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Evening all- No idea whats been posted so appologies if Im just churning the same info- The next 10 days ( more especially the latter 4 ) represents the best opportunity for this winter for the UK to see something more widespread on the snow front- Whilst the first low @96 gets East of the UK towards debilt, the pattern is already taking shape as the heights over russia & weakly over Scandi have proved to be much more impressive than originally projected - but not enough to back the cold over the UK- As a result of the amplifiying pattern (backed up by the heights to the east) the UKMO comes up with the rather tasty 144 chart- A very unstable polar blast pushing in from the NW with another system waiting in the wings behind it to bring perhaps some more organised wintryness- Post that the ECM on a similar par, also inline with its ensembles shows a nice atlantic high ridging across a dropping Easterlies at day 11 ( ish ) ECM also @ day 10 shows a split vortex as well which in terms of modelling this winter hasnt been very forthcoming since mid november- In terms of the strat - from T12 to day 10 shows the vortex being squeezed by a 2 wave pattern nearly forcing a split ( @feb1991blizzard) 12 then onto 240 So me must keep an eye on the Berlin & GFS forecasts post day 11-16 have a good eve S @Catacol @Tamaraare you saying ( plus assuming tamara ) that no chance of cold- just at a time when we see our biggest chance all winter post day 7 -10 & when the strat looks like beginning to move to a more favourable position- ( although more time needed ) Of note is the CFS jumping back on the SSw trail again this morning... just reading all the posts this evening I think in my world its fair to say that I dont really subscribe to the all the detail in the posts based on the fact that theres just to much 'spin' to make the peices seem like they fit up to now- The only disconnect I see if theres much confidence in why X & Y have happened this winter thus far then Z should be easy to forecast- all to much hindcasting I think ... S

