Model output discussion - into 2018

[Ali1977]

4 minutes ago, Malcolm Edwards said:

Off topic but have just notice 154 mph gust in farnborough?is this correct on xc weather?

 

It would be a news headline if true, and probably cause some bad damage etc - so no!! 

[phil nw.]

20 minutes ago, bluearmy said:

They have mogreps which will put the eps into more perspective. the two clusters away from the op one were more amplified and would therefore advect more cold. no one should be surprised about showers being of snow in January when it's cold! 

we can only interpret what we have access to - as has been said already, no one knows how this will play out but the trend is one of the ridge not bringing notable cold to the uk. However, this could easily reverse as small differences around day 5/6 will have larger consequences later on. With blocking set ups, the orientation of the blocking is everything for our small island. 

Yes pretty much how i see the ens BA.The later clusters in the last runs only reflect the current expectations that the wedge will give way with the heights holding just too far east afterwards.A small adjustment to the jet flow early on of course will change next week's pattern for the UK.

It should be said it's still looking colder in week 2 though whatever local synoptics evolve-as the ens 2m temp.graphs show -particularly further north the location.

Aberdeen gefs                                           Warks.gefs                                                        London combined 

The ens.at least have been consistent on this one aspect of a colder trend from next weekend.

[northwestsnow]

Well lets hope the 12z runs reflect the meto update as i cannot find any model showing 850s cold enough to produce snow by next friday, possibly the far north of scotland, at a push.

Fingers crossed for upgrades!!

[OfficialKevWX]

Remember the snow event on December 10th had quite high uppers and produced lots of snow..

[johnholmes]

15 minutes ago, Malcolm Edwards said:

Off topic but have just notice 154 mph gust in farnborough?is this correct on xc weather?

 

Not even in Kmph 

[A Frayed Knot]

[danm]

3 minutes ago, OfficialKevWX said:

Remember the snow event on December 10th had quite high uppers and produced lots of snow..

True, however if we want showers of snow from an easterly, the uppers matter more than they do in a battleground scenario. 

[Dennis]

first ideas later next week winter2018

[ACCOUNT DELETED]

17 minutes ago, Malcolm Edwards said:

Off topic but have just notice 154 mph gust in farnborough?is this correct on xc weather?

 

I see what you mean, very strange how that's showing, I know there's real squally showers with thunder in Weymouth earlier moving NE but that seems way too extreme. 

[lassie23]

23 minutes ago, Malcolm Edwards said:

Off topic but have just notice 154 mph gust in farnborough?is this correct on xc weather?

 

Wouldn't that send wheelie bins into the stratosphere?

[Frosty.]

Good news is it looks like turning a lot colder towards the end of next week from the north and lasting into the early part of week 2 with an increasing chance of snow..I would happily take that as things stand!!

Edited December 31, 2017 by Frosty.

[ACCOUNT DELETED]

31 minutes ago, Malcolm Edwards said:

Off topic but have just notice 154 mph gust in farnborough?is this correct on xc weather?

 

Met Office obs last 24 hours shows nothing like that lol, it must be an error 

[Paul]

Special new year resolution request

If you feel the need to start your post with 'Off topic but...' (or similar), please don't post it in here.

Thank you, and happy new year!

[comet]

1 hour ago, booferking said:

Metoffice update going with it's on model very cold later next week & snow.

It will be very interesting to see which way this goes. The UKMO says yes while the ecm and gfs ops say no. I wonder if anyone can remember what year it was when the metoffice along with the ecm and gfs were calling for an easterly but the ukmo model stubbornly refused to climb aboard. After several days the met and the other two models bowed to the ukmo model. This time things are reversed with the ukmo model and again the met more gun-ho for a colder more wintry east/north easterly and the ecm, gfs against. Whats the betting this time the UKMO model will be wrong this time that is the sort of luck us coldies in the UK have.

[feb1991blizzard]

There was another wind chart in the October storm showing 170mph gusts and the whole country plastered in 70-90mph with a good few over 100, Wolverhampton was 83mph, now if that happened in a densely populated city, trust me you would have heard about it on the news - its 8I_ILL5H1+ data.

