Model Output Discussion - Colder but how cold and for how long?

[tight isobar]

2 minutes ago, Tim Bland said:

Here’s another view of icon for midweek. Gets above m4 in the east and covers London and Essex up to beds and just scraping south cambs ..

The prognosis is …

[Tim Bland]

Areas north of the weds band get a few flurries Thursday 

[Methuselah]

3 minutes ago, tight isobar said:

The prognosis is …

Who knows? 

[Tim Bland]

GFS says no away from far south east 

[Johnp]

So Icon further north with the snow band and GFS further south at 18z.

Clear as mud. 

[Allseasons-Si]

Erm!!!

what's happening here at just t90?

it seems that there is height's trying to force/sheer this trough south,...mmm.

[Ali1977]

The op clips Kent , but didn’t follow the icon!! I’ll be looking for the ENS to improve on this - and see what the 00z bring !! 
im pretty sure the ship has sailed for me, but hopefully more of the south get a bit of snow. 

[BLAST FROM THE PAST]

 

this is getting interest rising.  Atlantic Express becoming Gatwick Express ?

 

BFTP 

 

 

[Daniel*]

Latest GFS making more of a shallow high to our west moving east, which sharpens the cold flow on Thursday interesting changes in short term.

[tight isobar]

Just b4? I rip through the eps throws like a hungry man going through a bin!!!   Let’s take a blend of upper temperatures/ member trends- and precipitation!!!   I’ll leave the longer term s said “ for now”!!    Let’s look at a random blend of icon/ gfs/gem- keeping it simple the guise of pressure- and precipitation spikes with a flat 24 hr zone in ens @cross ,,, more or less… these the London. Spreads.. precipitation- to level values say…. The ops/ raws are underestimating the frontal interruption “ pretty naively”!!! - watch this 1 upgrade in a massive/marked scale….

Edited January 13 by tight isobar

[Ali1977]

Prolonging the cold this run!! 

[Mike Poole]

37 minutes ago, Met4Cast said:

Really? 

This week has been largely below average with blocking. High pressure is now shifting NW towards Greenland ushering in much colder air for this coming week. That’s 2 weeks of below average & blocked conditions which has been well advertised within the GSDM/teleconnections. 

Is it widespread snow? No, perhaps but, but that wasn’t really advertised or promised. What was advertised is an increased likelihood of blocking & colder weather and in fairness that’s exactly what we’ve seen. 

Teleconnections can give a broad sense of the larger patterns but will never be able to tell you if X will see snow. 

It wasn’t a comment about teleconnections.  While not infallible, on this occasion they did what it says on the tin, I agree about that.  (The models, however, did overegg the blocking massively as this came into view which was an issue.)  

It is clear to anyone who has followed this winter chase for any number of years, that even with the right signals, it has become virtually impossible to get setups for significant snow in winter in southern UK.  Apart from a few inches in December 2020, there has been no cold and snowy period since 2018 (does that even count as it was in the spring?).  Changing climate seems to have done much more than increase average temperatures a bit, it also seems to have massively reduced decent patterns and altered patterns that once delivered into ones that don’t.  This year promised decent patterns and has flattered to deceive so far.  It may be many years before we get similarly favourable signals going into winter again.

Edited January 13 by Mike Poole

[Daniel*]

Doing a better job of thrawting Atlantic but I don’t think it’s going to be enough. Friday looks very cold for most under cold high. Could be some very low minima.

 

Edited January 13 by Daniel*

[BLAST FROM THE PAST]

 

t144 18z won’t look like this…going to be an enjoyable several days of lots of ups and downs….

 BFTP

[Scott Ingham]

Now we’re seeing signs of the wedges advertised by an atmosphere that in all fairness is still in a high GWO orbit. A case of not taking models at face value all the time. We could see an extension of the cold for a day or 3 

[Allseasons-Si]

I wonder if we can throw this tpv lobe SE with residual height's(white box) to the NE of it in future runs,the lobe already looks negatively tilted compared to the 12z.

 

Edited January 13 by Allseasons-Si
Added chart

[tight isobar]

I’m dropping v1- snap going forward- from tonight’s 12z epsf-     The next variation is there and … let’s hope it’s an evolutionary trait, @ eyes to the polar CONTINENTAL plots….

[Scott Ingham]

Just now, Allseasons-Si said:

I wonder if we can throw this tpv lobe SE with residual height's(white box) to the NE of it in future runs,the lobe already looks negatively tilted.

