upper air temperatures perhaps?

Thickness values (500-1,000 hPa) 520 to 528 from north to south.

Hardly extraordinary though, but I see your point. But in terms of actual 'potency', this westerly falls far short. Hopefully the next round progged for next week will bring something a bit more active. It probably won't, but one can only hope. 

Not April weather 

Cold unsettled snow in places 

Is this the result of the SSW

If only - snow in abundance in that flow 

I’m obviously a tad battle weary. In all respects that is a phenomenal chart - almost cross polar flow.

Its a testimony to the last few weeks of trials and tribulations that because of the date stamp it only raises one eyebrow.

Forgive me for being somewhat sceptical.  Let's see where the ensemble takes us. 

GFS 18z. Here we go again. Who's going to get sacked in this time ha ha

Roll on spring, the days are getting longer and it it's only a matter of weeks now before the sun will feel warm on the skin.

Which is not only worrying but how can we be sure that these northerlies the models show won't flip-flop? If it can happen by easterlies, then it can by northerlies!! I think that winterstorm over the eastern seaboard didn't help really as it's blasted up the jet and raced the LP systems across the Atlantic and not giving any Scandi HP or blocking time to build at northern latitudes! Sods law really! 

18z GFS ensembles for London: - Looks new to me:

Both operational run & control take us into the freezer as you can see!

But in the more reliable time frame on 22nd/23rd we have -7 or so uppers with some precipitation! Could be snow? 

Shame it goes average to milder but only for a time. - Just hope the FI charts don't downgrade then if we cant get the easterly end of next week!! - At least there is the snow potential for many Monday night into Tuesday.

Oh yeah... That's pretty funky!

Chin Chin.  There is weeks of this to come.

Once (or should I say 'if') synoptic scale troughing develops over Europe, it isn't going to matter if the jet gets 'blasted up', because there is only one primary route that it will take. 

What strikes me as odd is the Op, Control and probably Para runs all go very cold later, but very few other ensemble members go with them. 

That's my concern too! The GFS is not well supported. There is so much scatter going on as well. 

The trend is for the high level jet stream to dive south: However, predicting this is like trying to predict a fire hose thrashing about with no-one holding it. As modeled  - it is a beautiful thing!

JUST FOR FUN the 18z temp ensembles @ 850hpa for New York City: - The new ensemble chart is pretty cool actually!

Hands up those who can detect the precipitation spikes from the temp ensembles?

GFS for day 5:

UUKMO day 6:

GFS day 12: (Don't get Fooled Again!)

Not a case of getting fooled it just highlights the uncertainty so i wouldnt put your faith in any one run just now .