Model output discussion - into the start of Winter

[Daniel*]

I was surprised to see on day 9 from ECM widely gave an ice day 0C max in London with uppers barely negative captures very nicely 850s aren't everything.  

[sheikhy]

2 minutes ago, Daniel* said:

I was surprised to see on day 9 from ECM widely gave an ice day 0C max in London with uppers barely negative captures very nicely 850s aren't everything.  

Wow didnt expect that!!also gfs ensembles has a lot lower 850s compared to the op between 120 and 192 hours!!!op has minus 4 850s but quite a few ensembles at -7 or -8!!

[swfc]

2 minutes ago, Daniel* said:

I was surprised to see on day 9 from ECM widely gave an ice day 0C max in London with uppers barely negative captures very nicely 850s aren't everything.  

Slack air flow, mabye clear sky and low dew points. Not conjusive to snow but good point 

[SMU]

ECM snow depth for day 7

[I remember Atlantic 252]

5 minutes ago, sheikhy said:

Wow didnt expect that!!also gfs ensembles has a lot lower 850s compared to the op between 120 and 192 hours!!!op has minus 4 850s but quite a few ensembles at -7 or -8!!

GFS op is rubbish! EC and UKMO will give us some snow, even if not settling at low levels

[SMU]

Pretty decent ECM 216 mean - good upstream amplification!

[stodge]

Evening all

Well it seemed to work all right last evening - ignore what everyone else has said and look at the model output itself so I'll try that again.

12Z GEM: - a decent run last evening for fans of cold with a lot of disrupted troughs and negative alignment. Okay - the LP starts to sink south on cue more or less over the top of the British isles by T+144.  The trough heads south into the Med setting up a decent LP centre over Italy and leaving the trough line through the British Isles with hints of pressure rising both to the NE and NE so overall another decent effort. 850s are uninspiring however albeit with quite a push of cold air into Scandinavia.

12Z GFS OP - again a decent show for fans of cold yesterday evening. The LP disrupts south on cue but on this output the centre passes just to the east of the British Isles with a chilly N'ly for western areas at T+138. Unlike GEM, GFS OP keeps the LP in the North Sea before moving it east with a second LP setting up further south in Europe. The elongated Atlantic trough is much more prominent and the next LP duly follows the negative alignment moving SE first to the west of the British Isles and by T+240 moving slowly in over the British Isles from the west before sinking south allowing a lobe of the Azores HP to ridge to the north and put the British Isles in an E'ly flow by T+300. Further into FI the air mass becomes progressively colder as more of a continental feel becomes established. In all, another interesting run for fans of cold.

12Z ECM - the life and soul or a party pooper? There were aspects of last night's run I didn't like but I think I was in a minority. I'm looking to see any sign of the PV heading back to Canada in response to a Siberian-based warming. All good early on with a right Alan Partridge centred over Norfolk - sorry, couldn't resist.  It sinks away to the south though not entirely cleanly and the next Atlantic LP, albeit quite a shallow feature, is close on its tail so no opportunity for ridging so nearer GFS than GEM. The next LP heads SE over the west of Ireland and the block is building through Scandinavia to keep the negative trough alignment. We're relying on that as the NH profile, while suggesting a disorganised vortex, doesn't have any sign of heights over Greenland. However, all the energy seems to be on the other side of the Pole at this time so raging zonality it ain't.

Where are we then this evening? The trough disruption promises a cool and wet spell for many through into next weekend but there still remains a lot of doubt beyond that. GFS offers a classic path to an E'ly and perhaps quite a lasting one while both GEM and ECM provide the Eurasian bloc but not yet with any real frigid air. If we can get the bloc to the NE and a weak vortex, an extended period of negative trough alignment could work very well for fans of snow in northern and eastern areas as the air flow would be ESE'ly and the continental airflow would soon become much colder as we move toward mid-December and beyond.

[Man With Beard]

10 minutes ago, Steve Murr said:

ECM snow depth for day 7

Into that period of the year when a continental flow can produce snow without particularly low uppers. I'd imagine this is on the optimistic side of the spread, though.

[BlueHedgehog074]

The fabled NAVGEM (12Z) is disgusting too. But disgustingly good, synoptically, for the cold weather fans. It sinks the UK Low, South, later next week and we see quite a decent area of heights build North up towards Greenland (144 to 180 hours). Greenland and Canadian troposphere Vortex eliminated.

One aspect to note is that the 12Z ECMWF left behind more in the way of low heights over Western Greenland compared to the NAVGEM collapsing that vetical ridge in the mid-Atlantic. Not a massive area of Low heights mind you, and it was still no match for the Scandinavian block.

 

Low Pressure to the West of the Atlantic ridge over North-Eastern Cananda on the NAVGEM is more shallow, a little more stretchy and more vertically alligned. This of which likely helped. Plus, one part of that Low splits up with a tiny area heading South-East under the Greenland High, while another part slowly heads North up Western Greenland.

 

Edited November 28, 2020 by DiagonalRedLine

[Mike Poole]

It’s one of the few positives that, in spite of the covid nightmare, we can all still do this winter model watch hobby of ours isn’t it?  Of course, if it does snow, we might have to enjoy it alone, or with very restricted groups, I suppose...

Edited November 28, 2020 by Mike Poole

[WxHerts]

Regarding next week/weekend: the first example below was Nottingham earlier this year, under what the majority would classify as quite ‘poor’ 850hpa temperatures. Obviously nothing spectacular but it would please some. The second example is North London early in 2019, again under quite poor 850hpa temperatures. Both made possible via the magic of evaporative cooling and both largely unmodelled, some food for thought. 