Probably not the best time to post this and *appear* to burst any NWP virtual bubble over latest operational roll-out with some boring analysis, but nevertheless such that is intended to be objective and useful. The concerns expressed in the posts of late autumn and start of winter related to breakdown of +AAM/weak Nina disconnect and w/QBO stratospheric tightening through December have come to haunt - flying in the face of repeated alluring NWP ensemble suites which continued, periodically, to tempt many cold weather model watchers right up to the turn of the year. So further (apparent) kill-joy, however realistic it may be, is risked here. The evidence has been gathering through December to keep harbouring and increasing those early doubts, and some of the latest stats confirm exactly why we are struggling to carve out a consistently sustained upper cold pattern in the UK with a lower angular momentum state establishing and a seasonal vortex which has harnessed the assistance it needed. The Southern Oscillation Index, in contrast to the ENSO disconnect of autumn, is now steadily accumulating positive figure returns - typical of a Nina imprint on the atmosphere. However weak that is set against a neutral ENSO ocean state. https://www.longpaddock.qld.gov.au/seasonalclimateoutlook/southernoscillationindex/ The atmosphere/ocean disconnect process (declining SOI) reversing since start of winter. The disconnect period was when the initial starter destabilisation process on the early season vortex was created Easterly wind/+ve Outgoing Longwave Radiation (OLR) anomalies are evident close to the Dateline in the Pacific - also consistent with the weak La Nina signature that has been evolving through December on the atmosphere. Note also that currently the most organised tropical convection is indicated in the East Indian Ocean - further evidence to point to current lower atmospheric angular momentum state The Global Wind Oscillation has slumped and stagnated back to a very low amplitude and indeterminate orbit phase, consistent with lack of help from the tropics (MJO) to add westerly component to the atmospheric circulation and help amplify the pattern sufficiently downstream to create more sustained and meaningful cold air advection - than attempted topplers Never to be taken completely at face value anyway and the actual GWO signal is very weak, but this composite for GWO Phase 1 into 2 of mid latitude high pressure ridging extending from Atlantic to SW UK not a bad reflection of short term (to day 5) NWP in terms of height anomaly, albeit troughing across N Atlantic not so clearly in evidence The question further out is how much amplification is available to enable troughing to dig through Scandinavia along with greatest coldest air advection. To now the coldest upper air has continued to be taken south east through central/Eastern Europe into the Eastern Med, and the UK struggling to tap into more than transitional Polar Maritime air as the Jetstream flows around the Atlantic/Azores Ridge Notwithstanding the evenings NWP which has unravelled as I type and suggests what is probably, imo, the very maximum and temporary bandwidth that could be extracted from this very ordinary typical January La Nina mid latitude high pattern, what can weaken the Azores Ridge and add further amplification and make some of the FI extrapolations that have been/are being seen closer to reality? Frictional Torque enhancement is indicative of rising angular momentum tendency, southward moving tendency of the jet and greater amplification flux enablement. These factors relaxing the grip of the sub tropical ridging as dictated by the upstream Pacific Nina pattern of anomalous ridges in both the NE Pacific and the Atlantic Eastward propagation of tropical convection into the Western Pacific will forge such helpful trends closer but such an evolution is not as easy as the late autumn when the extra tropics were more co-operative and receptive to additions of westerly winds and poleward rossby wave propagation (amplification) heading eastward through the Northern Hemisphere. (This process was halted just as it was about to deliver - hence the seeming consensus for amplified cold early on). For the reason why it might not be totally straightforward, we return to the OLR anomalies map. MJO activity has to negotiate the easterly wind anomalies present in the Pacific which would tend to snuff out the convective wave through the wind shear evident in front of it. On this basis we can look at the W&H plots and extract early caution as to how attempted eastwards propagation might progress as we head through January. As much tropospheric forcing as possible will be needed to create amplification and also agitate the wQBO assisted vortex (sounds all to familiar). Hopes maybe rest on further retrogression of the Pacific ridge allowing the vortex position to shift NW,wards. This allowing some height rises to the NE to arrive via the back door courtesy of greater amplification arriving from upstream. Its in this sense that increased amplitude of any convective activity stemming from the Pacific is most required and welcomed. Seasonal wavelength changes as we head deeper into the second half of winter mean that such an evolution becomes more and more important to enable eastward propagating convection (and hence the downstream amplification) Otherwise this could well continue to be a season of mid latitude settled high pressure alternating with less settled westerlies and truncated chilly NW'erlies. @chris55 I think that it has to be pitched against the macro factors which haven't allowed the degree of amplification required. Close yes, but the weather patterns don't subscribe to being "unlucky" in terms of human wishes and preferences The fact is that the small degree of split energy to the southern arm of the Jetstream c/o the small area of low pressure close to the Azores (which supported the Atlantic ridge above it but ultimately destined to become the short term cut-off feature that indeed verified) was outweighed by the upstream energy c/o slightly supressed low AAM state and w/QBO vortex @Steve Murr Its worth reading the post which is detached from any emotional preference. It doesn't exclude any cold possibilities at all, what it does is continue to offer pointers to what can go wrong which this season proves again to be sensible and wise. Maybe also it tries to pitch probability against chasing lost causes. I am sure you will agree that a lot of wasted energy (and participant expectation) can attract attention to oneself, but ultimately be wasted and (in the second instance) over exposed and left unrequited..

I'm assuming you're basing your 'rogue run' theory on the fact that the GFS is quite different for 2m temperatures than the GEFS members, as you've used that to illustrate your point. If so, you're not correct. Virtually every run has that discrepancy because the GFS is run at a different resolution to the GEFS which is always more notiecable on the ground as that's where local variations with height / coasts / towns & cities etc play a much larger part. For instance - 6z and 00z runs for Cumbria (a hilly part of the country for illustration), the same discrepancy...

Really? Looking cold / below average on the daily GFS T2M anomalies from late next week if I'm not mistaken. OK, a northwesterly flow is certainly not ideal for sustained deep cold and snow away from northern areas, but it's look progressively colder on GFS and EC this morning. 00z ECM shows increasing snow potential by day 8 across Scotland, particularly over hills but perhaps lower down too, also hills of northern England and Wales. Days 9-10 it even shows a snow threat down the eastern side of Britain, with a 1 day strong northerly flow direct from he arctic, though by then good chance it won't verify. Certainly lots of wintry potential from tail end of next week from a NWly and perhaps briefly Nly direction showing, though obviously subject to downgrade this far off.

