[Model Output Discussion. 3/12/2022. How cold will it get?]

What a beautiful synoptic mess  

bet you won’t find many charts in the archives like this

[Model Output Discussion. 3/12/2022. How cold will it get?]

3 minutes ago, prolongedSnowLover said:

What’s the point of cold when we can’t even get snowfall for areas away from the usual places that get it in the winter ?

From chances of frontal snow to now more energy going in the northern arm of the jet stream is clearly a worry from the GFS, no ?

Unless you have come back from the future then you can’t say that yet. At this point it is better to wait and see what happens. There are always fine lines in this country to be able to achieve a significant snow event and the modelling is again demonstrating that. 

[Model Output Discussion. 3/12/2022. How cold will it get?]

Just now, Eagle Eye said:

Thank you, I've never really had the best knowledge of the intricacies of a SSW just a general overview. That's the one thing that reading documents can't give you, I guess I'll be able to understand this more with experience.

I wouldn’t worry. You are doing great for your age and it took me ages with scores of papers, and many years of monitoring- and I still have so much to learn still. 

[Model Output Discussion. 3/12/2022. How cold will it get?]

1 minute ago, Eagle Eye said:

What looks most likely at the moment is a slow move to zonal by the new year with a loss of mountain torque but we wouldn't see those effects properly kick in till around or beyond Christmas time. It's only 1 run and goes significantly against the other GWO runs so I would suggest that it could still be quite wrong. I think we'll still see a loss initially as you would expect but that doesn't mean we cant see a quick switch to positive torque and an increasing AAM. Still a lot of possibilities in the air beyond mid month. Im not going to stress too much over it for now, the GWO varies a lot.

Not to mention the continuing possibility of a SSW with fluctuating Eddy's propagating vertically into a fairly weak Stratospheric zonal wind as we aren't seeing a rapid zonal wind increase yet especially in the lower Stratosphere.

The bottom-up split route looks to be the most likely way at the moment.

Whereas any SSW is determined by trop wave breaks, the ‘internal upper cut’ is very unlikely to lead to a u wind reversal at 10hPa. I’ve never seen it. The way to achieve this is through the ‘riding external wave’ which leads to a tilt and baroclinic collapse from top to bottom. 

[Model Output Discussion. 3/12/2022. How cold will it get?]

1 hour ago, Scott Ingham said:

THIS.... eyes firmly peeled on this atm for me.

Hows the strat looking today Ed?

Strat is getting better and better. Not a SSW but I reckon on latest run u winds close to reversal at 1hPa. And this will take time to filter down to 10hPa. My guesstimate for SSW was late December. Now, that may be a bit too early for it. But not ruling it out. 

charts courtesy of NW extra. New addition of 1hPa by @Paul so great job

[Model Output Discussion. 3/12/2022. How cold will it get?]

2 hours ago, joggs said:

What could kick start that and do you expect it to?.

Tia 

There’s the difficulty - forecasting the MJO wave propagation and intensity

[Model Output Discussion. 3/12/2022. How cold will it get?]

50 minutes ago, Catacol said:

MJO is not as strong or forecast to be as strong as it was in November but the CPC still seeing it moving back to the maritimes (phase 7/8). From their expert report that you can access from https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjoupdate.pdf

" Good agreement exists among the ensemble means that the MJO remains weaker than the previous month, according to the RMM index. However, ensemble spread is large with a number of ensemble members depicting a continued eastward propagation from the Indian Ocean to the Maritime Continent."

 

 

It needs a good kick to get it restarted, cos that will help. A lot

[Polar Vortex / Stratosphere Watch 2022 / 2023]

1 minute ago, Catacol said:

I'm struck at 10 days how far off centre the 10hpa vortex is becoming, and through the layers it is lacking coherence of shape. A 90 degree twisted stretch profile. The extent to which a setup like this puts it close to being wobbled and squashed to the point of no return I do not have the skill to see - but for a mid December vortex it looks rather unhappy to me.

It’s the baroclinic tilt throughout the Strat that will be all important in bringing the Strat down. Lovely view there

[Model Output Discussion. 3/12/2022. How cold will it get?]

29 minutes ago, kold weather said:

Amazing looking pattern, but sadly its about as bad an outcome for the UK as you can get from such a position of strength with a developing central Atlantic upper low and as you say a Scandi high slanted in such a way as to promote a SW fetch.

Still theres been very little consistency so no point looking too far ahead just yet really other than there is a clear strong -ve AO signal present still.

I have every faith in the UK snatching defeat from the jaws of victory, as most here will have too. Still, theres a long way to go before we are into a reformed vortex over Greenland

[Model Output Discussion. 3/12/2022. How cold will it get?]

