According to my Collins weather guide November is the wettest month of the year on average for london so I'm hoping we can get this crud out of the way now and maybe by mid December there might be a light at the end of the tunnel.

GFS 12z Control run is very interesting from 192 hours, and ends with this beauty:

The control was a cold outlier.

Even though I've been into this model watching (for my sins) malarkey for quite a while, I still don't know the difference between the operational run and control run. All I know that I use the former for "trying" to forecast the medium range outlook in a JFF kind of way, but I'm still not sure what the purpose of the control run is.

The ECMWF almost brings a cold spell out of nowhere!

Easterly winds nearly develop with no upper level support at all!

Hi Ian

The Operational is the highest resolution result - and in theory the most likely.

The Control is a lower resolution ensemble with no starting point adjustments.

The twenty ensembles are the same lower resolution as the control with very small tweaks to defined starting parameters.

When there’s a big difference between the control and operational it’s likely the calc resolution is having an effect on the prediction.

In my experience it tends to be a dolphin, although I’m not sure how that fits in with the model output. 

On topic and I have noticed over the last few runs the trend away from any real mild weather up here in the coming days. Not sure it will be especially cold but who knows given the uncertainty. 

Looking at a chart like this (from the 18z GFS op run) I suspect that large “void”/col in the N Atlantic is associated with quite a bit uncertainty 

Does anyone get the feeling we could suddenly see a flip to promising model output?

It just seems that a lot more of the energy is going south and it wouldn't take much to put us into a colder regime even without the upper level support.

Brian - Uk is doing very well for Pizza slices this December!?

Move away from the South coast lads, it's like living in lerwick and moaning you don't see 30c in summer

Sets up for an easterly later in the run. Will be interesting to see where it sits in the ensembles

Big rain events for the southern half of the UK and an increasing risk of snow in the north. The outlook has gone from being sleep inducing to interesting in the last 48 hours.

Definitely more interesting this morning some sort of northerly in 9ish days time. Whether this heralds a long cold spell or a brief blip is yet to be determined. ECM and GFS ensembles would suggest a blip at the moment. 

Yes the ECM op was out of range at the end.

Mid-December cold snap looks on the cards at the moment, but that is nothing unusual. Unfortunately, one of Buchan's warm spells coincides with Christmas, which is one reason white Christmases are as rare as hen's teeth.

Its amazing how coldish outliers from the operational and control runs can change the whole mood in here.

Its also amazing how the atlantic has woken up in style as soon as we approach December after a primarily blocked year. 

One thing I learned very quickly about the model output in general when I first began following it regularly on this site some 13 years ago is that, for a lot of the time, it can be and is as unpredictable as the British weather often is. The slightly more optimistic mood in here this morning compared to earlier in the week is a case in point.

If I'm being honest, I think that sometimes a number of us get suckered too easily into thinking that whenever an unsettled atlantic-dominated spell in indicated by the models, it is always set to last for weeks on end. While that was certainly the case in the likes of the 2013/14 and 2015/16 winters, as far as I can recall we haven't had a prolonged assault from the atlantic in the winter since the latter of that of 2015/16. While 2016/17 and 2017/18 did produce the occasional such spell, none according to my recollection lasted an especially long time. Will this winter be mostly quiet like the last two or will it be more like the two I mentioned earlier in this paragraph? We shall see.

The beeb last night mentioned colder in the north and milder in the south for next week and this shows on GFS this morning

Obviously, a lot of caution is needed with these snow depth charts but it would certainly tie in with the colder air over Scotland. Not so sure about the snow heading further into England but you never know if the colder air tracks that bit further south.

Very interesting end to the EU nest ICON 6z. 

https://www.theweatheroutlook.com/charts/static/20181129103929404_06_120_ukpreciptype.png

Edit: GFS 6z showing something similar.

https://www.theweatheroutlook.com/twodata/gfs.aspx?run=06&charthour=129&chartname=preciptype&chartregion=uk&charttag=Precip%20type