Model output discussion - Winter approaches

[sheikhy]

1 minute ago, Steve Murr said:

Morning All > A slight relaxation of the Easterly pattern today in terms of cold uppers projected however the end result of a chilly airmass with frost at nights is still on the cards

Other than that the reamplification is still on the cards day 9/10

06z touting snow in the North & the south 216.

Dont think its over in regards to the easterly yet steve!!12zs could intensify it slightly again!!

[booferking]

So who do you trust for this low on ESB 168-192HR Ecm tends to over amplify high pressure while GFS tends to deepen low pressure.

GFS 06z was a small step towards ECM earlier run.

Edited November 24, 2020 by booferking

[Anthony Burden]

GFS 06hrs from 192hrs some northerly push over U.K. with very cold air pushing down over

most of country,looking very wintery.

[TSNWK]

Low res in 6z is pants.. quickly blown away is the cold air.  

But rather a improvement in high res which I think we got

Hoping this is low res outlier when ensemble come out

[Methuselah]

The 'bell end' of the 06Z doesn't look too bad... hardly raging zonality:

    

[IDO]

The Azores High is omnipresent to D16 and looks like it is in situ for a while:

There remains no consistent signal for any upstream amplification, the Pacific high much like the Azores, waxing and waning, and really no help to get any consistent v. cold flow. There are brief colder shots and overall more seasonal than we have had of late.

Looking at the GEFS, at least three different clusters, from great to sub-par (for cold) and the spread highlights this:

spread >  gefs at t218>  

Interesting to see where we land?

[snowking]

Looks like some little nibbles of more seasonal weather on offer in the day 6-14 range it would appear.

The main thing for me still at the moment to turn this from a couple of brief wintry spells into something a little more sustained is still the amount of vortex left around Greenland  an annoyingly small amount of cyclogenesis still remains in that area. This was first apparent to me on last nights EPS Day 10 mean.

On the face of things, a pretty decent mean overall with the main bulk of the vortex shifting towards the Asia/Pacific side of the globe. However, spot the little 1010mb LP feature just SW of Greenland. For that to appear on an ensemble mean shows the pretty strong support for such a scenario, and this sadly prevents us from benefiting further from height rises in NE Canada, for now at least. Had we seen a clean link between heights in the mid Atlantic and Canada, combined with the trough clearing SE-wards, we could have seen ourselves being set up for something a little more substantial.

Are there any more positive signs today? Well a little yes. The day 10 ECM mean, whilst still holding a trough in that position just SW of Greenland, is a little less pronounced than it was last night, perhaps suggested a slight switch towards a more promising outlook overall. And of course the PV is far from the beast it could potentially have been at this stage of the season. 

Right now though the signs are that anything seasonal in the shorter term which relies on things falling into place upstream (i.e. to our NW) will be rather short lived.

[Chesil View]

Always nice to see snow forecast for central southern England even if it is 9 days away and extremely unlikely to verify. Lol

[nick sussex]

Still not convinced by the ECM and its attempts to dig that low se . It only manages that because it clears the PV away from Greenland but there are still no proper height rises there. And models tend to be over eager to do that at longer range .

The GFS seems more interested in disrupting any troughing over the UK initially .

The dangers of the ECM is the pattern ends up too far west which could happen if the blocking to the east is under estimated .

Clearly we don’t want a solution which pushes the cold south to the west or one in which we get trough disruption over the UK but not enough cold to tap into from the continent to deliver some snow .

Lots of uncertainty remains which is par for the course anytime cold tries to pay a visit .

The potential is there , yes the most overused phrase when it comes to snow and cold for the UK !

Edited November 24, 2020 by nick sussex

[Jeremy Shockey]

Just a quick question for the more experienced posters.

if we do get a Northwesterly flow in this setup ( eg GFS 6Z on Dec 4th ) , do we need uppers of -8 c to deliver snow ?

Or would uppers of -5 suffice given the very low solar input at this time of year ?

regards JS

[weirpig]

Going  into low res  on the ensembles   there are quite a few that bring very stormy conditions to the uk   with a low anchored  close to the uk      if these are anything to go by  it may end up very stormy  going into week 2   winds mainly from the North west  or North  depending on the position.

[weirpig]

1 minute ago, Jeremy Shockey said:

Just a quick question for the more experienced posters.

if we do get a Northwesterly flow in this setup ( eg GFS 6Z on Dec 4th ) , do we need uppers of -8 c to deliver snow ?

