The hunt for cold - Model discussion (late November)

[Methuselah]

41 minutes ago, bluearmy said:

Hate to be a pedant but that was no lower than -8c over Scotland ....... I was talking below -10 c and that v unusual from a proper northerly in December .......

Something must have changed since then then: we wouldn't get umpteen days with minima around -8C and negative maxima (in southern England) from -8 uppers, these days...?

[jules216]

2 minutes ago, Seasonality said:

I know!  For Warsaw on the 1st of December the spread of 850hpa temps on the ensembles is from -15 to +6!

Imagine if this situation was unfolding in vicinity of UK right now, this forum would be going from heart attack to ecstasy every 4 hours   

[I remember Atlantic 252]

32 minutes ago, Decemberof2010 said:

Pert 10 says cheer up coldies I’ll be here in a couple of weeks

I like pert 2, but only deepest FI

https://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=2&mode=0&carte=0

[Decemberof2010]

Yes Atlantic 252, I saw that one too, very nice. Let’s hope these FI charts like these continue to grow in numbers and get closer. 

[Ventnor Viking]

I'm still struggling to see where any meaningful cold will come from.

I know we have all the background signals and so on but I cant see anything significant this side of Christmas.

I'm not trying to be cynical, but as long as a that high in Russia sits there we wont get any of the action.

[Mike Poole]

Well, the ECM continues to offer something of the expected return to a blocking pattern with the cross polar heights, here at T240:

The JMA could get there too later, amazing given the utter Horlicks it has made of the area to our NW at T192 - sorry, this one is for the bin:

Edited November 24, 2018 by Mike Poole

[Geordiesnow]

1 minute ago, Mike Poole said:

Well, the ECM continues to offer something of the expected return to a blocking pattern with the cross polar heights, here at T240:

The JMA could get there too later, amazing given the utter Horlicks it has made of the area to our NW at T192 - sorry, this one is for the bin:

Don't really see the blocking there myself really, the Arctic high will only come into play if it can squeeze further Southwards and ideally be more of a sausage type shape high like this morning's ECM. And even then if its too far North then it may not have much influence on our weather. 

At the moment, any cold air will come from after any low pressures swing through, won't rule out some sort of Northerly/NW'ly airflow if we get any heights building in the Atlantic although nothing is likely to be sustained. 

Speaking of lows, then Wednesday is still potentially a very disruptive day weather wise, lots of uncertainty though to nail down the details but even the UKMO is kind of interested in a deep low so the potential is definately there. 

[Mike Poole]

2 minutes ago, Geordiesnow said:

Don't really see the blocking there myself really, the Arctic high will only come into play if it can squeeze further Southwards and ideally be more of a sausage type shape high like this morning's ECM. And even then if its too far North then it may not have much influence on our weather. 

At the moment, any cold air will come from after any low pressures swing through, won't rule out some sort of Northerly/NW'ly airflow if we get any heights building in the Atlantic although nothing is likely to be sustained. 

Speaking of lows, then Wednesday is still potentially a very disruptive day weather wise, lots of uncertainty though to nail down the details but even the UKMO is kind of interested in a deep low so the potential is definately there. 

I'm still not thinking about the UK even on this timescale, it is about seeing the continuation of a disturbed tropospheric vortex, and the ECM follows a number of runs from yesterday with this evolution, anything likely to bring cold to UK is further down the line at the moment.

[Mike Poole]

ECM mean at T240 still indicative of arctic high:

Perhaps more importantly the split of the trop PV into two.  Following on from my CFS update last night, the last 4 runs for December, surface pressure anomaly:

Negative AO, it's what we want to see, from there, a setup for UK cold though likely is always a lottery, but at least we've got a considerable number of tickets!  Unlike the opposite positive AO when we have virtually none.

 

 

Edited November 24, 2018 by Mike Poole

[feb1991blizzard]

4 minutes ago, Mike Poole said:

ECM mean at T240 still indicative of arctic high:

 

 

 

Would rather have it as a 500mb feature as well TBH.

[Mike Poole]

1 minute ago, feb1991blizzard said:

Would rather have it as a 500mb feature as well TBH.

Mean, isn't it, on both surface and Z500, not much more we can tell until we can see the clusters, and they don't go over the pole, so I'm not sure much more info can be gleaned?