The colder outlook on GFS is supported by the anomaly charts, they have been suggesting a colder burst as a probability for several days in the time scale shown by GFS now. links below last evening from NOAA, less than the ECMWF below but the pattern certainly allows for deep cold incursions as being shown by GFS at times. http://www.cpc.noaa.gov/products/predictions/814day/500mb.php http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html not able spend much time this morning, trying to get my heating sorted, would occur when -2 C outside. Got more clothes on than when walking!

I'm always interested in trying to understand why one run can vary so much from the previous run. So just for interest, here's why I believe there's such a huge difference between last night's GFS 18z and this morning's 0z. And it's largely down to how GFS handles a shortwave developing in the Atlantic on the 18z. This goes on to form a dartboard Low and pulls in the frigid northerly airstream as it pulls away to our east. In the 0z there is no such shortwave. Such a relatively minor development, but with huge implications. The 18z charts versus 0z: T162 and near identical 18z 0z T171 and 18z has shortwave developing 18z 0z T186 and the dartboard Low develops 18z 0z T216 Low moves east pulling in northerly 18z 0z

Morning, just up date you with the latest over here. We currently have 16 cm of fresh snowfall in my location. The fine mesh model we used predicted 19cm at 1200 local today, so it will be mighty close to that mark and again very impressive tool for our planning. The main cold front is passing with a pronounced cold flow in its wake. -12c here in resort and -16 c at 2000m with a added wind chill . The same system brought snow to Stockholm yesterday and low temps. This picture sent by my daughter on her way to work this morning in the city centre, -11c. The models continue to show a very cold picture in Central Europe for the next 48 hours with further snowfall in the coming 24 hours. Should turn less cold over the coming weekend but no snow melt.

Lows like this on the 12Z GFS could sweep down at relative short notice in this type of flow and deliver quite a bit of snow to almost anywhere in the right conditions.

Clustering looking good, would take a similar ECM about face to the infamous 46 vs 5 ens members to derail. What could possibly go wrong ??! Encouraging to see the operational model align to the much maligned EC monthly prognosis. Fingers crossed everyone gets a visit from old man winter..

@Tamara Shut up and stop being sensible! Just out of interest, I'm saving the 12z ECM charts from 240 down to zero, starting yesterday. Just to see how accurate it has been. I'll post them all when complete. Watch this space....

That's one hell of a cold snap on the Gfs 12z which would produce much wanted snow for some parts of the uk, needless to say I hope the Gfs is on the right track regarding next week, especially the second half when the arctic air arrives! A nondescript weekend coming up but next week could become very interesting / exciting hopefully!

The Ecm 12z turns into a thing of beauty which even aces the Gfs run and snow, the missing ingredient so far this winter would certainly arrive if either the gfs or ecm are close!..could be exciting stuff later next week onwards..hopefullycheers gang

Two things - how the hell is this evolution a surprise to anyone ? and the eps have been notable in their desire to drop uppers days 8-12 to quite low mean values so -8 is not necessarily off the table

ECM/GFS/GEM at day 8 Solid agreement on a north west or even northerly flow developing as we become increasingly influenced by a trough just to our east. On the northern hemisphere perspective there is a lot of promise going forward with blocking possibly becoming increasingly extensive towards Siberia. We are heading in the right direction and mid-month is trending cold, possibly cold enough for snow to low levels. Can we work an even better solution down the line?

There was a beautiful example hit Brest a few years back and some of the most spectacular ones have travelled a long way down the North sea with huge snowfall as they landed. I'll be trawling the close-up satellite pictures from the IMO site if it turns out anything like modelled. The most recent one was a bit questionable as it started life as a baroclinic leaf to the east of Iceland - didn't really matter as it did the convective thing on its travels south and crossed central/southern England with a good amount of snow to please the chionomaniacs amongst us.

