Model output discussion - Closing in on Christmas

[nick sussex]

The options on the table seem to be cold to varying degrees in the medium term .

Which is a lot better than some of the horrors that coldies could have been subjected to .

The run upto Christmas and the day itself also still has a degree of uncertainty in terms of depth of cold and the chance of any snow .

Overall as much as I’d like to wheel out my crunchy snow and ice day alert, that has to wait but  the outputs are still very encouraging . 

[Mike Poole]

7 minutes ago, MKN said:

The ECM and GFS are poles apart. I don't understand this so called shift to the GFS, Of course im referring to a fair way off but at 216 Greenland is dominated by a 1040mb area of high pressure on the GFS compared to low pressure with the ECM.

I was talking of the T120-T144 timeframe re shift to GFS.  I’m not interested in drawing conclusions about shifts in comparisons in FI.

Edited December 19, 2020 by Mike Poole

[Allseasons-Si]

What do people won't...SW'ly crud?

these are great synoptic charts being churned out by both the gfs/gefs and ecm

i know this chart is at day ten but it looks like lock and load from the NW to me...

look at north America...you can virtually see the whole of the continent with low height's draining away,and as you can see by the red arrows there is still plenty of amplification to our NW to deflect more systems on a NW-SE trajectory (black circle/arrow).

 

 

[Vikos]

 

So, conclusion of todays runs: Cold will come, how much, how long, with or without snow, we'll see around tuesday/wednesday

Autumn finishes next weekend, winter starts next weekend

Chart shows total accumulation of snow by ECMWF up to +240h (still 00z, may will update by itself later)

 

 

[TSNWK]

1 minute ago, nick sussex said:

The options on the table seem to be cold to varying degrees in the medium term .

Which is a lot better than some of the horrors that coldies could have been subjected to .

The run upto Christmas and the day itself also still has a degree of uncertainty in terms of depth of cold and the chance of any snow .

Overall as much as I’d like to wheel out my crunchy snow and ice day alert, that has to wait but  the outputs are still very encouraging . 

Brilliant.. over the years I’ve always enjoyed your various alerts systems..can we at least dust it down place on standby  the 2020 crunchy snow and ice alert system?

[northwestsnow]

1 minute ago, Vikos said:

 

So, conclusion of todays runs: Cold will come, how much, how long, with or without snow, we'll see around tuesday/wednesday

Autumn finishes next weekend, winter starts next weekend

Chart shows total accumulation of snow by ECMWF up to +240h (still 00z, may will update by itself later)

 

 

Looks great for Europe!

Much better! Anything from the east will have low dews attached. .

[mountain shadow]

1 minute ago, Allseasons-si said:

What do people won't...SW'ly crud?

these are great synoptic charts being churned out by both the gfs/gefs and ecm

i know this chart is at day ten but it looks like lock and load from the NW to me...

look at north America...you can virtually see the whole of the continent with low height's draining away,and as you can see by the red arrows there is still plenty of amplification to our NW to deflect more systems on a NW-SE trajectory (black circle/arrow).

 

 

Aye, but we've seen those Day 10 charts umpteen times already. 

When we get closer to t+0, some spoiler low appears and stops the ridge and we have to wait 4 or 5 days for the next attempt. 

And before you know it, it's May.

[Mike Poole]

1 minute ago, Allseasons-si said:

What do people won't...SW'ly crud?

these are great synoptic charts being churned out by both the gfs/gefs and ecm

i know this chart is at day ten but it looks like lock and load from the NW to me...

look at north America...you can virtually see the whole of the continent with low height's draining away,and as you can see by the red arrows there is still plenty of amplification to our NW to deflect more systems on a NW-SE trajectory (black circle/arrow).

 

 

Yes, exactly, you can see that, as I said the whole vortex could come crashing down on us.  

JMA T192, looks to me like following GFS which is interesting because it is UKMO based model:

[mulzy]

Early indications of the EPS mean up to day 10 nowhere near as good as the GEFS. Displaced Azores High with lowish heights in Greenland persisting.

[swfc]

2 minutes ago, Allseasons-si said:

What do people won't...SW'ly crud?

these are great synoptic charts being churned out by both the gfs/gefs and ecm

i know this chart is at day ten but it looks like lock and load from the NW to me...

look at north America...you can virtually see the whole of the continent with low height's draining away,and as you can see by the red arrows there is still plenty of amplification to our NW to deflect more systems on a NW-SE trajectory (black circle/arrow).

