us, 3 with probably rather cold westerlies and 5 with less cold more south-westerly flows (but no really mild long fetch south-westerlies). The Arctic profile continues to offer a great deal of interest for later on. There are 4 cut-off Arctic HPs. There are 9 with varying degrees of either strong PV disruption, some at least halfway to splitting again plus a few others with highly unusual patterns. 

Overall, the period around next weekend and beyond will be truly essential model watching for coldies and the unusual patterns may even be of interest to a few of those from a less cold persuasion! With almost all the models showing a Scandi HP of sorts in the mid-term, the detail needs to be nailed during the next few days. Then, we need to focus on the period just beyond that (I'll probably look at D10 output early next week), to see if the colder spell can become entrenched or whether it proves to be transient. This post is already too long for me to include the jet stream variabilities but these charts should help to build the general picture. Then finally, for me most importantly, I want to see what happens around mid-January. Will the PV strengthen or will it remain in a very disrupted state? This will be at least one of the determining factors for later this month and as we move into February.

That's it for now. I'll be back with that Eurasian temperature report much later tonight but I need a break right now!

 

 

Thanks for your time and effort you put into your posts, much appreciated

[tight isobar]

4 minutes ago, snowray said:

Big improvement with the GFS ensembles, some very cold members now turning up from D6 onwards.

 

London & Manchester.

Thats a cracking set of ens.....

?

[Man With Beard]

6 minutes ago, Tamara said:

Just relatively briefly from me simply to wish members a Happy New Year

For what little it is worth, I would repeat the mantra I always used to suggest, and advise keeping some powder back in terms of too much intra suite NWP analysis - with some way to go with this upcoming evolution.    Tropical forcing is coming back into being with the MJO heading into and programmed to head through the Indian Ocean and impacting AAM tendency upwards again. In simplest layperson terms, this sequence is pivotal to how much amplification flux there is downstream to create any meaningful chance of cold air advection from the NE in the further outlook.

But a reminder of that Phase 4 Global Wind Oscillation which shows the possible prize.

Its a case of can we properly get there and if so how long can it hold?   Failure returns the pattern back to similar to what we currently have with Canadian vortex domination and downstream cyclonic cold rain and wind (and occasional snow away from the south and chiefly at northern altitude).

To part with: Composites need careful reading between the lines in terms of interpretation as much as NWP interpretations of signals. But the GWO doesn't lie whatever phase it passes through.

Great to see you back posting, thought we had lost you

The composite chart looks a lot like many of the GEFS ensembles tonight at T192.

On those GEFS members at T192, it's of course a slightly insane thing to try to pin exact details on such a pattern even 6 days out, but these ensembles make me even more hopeful of a classic Atlantic low/Scandi high standoff where the two meet head-on.

[syed2878]

im sure the met would go thru all the data before they make the current foorecast. after all they do have lot mor data than we have folks.  A very happy new year every one.

[Frosty.]

6 minutes ago, tight isobar said:

Thats a cracking set of ens.....

?

Agreed, the ens  look great..just highlights why there shouldn't be such a knee jerk reaction to every individual op run..I'm positive about our chances of another wintry period on the way!!

 

Edited December 31, 2017 by Frosty.