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Paul

Model output discussion - into 2018

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1 minute ago, Man With Beard said:

I would suggest both GFS and UKMO are in good positions by T144. Negative tilt on both - could well lead to an undercut (I appreciate the GFS may not actually show that in later frames, what I am saying is that it is in a good position to do that from here with a little nudge on the pattern)

UW144-21.GIF?04-17  gfs-0-144.png?12

I would like more models to develop the low SE of the high. If the ECM does it there could be some spectacular scenes later in the run.

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This is a all set up for us to miss out on the easterly only for the models to then start showing the "missing" deep cold start dropping into Europe!!

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14 minutes ago, mulzy said:

Jet not very well profiled out to the west though, if it was more NW/SE oriented then certainly something to keep an eye on.

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3 minutes ago, Mucka said:

Lest we forget. 

ECM 2 days ago V today's UKMO

ECM1-192.GIF?12UW144-21.GIF?04-17

GFS 2 days ago V today's UKMO.

gfs-0-192.png?12UW144-21.GIF?04-17

 

 

OK you make good sense - but the UKMO may actually be wrong, of course!

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Just now, Man With Beard said:

OK you make good sense - but the UKMO may actually be wrong, of course!

Ah, I didn't think of that! :pardon:

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Even if we don't get the easterly with snow we'll have chance as weather fronts push in from the west I remember back 2013 we had lot of snow in southern England..

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UKMO 144 looks very evenly poised IMHO-

Can that flimsy looking high cell  over scandy force the jet into Europe?

Hope so!!

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6 minutes ago, northwestsnow said:

UKMO 144 looks very evenly poised IMHO-

Can that flimsy looking high cell  over scandy force the jet into Europe?

Hope so!!

I really think this will happen - it may take a few bites of the cherry though!

Edited by mulzy

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WHERE DO WE GO FROM HERE?

In this post, I want to very briefly review the short to medium term period and then I will look slightly further ahead. I am very busy, so I will not have time for one of my thorough cross-model analyses and anyway, there has been a far larger number of posts than usual examining the model output (can’t think why!). I will take another look at northern hemisphere temperatures again (some much better news here for us going forward). It’s a month since I last updated my Arctic ice and temperature indicators, so I’ll do this now and we have the very latest monthly Arctic report released yesterday (more very bad news here). Despite all this, I will be painting a much more optimistic picture for later this month.

SHORT OVERVIEW ON THE UPCOMING COLD SPELL:

Those that have been reading my posts and reports will know that I am like the majority on this winter model thread in that I love cold and snowy weather. I am always searching for colder patterns and set ups but I do try to be realistic and provide some balance. I did say in several recent updates that I would be surprised if the forthcoming cold spell lasted for much longer than 4 or 5 days. The rising heights to our north-east, the Scandinavian HP and a possible easterly of sorts only look to be pretty temporary features given the backgrounds signals. We may get several days with a battleground scenario when the Atlantic tries to fight back and comes up against a “relatively” cold block. Some snowfall in parts of the UK seems likely but probably far less than many are hoping for. In fact, if the breakdown proves to be a slow and complex one this might be our best chance of getting something rather more memorable out of this.

How quickly it then warms up is still very uncertain and I feel that the models may struggle with this right up until T+72, which should make the new short term model thread much busier next week than it has been so far! I do not see the cold spell being extended into the following weekend but that does not mean that we’ll have many days of very mild weather either. The jet stream should break through and we may be back to a pattern that we saw for much of the last month with alternating short colder and milder spells. This time of year, Polar Maritime air can be potent enough to produce something more wintry (but see my Arctic update below).  Of course, I would love to be wrong about all of this but I’m trying desperately hard not to be persuaded by some of the eye candy that we have seen during the last few days, as deep down, I just feel that the models have not really latched on to the background signals (although they may just be starting to). On the other hand, do not feel too gloomy – please read on!

