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Love this time of year on the forum. The mod Thread really starts to get going again with all the craziness that I love so much. Looking forward to the many many laughs at the toy throwing incidents. The models are looking good for something cold at the end of the month. Cannot come soon enough, Hate this mild muck this time of year.

Yes - they look very promising! -NAO, retrogressing high and strong heights around Greenland. Coldies could be getting their early season wishes come true very soon!

Yes there's some good news for coldies, the Ecm 00z ensemble mean longer term favours a cold shot.

The one theme that remains consistent this morning is the dry theme. Which suits walkers like myself who love to enjoy the beautiful Autumn colours nature has afforded us .

The pattern is evolving pretty much as expected with the amplification upstream of the Aleutian low/Alaska ridge and vortex/ trough down the eastern side of N. America complex linking to the subsidiary vortex near northern Scandinavia, All neatly complimented by the burgeoning subtropical high in mid Atlantic. All of which portends a strong north westerly upper flow adjacent to the UK and generally a quieter and cooler spell of weather for same but there is still a lot of energy exiting upstream and the north could well experience more windy and changeable weather as systems swing around the high pressure. So to a tad more detail starting with the 500mb and surface analysis at midnight The front straddling the country will continue to struggle very slowly south east bhut weakening into a mainly cloudy feature with perhaps the odd patchy drizzle. Thus still pretty cloudy over much of England and Wales but not too bad in areas where this breaks with cooler and clearer air behind the front (note the different airmasses in the midnight Castor Bay and Nottingham soundings) with th high pressure ridging north east. Still a fresh breeze with some showers in the far north west. Overnight the front continues it's slow journey with the drier cooler air covering much of the country with a fair bit of frost around. So tomorrow, after the chilly start, will be dry and sunny, except perhaps early on in the south east Overnight Thursday through Friday the ridge generally stays in control but fronts associated with a low tracking north of Iceland do encroach and bring rain and freshening winds to the north west but remaining fine and relatively warm elsewhere By Saturday it's worth remembering the opening comment as another very deep low swings swings north east on the very strong jet with once again the associated fronts bringing strong winds and rain the north west, albeit temps a tad above average. The front(s) continue to move south east on Sunday accompanied by the rain and freshening wind so a rather N/S split temp wise with it remaining dry and warm in the latter before the rain arrives. And the NH profile at T120 which is not a million miles away from where we came in

If nobody objects i’d like to put an order in for P16 Oh I just love this time of year!

Come on guys, let’s keep this thread friendly please. Cheers.

With winter approaching over the horizon, a lot of people's thoughts are turning to cold weather potential, but while that's fine, it's not everyone's cup of tea. So, we've started this thread for the cold hunting side of model discussion, with a general discussion thread also up and running for those who'd rather look at all other aspects of the model output. Despite the focus on cold weather potential in this thread, please do keep it to the model output. Want to view the model outputs? You can get all the major ones here on Netweather: GFS GEFS Ensembles ECMWF ECMWF EPS NetWx-SR NetWx-MR Met-Office Fax GEM GFS Hourly Model Comparison Global Jet Stream Stratosphere

So what is this then? Bottomline, whether the blocking is in the -EPO or +PNA domain, the downstream troughing occurs in Central and Eastern US, with the polar lobe coming down over the Mid West and bringing snow to the Mid-Atlantic/New England. And this further demonstrates the downstream effects. This is not to say blocking doesn't occur in the Eastern US, during a -EPO. I am just stating that a -EPO is correlated with a trough over the Central and Eastern US. That blocking over the Bering Sea isn't what I would call a -EPO, too much leaking into the Far East Siberian region, with the troughing off Western Canada too. That would be the WPO domain. With a -EPO and +PNA pattern, the below graphic shows Eastern troughing, in combination with other factors. Shows that there can be successful cohesion, which drives troughing on the Eastern half of the continent. Here was the EPO during your period, first half dominated by a neutral EPO, then a weak-moderate negative phase, then a weakening of the -EPO towards the end. Meanwhile the -WPO was nearly off the charts in strength, so clearly you have picked the wrong domain. The WPO and PNA domains don't cross, nor often correlate. So your statement of "HUGE -EPO RIDGE" is quite misleading. You also ignored the more -EPO like blocking from the 8-18 Sept this year, which was also a period subject to a +PNA.

