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Evening All The ECM @ 144 is the first model that actually has a split flow over the UK with those low heights from europe all the back to De bilt just remember how far we have come!! ECM 192 for the same time frame x2 days before & The GFS 192 x2 days ago So im really pleased after the forecast how things have progressed - I think we do have a bit more room for manouvre west, however we are beginning to cap out on that correction, it would seem that behind the deflected low @ 144 we have lost a bit of amplification & the atlantic does push forward again- all be it on a SE trajectory- Overall the pattern ( post 144 ) screams chilly zonality with possible deeper cold in the mix down the line -But dont rule out further developments like above in the 120-168 arena- Also eyes on the strat for week 3 / week 4 Jan as developments are just starting to take shape ! S

Well the snow arrived exactly on time. Our fine mesh snow model last evening forecast snow to start at 1500 hours local time,in fact it was 15 mins too late !! It forecasts a 24 hour snowfall with 19cm by 1200 local tomorrow. Forecast temp of -14c at 2200m. Tomorrow night -25c in the valley. The forecast model is 2kx2k range for my location. Mountain top locations will see higher snow rates and values. Getting exited now, time for a walk in the stuff and celebrate this much needed snowfall in the pub! C

Certainly some cautious cause for optimism for second half of January, yes we've seen the positive signals from ops and ens for early Jan in late December and got burnt on New Year's Eve, but this time there is growing support from various signals for changes in the status quo of the upper flow. Here's why: The stratosphere is looking interesting in the medium range, with a decrease in zonal flow evident at 10 hPa as has already been posted, and check out the 12z EC stratosphere z500 at 10 hPa: the GEFS and EPS are indicating an eastward propagation of an increasingly active MJO wave into phase 8, GEFS is perhaps being too hasty, hence the amplification over the N Atlantic from day 10/11, whereas the EPS is slower and perhaps why we aren't seeing such amplification yet. AO trending negative in the means on GEFS, also NAO trending neutral to slightly -ve. EPS trending AO slightly -ve, NAO neutral. So those nice looking charts from GFS post day 10 do have some backing from the oscillations, but maybe too quick IMO in bringing in the amplification. Patience required, despite patience wearing thin!

that is not really how I see them but you are obviously entitled to give your view. As they are mean charts at 500mb they are far less liable to the switches one sees in the synoptic models. Part of that, not all, is due to the lowest 500mb in the atmosphere where the greater part of any moisture is held. It is also something old meteorologists used to call the level of non divergence. Prior to computers the surface chart and the 500mb charts were the basis of forecasting for 24 hours ahead, with some kind of guidance out to 48 hours. By gridding one with the other one arrived at the 'thickness' chart. Empirical research had shown that weather systems, lows especially, moved with these lines of 'thickness'. Convergence and divergence at this height helped decide whether to deepen a surface low or fill it. Sorry to ramble clogging up the thread mods so feel free to delete, just getting carried away-silly old duffa.

Yesterday afternoon i sent Judah Cohen a Email asking if the UK would get any colder or will we have any Snow ' I thought give it a go as he might reply ' and behold he did and this is his reply to me .

Assuming the eps don't jump ship in half an hour we approach a period of wintry potential we haven't seen on the modelling thus far this winter with all three ens suites in agreement that the low anomolies drop to our south. And yet the misery on here from coldies is palpable. cheer up - it could look zonal with a big euro hig!

Southwesterly 15 plus days Northerly 0 - 5 days 50/50 Easerterly 0 - about half an hour reliable

Just in case in the reliable...GFS 12 T63 You almost want to go for a swim, the cold is no near Forum cold chasing club

Keeping the dream alive!!!

Keep on rambling you silly old duffer

The later 100mb chart is showing ridging/HP to the NE/E of the UK with LP to the south. The 500mb anomaly charts have also hinted at this on a couple of recent runs. One way to a colder evolution down the line is developing high pressure to the NE and with LP centred to the SE/S thus CAA from the east. I'm not for one minute saying this is going to happen based on this scanty evidence but it's interesting enough to keep an eye on. IMO of course.