No it's -13

(my bolding for emphasis) Something always worth remembering, with current technology and model algorithms the forecast skill extends only to about six days. The atmosphere is governed by chaotic equations that can't be solved exactly so errors increase with time, doubling about every five days. Even with completely accurate starting data and a perfectly programmed model, accurate forecasts would be limited to about 14 days according to current understanding. So we can use various factors to make intelligent suppositions and discuss probabilities of outcomes further out but for any real accuracy we can only look short term, hence the term FI, which is particularly appropriate for model watching. The models are indeed successful to some degree within the current limitations of our programming, technology and data gathering. The verification stats illustrate to what degree this success is achieved. Understanding this makes for much less stress.

Evening gang ,nice to come on here and read some interesting posts ,and see some wintry looking charts ,probably the best position we have been at this winter .let's hope for some upgrades over the coming days ,cheers gang

The ECM and GFS are broadly similar in pattern but theres a key difference upstream which could tip things in our favour. For newbies take a look at the NH view of the ECM, you can see that as that amplification works across the USA between T168hrs and T240hrs how this attaches to the PV and causes that anti clockwise motion which pulls the PV away from the ne/n, helped also by the high over Siberia. We're not talking of deep FI here, the actual catalyst begins at T168hrs. We still could do with the PV further away especially over eastern Greenland and need those low heights there and Svalbard to be replaced with ridging.

Surely this cold an upper air mass could give a chance of polar low formation. It's originating over Greenland and following some of the favoured routes as in the papers linked by Knocker and John Holmes. Of course, we have to get it to verify but I'm more confident than usual, having looked at the finer detail for the ECM model on the Icelandic site. Both bring this in but there are issues with timing and no doubt shortwaves once we get to five days out. The EPS 00Z T850 mean +192 at circa -8C is nothing to be sniffed at.

No access to it, but I know a man that does, and the man from DelMonte... He say "YES"

My eyebrow is somewhat raised by tonights 12 ecm although I will be happier to see that exact development inside the 120 mark then I might raise my other eyebrow as well. Even allowing for Tamara's cautionary tale of things unconducive to prolonged cold and snow . If we were able to squeeze a cold and snowy week out of this otherwise rather boring (so far at least) winter a lot of us on here would be pretty happy.

Good agreement overall tonight at T144hrs, the ECM though looks like developing another wave of amplification upstream at T168hrs so a difference between it and the GFS at that stage. Yes just what we wanted the main PV chunk pulling nw at T192 hrs! this though helped by that amplification upstream. If we want to see deeper cold this is the only route within the current overall set up.

Afternoon all, well good news is I survived today (so far anyway). Today, as expected, dropped to around -6 with no wind although it is currently -7 with wind picking up. Visited Auschwitz today which is an experience that left me feeling numb. Posted some photos below. Should add the snow came on heavily overnight and added to current snowcover, Oswiecim (town which Auschwitz is located) had around 10-15cm of snow. Tomorrow now to be coldest day of winter with temperatures dropping to -12 and -20 at night. So as much as it is baltic, must admit I am loving the weather here.

without wishing to nag,some recent posts would probably be best suited to a PM conversation or the banter thread.......if we could keep on topic for the imminent runs, that would be super! Thanks!

GEFS mean anomalies looking very similar too

Agree with steve,best chance of widespread snow of the season coming up. ECM mean for the 12th over the last 3 days shows a clear trend to build strong heights in the mid north atlantic, each run has weaker heights to our south, and deeper low heights over Europe. ECM at 192 Very large block in atlantic, hinting towards atlantic high - siberian high link up. If this verifies I would have thought we would be locked into a cold pattern. quite encouraging to see such an anomaly at just 192 hours.

That would back up others suggesting we lose the maritime influence (Surface high or a continental flow) in the extended range somewhat. The set is certainly a good couple of degree colder compared to the 00z so that is progress. The operational is sitting nicely in the ensemble set too, pretty much on the mean throughout. Plenty of scope for a quite potent cold snap that could evolve into something more significant as we head deeper into week 2. The big question beyond the northerly is whether we see the Azores high nose in, the GEFs do suggest this at the moment with the lessening of the cold signal and becoming drier again. As we can see the high does nose eastwards again though the broad pattern remains similar with low heights draining south east into Europe, I guess the one way to spin this is the possibility of the suite being a bit progressive and hence too far east. Overall the outlook looks good for northern and western areas, southern and eastern areas need the wind to back towards the north or north east or see a disturbance develop in the projected arctic maritime flow to bring a more organised band of wintry showers or prolonged precipitation to areas away from exposed coasts.

