phil nw.

A great illustration of why you have to give time for the block to orientate favourably. Then we get the cold air.It isn't a matter of a flick of a switch. The period days 7 to 11 is the first stage where we are looking for the pattern change via the amplification.

It's starting to look more like Winter and just as we enter December so timely output tonight. Gefs 2mtr temperatures for C.England and C.Scotland. confirming surface temperatures dropping off next week as high pressure builds.Another thing of note is the much drier outlook on the graphs as we would expect. ECM at day 7 going the same way as the others continuing the trend to a blocking pattern. At that stage the pattern change is just getting underway and based on past experience it will quickly get colder under high pressure as long as the Atlantic flow is cutoff as modeled currently. We then have to see if the high orientates in a favourable position to draw cold uppers to the UK.We don't usually switch to bitter cold in the UK straight away,oftenit takes some days before this happens whilst the setup evolves. For me the best outcome would be the link up of the Scandinavia and Siberian high which will brings the coldest air from the north east.The ecm at day 10 is a close thing but not far enough north for perfection.Even so it still brings a cold flow from the east. Promising charts but even better if the blocking gets further north in time.

The models so far are all showing the Atlantic ridging and being held at bay by day 7 which is getting close to the reliable. I think i would take that for a start we already have the block around Scandinavia so it will be a case of how the whole area of heights develop from there.Modeling will of course show various ways forward but a change of pattern now looks odds on now as the chain of Atlantic lows gets broken. Whichever way the new pattern goes it looks the vortex is getting a hit and we should see temperatures fall away as the westerlies are stopped.

Not too excited by the ext(15 day) gefs/gps.Yes we develop a Scandi.trough but the High to the west not inclined to visit as far north as Greenland. Time yet of course for the pattern to evolve.

High pressure building around W.Europe/Scandinavia seems the trend now. Just a matter of getting the high far enough north to draw the cold in. If nothing else it will be good to see the Atlantic held at bay so we can dry out.

Yes see all that warm air advection heading north pumping up the High. Sometimes the Azores high is the starter for a pattern change.1947 a good example.

Of course one of the consequences of any pressure rise will be the pushing north of the Atlantic trough before it recedes later. This will likely keep us in a mildish flow at least temporarily until the pattern change resolves itself. This may be the further building of pressure further north but I think that will be into December if we get the MJO activity as forecasted.

Some promising charts showing now for coldies later on. Still a way to go before I expect things to get really interesting though. The coming week still pretty unsettled and Atlantic driven but week 2 modeling showing pressure rising around nw Europe/Scandinavia as the Atlantic trough is killed off. I think as we go into December though we could very well see blocking develop further. I don't wish to jump the gun but the positive ht anomalies across the Arctic are trending in the right direction to establish a negative nao/ao next month.

The Strat.polar vortex at 10hPa is now quite cold and well formed with mean zonal winds forecasted to pick up further by early December. We can see from the images though that it's a different story lower down. From mid-level down forecast is for negative anomalies to continue so for the time being opportunities for further blocking patterns remain until we see a connection with the increasing winds higher up.

I am just keeping an eye of the way the models are holding back those blues(vortex) across Greenland. The encouraging thing is the high pressure keeps hanging around Scandinavia and is looking to extend further towards the Iceland/Greenland area. Granted weakish heights but more signs of a different pattern to normal as the jet is forced south. The forecast of an active MJO continuing into December,currently in phase 5 expected through 6 and into 7 in December has got my attention.This would support ongoing heights further north. As i understand it the MJO is usually active between November and February especially in Nino years so i was somewhat surprised that this one is reasonably strong as the Tropical Pacific often dampens down convection in a Nina phase. as it heads east towards the dateline.Maybe signs of a fading cooler(nina) phase starting in that part of the ocean. Anyway a Link to discussions here Madden-Julian Oscillation: Recent Evolution, Current Status and Predictions (noaa.gov) Usually there is a lag effect of 10/12 days so we may well have to see the month out with this current Atlantic pattern.Colder and unsettled. So no short term switch but hopefully we will see another round of renewed blocking as we get into next month .As ever there is no certainty of the UK getting some real Winter cold but at least we would be in with another chance come December. Better than a raging Northern jet pushing right across N.Europe and Scandinavia.It would be a long road to cold from that position.