[bluearmy]

7 minutes ago, comet said:

It will be very interesting to see which way this goes. The UKMO says yes while the ecm and gfs ops say no. I wonder if anyone can remember what year it was when the metoffice along with the ecm and gfs were calling for an easterly but the ukmo model stubbornly refused to climb aboard. After several days the met and the other two models bowed to the ukmo model. This time things are reversed with the ukmo model and again the met more gun-ho for a colder more wintry east/north easterly and the ecm, gfs against. Whats the betting this time the UKMO model will be wrong this time that is the sort of luck us coldies in the UK have.

It was a few years ago - I recall some people saying sunspot activity was responsible for the collapse if  it's the one I'm thinking of

of course we aren't that close yet as ukmo only just in range of the ridge 

Edited December 31, 2017 by bluearmy

[Guest]

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!

 

 

Edited December 31, 2017 by Guest
Correct typos and check charts

[Frosty.]

I'm already looking forward to posting the wet bulb charts as the much colder wintry weather arrives towards the end of next week into week 2 with increasing snow risk...Happy New year y'all

Edited December 31, 2017 by Frosty.

[feb1991blizzard]

15 minutes ago, bluearmy said:

It was a few years ago - I recall some people saying sunspot activity was responsible for the collapse if  it's the one I'm thinking of

of course we aren't that close yet as ukmo only just in range of the ridge 

I think it was Dec 2012 - THAT ECM, but the one thing I remember about that, is the misconception that the Met Office were on board, they were on board for a much more watered down version and their update never ever reflected some of the extreme model output that was being emitted.

[Malcolm Edwards]

29 minutes ago, Paul said:

Special new year resolution request

If you feel the need to start your post with 'Off topic but...' (or similar), please don't post it in here.

Thank you, and happy new year!

Ok sorry for that. Happy new year to all.

 

[Chesil View]

Just now, Frosty. said:

I'm already looking forward to posting the wet bulb charts as the much colder wintry weather arrives towards the end of next week into week 2 with increasing snow risk...Happy New year y'all

yes Frosty I look forward to that. With all the rain down here during the coming week our bulbs will definitely be wet.

Happy new year.

[SMU]

1 hour ago, beng said:

Are you thinking of pressure dropping towards E Europe/Germany (lower than currently modelled) with the pressure build near Scandi which will then send more cold West - assuming the models are right about the pressure rise to begin with?

We've seen this before with this kind of setup.

Yes ( & for all watching the 12z )

This is the area to watch for a cleaner flow - ( & of course higher pressure over Iceland )

 

Notice the kink over Norway that’s essentially blocking the core of the cold coming westwards on the GFS

look around T126 for a better flow

also 06z was Lowish on data ( lowest run since Xmas day )

S

Edited December 31, 2017 by Steve Murr

[Mucka]

I think it is fair to say the models are continuing to firm up a briefer settled and cold spell second week of Jan.

But that said I'm not seeing much beyond run to run variability but the next 24/48h output should allow us to get a better idea of how long we can stretch out any cold.

It is true that the models underplay Scandi blocking, especially where there is a wall of very cold air just to the East of the UK but currently this doesn't look like a classic set up to me.

That may change of course and if we can get blocking a little further North and better orientated to get a block of frigid air further West across the UK and into the continent then so we are likely to see Atlantic lows disrupt and energy split with undercut to sustain the block.

That still seems a less favoured option but even if the block is not so resilient the potential for snow even to low levels, more especially the North, for a time is high.

Best guess so far is a few days of a wintry mix before the Atlantic gets back in but as said, the next 24/48h should tell us if anything more substantial is possible.

[comet]

18 minutes ago, feb1991blizzard said:

I think it was Dec 2012 - THAT ECM, but the one thing I remember about that, is the misconception that the Met Office were on board, they were on board for a much more watered down version and their update never ever reflected some of the extreme model output that was being emitted.

Cheers for the reply yourself and Bluearmy  but it was not that long ago and I am sure it was in January. I think I will trawl the archive charts to see they jog my memory.

[Johnp]

1 hour ago, Malcolm Edwards said:

Off topic but have just notice 154 mph gust in farnborough?is this correct on xc weather?

 

I'm in Farnborough and an almighty squall line passed through. I'd not be surprised at 60mph+ gusts but not that bad!