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

[Luke Attwood]

I would say now only 2 or 3 Perts show a cold Easterly developing later in the forecast,how can it go so wrong!

[ArHu3]

4 minutes ago, Purga said:

With respect to some recent posts one could think that all hope of cold weather had gone,

Note that we still have 8 runs breaching the -10C 850 mark in London - the same as the 12z GEFS of yesterday.

It never happens that the number of -10C runs increases with each model run... not even in 2010 did that happen.

The ECM ensembles remain solid in showing a majority cold cluster. The MetO updates are largely based on the ECM output and it's no surprise to see no alterations there. The next major update is likely to come on Tuesday when the next run of the ECM monthly model is made available.

Look - 40% of the ensemble members show very cold weather still, what would we have given for that only a few weeks ago in early December yet alone in the last 2 years!

Anyway, with due deference to our mods wishes, a brief mention that Darren Brett on BBC news channel hinted at very cold conditions from next Friday with NE winds per last night's update.

Of course it can always go the way of the pear but I'm not ready to throw in the towel yet - and please feel free to say 'we told you so' if it does!

2013

[Dennis]

There are still cold signs with a cold N-ly -  models have to re-focus i think

[shotski]

12 minutes ago, Purga said:

With respect to some recent posts one could think that all hope of cold weather had gone,

Note that we still have 8 runs breaching the -10C 850 mark in London - the same as the 12z GEFS of yesterday.

It never happens that the number of -10C runs increases with each model run... not even in 2010 did that happen.

The ECM ensembles remain solid in showing a majority cold cluster. The MetO updates are largely based on the ECM output and it's no surprise to see no alterations there. The next major update is likely to come on Tuesday when the next run of the ECM monthly model is made available.

Look - 40% of the ensemble members show very cold weather still, what would we have given for that only a few weeks ago in early December yet alone in the last 2 years!

Anyway, with due deference to our mods wishes, a brief mention that Darren Brett on BBC news channel hinted at very cold conditions from next Friday with NE winds per last night's update.

Of course it can always go the way of the pear but I'm not ready to throw in the towel yet - and please feel free to say 'we told you so' if it does!

Absolutely mate, i see it as just a transitional phase in the modelling of the high and things will probably flip again tonight or tomorrow. The anomaly charts certainly don't back up the return of the slug. 

Edited December 31, 2016 by shotski

[Catacol]

43 minutes ago, Northern Sky said:

Can I just ask a question to clarify? @Tamara mentioned firing the starting pistol analogy in her post yesterday which a number of people have picked up on, seeming to suggest possible developments in two weeks time? My interpretation was that we are still waiting for the starting pistol to fire and when/if it does the possible consequences will be two weeks from then (rather than now)?

 

I'll let Tamara expand on her own post but will PM you shortly...

[blizzard81]

Well, I have spent the last few hours trawling through the model output and reading this forum which by the way is by far the best weather forum out there. I have digested quite a lot (apart from bacon n egg and cheese cake) but I keep going back to the ecm day 7 op. Go on, have another look at it. It is a superb chart and the best thing is I usually find the ecm day 7 op charts are very accurate.

[Gowon]

1 minute ago, shotski said:

Absolutely mate, i see it as just a transitional phase in the modelling of the high and thing will probably flip again tonight or tomorrow. The anomaly charts certainly don't back up the return of the slug. 

Yeah that looks promising. Maybe that's why the meto are still going for NE winds?

[IDO]

4 minutes ago, D.V.R said:

Yeah that looks promising. Maybe that's why the meto are still going for NE winds?

That was based on 60% eps 0z for Friday and 40% GFS 06z op, also Friday. That is old news, things have moved on and I suspect the computerised version later will be different viz the UK perspective?

[radiohead]

4 minutes ago, blizzard81 said:

Well, I have spent the last few hours trawling through the model output and reading this forum which by the way is by far the best weather forum out there. I have digested quite a lot (apart from bacon n egg and cheese cake) but I keep going back to the ecm day 7 op. Go on, have another look at it. It is a superb chart and the best thing is I usually find the ecm day 7 op charts are very accurate.

ECM's Day 7 chart from yesterday has changed quite a lot on today's Day 6 chart though. Hard to have faith in anything beyond about 96 hours at the moment...

[snowwman]

I thought from reading this thread this afternoon that the world had ended, and it seems to be centred around a single GFS run. Even this run's ensemble stamps at day 16 are in favour of blocking or blocking potential; 13 out of 20 go for this

Edited December 31, 2016 by snowwman

[Weathizard]

Going through the ENS at day 7 and there's a couple of PTB's that give us the cold NE/N shot, I choose PTB 2 as the example to use.

It shows the key area we need to watch in the the Atlantic early on, the way the Azores low phases with the troughing around Greenland is absolutely vital.

 

Here are PTB 2 and the OP at T96 and you see the large differences in the Atlantic, this has massive knock on effect at t168 where you see the difference. 

Its not the deep freeze we want but if the Azores low was to stay cut off rather than phasing with the trough we could see a flip, very unlikely.. But worth a watch on the 12z all the same.

[bluearmy]

8 minutes ago, IDO said:

That was based on 60% eps 0z for Friday and 40% GFS 06z op, also Friday. That is old news, things have moved on and I suspect the computerised version later will be different viz the UK perspective?

And today it will be straight NAEFS as it's saturday

 so no eps input and no forecaster weighting 

[shotski]

9 minutes ago, IDO said:

That was based on 60% eps 0z for Friday and 40% GFS 06z op, also Friday. That is old news, things have moved on and I suspect the computerised version later will be different viz the UK perspective?

So are we saying we now bin the ever reliable anomaly charts as their a day old ? Also don't they have human input. 