0-5 days - reliable 6-10 days - 50/50 10 days+ - don't even bother.

Fits in nicely with the timeline of a failed winter. First comes the hype in either October or November..this winter begins with talk of "front loaded winter", which failed to materialise. Once we reach January then the talk turns to "it's only January...plenty of winter left"...or when things looks really lousy, describe transient cold shots as better than nothing. Jam tomorrow charts at Day 10 dominate the forum...none of them however come within 168 hours of fruition...The clock meanwhile ticks on. January passes into February...another snowless month away from high ground in Scotland...."February can be the coldest month of the winter' the optimists cry. More time goes by...the Spring flowers are out..February fails to deliver...another snowless winter...the cries of "remember March 2013" begin to pipe up... And on it goes....

Ok a few post have gone, Anything the Model Outputs are showing can be discussed in here. Where-ever you are/or discussing in the world.

very true but it is a very difficult thing to do. The inference that the NOAA 6-10 this evening fits the GFS idea at 12z is in fact, again in my view, not far off the mark. But it is the anomaly in heights in the Atlantic, coupled with the troughing well east in Europe that is allowing the surface features to run ESE bringing colder air into the UK. This is something I have suggested for the past two days. The lines Nick drew were what was puzzling me. They appeared to be drawn along the anomaly lines. They don't actually exist and certainly have nothing to do with the surface flow. off to bed will chat via p tomorrow if anyone wishes cheers folks-the cold is coming, honest!

A lot going against this winter delivering anything other than transient cold snaps delivering anything more than snow over northern hills and perhaps occasionally to lower levels in north. Most importantly, I think, we have a westerly QBO which tends to enhance the strength of the PV, despite being weak back in Nov, it has strengthened considerably and likely IMO to stay like that most of the winter. Also there are some anomalously warm SSTs off the eastern seaboard - which is perhaps enhancing the thermal gradient = stronger jet entrance over eastern NAM. Also, we have a few years until the solar minimum and also the MJO has been rather weak, despite the neutral to La Nina ENSO. I, like others, were easily taken in by the models and the ensembles, when they were showing bitter northerlies and easterlies just before New Year before the plug was cruelly pulled. I put my hands up and should have known to be more cautious, given the background signals that were against such winter nirvana for the UK. Not throwing in the towel for a long while, but really need to see drivers such as MJO, GWO and AAM work in our favour to work against the strong PV to perhaps deliver more in the way of blocking in the right place, but it will be an uphill struggle this month IMO. Perhaps next winter or more likely winter after, when we see the solar minimum arrive and perhaps an easterly QBO phase, we will see better chances for HLB and weaker PV. Though these in between years between the solar mins do seem an uphill struggle to get deep cold over the UK, especially in a wQBO. Perhaps the warming oceans maybe playing their part? As continental interiors still get very cold in winter despite this.

The usual 3 anomaly charts shown below. All 3 have a flow into the UK from a strongish Atlantic flow showing just n of west, more so on the ECMWF-GFS variants. Remember they are mean charts so any particular day will show s of and more n of west than the mean. I would expect changeable at times as lows run across the Atlantic, with a tendency to be further south with time. So I still expect a deeper cold spell occurring in this period, say 1-3 days. The flow does not suggest anything longer. Equally there is likely to be a day or so at a time when milder returns into at least the southern half of the UK. Just my ideas of course and not really borne out by our own Met Office, although there own thickness charts, see at the bottom of the Fax page link, does show that flow veering more to the north west late in the runs. ECMWF-GFS http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html NOAA http://www.cpc.noaa.gov/products/predictions/610day/fxus06.html UK Fax link http://www.weathercharts.org/ukmomslp.htm thank you to tightisobar for your text change last night

