Model Output Discussion 29th December - Into mid-Winter.

[northwestsnow]

Just now, feb1991blizzard said:

compare that to the stonking Easterly on the op.

If that ecm and mean is on the ball you should have snowcover ( esp with 200m) from thurs to sun, forget everything else and rejoice!!!

[IPredictASnowStorm]

Ecm is showing a great easterly  that would bring a load of snow showers for most of the uk

Edited January 7, 2017 by IPredictASnowStorm

[bluearmy]

oh dear - expecting the ens to show an easterly at day 10 ...........

the anomoly chart tells you all you need to know re the ens support for the op and that is there is support.  Of course the mean won't show it and the ridge sunk across the uk remains favoured but at day 8, the mslp anomoly is a tad further nw and certainly more solid than the previous run so we remain in the situation where the ens are catching up with the op run by run. 

 

[Just Below Zero]

17 minutes ago, northwestsnow said:

If that ecm and mean is on the ball you should have snowcover ( esp with 200m) from thurs to sun, forget everything else and rejoice!!!

Please don't mention "that ECM"

[feb1991blizzard]

6 minutes ago, bluearmy said:

oh dear - expecting the ens to show an easterly at day 10 ...........

the anomoly chart tells you all you need to know re the ens support for the op and that is there is support.  Of course the mean won't show it and the ridge sunk across the uk remains favoured but at day 8, the mslp anomoly is a tad further nw and certainly more solid than the previous run so we remain in the situation where the ens are catching up with the op run by run. 

 

Ive seen ecm ens means show an Easterly at D10 before, when there is a strong signal.

Edited January 7, 2017 by feb1991blizzard

[tight isobar]

It's been a funny old road getting through the dustbin'.. and as the fox notes. .he's now at the banquet. 

...

[bluearmy]

5 minutes ago, feb1991blizzard said:

Ive seen ecm ens means show an Easterly at D10 before, when there is a strong signal.

I'll call you on that Feb !

there are six years of ECM runs on meteociel to trawl through - good luck! 

[radiohead]

2 minutes ago, feb1991blizzard said:

Ive seen ecm ens means show an Easterly at D10 before, when there is a strong signal.

But was that a time when an easterly setup was already in place  at T168 or some earlier point in the model? 

Day 10 is a long way off for an Easterly to clearly appear on a 51 member ensemble mean. It would be quite an achievement. 

[The Enforcer]

34 minutes ago, feb1991blizzard said:

ECM op not supported by ens mean unfortunately.

That's not necessarily a bad thing if it pertains to 'rain day' Saturday.

Edited January 7, 2017 by The Enforcer

[feb1991blizzard]

Much better Dutch ensembles though, colder than the 0z.

1 minute ago, bluearmy said:

I'll call you on that Feb !

there are six years of ECM runs on meteociel to trawl through - good luck! 

Can you give me a few days though please?

[IDO]

9 minutes ago, bluearmy said:

oh dear - expecting the ens to show an easterly at day 10 ...........

the anomoly chart tells you all you need to know re the ens support for the op and that is there is support.  Of course the mean won't show it and the ridge sunk across the uk remains favoured but at day 8, the mslp anomoly is a tad further nw and certainly more solid than the previous run so we remain in the situation where the ens are catching up with the op run by run. 

 

Without looking at the EPS members we are blind. But looking at this morning temperature D15 members for London it was clear that there were two clusters, in fact much like the GEFS. It is quite likely both models have a similar split and cluster patterns. The difference is that the ops in each suite are sitting in the opposite cluster. 

I would not assume, like many on here that the ECM op is right, without some strong reasons, especially with the many fails at that range. But we are due one, so let's hope tomorrow's runs reinforce the ECM take on things, otherwise the rest of Jan looks decidedly mediocre.

[SMU]

23 minutes ago, bluearmy said:

I'll call you on that Feb !

there are six years of ECM runs on meteociel to trawl through - good luck! 