[Interitus]

3 hours ago, bluearmy said:

Hate to be a pedant but that was no lower than -8c over Scotland ....... I was talking below -10 c and that v unusual from a proper northerly in December .......

Later in that cold spell, Shanwell in Fife recorded an 850 of -11.5°C on the 12z radiosonde sounding of the 18th with this northerly -

[Interitus]

2 hours ago, Ed Stone said:

Something must have changed since then then: we wouldn't get umpteen days with minima around -8C and negative maxima (in southern England) from -8 uppers, these days...?

Deep snow cover and a lack of mild near surface air flow would allow surface cold to build again just the same, with relatively unimpressive 850s.

[bluearmy]

11 minutes ago, Interitus said:

Later in that cold spell, Shanwell in Fife recorded an 850 of -11.5°C on the 12z radiosonde sounding of the 18th with this northerly -

that’s a much colder chart than the original one posted ..... I wouldn’t have been a pedant if I had scrolled through a few more days output ! 

[Interitus]

18 minutes ago, bluearmy said:

that’s a much colder chart than the original one posted ..... I wouldn’t have been a pedant if I had scrolled through a few more days output ! 

Well to be pedantic, the Stornoway soundings for northerlies on the chart posted did subsequently go below -8°C and then -10°C

9/12z -8.3°C

10/00z -8.5°C

10/12z -8.1°C

11/00z -8.5°C

11/12z -9.1°C

12/00z -8.1°C

12/12z -10.1°C

Edited November 24, 2018 by Interitus

[ALL ABOARD]

Deep low has dissapered on the icon and almost a northerly in the offing as the low heads through... 

[bluearmy]

17 minutes ago, Interitus said:

Well to be pedantic, the Stornoway soundings for northerlies on the chart posted did subsequently go below -8°C and then -10°C

9/12z -8.3°C

10/00z -8.5°C

10/12z -8.1°C

11/00z -8.5°C

11/12z -9.1°C

12/00z -8.1°C

12/12z -10.1°C

Continuing the pedantry, I did say ‘majority of the uk’ ......... was trying to say ‘ignoring Scotland and n ireland’’.....Stornaway is almost bloody Norway !

 

[Had Worse]

1 minute ago, bluearmy said:

Continuing the pedantry, I did say ‘majority of the uk’ ......... was trying to say ‘ignoring Scotland and n ireland’’.....Stornaway is almost bloody Norway !

 

Iceland.  The Shetlands is Norway side

[feb1991blizzard]

12 minutes ago, bluearmy said:

Continuing the pedantry, I did say ‘majority of the uk’ ......... was trying to say ‘ignoring Scotland and n ireland’’.....Stornaway is almost bloody Norway !

 

Yes, you can probably get near to -10c of a WNW flow in Stornaway in December so sure as hell you can with a N'ly.

[bluearmy]

36 minutes ago, Had Worse said:

Iceland.  The Shetlands is Norway side

Been a long day ............

[Newberryone]

Been a long day is right, and doesn’t seem to be ending on a very cheerful note either, especially should those latter frames of tonight’s Ecm verify. Can’t see heights building from the south doing us any favours with regards to cold weather prospects. 

[Chesil View]

I don,t really understand the concerns regarding the ECM. No cold weather or cold synoptics were expected within that time frame anyway.

[blizzard81]

1 minute ago, Broadmayne blizzard said:

I don,t really understand the concerns regarding the ECM. No cold weather or cold synoptics were expected within that time frame anyway.

I am keeping an open mind about December's prospects. I really am 50/50 with regards to how next month turns out. I am going to wait another week before I can try to dicepher what is in store for the UK in the next few weeks. 

. 

[Mike Poole]

Something always has to give eventually, and it just has on the (delayed) FV3 12z, here at T300:

Slices the trop PV in two down the middle, great run!  Strat warming signal as well at the end:

Edited November 24, 2018 by Mike Poole

[feb1991blizzard]

41 minutes ago, Mike Poole said:

Something always has to give eventually, and it just has on the (delayed) FV3 12z, here at T300:

 

Slices the trop PV in two down the middle, great run!  Strat warming signal as well at the end:

 

That FV3 is backed up by the GEFS 18z, much more with ridging from our side of the pole and even a few hints of cross polar flows with a meet up of pacific ridge - just a brief glance at a few that is though - but definitely a good suite.