Looking through the GEFS 12z there is some snow potential towards the end of october into early november according to the postage stamps, especially further north and on higher ground..P9 for example..yes it's deep FI but there continues to be potential for a very early taste of winter beyond the anticyclonic spell..and I am hunting for cold / snow..and Frosts of course!!

Get out the shovels - it's time for the Cold Rush!

At 10hpa you wouldn't expect to see much else. Note the 10hpa strat charts in Feb 2018 when we were experiencing our mighty warming and eventual split lower down The key to the charts Recretos has posted is that we have an ensemble mean signal for a warming over Asia. That is good news if strat disruption is what you want.

There's an index member in my research model with a period of about 6-7 years (it hits with relative precision at 13, 20, 33, and 46 years and needs a slight adjustment at the 6-7, 26-27 and 39-40 year intervals. Look how juicy this analogue set is (going back to start of CET) ... this is listed by the January of each case so years before these contain the Nov-Dec analogues ... and this includes only those cases needing adjustments of less than ten days ... because we're talking about retrograde index, the off-set pairs run earlier for first more recent, going back in time, and later for second of the pair, by about 10 days, e.g., the 6,7 set would include for example 2013 an earlier index by 8 days than 2019, and 2012 a later index by 7 days. It's similar for the 39,40 pairs. For example there, 1979 would be running later than 2019 by about 7 days. For the 26, 27 set, we are looking at the more recent of the pairs being 6 days earlier and the second less recent being 8 days later than 2019. (6,7) 2012,2013 ... 1966, 1967 ... 1920, 1921 ... 1874, 1875 ... 1828, 1829 ... 1782, 1783 ... 1736, 1737 ... 1690, 1691 (13) ...... 2006 .......... 1960 ............ 1914 ............... 1868 .............. 1822 ............. 1776 ........... 1730 ............. 1684 (20) ....... 1999 .......... 1953 ............ 1907 ............... 1861 .............. 1815 ............. 1769 ........... 1723 ............. 1677 (26,27) . 1992,1993 . 1946,1947 . 1900,1901 ... 1854, 1855 ... 1808, 1809 ... 1762, 1763 ... 1716, 1717 ... 1670, 1671 (33) ....... 1986 .......... 1940 ............ 1894 .............. 1848 ............... 1802 .............. 1756 ........... 1710 ............. 1664 (39,40) . 1979,1980 . 1933,1934 . 1887,1888 ... 1841, 1842 ... 1795, 1796 ... 1749, 1750 ... 1703, 1704 ... (before CET) (46) ........ 1973 .......... 1927 ............ 1881 ............... 1835 .............. 1789 ............. 1743 ........... 1697 ......... _______________________________________________________________ This slice of the past catches quite a few of the exceptionally cold winters, narrowly missing 1709 which only needs a 15 day adjustment towards earlier dates, but being out of phase entirely with a few like 1740 and 1963. However, the overall average of these winters when adjusted by the required number of days (where daily data available) produces a profile that reaches a minimum of 2.5 deg below the current average around mid to late January and runs generally below normal throughout the winter season. The notable cold winters in the set include 1684, 1716, 1763, 1795, 1829, 1855, 1881, 1947, 1979, 1986, This index value is rated as 10 to 15 per cent of total variability and is second most significant. It is related to inner solar system magnetic field flux changes associated with the planet Mercury. The one slightly larger index value components is related to Jupiter and the analogue set there is regarded as linked to progressive features so less associated with blocking, more to do with position of long-wave ridge and trough features. One other detail that I can report from the research is that retrograde episodes can be expected roughly every second month from this index value, and on a longer, slower time cycle, about every 7-8 months from a separate index member, and that one has analogues with winter 2010-2011 and also includes 1978-79 and 1962-63, also 1946-47. The episodes would be expected to occur 2-3 days later each eight years going back in time, and you start to lose well-timed analogues before about 1906-07, running into a different set timed for somewhat earlier running back from 1823-24, so that includes 1816, 1808, 1800, 1792, 1784 and 1776 as analogues for January. This does not look to be a dominant index value in the research, but it's good to see a reasonably low temperature index from that one combined with the principal retrograde member. If we can't build the cold blocking pattern out of these materials, then we seem to be losing our best chance but the long solar downturn may allow weaker analogue sets to succeed in the future. You have to wonder if we have a "big one" in our near future despite what we are allegedly doing to the boundary layer. It does concern me, but a signal of +1.0 C competing with all these others may be in over its head, we can only hope, right Fred?