[BlueHedgehog074]

9 minutes ago, Mike Poole said:

It is such good news that, in spite of the covid nightmare we can all still do this winter model watch hobby of ours isn’t it?  Of course, if it does snow, we might have to enjoy it alone, I suppose...

That is very true Mike, it is good we can stil do that. I suppose the snow (I imagine some will turn up at some point, even if not next week) should help to brighten things up a bit. And hopefully by next Winter, more people including yourself will be able to enjoy any snow with others. I know how you feel.

Edited November 28, 2020 by DiagonalRedLine
Typos again

[I remember Atlantic 252]

1 minute ago, WxHerts said:

Regarding next week/weekend: the first example below was Nottingham earlier this year, under what the majority would classify as quite ‘poor’ 850hpa temperatures. Obviously nothing spectacular but it would please some. The second example is North London early in 2019, again under quite poor 850hpa temperatures. Both made possible via the magic of evaporative cooling and both largely unmodelled, some food for thought. 

Aye, was great that event, heavy snow during daytime, difference though that was Feb, much snowier

 

[Allseasons-Si]

11 minutes ago, Mike Poole said:

It’s one of the few positives that, in spite of the covid nightmare, we can all still do this winter model watch hobby of ours isn’t it?  Of course, if it does snow, we might have to enjoy it alone, or with very restricted groups, I suppose...

I will have to enjoy it with my snowman

jokes aside,you are right Mike and i feel that we all in here have become closer netweather friends,i am certainly one of them that usually doesn't post until the run upto winter but this year i have been posting all year round

anyway,back to discussion and that Scandi block is becoming strong,latest EPS at day ten.

 

[syed2878]

2 hours ago, Daniel* said:

Yes it looks some high ground is going to get buried. ECM too extreme on coverage, Snowdon good bet? 

  it’s interesting that you see some high grounds will get a dumping strange evolutions on the models all this excitement however looking at the Met office extended forecast for next week and beyond they have no mention of any snow apart from wintry showers for north and North West high ground on settled with rain and gales in the forecast

[Allseasons-Si]

Last one from me before the 18z pub run comes out,there is certainly some wintry potential (JUST FOR FUN)as we go into next week/weekend looking at the 12 gfs

rain/snowfall charts from day six...

Synop Imagery > UK

WWW.MYWEATHER2.COM

---

Information about Weather2, a company providing comprehensive forecasting and related weather services, historical climate...

looking at the latest De-Built ECM ens wind direction and as you can see there isn't much of a zonal flow happening anytime soon(black line) but we may have to put up with a southerly flow(orange circle) but hopefully backing E/NE in the extended(maroon circle)

of course this is across the channel in Holland but it gives you a general idea in our part of the world where the weather may come from,the temps and dew points are nothing special but i hope that changes over the coming days

http://www.weerplaza.nl//Content/Images/icon-app.png 15daagse Midden - Weerpluim ECMWF-EXPERT | Weerplaza.nl

WWW.WEERPLAZA.NL

---

Bekijk de 15 daagse trend Europees weermodel voor regio Midden. Weergave van de ECMWF-EXPERT pluim met de lange...

C U for now.

 

 

Edited November 28, 2020 by Allseasons-si
Added links.

[tight isobar]

Eps/GEFS 500s certainly growing in stance for either a Scandinavian/Greenland block format!! Or even the classic trough dropper+=double whammy..@greenland geographical-Scandinavia!! .. so all the cards are piling up.... anyway after the 18z suite... let’s see if I can russle  up some ensembles against it from june 1965.. or somink?!!

Edited November 28, 2020 by tight isobar

[sheikhy]

Much better icon 18z!!!low slightly further east!!!!thicknesses look very low and slack air flow across the uk!!

[SMU]

1 minute ago, sheikhy said:

Much better icon 18z!!!low slightly further east!!!!thicknesses look very low and slack air flow across the uk!!

The low moving up from the south at 120 may bring snow over the Midlands as it tracks into the cold air

[booferking]

1 minute ago, sheikhy said:

Much better icon 18z!!!low slightly further east!!!!thicknesses look very low and slack air flow across the uk!!

Yep eastward movement continues.

[sheikhy]

Just now, Steve Murr said:

The low moving up from the south at 120 may bring snow over the Midlands as it tracks into the cold air

IF the gfs 18z looks like that a lot of peeps will be happy!!!!as i mentioned earlier there were a lot of gfs ensembles colder than the op!!hopefully we see the op latch on to one of those in bout 45 mins!!

[Eskimo]

Eyes down for the GFS 18z.

Edited November 28, 2020 by PerfectStorm

[Mike Poole]

Yes, annoying that the ICON 18z stops at T120:

But more encouraging signs that we are not entering the typical UK winter, something else...but what else?  The trop vortex could not be more all over the place if it tried, little chance it will connect with the strat vortex anytime soon, and even if it does a SSW is very possible...there has to be something for coldies this winter with all that in our favour, we just have to roll the dice...and meanwhile, let’s see what the pub run throws up (dodgy metaphor now you have to match burgers with pints! )

[Allseasons-Si]

Another good feature on the site i posted previously is the 850's and 300mb jet stream,you can run it by pressing play and speed it up,it is mesmerizing to watch

Temperature @850mb > Europe

WWW.MYWEATHER2.COM

---

Information about Weather2, a company providing comprehensive forecasting and related weather services, historical climate...

 

[Allseasons-Si]

Yes a slight shift SE from the ICON with the pressure and 850's

18z 120 v's 12z 126

C'mon gfs