Model Output Discussion - mid Autumn

[adamgooner]

4 minutes ago, nick sussex said:

Hi all .

Hope everyone has recharged their batteries and is ready and raring to go as the winter season approaches ! 

Looks like I picked a good time to return from my hibernation. 

Nothing like a bit of early season drama which seems to be the case with 3 options on the table . GFS turning colder and wintry , UKMO generally drier and colder and the ECM more average and drier .

The divergence as is often the case due to upstream differences. Specifically here the area in the nw Atlantic and handling of shortwave energy, phasing issues which stop the ridge extending north .

I should say the UKMO has edged a bit towards the ECM this morning compared to last nights run . The GFS is the cleanest upstream evolution .

Not long till the the next GFS so more after that .

Great to see you posting again Nick. Always enjoy reading your posts and the knowledge you share is always excellent.

How many weeks until your SOS line opens up as the winter nirvana charts crash before our eyes at T-30 hrs.

[sheikhy]

Icon 06z moves towards gfs at 96 hours!!!lets see where it goes from here.....

[nick sussex]

11 minutes ago, adamgooner said:

Great to see you posting again Nick. Always enjoy reading your posts and the knowledge you share is always excellent.

How many weeks until your SOS line opens up as the winter nirvana charts crash before our eyes at T-30 hrs.

Thanks that’s very nice of you . It could be sooner than expected ! 

[nick sussex]

3 minutes ago, sheikhy said:

Icon 06z moves towards gfs at 96 hours!!!lets see where it goes from here.....

Interesting! Projecting forward from T120 hrs it can’t evolve as well as the GFS bit is a step in the right direction .

[sheikhy]

Yup yup icon moves to gfs!!the plot thickens!!!!

[sheikhy]

Just now, nick sussex said:

Interesting! Projecting forward from T120 hrs it can’t evolve as well as the GFS bit is a step in the right direction .

Put it this way it shall end way better than the ecm man!!!!goin for a 5k run now!!should be back in time for the interesting part of the 06z run!!

[Cambrian]

Putting the operational runs to one side, yesterday was a momentous day for the ECM. The readouts across the suite, when compared with the day before, were telling. 

The weekly heights anomalies charts for 27 Nov - 4 Dec gave up the idea of the evolution of a flatter west-east troughing pattern over Northern Europe and reinforced the Atlantic ridge and Scandinavian trough. Trough and ridge all pulled west again, opening up the UK and Ireland to much more chance of incursions from the northwest and north. 

 

There has been a consistent underestimation of this setup in the day-to-day runs, only for it to be repeatedly brought back, for several weeks now. 

The regimes forecast extended the Atlantic ridge signal for another 4 days, now running into December. 

 

A repeated feature of the last two weeks, shown clearly on the 13-day retrospective verification chart. Even the chart from just one week ago, when compared with the latest (above right), portrays the diminishing NAO+ signal.

 

The weekly mean temperature anomaly charts dropped the several weeks long theme of substantially above average temperatures for decidedly average temperatures, look at that pooling of cold air to the north. 

27th-4th;

 

4th-11th;

 

Possible reasons? There are notable synoptic differences between the outputs of the two days on the day 10 ensemble means, in the conversion of the Aleutian ridge into a polar high. Previous day vs. yesterday, mean and anomaly charts…

 
 

The low heights of the three PV lobes are diminished, with a 5mb increase in the surface pressure of the respective low pressure systems, though the hemispheric heights are broadly similar.

The formation of the polar high has quite literally taken the wind out of the tropospheric PV. It’s likely to translate to increasing meridional patterns and more defined poleward waves of amplification, working off the scaffold of an established 3-wave hemispheric pattern, troughs to the Bering Sea, eastern Canada and Scandinavia, the latter always close to the UK and Ireland.

That’s a compelling signal being transmitted through the entire ECM suite, through multiple levels and parameters. It’s like someone has just flicked the switch for the northern hemisphere winter. Winter is coming. 

Edited November 18, 2023 by Cambrian

[seabreeze86]

23 minutes ago, sheikhy said:

Icon 06z moves towards gfs at 96 hours!!!lets see where it goes from here.....

Yes big differences at short range in how it handles the low

Edited November 18, 2023 by seabreeze86

[sheikhy]

Well well gfs sticking to its guns it seems so far!!!!out to 120 hours and is massively different to ecm southwest of greenland!!

[sheikhy]

Hmmm dont look as good as the 00z so far but seems a move toward the ukmo instead!!how fitting considering my comnent about the ukmo earlier!!

[sheikhy]

Aaah looks to be the famous toppler on the 06z!i take that for now if its worst result!!!

[ItNeverSnowsInWindsor]

Good to see the amplification signal still present on the GFS 6z.

It could be a decent start to December if the cold pool to our North East could be maintained while the rest of Europe also cools down.

 

[nick sussex]

The GFS 06 hrs run not as good as the earlier 00hrs in terms of wintry potential but still doesn’t back the ECM .

We do see differences over the USA and Canada from its earlier run .

Quite a different jet pattern there .