LOOKING SLIGHTLY FURTHER AHEAD:  

Without going into my usual longer detail, the background signals do indicate that something better might be in the offing. Just re-read the excellent recent posts from the likes of @Tamara, @Glacier Point @Catacol, @Singularity@Snowy Hibbo as well as @carinthian. The down tick in angular momentum looks to be very temporary. Just as before Christmas when the signals suggested the rising heights to our north-east  for early January (which “had” been extremely well sign-posted), then the down tick in momentum indicated that these heights would be replaced by a flatter pattern, we once again see a “likely” uptick in momentum (this is obviously not certain and is a forecast at this stage) which will again favour stronger blocking to our north-east.  The timing for this is, as usual, going to be very problematic as GP highlighted this morning. I’ll be looking out for further updates from these posters on the AAM, GLAAM, GWO etc.

How the unusual (and recently changing) La Nina pattern interacts with the AAM (etc.) is also very important. The east Pacific based La Nina with the cold current upwellings there and the now almost average ocean temperatures in the central and western Pacific have created a profile which is unlikely to follow the normal Nina winter behaviour and impacts. No more detail but just to say that the current set up is much more likely to have favourable impacts compared to the usual Nina ENSO state.

Then we have the recent NOAA reports that have suggested a much more lively MJO as it moves out of the “circle of death” and progresses through phases 2 and 3 at a steadily increasing amplitude. Given the timing of the 30 to 45 day full cycle, we should reach the important stages of 7, 8 and 1 later this month. Providing the MJO doesn’t die again, then that should substantially assist with establishing HLB patterns. Ideally (for coldies), we would like to see the MJO remain in those key phases for as long as possible at decent amplitude.

Then we have the thoroughly disrupted tropospheric PV. There has been a huge battle for the seasonal peaks in the strength of the PV and the Jet Stream against the disruption and frequent injections of WAA into the Arctic. We have seen regular ridging of high pressure into the Pole but not sufficiently (yet) to produce much more widespread HP up there.

The stratosphere “may” be starting to play ball too. Remember this is NOT all about a sudden stratospheric warming (SSW) which is still a “possibility” for later in the winter”. Currently, it is the strength of the strat PV and how that might imprint on the trop PV. The previously predicted  “reconnect” has (fortunately, it seems) not been going smoothly. Then we have had some fairly brief downticks and upticks in strat temps at several levels and finally there have been some minor and short-lived warmings that have come and gone. (I’m still not able to comment coherently on things like wave1 and wave 2 impacts – so just study the strat thread for that).

Bringing all this together, I feel that frequent disruptions to the trop PV will continue: Just look at these two GEFS ensemble panel for day 10 and day 15 as an example:

        GEFS 6z ens Panel T+240            GEFS 6z ens Panel T+384 

      gens_panel_sdd3.png       gens_panel_kvc7.png

Once again we have varying degrees of disruption, including several fully split PVs and very few showing anything near to a well organised PV. Add to this the fact that the strength of the PV and the Jet Stream will have passed their usual seasonal peaks and from mid-January they usually steadily become much weaker again. Then add in the likely uptick in AAM (and GWO moving towards phase 4), the MJO progressing towards its more favourable phases as well as the eQBO favouring polar easterlies and HP near to or over the Pole, then we might have, for the first time this winter, all these signals starting to become far more harmonious. Timing of the “possible” (I feel “probable”) impacts is not straight forward but there could be an evolution from mid to later in January. Equally, I feel that once we manage to find this path, it could evolve pretty quickly. I’m still hanging my hopes on a cold regime becoming established later this month and that this time it will not be a short-lived affair. In fact when you read my next section, I’m going for it to last for much of February too (but I had better not get too carried away about this, otherwise somebody, like Knocker, will literally carry me away!). All this before a possible SSW impact perhaps for mid-February.

NORTHERN HEMISPHERE TEMPERATURE OUTLOOK:

Last week I provided a post on this subject and another one on European temperatures which should have made it clear how marginal the uppers and much of the surface cold are likely to be during the coming cold spell.  What I said in the first of those reports was how much more encouraging things looked from around mid-January onwards. So, given everything that I’ve said about the signals above, let’s have a brief update on the medium to longer term northern hemisphere temperature profile. I’ll compare current, day 10 and day 16 charts from GFS, ECM (only to day 10) and the GEFS panel for the 850 temperatures and substitute GEM (only to day 10) for ECM for the surface temperatures (as Meteoceil do not show ECM charts for these in this format). I have deliberately chosen alternative models to the GFS as they have (or at least "had") been favouring a more extended colder outcome.