 

 

Yes it's fine and heading in a good direction. Sometimes less is more ie comments but hey ho. Let's hope the 18z brings some  joy anyway

[Vikos]

1 minute ago, northwestsnow said:

Looks great for Europe!

Much better! Anything from the east will have low dews attached. .

Yep, we will produce our own cold air from the on, no need to put the straw into some arctic cold pools

[MKN]

9 minutes ago, Mike Poole said:

I was talking of the T120-T144 timeframe re shift to GFS.  I’m not interested in drawing conclusions about shifts in comparisons in FI.

Significant differences even at 144 if you look at the Eastern U.S. The differences there at that point are why the GFS sees the high pressure head into Greenland and why the ECM doesnt.

Edited December 19, 2020 by MKN

[northwestsnow]

1 minute ago, mulzy said:

Early indications of the EPS mean up to day 10 nowhere near as good as the GEFS. Displaced Azores High with lowish heights in Greenland persisting.

Typical.

LOL.

[TSNWK]

2 minutes ago, mulzy said:

Early indications of the EPS mean up to day 10 nowhere near as good as the GEFS. Displaced Azores High with lowish heights in Greenland persisting.

Hello. Any thoughts on how they trended against 00z EPS please

[stodge]

Evening all

Last evening's output was remarkable on a number of levels and probably some of the best for cold fans for a long time. It's hard to see how things could improve for cold fans from that and I imagine the slightest hint of a downgrade will bring out the "I told you so" merchants (trolls mostly) and the ritual toys being ejected from the permabulator.

It's only the weather for crying out loud...

Let's see what mood the models are putting us in this evening:

12Z GEM: - t'was Christmas Eve on the models (well, T+120 at any rate). GEM has downplayed the LP coming up from lower latitudes and it's now a secondary feature so we don't get a pull of PM air as suggested earlier in the week leaving the Atlantic HP to build toward us as the next trough emerges from Eastern Canada. We get a fine Christmas Day and Boxing Day too for most but by T+180 the HP is an elongated feature through north-west Europe and into the Atlantic. Meanwhile, the trough and the PV lobe is gathering to the north of Iceland so we'll see. By T+240 the LP has moved down into Scandinavia and extended into eastern Europe but the British Isles remains too close to the HP to pick up any real cold airflow and indeed a new LP is coming past Greenland so a disappointing end to this run for cold weather fans.  The PV looks to be rebuilding over NE Canada so I don't see a quick route to cold.

12Z GFS OP - a stellar run yesterday at this time but with GEM disappointing badly for cold fans, we really need GFS to stay on track. By T+120 only slight differences with the GEM - perhaps the HP ridging slightly more strongly to the north though I suspect it won't make any difference. The evolution from there goes much more according to plan than it did with GEM - the LP develops strongly to the north forcing the HP to retrogress as warmer air moves into Greenland and builds the HP. By T+240, the LP has sunk down over the British Isles but has become a complex feature - the 850s are zero to -4 so that should mean snow to higher ground and to lower ground in the north but I'm no expert. By New Year's Day, the trough is still over us - I suspect a slight build of heights to the south is preventing the trough sinking away but heights persist over Greenland and the jet looks well to the south.  850s generally -4 by this time. Unfortunately from there it all goes a bit wrong - the LP drops to the west of the British Isles in the pool of very cold air and re-invigorates but in a position that draws up a mild or very mild SW'ly airflow with heights building in Europe. For a second night running, the 10 HPA shows a split in the PV at the very end of FI. Fine margins but it doesn't end quite as well as the medium term might have led us to hope.

12Z ECM - the end notwithstanding, GFS would provide several days of cold and potentially wintry weather so not to be sniffed at. Will ECM make it 2-1 for the coldies or will it follow GEM into the mild camp? At T+120, I think I see the problem. There is a shortwave in mid-Atlantic and that pushes the HP closer to the British Isles and quickly cuts off the PM airflow. After the LP has cleared through, a clear and cold Christmas beckons. The LP develops but not as cleanly as GFS but better than GEM and the HP is giving ground. At T+192, the core of the LP looks to be heading for Norway rather than the British Isles.  That's pretty much what happens with the HP close to but not oriented over the British Isles. There's a cold col over Germany with LP to the north and south and HP to the east and west and that's where we should be. Upstream looks messy - there's an HP coming out of America and a weak LP near Iceland which might, I suppose, run SE towards the British Isles (or it might not). The 850s are rising slowly with some warmer air in the Atlantic but it may not be coming our way.

