Mucka

In the end things have developed pretty much as I expected with only a glancing N plunge but with an amplified pattern that ECM was resistant to for some time and any real hope of cold and snow being centred around another Atlantic ridge building toward end of Nov which was signalled a few days ago within GFS ensembles. It looks as though this won't give enough amplification to build high pressure over Greenland and will topple toward Scandinavia and normally into Europe without much interest but with some mid lat blocking still holding on and low pressure likely in Europe, then the potential for the Scandinavian ridge the models are toying with is obviously supported though by no means certain. So the assessment of a few days back of early Dec having potential for a cold spell has not changed other than the models giving it a little more representation. Interestingly there seems to be cause to be optimistic for further bouts of Atlantic ridging as we enter December (probably around 2nd) but at this time there is no way to know how strong that will be or what any mid latitude blocking it supports will look like at that time. In conclusion then I would say things are pretty finely balanced for December for now. The blocking could be overrun with a flatter Atlantic pattern or it could be reinforced with a more amplified pattern or we may continue with a messy half house and be in a similar position to now come early December. Hardly a conclusive conclusion was it? So for now I'm keeping a watching brief and checking in on the background signals and PV from time to time until there is a little more clarity (if there is a such a thing in NWP and British Winter forecasts) Certainly more interest than the usual zonal dross we are served at this time of year though.

Disappointing UKMO this morning with cold air just flirting with far N and E of Britain. GFS is better but also has the ridge further E with less of a direct Arctic flow. Might have been better but it stalls the shortwave low instead of pushing it through Which in turn erodes the blocking to our N So little chance of any low land snow for England away from the far NE (Either too dry or not cold enough) on either of those outputs and we would be relying on the Atlantic pattern reamplifying to deliver any real cold and snow chances. That said, quite big differences between UKMO and GFS at just 96h where it matters and with run to run variability we can't really take much from the output other than no firming up of a cold pattern and lowland snow chances in the mid term.

FI trend still helpful for early Dec Latest GFS mean continues to amplify the Atlantic sector for around the 28th so that signal has gained strength over the last couple of days, at least within GFS ensemble suite. If we do get a GFS like blocking scenario over the mid term then further blocking could well be supported into early Dec.

GFS 18z with the best mean chart so far, but will the positive trend continue tomorrow and which model will blink first.

It is just wishful thinking until it is proved one way or the other, but some wishes do come true. GFS still sniffing some amplification in the Atlantic again around the 28th which would be great if we can get some blocking to hold on until then.

If it is there it will be day 10 or around the 28th and show in the Atlantic, it is only hinted at for now but could just be a wrinkle that gets ironed out. Certainly ECM not interested as yet.

ECM surprisingly progressive again (to me), not often you see such disagreement between ECM and UKMO at 144 Let's see if there is at least some amplification upstream day 10 while it gets sorted out. As do ECM and Icon. Strange times.

GFS 12z sniffing out reamplification of the Atlantic toward end of Nov which could give an early Dec cold spell, especially if there is any residual blocking to our N. GEM has hinted at this though less amplified and ECM, although probably flatter, has looked primed so something to look out for on tonight's 9/10 day charts. In the closer term GFS is probably overdoing the Westward forcing of the Scandi trough and thus high pressure will likely be a little further E day 6/7 which would mean less cold 850 temps but on the flip side GFS generally models the area around SW Greenland better than ECM so I expect this mornings doom run to be thrown out and for a quite different outcome this evening re blocking. Regardless I will paying attention to FI for signs of another bout of WAA toward Greenland since any serious cold will be hard to come by on the shorter term though certainly not impossible. We could still see shortwaves S of Greenland actually work in our favour if they phase with the Scandi trough at the right time. Plenty going on so good model watching at least.

"So, you're saying there's a chance?" Not far off a link up with Atlantic ridge and Arctic high, although TBF cold spell chances have overall receded over the last 48 hours and we need some strong swings back toward Atlantic/Greenland blocking soon to have any real hope.

That's a pretty decent 10 day mean which suggests this chase has some legs yet. Countering that are recent UKMO and ECM Op runs which are very flat upstream and it seems this is a fine margins all or nothing situation as far as Atlantic blocking is concerned. Either the Atlantic amplification gets overrun and we see a flattening or it holds and energy is split and we see Atlantic blocking and Greenland height rises. That is all around 6/7 days out and the ensemble spreads show there is plenty of room for swings one way or the other in coming output. It would be nice if ECM Op swung back tonight but obviously not conclusive. If we do get the mid/high lat blocking to our W then cold & snow are still not guaranteed, but one step at a time...