850 Temps:                       GFS 6z T+6                                     ECM 0z T+0                               GEFS 6z ens Panel T+6

                       gfsnh-1-6.png?6?6         ECH0-0.GIF         gens_panel_gdf3.png  

The models show the extreme cold that pushed down through North America as far as the southern USA in recent days. Apart from Greenland there is just insufficient cold to go around. Even Siberia is slightly less cold than usual right now. Europe has very little cold to tap into. 

                                     GFS 6z T+240                                 ECM 0z T+240                        GEFS 6z ens Panel T+240

                       gfsnh-1-240.png?6?6         ECH0-240.GIF          gens_panel_cat6.png

By day 10 we are already seeing quite dramatic changes! The GFS shows North America giving up its monopoly with the deep cold there easing. The deepest cold is re-establishing itself in Asia and Russia. This change is very strongly supported by the GEFS. In fact only 3 of the ensemble members continue to show greater cold in North America and even those show increased cold in Asia. The ECM  shows a similar but rather more balanced pattern with a more equal distribution of cold in both continents but with Asia just starting to gain the ascendancy.

                                     GFS 6z T+384                      GEFS 6z ens Panel T+384

                       gfsnh-1-384.png?6?6         gens_panel_lkn4.png

By day 16 we only have the GFS to go on now but it shows the continuing evolution. By then "all" of the USA has well above average 850s (none below zero!). Even Canada only has slightly sub zero 850s with the lower (but much higher than now) values confined to the Canadian Arctic, the Arctic around the Pole (see later for fuller details) and Greenland have also warmed. So where has all this cold gone...yes, across to Asia, Siberia, Russian and towards Europe! "If" these conditions verify, then these parts will have their lowest values so far this winter. Look at those sub -12c 850s extending to Iceland and into Scandinavia. Then it would only be a question of delivering the right synoptic patterns (preferably north-easterlies or easterlies which I feel are more likely than not later this month) to set up to drag in some really low 850s with no "marginal" conditions to worry about. The ensemble means generally provide a lot of support for this. Only two of them show any deeper cold in North America. Another one has the deepest cold over Greenland but still with plenty of lower values in Asia.Three more have a fairly even distribution of cold but the vast majority have the coldest 850s over Siberia, Asia and Russia. Nearly half of them already show sub -4c or lower values across Europe (a couple include the UK). There are several with some sub -20c 850s already pushing steadily through western Russia and on towards Scandinavia and northern Europe. I really hope this lifts the gloom should the models continue to downgrade the upcoming cold spell. This change is extremely encouraging and obviously needs to be monitored closely.

2 M Surface Temps:               GFS 6z T+6                                    GEM 0z T+6                              GEFS 6z ens Panel T+6

                                  gfsnh-9-6.png?6         gemnh-9-6.png          gens_panel_nbe8.png

Moving on to the current surface temperatures, we again see that intense cold spell currently hitting North America with far less deep cold in Asia but at least Siberia has its usual deep surface cold for this time of the year. GEM is similar - watch out for those black areas which look quite sinister but actually on their charts never go down below sub -28s (the lowest they ever show), whereas the GFS "white" areas go down to sub -40s.  Please note that the GEFS panels for surface temperatures only show the enlarged Europe view (the Northern hemisphere view is not available on Meteoceil charts).

                                                 GFS 6z T+240                               GEM 0z T+240                          GEFS 6z ens Panel T+240

                                  gfsnh-9-240.png?6         gemnh-9-240.png            gens_panel_hpm7.png

As with the 850s. the surface temperature distribution has changed significantly by day 10. Remember that North America will hang onto to some of its surface cold unless the jet stream pushes across some much milder air from the Pacific. By then, the deepest cold has moved into central and northern Russia and way down to south-west Asia with some unusually cold conditions down there. The cold extends towards south-eastern Europe. The European pattern is shown in more detail in the GEFS panel. Actually rather more members show colder conditions pushing into eastern Europe and Scandinavia compared to the GFS operational run. GEM is broadly similar but with deeper cold into western Russia compared to GFS.