The only real time was when the signal for a GH was totally overwhelming at 168

note though how by 10 the means has muted the signal-

Edited January 7, 2017 by Steve Murr

[feb1991blizzard]

2 minutes ago, Steve Murr said:

The only real time was when the signal for a GH was totally overwhelming at 168

note though how by 10 the means has muted the signal-

And guess what, it verified - This time the signal isn't there, and guess what - it wont verify!!!   -   for these setups to verify, they need overwhelming support.

[knocker]

The anomalies this evening are a bit of a problem which highlights the differences which are pretty obvious with the det runs. Upstream no major disagreements but the problems arise with the handling of the vortex lobe that plunges down over Greenland and the connected impact on the Scandinavian trough and the simultaneous amplification of the Azores HP. The ecm amplifies this process much more and so has a much more meridional flow which plunges the trough SE much closer to the UK dragging down some much colder air from the NW/N whilst the GEFS tends to a more zonal approach. While these differences exist the detailed evolution cannot be pinned down with any certainty. The NOAA 6-10 supports the GEFs but as there is no forecaster import this is not that surprising

Whilst these differences exist there can be no great confidence in going forward and they still exist in the 8-18 time frame. The GEFS has weak trough over the UK and is very zonal whereas the EPS has neutrally aligned trough mid Atlantic, ridging  over the UK with the other trough down to SE Europe thus a fairly benign W/WSW flow. We have been here before

 

Edited January 7, 2017 by knocker

[SMU]

13 minutes ago, feb1991blizzard said:

And guess what, it verified - This time the signal isn't there, and guess what - it wont verify!!!   -   for these setups to verify, they need overwhelming support.

Well all I can say is yes it may not happen however if you look at the change in the last 24 hours from the 216 mean yest to the 192 mean today you will see that the clustering must have shifted towards cold ( hence why I posted it ) 

yest 216

 

today 192

 

also a very crude measure of why the scandi high means get muted

if we have 35 members with a 1040 MB high over scandi & just 15 rogue members that are flat & have a deep 980MB low over scandi at the same time them the mean pressure at day 10 will be 1022 MB -& the contour lines will look significantly flatter as a result...

Its all about clusters if you want to use the mean & the clusters have shifted more to cold tonight ....

 

[Man With Beard]

20 minutes ago, feb1991blizzard said:

Much better Dutch ensembles though, colder than the 0z.

Can you give me a few days though please?

I can help

although I agree with BAs general point!

[feb1991blizzard]

1 minute ago, Steve Murr said:

Well all I can say is yes it may not happen however if you look at the change in the last 24 hours from the 216 mean yest to the 192 mean today you will see that the clustering must have shifted towards cold ( hence why I posted it ) 

yest 216

 

today 192

 

also a very crude measure of why the scandi high means get muted

if we have 35 members with a 1040 MB high over scandi & just 15 rogue members that are flat & have a deep 980MB low over scandi at the same time them the mean pressure at day 10 will be 1022 MB -& the contour lines will look significantly flatter as a result...

Its all about clusters if you want to use the mean & the clusters have shifted more to cold tonight ....

 

Oh yes steve, but I can honestly say, lets take the GEFS for example, for any potent Easterly to verify, you really need a good number of members flatlining below -10c from 240 to towards the end of the run, and by 168-190 range, you really need the overwhelming cluster to show the Easterly, the Met Office have just ditched talking about an Easterly within T700, so I doubt they would have done that with any threat whatsoever of one popping up in the next 10 days!!, they would look mighty stupid.

[Met4Cast]

7-8 days ago we had the half the GFS and ECM ensembles calling for a Easterly including the ops. The UKMO said no and over 24 hours the ensembles and ops backed down and away from the Easterly. In fact, the evolution of the Easterly then wasn't too dissimilar to what the ECM op is currently showing.

The fact that it's currently only the ECM op (and perhaps UKMO op if it were to go out that far, but we can only speculate about that) showing higher amplitude of the high then leading to an Easterly doesn't really fill me with confidence, especially given the ECM bias to over amplify highs anyway. 

The cold spell next week is pretty much set in stone now, the details ie where snow will fall, etc is something that wont be resolved until the cold is actually embedded over us. Beyond that is anyones guess but i'm certainly not putting faith in a couple of ECM op runs. 