Don't let me stop you! There are two shortwaves, the first circled black manages to run east over the high and not keep any residual energy hanging back, the second stays just enough to the sw to allow the gap to appear to give the Euro slug high room to retrogress. However there won't be any eye candy if that shortwave circled red phases with the low pressure near the UK. The GFS manages not to but given our recent luck low margin for error evolutions are not what we want to see. The GFS then manages to take a high unlikely to get ne at T240hrs and miraculously catapults it ne as the lower resolution kicks in. Anyway lets hope we can have an evolution that's not such a white knuckle ride in future outputs. PS I hope people don't think I'm being a misery or wanting to drag down the mood but its best to view possible cold set ups in terms of margin for error and how many things need to go right. I'll be happy to ramp any cold when it passes my quality threshold! lol

The Euro slug high although edging west never really leaves the scene in the ECM and the pattern is too far east with a lack of amplitude upstream. Barring some PM incursions its really not upto much. With high pressure over Russia this does lock in the troughing so its a battle between that and the PV, the latter wants to send the jet pummelling eastwards the high wants to divert this se'wards. The only route to something interesting and not a few hours of slush and BBC reporter stuck on a hill somewhere bigging up a pants cold snap is for the PV to relocate nw as in the GFS FI. Otherwise theres really not that much to get excited about and after 5 weeks of crud I won't spinning a few brief PM incursions into anything other than average winter fare which normally wouldn't get a look in but because our bar has been set so low we're supposed to welcome this and say thanks! Thanks but no thanks!

Hello everyone! I greet you all with these picture from our hotel room and main sqaure in Krakow, currently snowing and around 1 celsius which feels much colder with bitter wind, bad news is tomorrow and especially Friday to be into -10 to -15 range. Will hopefully update tomorrow (if I survive).

Jeez gfs12z is an absolute humdinger. A proper cold spell right there, i want to believe, and i REALLY mean i want to believe...

Wrong thread I know but if this verifies, there will be reprocussions, big ones, for the currently dominate vortex.

Can you lend some of your negativity to the AO and NAO?

To my eyes we are about to see a significant change in Synoptics so far seen this winter. The blocking highs of December are moving and for the first time we can look north west for our weather and with this originating from Greenland directions it will be a very raw and seasonal mix of all sorts, which has to include snow. Both GFS and ECM are now showing this change for next week and I wouldn't look beyond 192 as that rarely varifies. So a long awaited change on its way and it's a wintry one !

Ok so we have models all honing in at approaching midmonth to polar maritime surge, and then potential from there onwards but with GFS consistently showing further and prolonged attacks of cold. If I have the signal right we have more than a 3 day cold dip coming, we have serious cold blast coming. I am very wary of how the slug messed up Dec but we were just missed some serious storms. Let's keep watching.....we have interesting developments ahead with improving cold chances BFTP

Two CFS perturbations go for an SSW in February, using the reversal of wind as central date as is the general custom, the other perturbation and control show no SSW into March. The CFS and GFS both suggest that the strongest 10mb winds are yet to occur in the meantime (courtesy weatheriscool.com) That shows 900m height at 10mb - only a little over the MERRA January average of 806 metres - which bear in mind includes predominately wave 1 phases when wave 2 dwindles. Put another way, there are four out of 30 SSW (first of season) since 1979 where wave 2 is the overwhelming contributor in the fortnight before and up to wind reversal, to the exclusion of wave 1 - 22/02/79, 01/01/85, 21/02/89 and 24/01/09, leading to classic split vortices. All these had wave heights over 2000 metres. When looking at wave 1 + 2 jointly, the only SSWs occurring with as low a combined height total are a few at the end of March when the vortex is giving up the ghost. Of course it's something to watch, but not amazing at this point. January days with wave 2 height between 850-950 metres have average 10mb 60°N wind 36.3m/s with an average minimum within 7 days of 27.4m/s. Only 1995 saw a weak reversal inside a week, but zonal wind was weak already, starting around 14 m/s. What is this disconnect that has been mentioned quite frequently? For several weeks the troposphere and stratosphere vortices have been well coupled with barotropic structure - output from the models has shown that every nuance in the trop is affecting the pattern of the strat and anomalies. An alternative view is this graph of AO (scaled *5) vs 10mb zonal wind during December The unlagged correlation is a highly significant 0.90

Nothing silly about your post, a very relevant look into the history of forecasting, and interesting to me, and I'm sure others as well.

