Really??!  Winter's ended before I migrated back to the Forum.  Typical.

waits patiently with her TWO forum Winter Bingo Card...

Won't be long before I can call BINGO!

In view of the posts above re SW/SSW, a question I would ask here is was there any SW or SSW event in the lead-up to the freezes which commenced just after mid-December 2009 and late November 2010?

It might be an idea for people to spend some cash on some sledges or a pair of skis, Maunder.

Eyes down for the 12z this is the most crucial run of the season so far.

LOL, yes.  By the time you've worked through every perturbation and compared with other model output it's probably pushing six hours and then the next set of runs are appearing....

haha, this is so true 

That would be a jinx David. I am going to wait until we have lying snow before getting the sledge runners oiled.

Problem with owning a sledge in this country, is that it gets so little use.

Not sure about any SSW then, but one linking factor with today is: deep solar minimum!

2009/10 - Yes, a SSW was involved.

2010 was a split PV - can't seem to find much evidence on a SSW apart from Paul Hudson's blog:

"A week before the onset of severe cold that begun at the end of November 2010, stratospheric warming was observed, which led to a forecast which successfully included a risk of cold conditions developing across the UK."

https://www.bbc.co.uk/blogs/paulhudson/2012/10/a-step-forward-in-forecasting.shtml

Which sounds a bit odd - "A week before..."?

Can / does a SSW have an affect on our weather that quickly? I thought it took weeks to 'transfer'

Yes, I thought it sounded suspect for the same reason.

However looking at the MetO long range forecasts I posted earlier, it was clear that something was afoot going back to October 2010, with talk of "well below average temperatures" in mid-November (although the timing was a bit out), so they could clearly identify some mechanism at work - whether that was a SSW or not, I don't know. 

This chart screams:

www.wetterzentrale.de/maps/GFSOPEU12_225_1.png

I don't have a clue

One for the bin. 

GFS goes from 

www.wetterzentrale.de/maps/GFSOPEU12_231_1.png

to this

www.wetterzentrale.de/maps/GFSOPEU12_276_1.png

Its far to progressive for my liking. But could still be a trend. All to play for still

When a SSW occurs you can have a QTR (quick trop response). This usually occurs a few days to a week after the SSW.

IIRC this was pretty much what happened in February 2018 which led to the "Beast from the East" event. If memory servies me well, the SSW itself happened around the middle of the month and it only took a couple of weeks or so for the effects of it to filter down from the stratosphere to the troposhere.

From what I have read about it, more often than not there is something of a time lag between a SSW taking place and it having any noticeable effect on the UK's weather. However, as I have mentioned in my post above, the events of February 2018 demonstrated quite clearly that this isn't always the case and that sometimes the effects of a SSW on the UK's weather can become apparent fairly quickly.

Will be interesting to see if ECM copies any of GEM's working-out later.

Looking like Greenie High on Ecm and UKMO tonight, everything moving rather quickly, and in our favour for once 

True, but the data I’ve seen suggests there’s a disconnect between strat and trop at the moment which suggests any downwelling of an SSW may take longer than usual. We’re in unusual territory here as the sort of warming being modelled currently rarely occurs this early.

Yes, interesting charts - regardless of any SSW or not, the Trop PV is struggling to get going this year and the purples are all on the Asian side of the Pole for once, instead of in the usual location of Canada/Greenland.

Negative NAO anyone?

Yes, but it looks far from being a static block. By the end of the ECM run it's weakened and retrogressed to the west of Greenland, which opens up a lot of mild options.

Some interesting prospective synoptics but I think the usual caution applies, i.e. consistency, cross-model agreement and clear ensemble support. Plus, it would be reassuring if the MetOffice was seeing a clear signal for something colder, which at the moment it isn't - they're still backing a basically mobile westerly pattern.

I think the trend is key - there's clearly an interesting trend evolving in the models.

With regard to the SSW impacts, from what I've read the disconnect Strat to Trop is unlikely to be bridged before mid December.

Potentially dumb but genuine question - so if there's a disconnect, doesn't that mean that any SSW won't impact on our little bit of the atmosphere?

Normally you'd look for a SSW to disrupt or split the PV but if we're still in a regime where the trop/strat forcings aren't in place then a SSW would presumably do nothing as it won't be able to downwell or whatever the expression is 

Model wise and must admit I'm finding it hard to get interested in the usual winter chase for some reason this year - been doing a quick scan of the reliable of the GFS ens and just seems like a slow crawl to slightly above average weather down here with more rain around and the usual 'who knows' scatter in FI.

ECM is interesting but with HP to the NW and E or SE just means for my back yard it's likely to be mild and damp- much more interesting for Scotland though, with colder air in place and some precip too.

IIRC, back in 2009 it wasn't until a few days after the models that we have access to began to consistently show a notable rise in pressure over the Greenland region that the MetO began to mention to possibility of a cold spell in their daily text updates. Prior to that, they had been going for a mostly unsettled and mostly mild outlook for most of December 2009. They seemed to be rather quicker at spotting the likelihood of a notable cold spell in November 2010 than they were the previous year.

I'm not for one second saying that things this year will play out like they did in 2009 in terms of the models leading the MetO, but it shall be interesting to see what the models produce over the coming days.