hi Gandalf. I think he simply means things turn anti cyclonic. In an unbelievable fashion (rather than uncredible).

Ah, that may be a good call.

But there's plenty of blocking in evidence at high latitudes from Day 7.  The exact positioning varies, as is not uncommon. I don't see anything particularly unusual in the evolution - except that the overall pattern is unusual.

Certainly looking anticyclonic going by the ECM late-term. Looking Nov '10 -eqsue

It's certainly not a million miles away from mid-late November 2010, Tom, that's for sure.

Whether or not we get a ending to this November that in any way resembles what happened in the final week or so of November seven years ago is another question entirely. However if we are to have a notable cold spell at some point in the near future, the building blocks will have to be put in place before anything can happen. Maybe, just maybe, what the models are showing could be the first blocks being put in place- we shall see.

 

It's certainly not a million miles away from mid-late November 2010, Tom, that's for sure.

Whether or not we get a ending to this November that in any way resembles what happened in the final week or so of November seven years ago is another question entirely. However if we are to have a notable cold spell at some point in the near future, the building blocks will have to be put in place before anything can happen. Maybe, just maybe, what the models are showing could be the first blocks being put in place- we shall see.

That is how I see it David. No two seasons are directly analogous and the positioning of blocks and troughs in late 2017 won't be exactly as it was in 2010. However, the important thing is that the PV is being disrupted and blocking is looking likely - how that pans out in our corner of the hemisphere is anybody's guess, but without blocking, we have no hope - so definitely glass half full at the moment.

If the ECM 12z isn't worth some fresh analysis from me here, I don't know what is, so here goes...

Right. Day 6, when ECM is usually king of the hill but not without some hiccups. We see that GFS (left) has a trough by Iceland with the deepest - near 985 mb - portion located between that island and Greenland. Meanwhile ECM (right), while also having a trough by Iceland, has the focal point a little east of GFS but shallower at near 990 mb, while on the western flank there is a small secondary low. 

Looking at the 12z UKMO and JMA runs, they both bare more resemblance to ECM than GFS, but while the secondary low is there, it's weaker and less well defined.

Another important feature to consider is the low by the East U.S. Coast.  GFS has this further NE than ECM, while JMA is similar to ECM and UKMO has the low even further SW and weaker too.

Now let's jump two days forward...

Well then. GFS' lack of secondary low has allowed the main trough to advance east without much trouble, while the faster low off the East U.S. Coast has managed to push through ahead of a ridge build taking place in the far-western N. Atlantic. By contrast, ECM's has the secondary low causing the trough to elongate on the SW flank and interact with the shallow low visible near the Azores back at +144 hours, while the slower low by the U.S. has become trapped behind the far-W. Atlantic ridge build (which in turn has been shunted a little east as the low hit the buffers). 

Now I can't clearly tell whether UKMO is set to have that interaction with the Azores low as a result of the secondary low on the western flank of the trough by Iceland, but I certainly see that JMA is, because the chart is right there for the admiration;

That's a strong vote for ECM having the right idea here, but as ever, we can't rule out the underdog GFS even at +6 days range.

Interestingly enough, yesterday's JMA 12z was similar to this morning's ECM 00z. So the two models seem to be moving in tandem.

It's fair to say that GFS has moved quite a bit toward ECM today too, with increased heights to the east in the 12z run for early-mid next week relative to the 00z, for example, so there's a lot of momentum in the trends here - but it's one that's still fresh enough to merit caution.

Now, I think it's only just if I post that ECM day 10 N. Hem perspective in large format to round this off;

- and yes, that really is a December 2010 style situation. A few other major examples also spring to mind - which I expect some of you on here can figure out .

Great read, Stormzy

You mean Similarities to Dec 1962 by any chance?

This could be quite the snow storm if it panned out

Looks like ECM was a little out on its own:
http://www.weersite.net/?actueel&ensemble&ecmwfpluim

Out to Day 10 the operational was very close to the ensemble mean.

Here's the London chart:

Of course the entire ensemble suite can flip as well as the operational but the trend at the moment is clearly colder with two main clusters - one showing rather cold (amxima 7-8C) and the other cold (maxima around 5C) beyond day 11.

This could be quite the snow storm if it panned out

 

Based on that run I'd say rain for all low ground because the uppers aren't cold enough.  The precipitation charts shows snow for the high ground of Wales and, I guess, the Pennines.

If the ECM 12z isn't worth some fresh analysis from me here, I don't know what is, so here goes...

Enjoyed that. Thanks

 

Based on that run I'd say rain for all low ground because the uppers aren't cold enough.  The precipitation charts shows snow for the high ground of Wales and, I guess, the Pennines.

There's hope even for the south (if you believe the models two weeks ahead!) Thu/Fri 23/24th worth a quick drool

https://www.netweather.tv/charts-and-data/snow-risk

Two different scenarios but both with the same outcome ( if FI is right that is ). The GFS looks epic in terms of wintry precipitation for those in the North and higher elevations with an alternating NW/N airflow, whilst the ECM has that low exiting Newfoundland much quicker thus flattening the pattern however by day 10 onwards both models appear to want to build heights over Greenland.

Two different scenarios but both with the same outcome ( if FI is right that is ). The GFS looks epic in terms of wintry precipitation for those in the North and higher elevations with an alternating NW/N airflow, whilst the ECM has that low exiting Newfoundland much quicker thus flattening the pattern however by day 10 onwards both models appear to want to build heights over Greenland.

Huge difference at D10 though you can have either a GFS northerly or an ECM Euro high which would keep us dry and cold

That.

We just know that as soon as cold air start to penetrate further south over North America (such as what appears to be happening right now) - there'll be increased chance of North Atlantic cyclogenesis  . . . and you know the rest.

I don't think it's that simple. Cyclogenesis isn't just a function of a cold air mass coming out of the US/Canada; there are other factors. Then, even if low pressure is developing the track it takes is also an important part of the jigsaw.  We've all seen occasions where low pressure develops and then tracks north, driving WAA up towards Greenland. Or the jet can take a more southerly track.

So, yes, it can be as you describe but it's not an inevitable evolution.

As Brian has alluded to there could be some sleetiness quite far south this weekend.

Interesting output to watch this morning. Again we are being teased by northern blocking in around 10 days time but I'll wait until it gets closer as these events seem to get toned down.

GFS catches my eye most, whereas there isn't anything particularly cold for the UK the amount of northern blocking across the NH is very impressive and a decent cold spell could materialise from such a pattern.

ECM remains dry and cold, UKMO remains quite flat. After the weekends northerly that is the theme for a short while, a very slack pattern setting up so we are likely to see more big fluctuations in the mid-long range model output.

Good to see lower SLP around the Azores again.

What i feared seems to be evolving in the charts this morning. Whereby we have the cold to our north,. We have the blocking in the right position.

Ye the atlantic tries to fire into life and results in the UK being held in a warm sector.

I do feel this might be the models yet again getting to grips with the start of winter and actually - is similar to previous attempts from winters gone by where we all Ramp away, and result with nothing.

Time will tell.