Still a cracking hemispheric profile - Oh and a Scandi high - though poorly orientated

[Model Output Discussion. 3/12/2022. How cold will it get?]

And there she goes..

.

[Model Output Discussion. 3/12/2022. How cold will it get?]

Better negative tilt on our tropical feature by T+126 and it is getting ready to split and undercut. On we go - should be a good run this

[Polar Vortex / Stratosphere Watch 2022 / 2023]

18Z gfs day 10 at 10hPa 

 

Wave 1 stress with hint of wave 2. Never say never…

 

[Model Output Discussion. 3/12/2022. How cold will it get?]

Just caught up and viewed the 18z gfs run. End of high res and low res 18z GFS is crazy in development. What it is seeing is signals, but can’t make head nor tail of them!
 

I consider it like it has certain jigsaw pieces (the signals) but has placed them in the wrong position or wrong way around. It is trying to work it out but can’t at the moment. So, it is difficult to see the picture even if you squint. But eventually those jigsaw pieces will be put the correct way up and in the right position. How long it takes is anyone’s guess. 
 

To edit. I consider the signals good and the long term picture will be too. 

[Model Output Discussion. 3/12/2022. How cold will it get?]

2 minutes ago, CreweCold said:

Which is the point I’ve made this evening, Chiono.

Usually in the UK after a spell fails we’re chasing 4 weeks down the line for something else.

This couldn’t be more different 

I have also updated the Strat situation in The Strat thread. Still promising. 

[Model Output Discussion. 3/12/2022. How cold will it get?]

23 minutes ago, irish1 said:

Latest ECM ensembles show a big increase in the number of milder members beyond the 12th but a whole lot of options there so really impossible to forecast beyond Monday at present.

Looks like there are 2 main clusters. One keeping the cold, and another with the AL heading north with Milder temps. 
 

But check out where a lot of these milder members head after the mild blip. Yep, back to cold. 

[Polar Vortex / Stratosphere Watch 2022 / 2023]

Still keeping an eye on the later reaches of modelling the Strat and we find the Strat still in distress from top to bottom. Significant distortion from wave one influencing things from 1-30hPa and wave 2 upwelling and splitting from the trop upwards. Not quite SSW territory…….. yet

 

if we get enough tilt of the vortex with altitude - a baroclinic vortex -then it will collapse easier. We need a bit more than shown here. 

[Model Output Discussion. 3/12/2022. How cold will it get?]

Definitely getting closer to that Scandi High scenario with the Azores low being sucked underneath like some sideways lava lamp

[Model Output Discussion. 3/12/2022. How cold will it get?]

Stalling Atlantic low, heading slightly north and not sliding with weak Scandi ridge. I like this run, but another variation on a theme

[Model Output Discussion. 3/12/2022. How cold will it get?]

Good to see the signal is still present for the strong wave 1 upper Strat event. 
 

I will keep monitoring this to see if we can get a full blown SSW down the line

[Model Output Discussion. 3/12/2022. How cold will it get?]

12 minutes ago, blizzard81 said:

I'm not too sure about the scandi high you are touting at the timeframe you suggest. Maybe back end of December. 

Days 10-15 over next few runs…jet stream positioning should open thermodynamic positioning to allow height rises. Obviously, I stick my neck out here, but it does look like a natural progression rather than retrogression at this point. If it doesn’t occur then I will be happy to say I am wrong. If it does then vice versa.  
 

oh. And I am not one to sit on a fence either!  I’d rather fall on my sword than not make a call!

[Model Output Discussion. 3/12/2022. How cold will it get?]

These are the ensembles that need watching. Helsinki surface pressure  will be interesting to see where they head

[Model Output Discussion. 3/12/2022. How cold will it get?]

The Azores low looks overblown to me, but in any case will have blown itself out before it reaches the UK. The modelling of the energy in jet stream dynamics here is all important. 
 

So let’s get back to basics… a surface low pressure forms at the left exit point of a strong jet stream where temperature differentials are at the maximum. Because of the Greenland high this is occurring far further south than usual as shown below

because of this we have a player in the placement of a battle zone. But this will be a dissipating event should it reach the UK and we need to be concentrating on the background long wave patterns to determine what the future holds post this. And imo these are embedded and will be tough to shift. Scandi high will follow. Mark my words. 

[Model Output Discussion - moving into Winter]

10 minutes so that those posting will not lose their posts…..

[Model Output Discussion - moving into Winter]

I have created a new thread here

this one will be locked shortly so get posting over there!