https://www.theweatheroutlook.com/twodata/ecmhr.aspx?run=12&charthour=210&chartname=gh_na&chartregion=uk-region&charttag=500hPa%20/%20MSLP

Assuming you use TWO charts, ECMH and select the 500hPa option and you'll get the EU view out to T360. 

The ECM AI thingy is also on TWOs viewer and goes out to T360 too - it's not as interesting as the normal run but it's not too shabby.

ECM goes out to 360hr .

It will be interesting to see if the 18z GFS op run continues with the NY wintry potential.

Yes, the link to the ECM AIFS is:

https://www.theweatheroutlook.com/twodata/ecmhrai.aspx 

More info about it from ECMWF:

https://www.ecmwf.int/en/newsletter/178/news/aifs-new-ecmwf-forecasting-system 

The floodgates would really open with lots of bottled up cold potentially washing over the UK. 

Certainly more entertaining model watching than the drab times of late. 

Not sure it’s possible to kill something that’s already dead. 

This need to be done asap and not in Spring and summer seasons which both was coolest this year. 

It certainly looks like the dry spell will come to a crashing end on New Year's Eve, anyway.

GFS Op - HP pushing in from the SW and completely covering Britain 1035mb Thu/Fri 26th/27th (but cloudy according to MetO). It declines SE-wards over the weekend as LP develops S of Iceland and  moves to N Ireland 970mb Thu 2nd and eventually across to the N Sea Sun 5th with N-lies for Britain, and then a reload as this LP is boosted by a Channel Low Wed 8th with more direct Arctic air. 

ECM - differs from GFS midway with the weekend LP moves east  at first rather than south but in the end finishes up in the N Sea Sun 5th converging with GFS.

GEFS - mild and dry to Tue 31st then back to mean with good ens agreement (temps drop off a couple of days earlier in the north), then a wide spread of temps develop; by Wed 8th mean is a little below norm but this disguises a range of some 10C on either side, op mostly cold and control mostly mild. Pptn starts around the 31st, snow row figures from 7/33 on the S Coast to 12/33 in N England to 20/33 in the Highlands.

Don’t forget the mild/cold runs will be down to lack of data 😂

The overall trend around the New Year period is still apparent and worth monitoring, keeping in mind all the usual caveats given the time scale.

I’m also wondering just how mild/warm it will get tomorrow. Any chance of a date record? 

https://modeles16.meteociel.fr/modeles/gfs/runs/2024122306/gfsnh-13-156.png?6 

00z Brought low pressure to the west of Bay Of biscay with UK in northerly at the end of run where as 06z brings back the azores high pressure.

To re-cap from the Christmas weather thread, watch for 15.6C both tomorrow and Christmas Day

If you have a look at the ensemble table (available via Meteociel) and the values for each ensemble member you find differences even at T+0. 

Take today’s GFS 06z run for London, where you’d expect plenty of data and very few estimated values:  there’s almost a 1 degree spread in the 850hPa temperature, a 300 metre (640-926) spread in the height of the 0 degree isotherm. Even the 2m temperature varies by a degree (3.8-4.7).

If you look at some locations likely to have less actual data it’s even more stark.

My point is that with that degree of uncertainty at the beginning it’s not surprising that such different evolutions are produced.

I think the Christmas Eve record will go. Somewhere in the north east Highlands probably.  

That’s very interesting.

So does the degree of variation in the data points at T+0 reflect uncertainty in the data, or is it simply that, by definition, the starting conditions for each ensemble member are varied by design (in order to model the different evolutions that inevitably result from having different starting points)?  

Of course, it may also be that I don’t fully understand how the ensemble suite works …. 😬

It's this - the ensemble members are produced by slightly altering starting conditions. It's why they're called perturbations!

(EDIT: And the idea is that if you had 30 members each using exactly the same starting conditions, you'd get 30 members each exactly the same. That's no use to anybody, hence the starting conditions are modified. It's not to reflect uncertainty, it's simply providing a bit of a random "seed". The only ensemble member which has the same starting conditions as the operational run is the control run, but as the ensemble suites use fewer points in their modelling it will end up different to the operational run.)

Surely a starting point of full certainty (of the current conditions) would still result in similarly choas within similar time frames?  

You can't have a starting point of full certainty if you think about it. Think about the variation in temperature in your garden (if you have one) and how that isn't reflected in the starting conditions of the models.

That’s what I thought.  Thanks.