It’s possible. The evolution looks like heights up through or to the west of the UK migrating East, then West to Greenland. Similar to the 2018 evolution when the western conveyor belt hit a brick wall out of nowhere. The chart you posted is certainly an early crumb towards that

[IDO]

GFS joined the other models with the Bay of Biscay low supporting the HP as it passes east to west, delaying the colder air departure by a little bit:

T132:

As of now, all models have this part of the puzzle, so we get a fuller picture of the final fall of the GH. Cold lingers until early Sat.

T156:

Similar to every other model around that time. EC for example:

 

[BLAST FROM THE PAST]

 

my earlier post re this about the Atlantic unfiring as we look at US

 

well 18z brings that forward…by a lot…24-30 hrs

 

 

BFTP

Edited January 13 by BLAST FROM THE PAST

[LetItSnow!]

Changes around the 18th/19th makes me wonder if the models are starting to sniff the coffee a little bit. Eagerly anticipate the next frames. Biscay low is a positive sign IMO. All we need is just a bit more NW/SE trajectory then we could be primed again. All to play for. 

1 minute ago, BLAST FROM THE PAST said:

 

my earlier post re this about the Atlantic unfiring as we look at US

 

well 18z brings that forward…by a lot…24-30 hrs

 

 

BFTP

The weaker heights directly to our south look positive to me. Instead of fuelling a giant Euro block the heights are pushing closer to Scandinavia and the Azores high is pushed back west.

[Metwatch]

18 minutes ago, Daniel* said:

Doing a better job of thrawting Atlantic but I don’t think it’s going to be enough. Friday looks very cold for most under cold high. Could be some very low minima.

 

Trough over Iberia, and the Atlantic still comes roaring in, I wonder how often that happens.

 

Tamara would be quite excited I think with this deluge over Iberia if it happened. Other model runs apart from the UKMO 12z have the low sinking into a cut-off system around the Canary Islands so probably not fully set in stone what happens in that part of Europe later next week.

Edited January 13 by Metwatch

[kold weather]

I think regardless of how much the HP tries to build nearby the UK there is huge momentum coming from the jet around 168-216hrs that almost certainly kick it too far SE. Whilst the models maybe being too forceful with this, I think its pretty inevitable the Atlantic is coming back in, at least for a time.

Before that we still have some interest, though experience suggests these channel runner lows tend to end up being just a little too far south. I suspect at this point that will be the case here as well and it'll be close but no cigar with this one, sadly.

That all being said, I think we will get at least one more good shot at a cold pattern through February so for now I'm not hugely concerned about how rough the mid term looks.

EDIT - 12z ECM is amazing at 240hrs, for all the wrong reasons, probably a record breaker there!

Edited January 13 by kold weather

[BLAST FROM THE PAST]

Just now, kold weather said:

I think regardless of how much the HP tries to build there is huge momentum coming from the jet around 168-216hrs that almost certainly kick it too far SE. Whilst the models maybe being too forceful with this, I think its pretty inevitable the Atlantic is coming back in, at least for a time.

Before that we still have some interest, though experience suggests these channel runner lows tend to end up being just a little too far south. I suspect at this point that will be the case here as well and it'll be close but no cigar with this one, sadly.

That all being said, I think we will get at least one more good shot at a cold pattern through February so for now I'm not hugely concerned about how rough the mid term looks.

More than one shot, and the Atlantic coming back in is not set in its ferocity or longevity.

 

BFTP

[WINTRY WALES]

32 minutes ago, Mike Poole said:

It wasn’t a comment about teleconnections.  While not infallible, on this occasion they did what it says on the tin, I agree about that.  (The models, however, did overegg the blocking massively as this came into view which was an issue.)  

It is clear to anyone who has followed this winter chase for any number of years, that even with the right signals, it has become virtually impossible to get setups for significant snow in winter in southern UK.  Apart from a few inches in December 2020, there has been no cold and snowy period since 2018 (does that even count as it was in the spring?).  Changing climate seems to have done much more than increase average temperatures a bit, it also seems to have massively reduced decent patterns and altered patterns that once delivered into ones that don’t.  This year promised decent patterns and has flattered to deceive so far.  It may be many years before we get similarly favourable signals going into winter again.

I agree ….i know it’s not as simple as this but if there were say 8 variables required to result in uk wide snow like in the past…we need all 8. And then…what would we say we had this spell…90% of the variables favourable?? And still quite a let down. Could be a good while to have so many favourable.

But in the past ….again shooting from the hip here….maybe 65-75% of the variables required for the patterns to result in the majority of the uk seeing snow.

From a non teleconnections expert…and at afar this is how it seems to have panned out over recent years