No significant changes with the ten day anomalies this evening but one perhaps worth noting. The pattern change upstream with the rerogression of the Alaskan high pressure gets underway towards the end of the ten day period and briefly initiates some retrogression and amplification downstream thus allowing the energy/trough from the vortex via Greenland to dip SE over the UK bringing with it some wintry weather for a two or three day interlude. NOAA might not pick this up in the time frame but that is not to say NOAA should be ignored. Nothing here that hasn't been indicated over the last few runs Keeping in mind the above still looking upstream at ridging Alaska into the arctic, and active Canadian vortex with the positively tilted trough running SW and the connection via Greenland to the negatively tilted trough to the east of the UK. With a flat upper flow across the US and a strong jet still leaving the eastern seaboard the zonality of the Atlantic still rather depends on the relative positions of the Azores ridge and the trough(s) as briefly discussed above the details of which will be sorted by the det, runs, A pretty safe bet that there will be short period of wintry weather later next week and overall the temps will trend below average. The 10-15 period sees the completion of the pattern change upstream with an active vortex and a general low pressure area in the NE Pacific. Still a flat upper flow across the US and a strong jet leaving but there is still some life in the Azores HP and with weak positive anomalies in the eastern Atlantic still an upper flow over the UK from around the NW.with the trough to the east tending to positive tilt. Thus still looking at systems tracking SE and unsettled interludes with the south escaping the worst and temps still below average but a little higher than at the end of the ten day period.

It's a New Year, a fantastic forum and now even the models are starting to look a whole lot more promising. So let's all in enjoy whatever the models ( and the weather) throw at us as something is definitely afoot. Hopefully 3 feet deep!!!! Proper winter is coming soon!! MNR

It would be nice to finally look outside and then shout, it's it's it's snowing!!!

Not too concerned about the break down of cold in the low-res deep FI. The T240+ charts will be different again on the 18Z, 0Z etc. The more important thing is that the onset of the cold shot is edging closer to the reliable timeframe.

Im sitting on the fence this evening and this is purely based on following the ECM & GFS over many years. The ECM whilst regarded as the best model does have a tendancy of over amplifying whereas the GFS tends to do the opposite and flatten too quickly. So yes to the colder NW,ly outbreaks but on the fence with regards to a prolonged, colder N/NE,ly. I will add despite the various forecasting methods on this thread i.e teleconnections. Nobody can really say how this will develop. Look at tonights 18Z compared to last nights and in F.I we see a very cold E,ly being replaced by a very mild.SW,ly. If a supercomputer shows such a massive difference in 24hrs for 14 days out, is it any wonder why long range forecasts especially seasonal forecasts often fail.

Tamara is right - we are stuck at the moment in a static pacific pattern. The graph below shows the progression of the MJO in terms of velocity potential - in an active phase the warmer colours starting in the Indian Ocean (left hand side of the graph) progress to the right as time passes. But we are not getting convection anomalies showing up as moving sufficiently into the Western Pacific (centre of the graph) to get the Rossby Wave amplification from this process to help drive our mid lat ridge higher. The forecast here sees no immediate change. It's a very flat looking profile. There is some wave 2 action on the vortex forecast But the signal for a disrupted lower vortex for mid month to my eye has faded a bit, and the projected zonal wind profile is fairly unexciting. It doesnt represent a vortex pumped up like last year, but it isnt a vortex on the edge of collapse either. Let's call it "average"... End result? More of the same. Ridging of the Azores High under weak Nina conditions to continue - frost and seasonal cold waxing and waning for the foreseeable as demonstrated in the charts posted regularly by Knocker and John.... but for all the straining of my eyes I cant see a sustained cold pattern on the near horizon yet. A temporary toppler style pattern next week is possible as NWP is suggesting - and some snow may/will fall in places... but it isnt the sustained winter foundation many of us have been hoping/looking for so far this season. The pacific pattern certainly chose a damned bad time to move to a different phase and then go quiet. I'm enjoying the frost and sunshine, but 10 days away from mid January it is high time the dice rolled in favour of UK winter and changed something. So far the winter has been as dry and blocked down here in the SW as has been the case for many years - but if the rest of winter plays out under these weak Nina conditions after such promising signs in November it will have to go down as a major disappointment. However - lots of time remains.... and fingers continue to be crossed for change.