Or would uppers of -5 suffice given the very low solar input at this time of year ?

regards JS

For my Location  and height -8  will do fine   closer to the irish sea  i would think around -10   really is hit and miss from that direction 

[I remember Atlantic 252]

15 minutes ago, Jeremy Shockey said:

Just a quick question for the more experienced posters.

if we do get a Northwesterly flow in this setup ( eg GFS 6Z on Dec 4th ) , do we need uppers of -8 c to deliver snow ?

Or would uppers of -5 suffice given the very low solar input at this time of year ?

regards JS

-10 here, anything else rain off any kind of Atlantic air showery setup

[Uncertainty]

The latest GEFS edging towards the scenario highlighted by the GEM and ECM ensembles for a good few days now. 
Back this pattern further East we’re in business, further West you’d be wet and wondering what could have been. Also good too see some heights over the Urals and and Aleutian troughing. Perhaps that’s why the EC46 toned down the strong vortex signal into mid December?

Below average from the 16th ish.

Remember that singularity wise, this upcoming period is usually a dreadful barrage of south westerlies and storms. The ‘early December storms’ occur very frequently so even if we end up seasonal with North westerlies or better yet a cold UK high then we’ve done great in my book.

[Snow lover 2020]

1 hour ago, Steve Murr said:

Morning All > A slight relaxation of the Easterly pattern today in terms of cold uppers projected however the end result of a chilly airmass with frost at nights is still on the cards

Other than that the reamplification is still on the cards day 9/10

06z touting snow in the North & the south 216.

Wow the south is in for a dumping of snow!!!

[That ECM]

4 minutes ago, Snow lover 2020 said:

Wow the south is in for a dumping of snow!!!

Do you work for the Express? There is little in any output that I’ve seen to suggest this correct. What output makes you come to that conclusion? TIA

[Snow lover 2020]

Just now, That ECM said:

Do you work for the Express? There is little in any output that I’ve seen to suggest this correct. What output makes you come to that conclusion? TIA

The chart I just quoted 1-5cm snow laying 

[Mapantz]

11 minutes ago, Snow lover 2020 said:

The chart I just quoted 1-5cm snow laying 

That particular chart doesn't show snow depth, just how much could fall over a 6 hour period. There's a whole host of factors to be taken in to account to get an idea of accumulations.

In any case, I suggest you save that chart to your computer/phone/tablet, then have a look at it on December 3rd.

[MP-R]

19 minutes ago, Snow lover 2020 said:

The chart I just quoted 1-5cm snow laying 

That's precipitation falling, not lying. We could quite easily have snow falling but not settling, as happens quite often.

Edit: just seen the above reply.

Edited November 24, 2020 by MP-R

[dragan]

latest gfs suggests weather cooling down, before becoming ‘average’ later on. It will no doubt feel chillier than at present, 160m in Eastern Scotland, and it’s 13c !

Edited November 24, 2020 by dragan

[jules216]

The beast from the east is tantalizing close to reach me in Slovakia this weekend. The entropy is so high that even 96h is FI and it can still pass by me to the north or to the east. The surface cold is already here anyway. Got below -5C last few nights and also some frost valleys are attacking -10C now on daily basis. Thanks to that little NW from last Friday. To lock in surface cold is imperative so when the Atlantic ridge takes hold and lows dive in east of UK the warming uppers wont matter that much,hopefully. 

[feb1991blizzard]

No 29 is the Dec 1990 redux.

[booferking]

Pretty good upgrade easterly flow on ukmo.

[Lewesdon]

4 hours ago, Broadmayne blizzard said:

Always nice to see snow forecast for central southern England even if it is 9 days away and extremely unlikely to verify. Lol

It will snow in Southern England on this date, it was written in the stars.

[Ali1977]

The METO seem to be going for spells of cooler weather from the W/NW following by drier interludes, that isn’t too bad if the WAA between systems can get far enough north to produce the odd decent Northerly, but doesn’t scream blocking anytime soon.  Northerly short blasts in December are no way near as potent as late Jan or Feb, but the hills up North May do ok - as usual

I think any Northern blocking (should it happen) won’t be showing in the models just yet. 

The METO forecast is changing more often than COVID guidance, so I’m not saying that their forecast is correct but it’s nice to have some positivity on their forecasts that we can look for in the models !!