When reading pressure anomaly charts you have to take into account the location of the anomaly features. For example a weak positive ( pale pink)over Greenland will still indicate low pressure up there as that is the climatic norm.You would need to see a dark red to suggest different. On the other hand a weak positive over the Azores would confirm a high pressure area as that is the normal setup. A bit of a generalised summary but just to give an idea.

Slowly slowly the Scandinavia/W.Russian block is (h)eating away at the pv as it looks to extend west . Over time this is pushing the jet further south with trough disruption around the uk and now looking to edge further south east into Europe. We can see this trend by viewing todays ECM 500 mean charts and out at day 10 with a mean chart the features tend to get washed out a little as we go further out but we can see those blues over Greenland on the retreat . At this stage the Atlantic still holds sway-just -but if this trend continues then a switch to a negative NAO is likely eventually as heights extend to the north forcing low pressure into mainland Europe to our south. It is a slow burn going down this route but an interesting one never the less.

I prefer that evolution Mike. The eastern block pushing west usually is a much slower way of getting cold in.It's usually a case of last minute hurdles and often fails under pressure from the Jet. The pattern showing in that 6 z GFS is a quicker route to forcing the jet south as heights rise over the top. Much easier way of drawing the cold in from the east or north.

Certainly a big drop in temperatures coming Pete. London ens show 10/11c fall in the 850s next week.Would suggest max's in single figures for most. A big change as we get a colder flow from the west.

From a cold pov it's encouraging to see the ongoing +ve hts being modeled around Scandinavia and trying to build further north. No immediate cold from this but the block is forcing the Atlantic lows further south which is a sign that the pv is not fully dominant as yet with this buckling Atlantic jet. If the block strengthens the low pressure would be forced to go under. In the meantime we will see cooler temperatures as the mild flow is cut off early next week with a wet spell as fronts slow down against the blocking. Plenty of interest to come in the charts whilst this skirmish continues.

The Atlantic struggling to win against the block next week.The battleground looks like creating some wet conditions as the trough disrupts nearby. The skirmish could continue for a while as those heights to our east look persistent. Temperatures set to fall as the mild flow gets cut off in the coming days so a different and more seasonal feel to things. Certainly a different and more interesting pattern than normal for late Autumn that's for sure.

Yes an observation voiced before. I just look at overall trends beyond a few days really including the anomaly means. There is plenty of support for ridging to our east which seems harder to shift as we get closer to the time. The UK model is not beyond a reasonable outlook even at day 7 . Time will tell as they say.

Yes we will have to see how this evolves.Indications though that the Atlantic is not pushing through and modelling is showing possible changes.

The UK model hints that heights are trying to build north. Not a done deal but a negatively tilted high is a good sign as it forces the Atlantic trough underneath towards the continent. Maybe the start of a change to a negative nao and a colder pattern.

At this stage the forecasted E.European block doesn't look to position favourably for any cold from the east. It does however eventually force the jet further south as Atlantic lows come against it. This cuts off the mild flow and lowers temperatures as we start to get cooler Atlantic air as shown in the gefs graph above. Nothing too dramatic as yet but a promise at least of a more seasonal feel.

No quick way to any real cold yet. It looks like the euro block will slow the Atlantic next week with the flow from the south west. The positive anomalies around Scandinavian and E.Europe look like persisting for a while but are poorly positioned .

Interesting ouputs from the 12s.with the later frames showing those Scandinavian heights again. We need to see the high far enough north and oriented west to east to bring in any easterly further on of course this would force lower pressure underneath. A way to go yet but those heights to the east are supported in recent ens.outputs so promising charts so far.

Yes.

Lol It's a mongrel name some of us have adopted to cover a combination Euro/Scandinavian high pressure area.

The coming 2/3 weeks will be a good test for the mjo forecast and it's associated analogue. Certainly recent ens guidance shows the Scuero ridge and likely development of a high close to our east or north east in week 2. Let's see if the Atlantic jet is forced further south in time and undercuts the high. Not yet though but possibly later in the month when conditions become more favourable to get the cold. Certainly it's early days yet I am thinking let the Atlantic roar for now allow for the lag effect and see what happens around mid month onwards.