This is the thing - the latter will all depend on whether or not we have a short-loved milder spell with winds from the west, or perhaps colder weather with winds turning more northerly or northeasterly! 

If milder from the west this can go on for days if not weeks of zonality if not then we have winds from the east or north east then we could build a block so the latter 5th to 19th is difficult to forecast, because of the uncertainty in the forecast between 25th and 4th December . GFS has the cold spell upgraded for next week that;s for sure!!

UK Outlook for Monday 26 Nov 2018 to Wednesday 5 Dec 2018:

Many places will be dry early next week, but often with large amounts of cloud around. Eastern and perhaps southern parts however may continue to see some showers around initially, with the a few heavier showers possible. The west and southwest of the UK will then likely turn more unsettled as we finish November, with these conditions possibly progressing northeastwards. It will generally remain on the cold side for the time of year, with the risk of some frosty nights and also some transient hill snow. Into early December, there is a lot of uncertainty in the forecast, as there is the chance of either a short-lived milder spell with winds from the west, or perhaps colder but drier weather if the winds turn more northerly or northeasterly.

UK Outlook for Thursday 6 Dec 2018 to Thursday 20 Dec 2018:

Through this period, there is likely to be a continuation of cold and mainly dry weather for much of the UK, with sunny spells and a few showers. However, there is a chance the weather pattern may change temporarily, with fronts moving in from Atlantic. This would bring longer spells of rain, interspersed with brighter, showery interludes, and it would also become less cold. However, even if this change does happen, it won't be long before we have more settled weather again, perhaps by the middle of December. This would mean a return to colder conditions, with overnight frost and fog more likely.

https://www.metoffice.gov.uk/public/weather/forecast 

Today's Met Office UK Outlook for Thursday 6 Dec 2018 to Thursday 20 Dec 2018 is same as yesterday's UK Outlook for Wednesday 5 Dec 2018 to Wednesday 19 Dec 2018.

Which is often the case in the longer range text updates some weeks it's only updated once or twice

yes - I did/do wonder when they last updated the 16 to 30 day outlook?

The last major change was November 15th & 16th 

UK Outlook for Friday 30 Nov 2018 to Friday 14 Dec 2018:

This period is likely to begin with a continuation of cold conditions. The best of any sunshine is likely in the west with generally cloudier skies in the east. There is a continued chance of showers for all areas with snow over the hills, mainly in the east and north. More organised areas of rain and hill snow could affect many areas at times, and there is a low risk of snow to low levels. Confidence is currently low towards the middle of December. However, there is an increased chance of less cold conditions arriving as weather systems moving in from the Atlantic.

UK Outlook for Saturday 1 Dec 2018 to Saturday 15 Dec 2018:

This period is likely to begin with a continuation of cold conditions for much of the country. There is a small chance that during early December, the weather pattern may change, with fronts moving in from the Atlantic, bringing rain, interspersed with brighter, showery interludes and also less cold weather. However, should this come off, then this change will likely be short lived, with more settled conditions becoming re-established by the middle of December. This would mean a return to increased incidences of overnight frost as well as the risk of fog.

They've made a few tweaks since then but pretty much along the same line

Again it's mid December! 

Yes similar theme - So mild or less cold until mid December at the very least.

Holidays have been cancelled, families are crestfallen, and projections suggest a further decline in snowfall in coming years.

"Exceptional" weather in Lapland means no snow has fallen on Santa's homeland this year.

Unseasonably mild conditions, which are likely to become more common as climate changes causes global temperatures to rise, has left many families crestfallen by dream holidays that failed to crystallise.

At a time when northern Lapland would normally have 20-30cm of snow on the ground, there are now no more than a couple of centimetres in isolated patches, and the majority of the area has no snow at all"

https://news.sky.com/story/no-snow-in-lapland-as-rising-temperatures-take-sparkle-away-from-dream-holidays-11559423?dcmp=snt-sf-twitter 

BBC monthly outlook

Summary

A chilly start, but gradually turning milder

Wednesday 21 November—Sunday 25 November

Cloudy and chilly with an easterly airflow

Until Friday, chilly east to south-easterly winds are expected to dominate for most of the country, and will continue to bring in a feed of frequent cloud and patchy rain from the North Sea. There will be some cloud breaks at times too - a widespread air frost will develop in the south on Thursday morning, thanks to clearer skies overnight - but in general, western and southern Britain will be driest with some sunny interludes. A front approaching from the south-west may bring some showers or patchy rain to southern and south-western Britain on Friday night and Saturday. By Sunday, it looks like cloud and patchy rain will linger for the southern and eastern half of the country; some snow flurries are likely over high ground in the north. The driest, sunniest weather looks to be in western Britain this weekend, although even here there is the potential for the odd rogue shower. It will be chilly for all areas, with the coldest weather likely in eastern counties of Scotland and northern England, where a cold east to north-easterly airflow will continue from the North Sea.

