Model output discussion - Winter has arrived

[Day_9]

Russian high is also rapidly cooling down a significant landmass to our east.  It is December 3rd.

the problem With models Is that they are just that.  Models. 

[damianslaw]

1 hour ago, Mucka said:

I think that mean when compared to the Op also shows the Op was very progressive, possibly due to the phasing of lows 144/168.  especially when you consider a mean represents not just the blocked runs but also the more progressive ones,

Plenty more fight in this Dog yet. Woof!

Danger with means is they can be skewed by a few outliers either side, think of throwing a dice 12 times, 8 times might record 1 and 2, 4 times a 6, the mean will be skewed by the number of times get a 6, with a mean in the 3-4 category, doesn't tell you the full picture, just like average mean temps. 

[Mike Poole]

35 minutes ago, northwestsnow said:

Thanks mate ...

Dreading the prospect of a +NAO regime taking over next week...

Post Christmas much preferable if it has to happen at all !!

My thinking is that it will have to happen at some point.  This winter seems to me in 3 parts, coldish, but Atlantic free for most of December, then a strat trop coupling which could go one or two ways - either the strat continues fast, and the trop responds and we get a +NAO nightmare, or more likely, it seems to me they meet somewhere in the middle and we still get Atlantic dominated weather for a few weeks.  Beyond that, will depend on the SSW, but if that goes swimmingly (it often does but sometimes doesn’t) the final third of winter should be of more interest again.  

I think the things we should be looking for in the model output for the longer term, are those things that make the middle part as short as possible, so that means disturbed trop vortex as long as possible, and pressure on the strat vortex towards a SSW as quickly as possible...

[Kentspur]

3 minutes ago, Mike Poole said:

My thinking is that it will have to happen at some point.  This winter seems to me in 3 parts, coldish, but Atlantic free for most of December, then a strat trop coupling which could go one or two ways - either the strat continues fast, and the trop responds and we get a +NAO nightmare, or more likely, it seems to me they meet somewhere in the middle and we still get Atlantic dominated weather for a few weeks.  Beyond that, will depend on the SSW, but if that goes swimmingly (it often does but sometimes doesn’t) the final third of winter should be of more interest again.  

I think the things we should be looking for in the model output for the longer term, are those things that make the middle part as short as possible, so that means disturbed trop vortex as long as possible, and pressure on the strat vortex towards a SSW as quickly as possible...

One of those steps that can help make it happen- latest Zonal winds update continues to show the mean falling below average through to mid January 

[Matt H]

Atlantic definitely struggling more on the 18z, still in a continental flow at t180.

[nick sussex]

Central Europe developing its own cold pool under the slack flow .

Should be sufficient cold air now to engage any frontal band that edges into the UK.

It was a close run thing as the upstream low was reluctant to disrupt and low heights hold long enough over Southern Europe .

[Mike Poole]

Re the short term, this is the thing that has been  causing all this discussion, GFS 18z T3:

Three different lows now swirling about.  But you cant see that on the radar yet:

Just the southerly one.  So much uncertainty here, about where the lows are going, let alone whether what falls from the sky is rain or snow.  Nowcasting situation for sure, some people might get lucky...

[joggs]

1 minute ago, Frosty Winter said:

Atlantic definitely struggling more on the 18z, still in a continental flow at t180.

This is what we have to follow if it's cold you're after.

This is our route to cold n snow imo, home grown cold and continent if Atlantic and jet stream play ball.......

[Anthony Burden]

GFS pub run Russian high stretching it’s legs and engulfing UK,as I said earlier in my blog 

very interesting times ahead.Who will win the battle Russian high or Atlantic?ANY BODIES GUESS

great watching.

[nick sussex]

The upstream troughing and overall pattern here is similar to the earlier ECM run but the GFS has the jet further south .

Not sufficient trough disruption though on the second attempt by that to dislodge the cold .

The first frontal band fizzles out but the developing cold pool over Central Europe could be crucial if we see more trough disruption .