Looking elsewhere, 12Z JMA looks okay, 12Z UKMO less convincing while 12Z GFS Control is not that different to the OP.

Conclusion: - the value of caution was never more evident. The stellar medium term charts from last evening haven't disappeared (GFS OP is certainly good) but there's still plenty to resolve with FI perhaps as early as T+120 this evening. The major LP coming out of Canada and moving round the top of the Atlantic HP is the key player - GEM keeps it far to the north with the HP close to the British Isles, GFS OP drops it over the British Isles but then brings back milder air through the back door while ECM is messy. I do wonder if the LP over the Canaries is propping the HP up at mid-latitude and stopping the LP dropping cleanly through the British Isles but we'll see. Much still to be resolved but encouraging to see the possibility of a split PV to start 2021 very much in evidence. 

[Mike Poole]

3 minutes ago, MKN said:

Significant differences even at 144 if you look at the Eastern U.S. The differences there at that point are why the GFS sees the high pressure head into Greenland and why the ECM doesnt.

Not saying there aren’t differences, there clearly are, but over the last couple of days, ECM is moving to GFS, rather than the other way around.  

[bluearmy]

10 minutes ago, mulzy said:

Early indications of the EPS mean up to day 10 nowhere near as good as the GEFS. Displaced Azores High with lowish heights in Greenland persisting.

Just noticed that ....the Atlantic high ridging into nw Europe as shown on half the eps clusters from the 00z will undoubtedly have increased from the 00z suite 

6 minutes ago, TSNWK said:

Hello. Any thoughts on how they trended against 00z EPS please

further east with the sceuro trough .... see the 12z gem for a good indication 

Eps Height change run to run at T258

Edited December 19, 2020 by bluearmy

[Vikos]

for me a wow!

[BLAST FROM THE PAST]

14 minutes ago, Allseasons-si said:

What do people won't...SW'ly crud?

these are great synoptic charts being churned out by both the gfs/gefs and ecm

i know this chart is at day ten but it looks like lock and load from the NW to me...

look at north America...you can virtually see the whole of the continent with low height's draining away,and as you can see by the red arrows there is still plenty of amplification to our NW to deflect more systems on a NW-SE trajectory (black circle/arrow).

 

 

Great post imo...just as I read it

 

BFTP

[BLAST FROM THE PAST]

10 minutes ago, northwestsnow said:

Typical.

LOL.

Unfortunately always likely...true GHP not in the script

 

BFTP

Edited December 19, 2020 by BLAST FROM THE PAST

[Kasim Awan]

36 minutes ago, MKN said:

The ECM is not a great run, The high pressure never gets far enough North for sustained cold (Greenland or Scandinavian high or both) and given the initial blast is unlikely to see anything noteworthy for most its pretty mundane imo.

Still, the NW-SE jet alignment is an intriguing trend, and would likely bring both cold air and precipitation. 

[northwestsnow]

8 minutes ago, bluearmy said:

Just noticed that ....the Atlantic high ridging into nw Europe as shown on half the eps clusters from the 00z will undoubtedly have increased from the 00z suite 

further east with the sceuro trough .... see the 12z gem for a good indication 

Eps Height change run to run at T258

sun cream it is then.

I jest of course..I'm more interested in keeping the Euro anomoly but a bit concerned its going to get shunted east !

 

Edited December 19, 2020 by northwestsnow

[mulzy]

6 minutes ago, bluearmy said:

Just noticed that ....the Atlantic high ridging into nw Europe as shown on half the eps clusters from the 00z will undoubtedly have increased from the 00z suite 

further east with the sceuro trough .... see the 12z gem for a good indication 

Eps Height change run to run at T258

It does get better in the 11-15 day period with heights returning to the north west and low Euro heights.

[Cheshire Freeze]

2 minutes ago, mulzy said:

It does get better in the 11-15 day period with heights returning to the north west and low Euro heights.

Makes sense as we're likely to see repeated bouts of amplification. Each time we get a little closer...

[TSNWK]

8 minutes ago, bluearmy said:

Just noticed that ....the Atlantic high ridging into nw Europe as shown on half the eps clusters from the 00z will undoubtedly have increased from the 00z suite 

further east with the sceuro trough .... see the 12z gem for a good indication 

Eps Height change run to run at T258

I took a peep at GEM240 I will not tarnish this thread by posting it.. A sobering mean