What a pretty picture... A tri-pronged attack on the trop vortex and a tanking AO

What you call a bore fest I call a great outlook, perfect autumn weather in that gfs run, I've had enough of the wet and windy weather for the time being

i know it will not happen but this should lip the lips of the coldies

Strap yourselves in folks...it’s going to be a long 6 months

Hi @Catacol Im having a great day thanks - I guess for me- there was a differentiator in the patterns highlighted yesterday - The Alaska high / Canadian trough for the East coast is a bit like the West based NAO for the Uk - The cold 'can' get all the way to the east however usually where the high sets up - in this case alaska, the trough digs a long way south through the central Plains then lifts out along the ridge up the east coast- so the jet exit point for a high based over Alaska is certainly more often than not warm for the east coast - Where the arguement may ensue is that where people actually think the loading pattern is to measure the EPO pattern - If you overlay into the PNA to much then you cannot differentiate or reanalise either pattern with clarity- & certainly a +PNA is a better fit ( in the round ) for east coast cold than a -EPO Same as ENAO is better for the UK than WNAO but WNAO can still deliver - FWIW I believe there will be 2 super high pressures this winter dominating the pattern across Northern US & for Europe it would either be Scandi or Greenland - For me the link ( again in the round ) is more likely to be -EPO / -PNA encouraging more atlantic / Greenland blocking +EPO / +PNA encouraging more scandi high pressure - Again all relating to the jet exit off the states- The first being more NNE then second being more East then being forced to recurve.... Thanks Also the is picture for a loading pattern is really badly worded The Trough is in Canada.... ! Remember when we get one of these super high pressures like Sept they will distort the eastward flow & send the main trough south. so with either pattern the stronger the index of -EPO / + PNA will distupt the jet towards the atlantic

Thanks Snowy - yes - this is my take on RJS's early season descriptor and on the pattern as I see it related to the current shape of Nino and AAM trends. Beyond November is really tough at the moment: we dont have a handle yet on the vortex (though Recretos' diagramme in another thread is really interesting, suggesting 2 key long range models seeing a warming again...) and for followers of Cohen's theory it is also 2 weeks too soon to draw a conclusion. A mid atlantic ridge giving us some frosty conditions into November would be a good start. I'm not particularly keen on the idea of November snow - I've only ever seen it once in lowland England close to me (and it was the last few days of the month) and it lasted less than 36 hours. Let's not waste good synoptics on November! Mid December following a continental cooldown is the start of the sweet spot.. :-) Steve - I hope you are having a better day today!! All I posted yesterday was a personal opinion based on a starting point of Roger's strong sense that a cold start to the Canadian arctic season is likely to produce a downstream cold East US trough and from there a mid atlantic ridge under high AAM conditions supported by Nino and a high orbit GWO. Let's see if it transpires that way. If November doesnt pan out that way then we havent lost any of the "real" winter season...so everyone stays happy..

Lovely strong blocking high to the west of Ireland next week. This would bring cooler conditions than lately but most importantly would allow the ground to dry out and a lowering of rivers once again after the awful flooding in places here in South Wales last weekend.

A good ideal there Paul. Think this will be the Cup of Tea for a lot of folk on here chasing a fantasy world of endless cold and snow. Getting excited already ! C

Yawn. Can we have some interesting weather please. Feels like stuck in a rut for so long boring mild dross. It's autumn now lets have some fireworks or cold crisp sunny days not this stagnant sir moving down from the north s decaying weather front. 3 of last four weekends have been wash outs. But not in an exciting way just wet no wind to speak of. The rollercoaster is about to start. I just gave this funny feeling this is not your average winter. And no I don't want it front loaded. Let's get proper snow in Jan Ppppplllllleeaaaaaseeeeeee not. Why do I think it's not going to be your average fair.... well the northern hemisphere is still recovering from that sst. Weather patterns have been all over the place. Current weather YAWN

I noticed talks of QBO, and decided to look at it via GFS, and it is in the positive values already, so October mean might end up near or at positive values. I made one HD graphic of QBO progress at 10mb and 30mb from GFS data.