 

[Mike Poole]

GFS Scotch Egg run T240, sliders???

[Cheshire Freeze]

Atlantic snookered pretty much throughout the run, can't get past the meridian at any point and finds itself shut out later on in FI

[Daniel*]

It’s fun to see how different each run is I take it as good thing, large swings suggests normal state is threatened. 

[Cheshire Freeze]

8 minutes ago, Daniel* said:

It’s fun to see how different each run is I take it as good thing, large swings suggests normal state is threatened. 

Yeah, I can't understand the negativity from earlier. In my honest opinion we're loaded towards a spell of potentially severe wintry weather at some point in the next 4 weeks. As ever, no promises with the weather but I'd put the chances of a decent cold/wintry spell at around 70%

A SSW at some point in January looks nailed on to me either way. Given the pattern we've seen consistently over the past few weeks, I'd be staggered if one doesn't occur.

Edited December 3, 2020 by CreweCold

[Mike Poole]

2 minutes ago, CreweCold said:

Atlantic snookered pretty much throughout the run, can't get past the meridian at any point and finds itself shut out later on in FI

Yes, the inability of anything from the Atlantic to get past the UK has been telling so far, and is telling into the (modelled) future.  

[Allseasons-Si]

The 18z makes mincemeat of the trough out west thanks to the omnipresent block to our SE/E

game on.

Edited December 3, 2020 by Allseasons-si
typo

[chris55]

The mid term seems to be in a kind of lull re model output at the moment, nothing to cold but equally no raging jet. 
 

A sit back and watch kind of period. Hopefully the lead up to Xmas will trend cold  

[Snowman.]

Very far from a normal December below. An extremely disturbed PV squeezed to operate at almost half of its normal area.

 

[ALL ABOARD]

Is that a mid Atlantic UK scandi Russian high I see?

Huge area of high pressure. 

Getting toasty up top too. 

 

[Mike Poole]

19 minutes ago, CreweCold said:

Yeah, I can't understand the negativity from earlier. In my honest opinion we're loaded towards a spell of potentially severe wintry weather at some point in the next 4 weeks. As ever, no promises with the weather but I'd put the chances of a decent cold/wintry spell at around 70%

A SSW at some point in January looks nailed on to me either way. Given the pattern we've seen consistently over the past few weeks, I'd be staggered if one doesn't occur.

Already the signs are there, pub run T384:

GFS Parallel this morning:

And, as i noted in the strat thread, one reversal of the zonal winds from GEM ensemble 2.  First signal, but of what...we will see...

[Mucka]

http://www.meteo24.fr/meteo/eps/ensemble-tt6-london.gif

 

ECM ensembles chart says it all about that Op run.

[ALL ABOARD]

Is cold that grows in situ likely to be harder to shift than cold carried in by winds?

Usually when we have a high pressure system over scandi we have a wrap around of cold air that feeds along the isobars towards the UK. 

If Europe develops its own cold pool due to the omnipresent high pressure would that mean the air is denser and harder to shift? 

 

[BlueHedgehog074]

3 minutes ago, Mucka said:

http://www.meteo24.fr/meteo/eps/ensemble-tt6-london.gif

 

ECM ensembles chart says it all about that Op run.

Indeed, Mucka. ECMWF operational becomes a bit of a mild outlier between the 11th to 13th December. Perhaps might mean we could get something cooler on its next run in FI. Can’t be discounted, off course, but tonight’s ECMWF did feel a little progressive with the Atlantic.

[Froze were the Days]

22 minutes ago, ALL ABOARD said:

Is that a mid Atlantic UK scandi Russian high I see?

Yep! practically stretches around the globe at a certain latitude and all the disturbances are taking place towards the Arctic...not much mixing of cold and mild air masses at our latitude...maybe some inversion cold from a cooling continent.

[booferking]

I wouldn't  be surprised if we look more like ens 12 & 9 come next week Atlantic held right back zonal wind decreasing la nina footprint cold pool growing in Europe hard to shift.

Ps solar min

Edited December 3, 2020 by booferking