All a bit convoluted and full of traps but GFS gets there Not often you get a Greenland high from Arctic blocking moving into Greenland By the way, what is the record negative AO

ECM Op is somewhat at odds with its ensemble mean from day 6/7 re pressure and 850hpa temps but with a very wide spread. It will likely be quite different again tomorrow but the total lack of mention of N blocking let alone cold at the MetO along with no consistent cold signal in the output means we should be pessimistic in our optimism. Sorry, 00z ensemble graph, spread tonight will likely be similar.

The models always struggle beyond 120 with blocking patterns but when background signals threaten to interrupt the Atlantic flux outside that range it is pretty hopeless trying to 2nd guess what blocking pattern may set up let alone how it may affect our weather. To emphasise this look at the differences between UKMO 00z and 12z even at day 6. Perhaps we can say there will be some form of Atlantic blocking setting up days 8 through 10 but that could be anything from a toppler,to a precursor for a Greenland or UK high.

UKMO also showing some pretty big changes from this mornings run by day 7 so any hope ECM has it nailed at day 10 already would be rather wishful.

Yes that it is encouraging whether the Operation runs give us the eye candy or not. The upstream changes from the 00z to 12z on GFS are huge so it is a case of nailing down the upstream amplification for now. GFS 12z/00z comparison day 10.

GFS 12z Op very different to this mornings 00z by day 7 and more in line with ECM with having the high further W although still not as amplified in the Atlantic at this point. GFS 12z/00z Check the difference in orientation of the high as well.

Hey bud' I'm good thanks and hope the same for you and yours and everyone else through this Winter's fun and games. Should be a good one and a nice early chase should get everyone in the mood.

Yes ECM is an absolute stonker this morning day 10. Winter will come early if that comes off. UKMO is more in line with ECM 168 with GFS somewhat out on its own. There will be some excited boys and girls this morning and I'm one of them.

Who needs coffee with ECM 10 day charts like that? Interesting...

Blimey, just checked the output this morning expecting to see some form of blocking set up and... What happened? Looks like I jumped the shark on that one. First false alarm of the season, glad it isn't even Bonfire night.

I see some posters have mentioned the potential for blocking toward mid month and I would go with that. This mornings runs seem to affirm the suggestion we have seen in various runs prior for blocking to the N and/or E take hold 2nd week of Nov. As always though it is very difficult know exactly what that will mean for the UK if it does set up in any meaningful way. An Easterly flow of some form, at least for a while seems most likely but often the models put out Easterlies when they first sniff out blocking but ultimately have the blocking further W and more Northerly component. And of course wherever any blocking sets up just the orientation can make the difference between cold or relatively mild. GFS mean picking up potential Atlantic ridge day 7 UKMO day 7 So it looks as though a Sceuro ridge of some form will stall the Atlantic trough and force it to dig S with the potential ridging behind. It takes something exceptional to get proper Arctic cold to our shores in November so a long way to go, but of course we can dream of that record breaking late November cold spell. Original post: https://community.netweather.tv/topic/99428-model-output-discussion-mid-autumn/?do=findComment&comment=4946796

I see some posters have mentioned the potential for blocking toward mid month and I would go with that. This mornings runs seem to affirm the suggestion we have seen in various runs prior for blocking to the N and/or E take hold 2nd week of Nov. As always though it is very difficult know exactly what that will mean for the UK if it does set up in any meaningful way. An Easterly flow of some form, at least for a while seems most likely but often the models put out Easterlies when they first sniff out blocking but ultimately have the blocking further W and more Northerly component. And of course wherever any blocking sets up just the orientation can make the difference between cold or relatively mild. GFS mean picking up potential Atlantic ridge day 7 UKMO day 7 So it looks as though a Sceuro ridge of some form will stall the Atlantic trough and force it to dig S with the potential ridging behind. It takes something exceptional to get proper Arctic cold to our shores in November so a long way to go, but of course we can dream of that record breaking late November cold spell.

I don't know about the use of th3 word "bomb," typical media hype, but explosive cyclogenesis looks probable at the base of the trough for 2nd and 4th Nov. Currently, the 2nd looks more likely to be a potentially disruptive storm and coastal flooding could well be a headline feature along with any exceptional winds.

Looking like the models are firming up on potential storms for 2nd and/or 4th Nov. At least one of those looks like it could be severe with coastal flooding. I'm sure MetO are keeping a close eye on that potential beyond heavy rains in the more immediate.

It is still away out for any detail but it is starting to look like November could begin with a bang even before Bonfire night.