Further ice build up along Greenland's eastern coast.

The best news from today is seeing @Recretos back here! Per those seasonal 10 hpa mean profiles, I would take the following on board ..... jan and feb are unlikely to be very blocked over n Europe. The strat vortex seems likely to be around Svalbard/n Scandinavia through jan, slowly retrograding into feb.the chances of a North Pacific ridge west of kamkatchka seem pretty strong. how big could the strat/trop diconnect be during jan and feb ? And yet we have seen that the 500hpa charts show high height anomalies to our north where the ec and glosea place the core of the strat vortex . ive seen enough today to make me think jan and feb could be anything ....... I’m expecting a pretty blocked December so the idea of a very mobile second half jan and feb seems a reasonable statistical call for the time being.

Its brilliant to see so many posters come out of their Summer Hiberanation, gearing up during this Autumn and to the coming winter! This place is buzzing tonight!!! But who can't get excited when your a coldie and the ECM teases you with this.... All fun and games of course just for now, cause we all know how fate likes to tease us and when it looks all too good to be true, its snatched away before our very eyes! But there is much to be optimistic about this year! Let the roller-coaster that is model watching, commence!

It has been a while since my last posting about the stratosphere. I remember back in the days, I was trying to be a strat modelling pioneer, making graphics that people demanded but were rare to come by. I was among the first, if not the first in the world to produce fully public HD-3D/4D polar vortex animations. I am here again now because there is still something that people demand but it is hard to come by. It is seasonal stratospheric forecasts. Those are almost impossible to come by as far as I have searched, unless you have a fat wallet or you are full time professional. Thanks to the Copernicus project, I now have access to stratospheric grids of ECMWF and UKMO Glosea5 models. Configuration wise, those are the best two models in the world for seasonal stratospheric forecasting. The only one that could join them is the JMA-SEAS model. So I present you four graphics for now, monthly mean forecast. Considering it is just the October initiated forecast, so we have a long lead time, and its a monthly mean of 50 members, its actually impressive. The signal is visible. I will add more graphics with time and every month with new runs. I do plan to make a permanent home eventually for these graphics to be regularly updated on the Severe Weather Europe page where I am one of the admins. Will also add 500mb monthly anomalies there in the far future. The grids were in GRIB1 format with some non-conventional coding, so it took some trickery to produce it, but I have "cracked the code", so there is much more of this to come.

A new thread as we move past the mid-point of Autumn.. This thread is for more general model discussion - eg without the specific focus on the hunt for cold weather, which can be found in the hunt for cold model thread. As ever, please keep it to the models in here. Want to view the model outputs? You can get all the major ones here on Netweather: GFS GEFS Ensembles ECMWF ECMWF EPS NetWx-SR NetWx-MR Met-Office Fax GEM GFS Hourly Model Comparison Global Jet Stream Stratosphere

Yes it's a run dominated by high pressure (s) so at least predominantly settled with some pleasant sunny spells and light winds with some crisp frosty early mornings as you say..still a chance of a Northerly but on this run it misses the uk to the east.

That is an intense area of high pressure, possibly some local pressure reading records maybe broken for October.

You won’t be when we are all booking trips to come stay with you due to the mild mush ! I jest ! Fingers crossed for a real winter season !