Edited January 7, 2017 by Daniel Smith

[nick sussex]

3 minutes ago, feb1991blizzard said:

Oh yes steve, but I can honestly say, lets take the GEFS for example, for any potent Easterly to verify, you really need a good number of members flatlining below -10c from 240 to towards the end of the run, and by 168-190 range, you really need the overwhelming cluster to show the Easterly, the Met Office have just ditched talking about an Easterly within T700, so I doubt they would have done that with any threat whatsoever of one popping up in the next 10 days!!, they would look mighty stupid.

The GEFS is not great at picking out easterlies, its flat bias will inevitably lead to a lot more energy heading east. It really hasn't covered itself in glory the last week. The GFS op has done a subtle backtrack hoping no one would realize, do we remember what it was doing with shortwaves over ne Canada which were delaying the retrogression of the Euro high whereas the Euros had a cleaner evolution. Those shortwaves got ditched but because our attention has been elsewhere it avoided scrutiny!

[feb1991blizzard]

Also, if there is 35 members showing a big scandi high (like the one on the ECM op), then you would see a lot of runs with max temps for London below freezing on the Graph between 240 and 360.

[feb1991blizzard]

2 minutes ago, nick sussex said:

The GEFS is not great at picking out easterlies, its flat bias will inevitably lead to a lot more energy heading east. It really hasn't covered itself in glory the last week. The GFS op has done a subtle backtrack hoping no one would realize, do we remember what it was doing with shortwaves over ne Canada which were delaying the retrogression of the Euro high whereas the Euros had a cleaner evolution. Those shortwaves got ditched but because our attention has been elsewhere it avoided scrutiny!

As per above post, you need both suites to show a lot of Easterlies, once you get to within 192 even on the GEFS and less than half the suite are showing an Easterly (especially when the Met Office are not buying it), you can almost certainly know the Jet will in some form or other be too strong, especially when this strat ridge is supporting a mid latitude high only.

[Purga]

De Bilt ENS showing a good very cold clustering trend = Easterly MO

Positive for Holland and us as well we hope.

EDIT: PS Note the Op is on the MILD side of the run!

Edited January 7, 2017 by Purga

[nick sussex]

Just now, feb1991blizzard said:

As per above post, you need both suites to show a lot of Easterlies, once you get to within 192 even on the GEFS and less than half the suite are showing an Easterly (especially when the Met Office are not buying it), you can almost certainly know the Jet will in some form or other be too strong, especially when this strat ridge is supporting a mid latitude high only.

Easterlies are generally led by the ops with the ensembles slowly coming on board. I'm surprised the UKMO ditched even giving it a low probability because the overall set up doesn't need some big NH pattern change to deliver that and with the PV elongated and heading back south towards the Atlantic any ridge response to the east of its landing point would be to head ne'wards. I'm not saying an easterly is going to verify but just its a possibility.

[Cheshire Freeze]

5 minutes ago, nick sussex said:

Easterlies are generally led by the ops with the ensembles slowly coming on board. I'm surprised the UKMO ditched even giving it a low probability because the overall set up doesn't need some big NH pattern change to deliver that and with the PV elongated and heading back south towards the Atlantic any ridge response to the east of its landing point would be to head ne'wards. I'm not saying an easterly is going to verify but just its a possibility.

The Metoffice have been reactive rather than proactive IMO this winter- something I mentioned a couple of weeks back. I think this is due, and has been due, to the lack of steering via drivers such as the MJO. They're relying more on model output...which has been all over the show.

[damianslaw]

5 minutes ago, CreweCold said:

The Metoffice have been reactive rather than proactive IMO this winter- something I mentioned a couple of weeks back. I think this is due, and has been due, to the lack of steering via drivers such as the MJO. They're relying more on model output...which has been all over the show.

Agree with the above, the 6-10 day forecasts have changed on a rapid basis. Also the met office long range forecast seems to change on a day by day basis, one day saying dry anticyclonic cold, another wet and windy, flip flopping all over the place. This is proving to be quite a tricky winter weather forecasting, the margins for error are huge this year.