[Scandinavian High.]

21 minutes ago, IDO said:

That was based on 60% eps 0z for Friday and 40% GFS 06z op, also Friday. That is old news, things have moved on and I suspect the computerised version later will be different viz the UK perspective?

What so your telling me thay are  donig a forecast on old data from Friday and we are in Saturday.

Edited December 31, 2016 by abbie123

[There's a storm a coming]

Hi all. I've been reading this great forum for over 5 years and been interested in the weather for many, many more. The knowledge I have gained from the great  and informative posts on here has been great. Hats off to you all. I thought I would finally add a comment as it must be what we are all thinking......wouldn't it be ironic that a n Azores low scuppers our chances of a cold spell when it's usually the Azores high!

Tasac.

[TEITS]

39 minutes ago, D.V.R said:

What happened to your monitoring of how many members build HP around Iceland?

Very different.

A N,ly via a Greenland high has a much better chance of verifying than an E,ly via a Scandi HP.  You get a lot less drama with a Greenland high i.e 2009, 2010 was relatively straightforward. An E,ly via a Scandi HP has been a nightmare to follow in the model output since I joined this forum.

The simple fact is the operationals with the exception of the UKMO have been rather erratic. So due to this the ensembles become even more unreliable. If the 06Z is repeated on the 12Z then even more ensembles will slowly follow. Bascially the ensembles lag behind the operationals when it comes to an E,ly.

[IDO]

1 minute ago, abbie123 said:

What so your telling me thay are  donig a forecast on old data from Friday and we are in Saturday.

They were compiled Friday evening our time with 0z and 06z data blended from the forecaster's POV with respect to their thoughts. So of course in a dynamic situation from a UK perspective where the long wave pattern can shift east or west on a whim the D9-16 chart anomaly may be different over 30-36 hours later! Subtle changes could be the difference between a NW'ly and a SW'ly. All rather irrelevant as the 06z does its own thing and not trustworthy at the moment; the 12z will be more definitive as to trend.

[fromey]

I've just seen this, where would this sit within the models, if any where and what is it showing, it's for the 8th Jan

[Catacol]

25 minutes ago, blizzard81 said:

Well, I have spent the last few hours trawling through the model output and reading this forum which by the way is by far the best weather forum out there. I have digested quite a lot (apart from bacon n egg and cheese cake) but I keep going back to the ecm day 7 op. Go on, have another look at it. It is a superb chart and the best thing is I usually find the ecm day 7 op charts are very accurate.

Yes - agreed. The starting point. Much to be optimistic about - good to read you more upbeat. Here is the chart

 

I note - as usually happens - that the overall pattern evolution involving the block is being pushed back. 14 years of weather forum reading and chart watching has shown me clearly that the models almost always move blocks around faster than actually happens. I think there is a lot still to be resolved from the end of next week, but blocking not westerlies is the subject of the conversation. That on its own is a pleasant change to recent winters...

[Luke Attwood]

Sadly to see I feel what we are seeing now is the cold being put back and back even further, to the point where it actually rarely delivers. We always see this in the UK as it never gets this far west.it makes you wonder why we get so excited with the charts really.

[TEITS]

12 minutes ago, shotski said:

So are we saying we now bin the ever reliable anomaly charts as their a day old ? Also don't they have human input. 

The Anomaly charts are even more of a waste of time than the ensembles.

Let me explain what typically happens in the exact sequence.

Operationals, ensembles show a freeze from the E. This is then backed by the anomaly charts because really they are based on the same output. Suddenly the operationals start backing away from an E,ly but many ensemble members continue to predict an E,ly as do the anomaly charts. Slowly with subsequent runs the ensemble members showing an E,ly become less and then become non existent. All of a sudden you are then looking at the anomaly charts that are completely different.

[blizzard81]

2 minutes ago, Catacol said:

Yes - agreed. The starting point. Much to be optimistic about - good to read you more upbeat. Here is the chart

 

I note - as usually happens - that the overall pattern evolution involving the block is being pushed back. 14 years of weather forum reading and chart watching has shown me clearly that the models almost always move blocks around faster than actually happens. I think there is a lot still to be resolved from the end of next week, but blocking not westerlies is the subject of the conversation. That on its own is a pleasant change to recent winters...

Absolutely The other thing I like about that chart is that upgrades could very easily occur from that point onwards.

[bluearmy]

16 minutes ago, shotski said:

So are we saying we now bin the ever reliable anomaly charts as their a day old ? Also don't they have human input. 

Absolutely not - would rather take yesterday's blend inc eps than today's  straight naefs. Probably won't be too much difference in the upper pattern but the anomolies will likely be weaker 

[Dennis]

1 hour ago, fromey said:

I've just seen this, where would this sit within the models, if any where and what is it showing, it's for the 8th Jan

Its shows the stratosheric output with a poss split setting - things need time to work out so its later in Jan poss if all works fine (more cold) - but its one setting there are more to bring winter cold

Weather effects (Wikipedia)

Although sudden stratospheric warmings are mainly forced by planetary scale waves which propagate up from the lower atmosphere, there is also a subsequent return effect of sudden stratospheric warmings on surface weather. Following a sudden stratospheric warming, the high altitude winds reverse to flow eastward instead of their usual westward. The eastward winds progress down through the atmosphere and weaken the jet stream, often giving easterly winds near the surface and resulting in dramatic reductions in temperature in Europe.

Edited December 31, 2016 by Dennis

[bluearmy]

8 minutes ago, fromey said:

I've just seen this, where would this sit within the models, if any where and what is it showing, it's for the 8th Jan

It's not there on the 00z!

still chances of a split but the latest run was different