Couldn’t resist hacking this (@Paul‘s) thread to add a banner at the top of his original post. Edit: something thing to add (and not sure if there’s been any posts on the particular model): the 00Z GEM attempts to go for a Northerly right at the end of its run with High Pressure amplifying in the Atlantic, though it looks as though the main part of the Northerly dodges the U.K. to the East: Perhaps close enough maybe for a high-ground wintry shower or two over Northern and North-Eastern areas. Looks a bit similar to yesterday’s 12Z ECMWF run - albiet that had stronger amplification in the Atlantic and the pattern seemed a little bit further West. Mostly for a bit of amazement really as it will, no doubt, change again on the next GEM run. Whether a Northerly occurs or not within the next ten days will, I think, partly depend how much High Pressure in the Atlantic can amplify. Helped also by upstream troughing/Low Pressure systems digging far enough South to the West of the Atlantic High so the Low Pressure doesn’t steam roll over it. This, along with any Lows that swing down from the North-West on the Eastern side of the Atlantic High going far enough South to the East of the UK into mainland Europe, to provide an Arctic blast for the cold weather fans to drool over.

Just seeing the names Piers Corbyn & James Madden and you know you're in the silly season. Imagine if one year these predictions actually come true, huge "I told you so" redtop headlines!!

I sense the first MetO 'epic fail' of the new season might only be a few weeks' away: 'They gave me a red warning and I only saw 45 inches'?

When will the moods thread open ?

Thanks guys for the feedback. Yes, these are monthly means and heavily diluted, and also considering its a 50-member weighted average. As far as the vortex core goes, its spatial area is much larger than any area of the potential warming onset from the Asian sector, so the dilution effect is greater on the warming part then on the cold core of the polar vortex. Not to mention that in some individual ens-member cases there likely isn't even any Asian warming occurring, so that is a heavy dilution effect, unlike the polar vortex core which is always present, just spatially shifted by a few 100-1000 kilometres. Now I am not saying that the warming signal on the ENS-mean maps is a given, but we have to consider entire model circumstances when interpreting such ensemble charts. That is why anomalies were invented. Yes I have those too. They are from models' own hindcast climatology. It gives a bit better impression what is the actual abnormality in the forecast. for example from the Glosea5: And some ECMWF

@Snowy Hibbo Even the teleconnection data shows your wrong Reanalysis 28 Aug - 10th sept Huge -EPO RIDGE in a classic Alaska location Not an east coast trough in sight... PNA metric NOAA data shows huge -EPO & -PNA pattern traversing to +PNA / +EPO pattern. So dont take my word for it- take the NOAA if you like.

ECM 168> 192 says hello to a new pattern for the end if October - AO heading south - Huge PNA + Pattern - Deep Scandi Trough - Retrograding Atlantic high...

They are fairly new there were only set up after John Hammond left the beeb for full-time work They were caught out in the summer a few times incorrectly predicting breakdowns from the heat but they didn't shy away and admitted they got it wrong

The GFS 12z run looks like a bore fest although with some potentially nice crispy frosty mornings

Short term high pressure looks to be the main features sat to our west at times allowing a cooler breeze but still pleasant enough in any sunnshine

With all due respect, you are wrong. A -EPO's downstream effects often create a Eastern trough. That is what it is known for doing, disturbing the polar jetstream up to Alaska, and bringing cold down to the Eastern Half of the United States. A -EPO if it stretches down towards the West Coast of America often gets called a joint +PNA and -EPO. So the assertion that a -EPO must go with a -PNA or vice versa is entirely misleading.

In the run up to winter - revel in the good old days. Enjoy!

20c in Reigate, lots of sun today after early mist shuffled away. I imagine 21/22c was hit somewhere in our neck of the woods. Love this bonus weather and frankly would be happy if it lasted until spring. A week in North Pembrokeshire from this weekend, back to the old place. Can't wait. Wild weather off the sea, extra evening daylight and cliff paths precipitous as the rain steams in with the tide and makes paths sinuous, alive and just scary enough.

A generally pleasant spell ahead, with a rather ineffectual atlantic, thanks to significant ridge development over the UK, edging west as we move through the weekend, allowing frontal/trough to move down from the NW, bringing a spell of moderate rain for the NW, petering out as it moves into the ridge. Into next week both ECM and GFS consistent in showing the ridge holding firm to our west, and building which should maintain the generally calm conditions, risk of frost and fog and night, and a change in airstream will pull in some cooler air from off the atlantic as well, so maxima won't be far off average. As we approach latter stages of next week, indications the ridge may shift sufficiently west to bring down a much chillier airstream from the north, with some form of trough/frontal feature - it might slip to our east which would prevent a full on northerly, conversely we might see developments to our NW which would send the ridge towards Greenland and leave us exposed to a cold polar outbreak as we end the month. Late October can be a very stormy period full of wind and rain - this year it looks like being relatively quieter, with fog and frost probably the most notable feature.