Monday 26 November—Sunday 2 December

A chilly easterly at first, but milder later

On Monday, cold east to north-easterly winds will continue across the northern half of the country, continuing to bring a lot of cloud, as well as some showers or patchy rain. Again, western areas are likely to remain driest and brightest. Next Tuesday looks to be drier, as a ridge of high pressure builds across the country, although low cloud may linger in some areas. By Wednesday and Thursday, milder south to southeasterly winds should develop ahead of an active warm front, which will bring rain to most of the country from the south-west, and mountain snow to northern Britain. It then looks likely that we will see more of an Atlantic influence later in the week, with low pressure generally expected to remain close to the west or south-west of the UK. This should continue to bring mild and moisture-laden south to south-westerly airflows, which will favour lots of cloud and frequent bands of rain, particularly for the southern half of the country. Scotland may take longer to warm up during the middle of the week, although it should become milder here too by the weekend.

Monday 3 December—Sunday 16 December

Becoming mild, breezy and wet for many

It still looks like the beginning of December will maintain the rather mild theme expected to develop at the end of this month, with rather mild, breezy and often wet conditions for many areas. A broad west to south-westerly airflow should take charge, bringing frequent outbreaks of rain to southern and central Britain. However, with cold air still lingering over Scandinavia, there could be some chillier interludes from the east or north-east into Scotland, perhaps allowing snow to fall to low levels. By the middle of December, there is unusually high confidence at this range for mild conditions to develop widely across the UK, as a frequent south to south-westerly airflow becomes more likely. With the airmasses being drawn up from the sub-tropics at times, there will be a more widespread risk of heavy rainfall across Scotland and Northern Ireland, and there is a slight risk of some strong wind events across western and northern Britain. Despite the mild conditions, a stiff breeze and rather cloudy weather should take the edge off the temperatures. The main risk by mid-month is that high pressure develops closer to the UK, displacing the low pressure track to the north and bringing drier and cooler conditions for most areas.

Next Update

Could there be hints of some stormier weather developing in the run-up to Christmas?

https://www.bbc.co.uk/weather/outlook

Into next week

More uncertain
Some rain
Southwesterly wind
Milder

https://www.bbc.co.uk/weather/features/46297249

Woah! Wait a sec V's the Met office's 'a lot of uncertainty' - interesting how the BBC monthly outlook talk about unusually high confidence? WHy unusually high confidence? WHta makes it unusually high at this range?

UK Outlook for Tuesday 27 Nov 2018 to Thursday 6 Dec 2018:

Many places will be dry on Tuesday with variable, often large amounts of cloud. The best of the sunshine is likely in the west, with scattered showers, chiefly affecting the north and east. On Wednesday it will probably turn cloudier and windier across the west and southwest, whilst areas further east and northeast turn drier with some hazy sunshine. Temperatures are likely to stay below normal on both Tuesday and Wednesday. The end of November and start of December may see some less cold, albeit wet and windy weather spread from the west to all areas, possibly giving transient hill snow. This could then be followed by colder, showery conditions. However, an alternative scenario is that largely dry and cold conditions persist during the latter stages of this period.

UK Outlook for Friday 7 Dec 2018 to Friday 21 Dec 2018:

There is a chance during the first few days of this period that areas of low pressure could spread some relatively mild and wet weather in across the British Isles from the west. However, if this happens it is likely to be short lived and the majority of this period is set to continue being dominated by a blocking weather pattern, giving predominantly dry but cold conditions. This mostly settled weather will give an increased chance of overnight frost, and some fog is also likely.

https://www.metoffice.gov.uk/public/weather/forecast 

Next week

Starts cold and dry

Probably turning milder

https://www.metoffice.gov.uk/videos/5970019262001 

No high confidence as per Beeb 

MetO update from this afternoon:

UK Outlook for Tuesday 27 Nov 2018 to Thursday 6 Dec 2018:

Many places will be dry on Tuesday with variable, often large amounts of cloud. The best of the sunshine is likely in the west, with scattered showers, chiefly affecting the north and east. On Wednesday it will probably turn cloudier and windier across the west and southwest, whilst areas further east and northeast turn drier with some hazy sunshine. Temperatures are likely to stay below normal on both Tuesday and Wednesday. The end of November and start of December may see some less cold, albeit wet and windy weather spread from the west to all areas, possibly giving transient hill snow. This could then be followed by colder, showery conditions. However, an alternative scenario is that largely dry and cold conditions persist during the latter stages of this period.

UK Outlook for Friday 7 Dec 2018 to Friday 21 Dec 2018:

There is a chance during the first few days of this period that areas of low pressure could spread some relatively mild and wet weather in across the British Isles from the west. However, if this happens it is likely to be short lived and the majority of this period is set to continue being dominated by a blocking weather pattern, giving predominantly dry but cold conditions. This mostly settled weather will give an increased chance of overnight frost, and some fog is also likely.

Updated: 13:59 on Thu 22 Nov 2018 GMT

No change in forecast from the MetO, contrary to what one or two were predicting in the model thread this morning and last night.

^^^^^^^^

Met seem keen on a blocking pattern 

Into next week

Unsettled
Generally mild
Winds from the south
Growing confidence

https://www.bbc.co.uk/weather/features/46311812

Interesting that the METO stay with a largely blocked and cooler theme.

The BBC seem very much an outlier with the medium term forecast at the moment.  

Love the "Growing confidence" part of the forecast - very similar tO the BBC monthly outlook's 'unusually high confidence of milder weather'. - later down the line.