If nothing else, its just nice to see an LP head under a HP northerly toppler than run over the top.

First time  - well, maybe 7-8 yrs since i saw that happen, (at this point in the charts), last?

Did that not happen in 2013?

Well the GFS ends on a pretty perfect set-up to start the Christmas break :)

It's been trying to do this for a while but this is the first time we've seen a proper Scandi high crop up for a while. Heights over Greenland as well which would hopefully encourage trough disruption and send a low underneath to squeeze some of that cold air our way. Yes please.

My only quibble would be the rather pathetic cold pool to the east, but never mind!

That wasnt a northerly toppler - that was more a block to the east with slider lows running up then deflecting south east.

Isn't that because it’s not a toppler? There’s enough of an upper high to prevent that pulse of energy driving through. A bit like pushing at the lower part of a balloon instead of the upper part.

It’s such a delicate balancing act with sliders: too little energy and they slip away SSE and stay to the west; too much and they can end up too far east and put southern/western areas the wrong side of the cold/mild divide. This looks like the former.

GEM is fun this morning with a trough disrupting and spawning a closed low as it heads SE. Lots of snow for some off this:

ECM clusters anyone 

Not quite sure what the bottom charts indicate - any Icelandic speakers here?

Not often I say it, but I'm with GtW on this, and don't view this strictly as a toppler situation. I thought you were just talking about energy sliding under blocking to our north (2013 had a few different scenarios that delivered here, including, IIRC, blocking to our N/NW?)

Yeh, I realise this hasnt (yet) turned into a toppler situation.  Theres obvs better connection to GH at this point.

My point i suppose if there is one.. is that in years gone by - after say 10 days of model following this feature, the HP has maintained its desire to stay with a northern GH link bias... rather than dissolving to the south and introducing milder air via Iceland (the later aspect always has me saying that through gritted teeth)

I suppose this should be in the moaning thread on some level - as its a bit of a rant at our weather.  

Yes, that is the major change with this initial cold set up, well in the modeling anyway.  It does seem to happen annoyingly often but the background appears more set this time for other opportunities along the line as well as this one, which even with that shift N.E of the LP, still looks reasonably potent 4 days out.

The first two are ‘text book examples’ of a positive and negative NAO: the third one seems to translate as the current pattern; not sure about the 4th - Google translate says it means ‘sorry’...!

The 06 h has the ideal evolution we are hoping for.Starting at 252h  a depression crosses UK finishing up close to eastern England before moving away.This allow a more northeasterly flow to develop,  the development of HP to the northeast and finally an easterly flow over the UK.

Chance of this coming off inevitably low!

Yes the ensemble shows that the OP is rather out on its own for that evolution. However there is still a colder cluster in the medium range, several of which show an easterly or northeasterly pattern.

With regard to the upper air temps, and the upcoming NW'ly spell, whether it will or won't be cold enough..

A good benchmark I like to use is Christmas Day 2004. At 6pm it started snowing here and much of the NW had lying snow. I think there was a dusting further south too?

FWIW - these were the uppers at the time of the snowfall.

http://www.wetterzentrale.de/maps/archive/2004/cfsr/CFSR_1_2004122518_2.png

The end of this week looks colder.

Hey Joe

I already dug out those charts earlier as a comparison.  youre right.  This event was one of a few i remember giving a decent 6cm depth from actual snow showers in merseyside.

I can't see it being anything other than lying snow for you as long as you get the showers. You look to be in a very good position.

However on comparing 2004 to this week, it is worth noting that that pressure was around 15mb lower in 2004. Therefore the 850hpa temperature level will be higher this time around.  Equals losing about 130m in elevation . Also the wind is stronger this time so perhaps the Irish Sea will modify thinges more. However if I lived in Manchester this wouldn't concern me, only the coastal fringes.

As i recall one of the November 2016 snowfalls , convective showers from a westerly happened with 850hpa temps of above -5c . But pressure was very low.  Surprised a few people  who initially discounted it on the 850''s alone. 

As the skies cleared later in the evening, it froze, too.

Looks like being a pretty average cold snap coming up in my back yard (Worcestershire) - however, when there is a meridional jet pattern, there is always hope of landing something special. The best winter in our region since the classic 62/63, was 1981 - fabulous in the West Midlands - how I would love a repeat of that. But that requires something a lot more prolonged than a transient northerly.

yeh all pretty standard stuff, in fact in the longer term it wouldn't surprise me to see temps rise fairly readily towards the Christmas period- only a personal opinion of course.

Skewing the aul stats there a bit aren't we GTW?

Tallyho & John2016, interesting points!

Nope, the stats are spot on, thanks.

Closer to 79% of Winter left when you consider the context of time I was talking about. I didn't use the then present as a starting point.