                                               GFS 6z T+384                                     GEFS 6z ens Panel T+384

                                    gfsnh-9-384.png?6                    gens_panel_sgn9.png

By day 16, North America has continued to warm up. In fact the southern and central states are well above zero by then and even northern USA and southern Canada are barely below zero. North-eastern Canada and Greenland have some deep cold but again, the most extensive deep cold is well and truly established across Asia. In fact the extent of the white area of sub -32s over Siberia, much of Russia and parts of western Asia is the largest that I have seen for many years (unless someone else can find something lower?). The area of sub -40s within that is also the largest for a very long time. Further west, towards eastern Europe, surface temperatures are widely just below zero. The cold air has extended across Scandinavia.  Much of central and western Europe and the UK are rather cold (mostly 0c to 4c). The great news is that we should have some deep cold in place not too far away to our north-east and east. The panel members mostly revolve around this pattern with an equal number showing slightly colder conditions closer to the UK and others slightly less cold conditions.  

Arctic Sea Ice News and Analysis:

During last July the Arctic sea ice extent briefly hit a new low for that time of the year challenging the overall record lows seen in 2102. It reached its lowest point in mid-September when it was the fourth lowest on record. There was a limited recovery during October and through November and an even slower rate of recovery during December and in mid-December this winter (2017-18) was actually the lowest! Right now, only last winter (2016-17) was slightly lower still. This can be seen in the charts below: 

N_daily_extent.png      N_daily_concentration_hires.png    N_iqr_timeseries.png  Figure2-1-350x280.png

Source: National Snow and Ice Data Center (NSIDC)

The latest monthly update (for January) was published last week and makes for compelling read but with some absolutely dreadful news for the Arctic sea ice extent. "President Trump - you "must" take note!  Please use the link below which also shows all the charts (and many other details):

http://nsidc.org/arcticseaicenews/

Arctic Current Sea Surface Temperatures (SSTs):

          SSTs  January 3rd               SST Anomalies January 3rd

color_newdisp_sst_north_pole_stereo_ophi      color_newdisp_anomaly_north_pole_stereo_

Source: NOAA Marine Modelling and Analysis Branch

The anomaly chart shows that there is a wide area of open water in the Arctic with well above surface temperatures. The SSTs need to be below the -1.5c threshold (the purple colour). Sea water will start to freeze when it is below -2c but that is for normal salinity. There is slightly lower salt content in the Arctic (mainly due to ice melt) and the threshold is nearer to -1.5c. There are some areas with SSTs well above freezing and the current anomalies are widely over 4c above average and up to 8c above in places. Unfortunately, although the SSTs themselves have fallen very slightly, the SST anomalies have risen even further during the last couple of weeks (the normal seasonal decline through the winter months),  some of the anomalies have increased – eg: now over +8c around Svalbard. These higher SSTs are a legacy of the 2015-16 winter when the Atlantic jet stream powered well into the Arctic for much of the first half of winter. This shifted much warmer than average currents right up to the edge of the ice sheet. This strong anomaly has persisted for 3 years and is exceptional and comes on top of the already generally warming Arctic. Unless the SSTs reduce substantially, the anomalies might be carried through to next summer and into a fourth winter.  There is a small area of the North Atlantic, mostly south-east of Greenland with a negative anomaly. 

Unfortunately I have run out of time to produce my detailed analysis of Svalbard temperatures (these will appear again with my next Arctic update in several weeks time) but needless to say those readings just add to the extremely worrying Arctic temperature profile. Even though this is probably good news for us in the UK in seeing more cold air here, I'm sure that most of us do not want to the Arctic warming at such a dramatic rate.

Well, did I say a less long report – you should know me better than that! Once I get going, I just cannot stop, especially when I really like the look of some of the signals that are appearing.  I sincerely believe that there is no need to get too concerned if the upcoming cold spell fizzles out quite quickly. The ongoing events are highly likely to give us at least one or more bites at the cherry. It’s even possible that we can extend the near term cold spell and shorten the gap to the more prolonged cold. Nothing is set in stone and I have well and truly put my neck on the line! So, if it goes wrong, tie me to the final piece of the Arctic ice sheet as it drifts off into oblivion early next summer!