No surprise that the anomalies this evening continue in good agreement in the ten day range. Still with the HP western Alaska with an active Canadian vortex (and a Siberian lobe) with the trough with a positive tilt SW. Still the ongoing connection via Greenland to the trough with a negative tilt orientated SE over Europe. Thus a continuation of a flat upper flow across the United states with a strong jet still leaving the eastern seaboard. This jet will track around the Azores high pressure which has the stronger positive anomalies in slight retrogression mode along with the ridging north. All three are in pretty fair agreement on the relative portions of the HP and the alignment of the aforementioned trough to the east so pretty high confidence in a period on unsettled wintry weather in the Pm incursions from the NW with temps below average. The det. runs will of course sort out the detail In the 10-15 time frame the expected retrogression of the Alaskan HP still in play with broad low pressure area in the N Pacific but the Canadian vortex still a player. But there is no agreement on the vortex - trough to the east connection with the GEFS playing it down and encouraging some more mid Atlantic ridging and thus still a NW flow to the trough to the east which has got a negative orientation to the SE. The ecm is not liking this and generally moves to a zonal upper flow with a very weak trough to the east. Which ever way you hang this it is difficult to see any other solution than a general W/NW upper flow and with the strong jet a continuation of periodic incursions of Wintry PM fayre and temps below average

Afraid of what? BFTP

The GEFS anomalies are interesting this evening for two reasons. Well that I could find. The 8-13 upstream is consistent with previous but down stream has more pronounced ridging in the western Atlantic and a deeper trough to the east which, quite importantly, is tending towards a positive tilt. And then the evolution from there which has been mentioned previously Be afraid, be very afraid.

Phantom easterlies post day 10 again, what a surprise A word of caution re: uppers from the north west, we've seen this before where 850's are modelled much lower than they turn out to be.

A couple of observations this morning to start the ball rolling. Quite and interesting tweet by Sam Lillo which I posted in the other thread which I feel is worth repeating as it's very interesting. IMO. in the context of the problems with the medium range forecasts this winter. "The entrance region to the climatological W Atlantic jet was the strongest on record for December in 2016" and this trend is continuing And secondly the GEFS is showing some inclination to retrogress the HP this morning which could bring more inclement wintry weather to the UK towards the end of the ten day period. So a little more detail. High pressure remains in control up too and including the weekend with just a minor blip as weak fronts slide SE over the country on Friday. With reference to the point made above the usual upstream energy distribution vis the jet. So remaining dry with temps a little below average. next week sees the high pressure relegated south west under pressure from the energy flow thus troughs will now travel around the HP and track SE across the UK bringing some wet and windy conditions to all with the strong winds tending to veer NW to N in this transient development. A quick look further ahead and the pattern changes upstream still on the cards with another Atlantic wave taking place during the transition. But this for another time.

Yup pretty much the same theme being modeled by the GFS. Very cold, potentially snowy with raw winds.

This is a cracking run. T312.

By party I assume to mean the zonal party as the ecm T192 chart has westerly 180Kt jet blowing straight across Scotland.

I was never under the impression that the red/blue lines were denoting mslp, given they are 500mb anomalies. But enough humiliation from the ex MetO duffers, a nasty depression running SE across Scotland next Friday with some cold air tucked in behind. Quite a strong/active jet next week moving in across the Uk, so quite a stormy period we could be entering of the likes we haven't been used too.

