Roll up, roll up for the Mystery Tour,

here's your invitation.........

Great article on the SSW on the BBC weather website, saying how the first SSW disrupted the polar vortex but did not affect the weather - but the second SSW is weak, but might affect weather because the PV is already weakened. Says that models cant cope with it, so short term outputs only and nothing further out is worth much.

Given some of the charts, a yellow submarine may be more useful. 

Incidentally - enjoying heavy, fluffy properly settling snow here right now. Started on time - ground frozen from a night of frost, which had lifted to 1 degree, but now back below zero and light to moderate snow has already covered everything in a white layer: Sorry off topic: 

I am going to concentrate on the UKMO and fax charts for the next two weeks, with the SSW effects not able to be modelled by the big 2, because even this current snow event was not forecast much before 3-4 days ahead, and then heralded as a very transitory event. 

Point about present long-term unreliability of models in the present situation is well made, but might as have a rummage around ...

http://www.wxmaps.org/pix/temp4 A really large mass of really cold air over NW Europe in week 2 but not getting across the N Sea. All we  get is the rain but (hopefully) the worst of that is being pushed south into France in week 2

Jetstream irregular but mostly weak and across Uk from NW to Wed 20th after which a string swathe all the way across the Atlantic and mostly across France - closer to S UK around Mon 25th and Fri 29th, closer to the Med at other times esp at end of Run Mon 1st/.

GFS op synoptics start with sequence of depressions moving towards and/or across UK this week until one manages to stick around and settle 970mb Sun 24th Irish Sea with cold air entrained in its circulation. That fills and then there's a repeat from the Atlantic but with the next cold LP sticking over the UK Mon 1st

GEFS apart from a couple of days around Sat 23rd, pptn is quite general. Temp profile is different in the S (cold 18th & 22nd, mild in between with all runs agreeing, then mostly around seasonal norm with poor agreement) from Scotland (consistently somewhat below norm throughout)

FCM has a less mobile pattern with LP slowing up over UK Thu 21st swinging N-wards the back S-wards with more or less cold air associated esp at first.

BBC model suggesting significant flood risk next week

Seems to be so much uncertainty at the moment, the double SSW (is that correct term) appears to be something the models don’t understand, and are thus going all over the place in next 2 weeks

Therefore here is summary of main models predictions, big spread in week 2 (although a fair cluster of coldies amongst the milder outcomes), so not worth trying to analyse at this time in my view

http://www.weathercast.co.uk/services/ensemble-forecast.html

but the real fun is if you change the location to Stockholm and hope we get weather from Scandinavia (low chance, but fun anyway)

http://www.weathercast.co.uk/services/ensemble-forecast.html?eps=stockholm

The tour is looking much less interesting of late.  Irrespective of SSWs and impacts the outlook, whilst still not zonal SWesterly, is more cool then cold,  cool enough to give some snowy potential to north but the charts of a week ago are almost absent now in the output.   After the cool down later this week it seems like a warm up will follow although there does remain a potential indication of a cool down as we go towards Feb, that could well be the next chase, if anyone had any energy left 😂

It built the high, just I suspect such a strong reversal that it pulled it north and west. I suspect what has happened is the reversal has been so strong that we almost have a reverse reformation of the Pv of sorts. The fun will happen when the reversal begins to wane toward the end of january

Yes - Op, control, and para all show a potential block developing. The BBC article says that this is in response to the second, weaker SSW event  - which will affect the troposphere more significantly - due to the first one doing the damage to the PV.

Rule one of the UK weather. There will always be an excuse available why it won't snow in the South 

Rule two - the degree of perceived uncertainty in the charts is directly proportional to how mild they are.

The medium term favours a short burst of potential from the NW with snow showers for the usual suspects - Western Scotland, North Wales, NW England, Cheshire gap etc.

After this towards FI, low pressure pushes back in and we run the risk of battleground snow events, or just plain old rain. 

My favourite chart of the day is shown below - 00z ECM at t+144 , plenty cold enough too . https://www.wetterzentrale.de/maps/ECMOPEU00_144_1.png

Think of it like stirring cream into coffee. You stir the spoon in an anti clockwise direction the the cream merges toward the middle in a tight whirl, this is the normal PV 
Now we have had a huge reversal, so again you are stirring in an anti clockwise direction, but suddenly stir in a clockwise direction, the cream spreads out and disperse (this is now for the charts with the pv all over the place and with a weaker reversal that is what you get, hence the fun and games), but if you stir more in a clockwise direction the cream goes to the middle again (mid range of the models and a kind of reforming of the pv).
The fun starts when either a smaller warming can disturb the flow or the flow starts to revert back to normal, this is when the cream gets spread out again and the pv disintegrates again.

Based on some of the indications in the output might I counter with 'Yellow Submarine'?

😉

Such a shame it goes badly wrong from here. Normally you would bank this

It’s interesting to see the Inter-run volatility, not just in the op runs but also the ensembles, highlighting the uncertainty in the medium to longer range. Even at day 6/7 on this GFS op run there are a few notable differences in the detail if not in the larger picture.

Is the GFS “aware” of you Brian?!

My understanding is that although there is no inherent bias or AI architecture in NWP algorithms, the resolution with height varies model to model (the EC having more layers than the other two top models). Therefore changes filtering down from above may not be modelled very well with respect surface output, and as said parameters are subject to almost hourly adjustment (primarily satellite data), the volatility is adversely affected.

For the resolution reasons I tend to take more note of the extended EC ensemble when we’re interested in 15 plus days in a SSW (ongoing with another warming) event.

This output is predicting a shift of the mean trough east in the next ten days and heights building to our N and NE and the reason why I’m still optimistic of a colder end of January than the GEFS for example is currently projecting. 

Had some fun this morning in the snow. Just over 2cm over the higher ground and drifted in places to have a snowball fight with the kids, albeit briefly. My winter perception has changed a little now with this experience.

All eyes down for the next event.

Yes exactly - onje would look at that chart and it's eye candy with a perfect set up with HP over Svalbard and into Greenland a very strong ridge but for some reason it doesn't deliver and I don't know why that low pressure doesn't get forced southwards - is it the low pressure out in Atlantic or the Azores high pushing another low in or both?? It's frustrating! What's the cause here?

Norwegian Flood?

I can agree with that completely. However, my point was that it is wrong for people to say the models are "not aware" of the SSW. They are not aware of anything because it is all simply 1s and 0s resolving complex equations ( see Wiki: Navier-Stokes).