[Model output discussion - Closing in on Christmas]

Iconic Xmas day run from the ICON 

Would produce a white xmas for many

Sadly it is the icon..

[Model output discussion - Closing in on Christmas]

Is the ECM the new GFS?

Could sell this chart as a dartboard..

[Model output discussion - Closing in on Christmas]

It appears ECM might be connecting the undercutting low at 96h, adding to the low heights that will form the northerly. So, i would expect a more potent initial northerly from this run. 

Edit: maybe not..

[Model output discussion - Closing in on Christmas]

16 minutes ago, O'Maille80 said:

Prob a stupid question but why if these charts are so good does it not show much snow when you click on the precipitation tab on meteociel?

Low resolution of most models at that time frame will not resolve the full extent of convective bands / streamers from a showery flow well, whist retaining capability for modelling frontal systems. noaa for example does not prioritize this in their medium range gfs model. there would be more than suggested. the icon is especially poor for this.

 

addition: there is a fair bit of north sea ppn and it would be snow, 10-20cms widely on the run 

[Model output discussion - Closing in on Christmas]

That pesky shortwave sw of Greenland ruined this one..

 

[Model output discussion - Closing in on Christmas]

The GEM is an absolute GEM at 240h with this strength of trough, a gfs 00z synoptic would likely follow

 

[Model output discussion - Closing in on Christmas]

Every cloud has a silver lining - The lack of amplification to Greenland around 23rd/24th seen on the ukmo, gfs would make room for the secondary low to stir around GL, before attack. So even in the event of a muted initial northerly as per icon/gfs, we're in for a decent chance of a festive Northerly.. 

One of those instances where both favored possible outcomes could deliver..

As long as we can keep healthy tilting of the high on the Newfoundland side, as hinted on ecm #12z

[Model output discussion - Closing in on Christmas]

This is a "binary logic"

Either the shortwave tags onto the main low or fails to connect. ICON connects it which helps amplify the low and therefore the northerly. Fail to connect and loose all vigor.

This binary problem is why often see such large differences in output. It either works or doesn't. Very difficult to make the call.