With regards any SSW I was always on the understanding there was a 4-6 week time delay with regards blocking 

Any thoughts ?

I believe it’s more like 2-3 weeks. Bear in mind the SSW is only just coming to a slow end. Let’s give it until the end of the year before we write January off.....

Yes, but at least we have lots of interesting politics to keep us amused next month, and we can use the money we save on heating to buy tins of British grown beans to stockpile for Brexit

However, the signals from all the other models is at least a little encouraging as is the consistent and unusually high confidence from Met Office forecasts.

I will certainly not be throwing in the towel just yet because I honestly believe we will see a big flip from GFS in the next 3-4 days.

Really?

Blimey you are confident mate 

Soon we will be 6 weeks into winter come 1st week of January and there has been no frost or cold to talk about! So I am sure you can appreciate the frustration from cold weather enthusiasts - even without the SSW we don't even seem to be getting transient North westerlies or northerlies like last year or year before etc....?! Virtually nothing of interest from a cold perspective on the 06z run. 

Not another Pizza that again?!!

More like a Greggs pizza slice that one!

either the GFS will flip cold or met Office update will go mild in line with models. Hope it's not the latter?

The Met Office forecast which suggests a change to cold weather from mid-January or the GFS which goes out to the 12th of January? 

if you are that worked, take a break and look next week you might be surprised failing that upset !!  Zonal will not prevail for eternity and a change will happen it just might not make us go into the freezer

And we all know how accurate GFS T384 charts are 

The long range models/teleconnections seem to have indicated a change to cold from around the 10th to 15th of Jan. At the moment that's still 14 days away at the earliest. If in a weeks time there are no building blocks to cold showing in the output then it's time to get worried. I know there will still be plenty of Winter left but one thing I really don't want is a repeat of last Spring.

Please can we have some cold in actual Winter? 

The standard propergation time for a SSW is 10-14 days, thats from the top down to the troposphere.

Post the final date where the winds have reversed you would expect to see heigher heights extending into the pole & more high lattitude blocking, the blocking pattern 'locale' is directly related to where the lobes of the vortex are when theres a 'split'

This is where models like the GFS fail moreover than the Euro/ Euros- the vertical resolution of the ECM is far superior to the GFS- Which is why the GFs couldnt see a split @10HPA when the ECM has it nailed days out, the GFS just sees a blob of displaced energy.

With that in mind we move onto a 'QTR' - quick tropospheric resonse, which as the name would suggest- The troposphere responds to the reversal far quicker than the standard 10-14 day window.

A QTR will create high entropy ( what we have now ) & for a non 'high top' model like the GFS it will not resolve the jet deceleration until much closer to T0. ( Vis a vee GFS will 'project' everything further East as opposed to the Euros that will resolve the deceleration quicker- ( within that initial signal of high entropy )

What this means essentially is if your an avid GFS fan your 'zonal' flow will ever so slowly be replaced by an amplified pattern, not across one run but ever so slowly the over projection east will correct West & North.

As we stand today, this mood of this forum is highly gravitated towards the GFS ( still not sure why when its poor ) so to that end its no suprise theres minimal excitement here-

However all the other models have caught up- The ECM operational yesterday, most of the EPS today- with the ICON being the slowest & most farthest west-

So, the winds of change or shall I say deceleration are blowing over the models at the moment, it hasnt quite reached the GFs which is about 6/700 miles to far east @144 this morning....

S

(a) Not all SSW's produce cold spells in the UK - they increase the chances of blocking and colder weather.

(b) Not all SSW's are the same. This one appears to have been a 'displacement' type event followed by a split.

(c) Historically, repercussions of stratospheric events do indeed take 2 to 3 weeks to completely impact the troposphere - if indeed they do...not all do.

(d) All other 'ducks' need to line up......soooooo

(e) The current MJO is in phase 5 and expected to propagate into a strong phase 6/7 which would tend to encourage a negative NAO by late January.

(f). We're in a moderate El Nino - which tends to produce milder first halves to winter in northwest Europe and 'colder' second halves. (This can be masked though by the general ongoing seasonal cooling which makes January/February colder than December anyway).

(g) We're at the bottom of the 11 year solar cycle where colder, more blocked winter tend to cluster.

(h) Unfortunately the QBO is the one big player which has now gone westerly (having previously been easterly) - milder winters are therefore favoured - but not guaranteed.

Only on the very latest Contingency Planners Forecast have the Met Office suggested below average temperatures are more likely than above. All of those issued to the end of November had favoured above average temperatures.

The strongest signal for easterlies from both GLOSEA and ECM has always been February.

So far the seasonal expectations have gone well - a mild first half. We're now entering the business end of winter. I'd expect, not least that we're entering (climatologically) the coldest eight weeks of the year that winter weather will put in an appearance. What form this takes, its severity or longevity is still open to debate - but personally I feel there is enough evidence to suggest colder easterly types could become more apparent as time progresses.

Hold the faith....

I feel that the GFS is leading the way at the moment, first to identify the sinking of the High for early Jan.

It should be noted that the METO cold period though is mid-Jan and not even at the beginning of the period starting Jan 11th on their update so even the GFS at T384 only takes us up to Jan 12th.

What everyone should bear in mind IMO is that though what GFS shows is an important part of the overall picture, is it not the be all and end all. I think that GFS sometimes gets more attention that the others because it issues four updates a day whereas ECM and UKMO only issue two per day, but the solutions they come up with are no less important even though they don't go as far ahead and they only issue two updates per day as opposed to four.

What I have noticed about the FI section of a number of recent GFS op runs is that while it shows things turning generally unsettled, it does at the same time show the jet stream taking a more southerly track with what looks to be some fairly cold air moving into nothern areas. This was a pattern what we had on a few occasions last winter IIRC and one which delivered a few transient snow events to parts of Scotland and possibly northern England; we had snow on about five or six consecutive days back in mid-January where I live.

That is true, however the 384 stamps virtually all look a good way off a significant cold snap.  

https://www.theweatheroutlook.com/twodata/gefs.aspx?run=na&charthour=384&chartname=ps_500hpa&chartregion=na-region&p=1&charttag=PS%20500hPa%20(GPDM)

PS: I see some people are now falling back on to El Nino back loading the winter.

Great summary John. 

I mentioned this a couple months back.. this forum should be renamed 'Model output (mainly gfs) discussion *date*'..

It's the only one people only take notice of in here.

6 January and gfs has low pressure slap bang over UK and awful weather..

same time ecm has high pressure over lower Scandinavia with a low over Italy and easterly winds just clipping South East England but with the real cold heading into France and towards Spain.... wouldn't take much direction north or west to bring some deep cold to England. 

Good stuff John (and a belated Merry Christmas!)

I'd disagree , there are far too many knowledgeable people in here.

More charts get posted and more comments made but only because it goes out to 384 and appears 4x a day