Whatever happens post day 6 it’s really the day 4 into 5 which either shuts the door on colder or leaves it open .

The gap of hope as it shall be named ! No gap no hope !

The high over the UK needs a path nw to ridge to and that’s the key , without the gap it will remain stuck over the UK with upstream energy spilling over the top . That’s what happens in the ECM .The GFS has the gap .

GFS 06 hrs to T114 hours .

 

ECM 06 hrs to T120 hrs .

It’s finely balanced because there’s not a big margin for error . Once energy spills over the top you’re at the point of no return . The chance has gone .

Edited November 18, 2023 by nick sussex

[ANYWEATHER]

I have to say ecm and gfs at 00z could not be more different at the T+168 . Not buying into gfs evolution,or not the extreme side of it anyway, I hope I'm wrong for you cold fans out there.

[sheikhy]

35 minutes ago, nick sussex said:

The GFS 06 hrs run not as good as the earlier 00hrs in terms of wintry potential but still doesn’t back the ECM .

We do see differences over the USA and Canada from its earlier run .

Quite a different jet pattern there .

Whatever happens post day 6 it’s really the day 4 into 5 which either shuts the door on colder or leaves it open .

The gap of hope as it shall be named ! No gap no hope !

The high over the UK needs a path nw to ridge to and that’s the key , without the gap it will remain stuck over the UK with upstream energy spilling over the top . That’s what happens in the ECM .The GFS has the gap .

GFS 06 hrs to T114 hours .

 

ECM 06 hrs to T120 hrs .

It’s finely balanced because there’s not a big margin for error . Once energy spills over the top you’re at the point of no return . The chance has gone .

I still think ecm has this more correct than gfs!!!i would love to be wrong though if its for cold and snow!!

[MP-R]

3 hours ago, That ECM said:

Gfs isn’t all that at t144 either.

When did the Phallus Verticus start getting so rude..!

Anyway, I’m liking the increasing likelihood of high pressure, regardless of cold. The high will probably become squashed from above over time but at least a drier spell would ensue.

[Tim Bland]

Nice end from GFS 06z ️ 

[Met4Cast]

Oooof..

The GFS is looking more and more isolated with the burst of amplification, the ECM mean is having absolutely none of it!

[swfc]

17 minutes ago, Tim Bland said:

Nice end from GFS 06z ️ 

Some great snowcover across europe on that run. Be ideal going into early winter

[Premiere Neige]

6 minutes ago, Met4Cast said:

Oooof..

The GFS is looking more and more isolated with the burst of amplification, the ECM mean is having absolutely none of it!

You have to wonder how 2 of the best models can be so different...

[CoventryWeather]

11 minutes ago, Met4Cast said:

Oooof..

The GFS is looking more and more isolated with the burst of amplification, the ECM mean is having absolutely none of it!

Not quite that isolated I'd say. The UKMO seems interested, probably a mid ground but wouldn't say the solution is completely unlikely. The GFS has moved towards the UKMO but it would still provide a pattern completely different to the ECM. The ECM is the outlier I'd say here - other models have it collapsing into a drier seasonal pattern. 

Here are the charts from the ECM and MOgreps for 192hrs. Plenty of solutions, and I'd say more look like the GFS than ECM, but that's my viewpoint. Feel a few more movements are likely from the models over the coming days. 

Edited November 18, 2023 by CoventryWeather

[MATTWOLVES 3]

Well it's Saturday and the drama continues. Gfs still remains steadfast,UKMO brings hope and ECM remains a festive killer...perhaps the uncertainty around the NH is causing a little confusion and background drivers can at times become muted to other variables now being in force...folks we have reached the times when you can expect the unexpected,and not necessarily that current drivers will be concrete nailed on factors!

This place is gr8...nick sussex has just returned after a long hibernation and hits us with the shortwave almost instantly...lol..glad to have you back nick lad and hope ya well...and our legend Shaky is so excited he's going for a 5k run...now most folks would take the I pod music player with them..but i reckon Shaky will have a laptop taped to his head so he can watch the 6z roll out..folks are gonna think your losing it mate..

Absolutely love it...legends the lot of ya.

Eyes down for plenty of entertainment from the weather gods this coming season..and I feel there will be interesting times ahead.

And just to mention those ens show a NH that looks confused and primed with options a plenty.

Bring it on...

Edited November 18, 2023 by MATTWOLVES 3

[Notty]

Experimental: GraphCast ML model: Temperature and geopotential at various pressure levels

CHARTS.ECMWF.INT

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**ECMWF is now running an experimental suite to evaluate the forecasting skill of a series of publicly available data-driven forecast models initialised by ECMWF 4D-Var...

Experimental AI model showing a cooler flow for 28/11

[Kentspur]

35 minutes ago, Tim Bland said:

Nice end from GFS 06z ️ 

Excellent having come back from a snow filled swedish break 30th November ill be at Elveden forest in East Anglia during this period  

[northwestsnow]

Well only my very amateur opinion but GFS has dangled more carrots than I care to remember over the last 20 years.

In a run off with GFS  the result will be EC victory 9 times out of 10.