Not a particularly inspiring EPS mean in the 11-15 day range with the anomalies suggesting a continuation of the 500mb pattern in the 8-10 day of the deterministic with a NWly or Wly flow However, the NOAA CPC 8-14 day indicates support for the 12z GFS, with a flow more N/NE than NW with perhaps the Euro trough eventually cutting off from the upper westerlies. So, some divergence past day 8 GFS v ECM, so be interesting next few runs to see where we are headed. Now I'm ultra cautious since the New Year's Eve fail, I would go for the ECM as the form horse, but with the NOAA 8-14 day amomalies siding more with GFS, not so sure.

Hello Mate. Generally that would be a fair assumption of PM air, but occasionally like it did back in late 2000 an extremely active cold front from Greenland called the " The Snow Plough" delivered snow to all parts of the UK ,

Not so sure Nick... Now of course a day 10 chart is unlikely to verify, however, I've had the electronic crayons out. In the 240 chart we see the Azores ridge as usual. But we also see a strong ridge building over NE Canada. The low in the Atlantic (circled) hangs about and stops the two HP's linking. The Azores high gets flattened and the Canadian high pushes into Greenland. A couple of days later and the UK population of snowmen explodes.... Well, maybe not but hey... Johnholmes mentioned such a ridge having significance a couple of days ago. Cold weather sneaking in the back door?

Sorepaw - we're a looong way from weather warnings being issued! Except maybe in the Express.

Temps hardly above 0c plenty of snow showers and a wind chill average of around -10c......YES! Please

Lovely jubbly GFS 12z op offering sustained cold. It gets better and better in fact FI is very similar to that of the GFS 18hrs from last night, almost a mirror image.

Been snowing here on and off since lunchtime and its now getting heavier. Not lying yet but theres no mention of snow in the MetO 7 day forecast for my location.

Morning all - so the next colder shot firming up for 12th-16th Jan - at D10, 850hpa anomalies on both GEFS and ECM at -4C below normal - very tight clustering around or just below the -5C line for London on GEFS and a range from -2C to -8C on the ECM ensembles across the country. So I imagine the ECM ensembles will look pretty similar to GEFS at D10, with a range of options from WNWlies to NNWlies i.e. both "cooler" runs and "colder" runs. Longer out, ECM ensembles generally keep Atlantic heights and Euro troughing and looks like more "cold zonal" with occasional amplification bringing down something even colder. In summary then, we're on the cusp of a pattern cold enough to bring snow to all, but probably not potent enough for widespread snow without a few further tweaks (possible), and not amplified enough to prevent further flattening if the PV once again pushes the pattern more than forecast. At least we're seeing a bit more consistency now, though. I can't see the Murr sinking low coming off now as the pattern is too far east even with the most extreme corrections - good spot though Steve!

Judging by the latest models I would say we are on track for a couple of polar maritime outbreaks next week, cold enough at times for wintry showers to low levels and night frosts.

For Nick s. - at day 9 now! Impossible to know how transitory any troughing will actualky be but the ens charts are keen to hold it in place (hopefully not due to a timing issue between members) at first glance the new eps are colder than previous runs day 10/15 under the cyclonic n flow (nw/n/ne)

Isn't that the same chart twice? Or am I being thick (again!)

I think what you mean is, if FI trends/ensembles/long range forecasts etc WERE RIGHT we'd have all seen some snow a while back. Are they going to be wrong all winter? I doubt it. This winter may not have been great so far but look at summer. It looked like it was going to be a washout and it redeemed itself in the end. Well, halfway through actually. The vast majority of 'memorable' winters only actually had a week or two of proper snowy spells. It's only the 4th January. Do you think that if we had the model range in, for example, 1991, we would have seen the 2nd week in February coming? No we wouldn't. I know it's frustrating but keep the despair for the 2nd week of March. Then I'll join you!