i posted them on here for you I think ian reads stuff on here, but does not post, Just a hunch as the second part of his message seemed to answer my post on here. Its a huge loss that we have lost such a respectable professional. May be some common curtesy on the model threads even if a poster says something you don't want to hear or don't agree with. There are many on here that would be severely missed as is Ian. Here they are again Ian Fergusson ‏@fergieweather 42 minutes ago @Floodwarncouk models have been toying for a few runs now with broad idea of a more pronounced NW'ly to N'ly outbreak, but still early days .cont'd... so yes, the likelihood of that has increased, albeit much too early to be deterministic on scope/outcome.

Quick look at the 12z EPS mean, as at work, but more pronounced ridge NE across the UK towards Norwegian Sea / northern Scandi days 11-12 which hasn't been evident in 11-15 day period of the EPS on recent runs - so perhaps some support for ridging in this direction to maintain post day 10.

Nice to see you back posting the cold charts Frosty Fingers crossed you'll be posting a lot more cold charts in the coming days!!!

Ecm brings winter at last!!! Its a cold run and gets colder, we can dream!

Excellent post - makes it easy for the more novice of us here to understand how minor details can have huge impacts as they develop

12Z ECM ENS means has excellent support for the Op at T192

Oh dear! You are fast becoming the grim reaper of this forum lol. Seriously though, your post may help to keep us coldies grounded. We have all been bitten too many times this season so far.

Can i saliviate over the ecm? Its fanastic isnt ! Wondering if we might hear from matt hugo soon!!!

Just wondering how long its been since those in the north west have seen a good old fashioned polar north westerly. I guess as ever geography playa a part in preferences but if i were on high ground in NW Britain i think i would be getting interested now....

Just for fun.

I think Nick has alluded to this but I would be wary of any clean polar flow and low uppers for now. The models often oversimplify a troughs behaviour, which while making little difference to to the longwave pattern, can have a big impact on how cleanly we draw in any polar air. Often there will be shortwave troughs that develop within the flow cutting off any polar component and introducing warm sectors so generally the 850's are overdone (too cold) at those sort of ranges. We won't really know until it gets inside 120 and we have more idea of how complex the trough will be and far Southwest it can dig. That said we should at least see a fairly cold PM flow at some stage which will be the best we have done so far this winter.

Much better 6z with snow showers piling into the North west at 192..

Just so everyone realises, this is the upper trough we should be under if the returning jet hadn't shoved the Azores trough nw and sunk the ridge se ! fine margins !

GFS Op doesn't offer much encouragement with it's love affair with the Azores high but fortunately UKMO is a bit more interested in squeezing it West and putting us in a decent PM flow at least. For once we want the more progressive solution of UKMO phasing the two lows through 120/144 to flatten the ridge and force the pattern West for any Northerly down the line as the first whiff of PM air will be a waste of time anyway Looks better upstream as well which, along with the trough being further South and West than GFS, would give a chance of a decent Atlantic ridge building. So let's hope GFS is on one and UKMO onto something. Edit Just to illustrate why we want the lows to phase and power up the trough here are 2 extreme examples from withing GFS ensembles. The first example, with more separation between the lows at 144 which allows the 2nd low to extend the ridge The second example, the lows phase and create a deep trough. It should be said the most members offer something between these two examples. Seems odd rooting for the opposite of what we usually want but there you go. Any amplification/ridging through the mid term is now more likely to be a hindrance than a help. Edit 2 GEM phases the lows and goes on to produce a wintry if unlikely trough. UKMO is actually slightly better at 144 IMO though impossible to know how long it could sustain a cold PM flow.

Hard to see anything other than a transient Northerly 24/72 hrs as long as there is so much spread among the ensembles The North and West could get lucky around the 12th/13th as far as actually seeing a flake of... What's it called now? Damn I forgot.