It may be a few days (or longer) until I post again on here as I’m working on an exciting new project that you’ll hear about during next week.

 

 

Edited by Guest
Correct typos and check charts & links

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GFS is rancid.. less comment on it the better! UKMO not bad but not great either, and it's always at 144... have you noticed?

I don't buy the GFS is catching up stuff, the models seem to just be converging on a middle ground nothing fest, which is unfortunate. I don't see the GFS as being any more or less wrong in this saga than the ECM, the ECM said undercut consistently for days, doesn't look like happening does it?

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14 minutes ago, Mucka said:

Lest we forget. 

ECM 2 days ago V today's UKMO

ECM1-192.GIF?12UW144-21.GIF?04-17

GFS 2 days ago V today's UKMO.

gfs-0-192.png?12UW144-21.GIF?04-17

 

 

Looks like the ecm was way off with that chart.

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16 minutes ago, Mucka said:

Lest we forget. 

ECM 2 days ago V today's UKMO

ECM1-192.GIF?12UW144-21.GIF?04-17

GFS 2 days ago V today's UKMO.

gfs-0-192.png?12UW144-21.GIF?04-17

 

 

If UKMO is right @144 and thats a big if then the GFS smashed the ECM this time around.

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33 minutes ago, Steve Murr said:

You would like to think so- problem is GFS is on the back foot catch up!

Steve after takin a look at the arpege!!its got 850 temps of +4 across the midlands and east anglia but the dew points are a frigid -2 or -3 widely!!even colder in the netherlands!!is that even possible🤔!!its even got the lightest fall of snow near the south coast!!sorry just to add it has temps of -2 widely tuesday morning even across the channel!!

Edited by shaky

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19 minutes ago, Mucka said:

Lest we forget. 

ECM 2 days ago V today's UKMO

ECM1-192.GIF?12UW144-21.GIF?04-17

GFS 2 days ago V today's UKMO.

gfs-0-192.png?12UW144-21.GIF?04-17

 

 

It would be interesting to repeat this exercise next Wednesday, when we compare these charts with the T0 charts.

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Judging by the output so far I think we can dismiss any possabillty of any sort of snowfall next week, any encroachment of the Atlantic over the UK will be met with Warm uppers and rain. 

Freezing rain if the surface is cold enough for a time.

Edited by frosty ground

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I'm more of lurker than a poster on here but having been on here for years one thing I've always noticed is everytime we all get excited at a potential cold spell modelled by the ECM and the GFS doesn't agree we nearly always end up with a blend of the model outputs occurring. I never bought into thie idea of a snowy Easterly of course it may still happen at some point but for me we need cross model agreement between all models

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6 minutes ago, Weathizard said:

GFS is rancid.. less comment on it the better! UKMO not bad but not great either, and it's always at 144... have you noticed?

I don't buy the GFS is catching up stuff, the models seem to just be converging on a middle ground nothing fest, which is unfortunate. I don't see the GFS as being any more or less wrong in this saga than the ECM, the ECM said undercut consistently for days, doesn't look like happening does it?

GFS isn't too bad at all, it keeps the heavy rain & gales well away until at least the end of next week which is excellent news in my opinion 

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Nothing bad about UKMO the block is there for the long haul. Decent.

166A70F3-233F-4A20-AC5A-E34016F084DA.thumb.gif.55f0991830ffe7688806e84c06d7ab6e.gif

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Just now, northwestsnow said:

GFS again bringing in PM incursions into FI.

 

Something to look forward to. :D

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1 minute ago, Daniel* said:

Nothing bad about UKMO the block is there for the long haul. Decent.

166A70F3-233F-4A20-AC5A-E34016F084DA.thumb.gif.55f0991830ffe7688806e84c06d7ab6e.gif

The problem is without a proper undercut or cold to tap into, this chart is essentially cold with rain. To get an easterly from this would be at best day 8, even then unlikely.

 

dont mean to be a negative nelly but I feel it's realistic 

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18 minutes ago, frosty ground said:

GEM has left the party, Warm uppers and the Block sulks away East.,

Never rated it:crazy:

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