p-stamps...out @months end.... some really intresting mixes there. meanwhile the designs are firmly in place for a monster pacific/western seaboard-bite....or formation into large mass USA. bossing' any gain of the pv into usual territory....and ainding squeeze of smaller...yet significant arms of waa in and around the mid/upper latts... just a case of trough and cell segment exactions.....winter in the northern hem has kicked off....and ...and is eyecatching on many levels.....

In the land of repeating patterns, the modelling over the past few days continues to promise much for coldies ..............

Evening All So my second main post in relation to Autumn / Winter 18. Thus far the initial forecast for this first half of Autumn has been really satisfactory with some notable successes- The Anomaly chart for Sept 1 to the 13th has shown that the jet has been forced off way to the North allowing perpetual Southerlies / SE winds to invade the UK & indeed western Europe- * We have seen notable heat - nearly 80F on 13/10 Oct - * There havent been many 'westerly days' & rainfall has accumulated for some over short sharp bursts as opposed to the usual steady build up. ( Again highlighted in the first post ) * Also whats been a key player & also has close similarities with Summer is the depth of the blocking around the mid lattitudes - Record breaking High Pressure in July over Europe , & September sees record breaking High pressure over Alaska- Sept 1-Sept 15 Global Anomaly This anomaly thats lingered up until the tail of September has been the main reason that W Canada has had the very cold start to the Autumn & also why Siberia has been a little slow to start with snowcover - The ice anomalies & low thermal gradient this year are really allowing for Higher than average pressure to exist in 'situ' even at Northerly Lattitudes - Examples of these powerful highs appearing at high lattitudes started appearing in 2010- Note The december to Remember- The second spell started with a 'super high' What these High pressures create is intense areas of WAA on the western flank & the same with cold on the eastern flank- they also allow for more Northward / southward penetration of the warm/cold So the conditions they bring are deemed 'extreme' for the localities on the recieving end of the advection- Backing up this theory of Low ice / warmer arctic seas > Higher Arctic Amplification > Intense WAA/CAA is the range of the metric of AO which in the past 10 years has gradually been stretched scalewise up & down - This Late Autumn / Winter - seems the perfect platform to deliver more of the same - Exceptional warmth interlinked with some potential for exceptional cold ! There are unlikely to be any over riding negative signals this winter- - Neutral El Nino Signature - Downwelling westerly QBO unlikely to be to adverse to the pattern- With more emphasis on positive links - Weak to possibly 'very' weak stratospheric vortex including a possible early warming event December to weaken the vortex further - Stronger disconnect in terms of tropospheric & stratospheric coupling - again the very shallow gradient weakening the 'westerlies' - Very low solar activity supporting the westerly weakness - 'Super high pressures' migrating Northwards towards the pole creating sharp transitions / modality changes in teleconnection metrics ( AO / NAO / PNA & POL ) these will also create big Stationary patterns of warmth & cold around the mid lattitudes For me the signals are overwhelming & give us a range of solutions for Winter that strongly suggest a below average DJF with a high probability of at least a 1 monthly rolling period ( not to be confused with a recorded CET month ) being below 2c. Higher incidence of Northerly & Easterly outbreaks. I dont rule this out exclusive to DJF - but also with the pattern expected to flip towards the end of October we could see some of this blocking in place throughout November. My eyes have turned to the stratosphere, which has seen a burst of activity lately bringing the zonal wind up above average of about 22 M/S - however the ensemble suite has shown that this may well be the peak for the moment as we drop back towards 20 M/S again in November ( the average being 30-40M/S as we head towards December ) So there we have it- some late Autumn / Early Winter insight - - Big Flips in the AO with some decent negative values arriving - Super High pressures retrograding up towards the arctic Circle generating significant CAA & stationary cold patterns - Possible early warming Late Nov / Early Dec to really take any Westerly sting out of the Jet CIAO for now....