Model output discussion - 5th December 2016 - Into Winter we go

[knocker]

6 minutes ago, ArHu3 said:

 

And then ecwmf comes with this surprise and only +144h out

Help me out here ArH, what's the surprise?

[Iceberg]

The general trend from the models seem to be predominately boring and average weather temps a little higher than average at times. 

Then from the 22-24th time range a blast of pm air, modelled at its extreme by ecm yesterday but even today's gfs has max temps on the 23rd of 2-4c widely with 5-6c in the far south and sw.  Particularly on 23-24th is the chance of snow showers into the nw. The above is pretty well backed up by ens as well as reasonable cross model agreement. 

At t144 all the models support a similar set up. Ecm, just coming out has a better jet angle with more energy at that time frame. Meto the least. 

Beyond the 23-24 and considerable uncertainty still reigns    As expected at this time range it's unlikely that any models have the actual forecast sorted yet. 

[Seasonality]

Fascinating 00z. The high pressure moves to north west Russia, bring colder unstable air over the uk in the process. We then end 2016 with two centres of high pressure over Poland and Northwest Russia with cold lurking to the east aided by low pressure across Greece. Also i note the Warsaw ensembles are on the milder end on the 00z but show even more cold options than the 18z! A bit of a change from yesterday.

[ArHu3]

9 minutes ago, knocker said:

Help me out here ArH, what's the surprise?

Wait till later, until +240h renders, this is completely different from yesterday's 0z and 12z. Nice setup with low in around genua and high in scandi/ western Russia much more too the north 

 

[daz_4]

2 minutes ago, Seasonality said:

Fascinating 00z. The high pressure moves to north west Russia, bring colder unstable air over the uk in the process. We then end 2016 with two centres of high pressure over Poland and Northwest Russia with cold lurking to the east aided by low pressure across Greece. Also i note the Warsaw ensembles are on the milder end on the 00z but show even more cold options than the 18z! A bit of a change from yesterday.

Interesting ENS for sure with high pressure from the east dominating with some bringing easterly right after Christmas. 90% even show below freezing temps for 24th over central Europe. Potential (ugh ) is there.

[Man With Beard]

Focusing just on the op runs this morning, pretty standard uk winter fair. A few more settled days coming up with perhaps a few frost's, before the pattern flattens somewhat with Atlantic storms barrelling in, the extent to which they affect the UK being quite varied - some passing through NW regions only, and some making further progress into the UK. On balance, most areas likely to see some rain before Christmas. No blocking worth mentioning in the proximity of the UK, IMO.

Edited December 15, 2016 by Man With Beard

[Iceberg]

I see very very little chance of an easterly in the models this side of ny. I can't just can't see anything in the profile to suggest it. 5-10% chance at best. 

[Man With Beard]

OK and onto the ens ... Like a different world on the GEFS, at just T144 there are a plethora of options on the table and many of them easterly. Of course, it makes sense to follow the op runs at such short range, but it does remind us how there is still some uncertainty about the middle of next week.

[ArHu3]

5 minutes ago, Man With Beard said:

OK and onto the ens ... Like a different world on the GEFS, at just T144 there are a plethora of options on the table and many of them easterly. Of course, it makes sense to follow the op runs at such short range, but it does remind us how there is still some uncertainty about the middle of next week.

the difference already become clear after 54 to 60h with the formation of the little trough arounde iceland http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=6&ech=54

[knocker]

1 hour ago, ArHu3 said:

Wait till later, until +240h renders, this is completely different from yesterday's 0z and 12z. Nice setup with low in around genua and high in scandi/ western Russia much more too the north 

 

Not wishing to be pedantic you said this

Quote

And then ecwmf comes with this surprise and only +144h out

At that time it was virtually the same as the previous run and you had no idea what was coming later  As it turns out it's just the usual variation on a theme with the back end of the run having some wet and windy intervals so very unsettled.

Edited December 15, 2016 by knocker

[mb018538]

Also worth nothing that a few runs are now hinting at perhaps (!) quite a vigorous storm to pass the UK around xmas eve/day. Not showing on all, but both the GFS and ECM op runs have it in a form. Finer details not worth talking about in too much detail at this stage, but one to certainly watch out for.

[ArHu3]

39 minutes ago, knocker said:

Help me out here ArH, what's the surprise?

 

big changes, for my area we could actually see some snow if that low on the french coast does its thing right

Edited December 15, 2016 by ArHu3

[TEITS]

18 minutes ago, Iceberg said:

I see very very little chance of an easterly in the models this side of ny. I can't just can't see anything in the profile to suggest it. 5-10% chance at best. 

I agree we are unlikely to see an E,ly between now and xmas. However I wouldn't rule out an E/SE,ly flow between Xmas and New Year. Sadly though at this stage it would be more likely to be a cold, dry, frosty E,ly than a very cold convective E,ly.

[knocker]

4 minutes ago, ArHu3 said:

the difference already become clear after 54 to 60h with the formation of the little trough arounde iceland http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=6&ech=54

That little trough, which has broken off from the main upper trough is quite insignificant and is soon lost in eastern Europe as it wings around the high pressure.

Edited December 15, 2016 by knocker

[fergieweather]

7 hours ago, Steve Murr said:

The only real assessment that really needs to be made by METO is why that 'strat top' models missed the boat on the 40M/S swing in the 10HPA 60N zonal mean from 10M/S on Nov 25th & again @ 13 M/S on Dec 3rd to where we are now 10 days later @ near 50M/S - 

If the models cant model the variability in the strat then they cant progress forward.

ECM shows continued clear downward propergation

PS I will add this daily

CFS DATE FOR SSW IS 14th Jan ..

 

 

Hi Steve: not sure which models you mean (missing the stratospheric trend), but GloSea5 certainly didn't. Here's snapshot of output from way back in late October (hence not latest modelling, which I can't show). Red is forecast mean; blue the hindcast mean. Note much weaker period foreseen during Nov; then marked uptick in 10hPa zonal winds (most members heading above average) during December. This signal was repeated and strengthened each run thereafter. UKMO were confident on the turnaround in SPV that has now unfolded, and GloSea5 timing for this was actually good. So it's incorrect to suggest UKMO missed this: quite the opposite; they were ahead of the game. 

[northwestsnow]

9 minutes ago, fergieweather said:

Hi Steve: not sure which models you mean (missing the stratospheric trend), but GloSea5 certainly didn't. Here's snapshot of output from way back in late October (hence not latest modelling, which I can't show). Red is forecast mean; blue the hindcast mean. Note much weaker period foreseen during Nov; then marked uptick in 10hPa zonal winds (most members heading above average) during December. This signal was repeated and strengthened each run thereafter. UKMO were confident on the turnaround in SPV that has now unfolded, and GloSea5 timing for this was actually good. So it's incorrect to suggest UKMO missed this: quite the opposite; they were ahead of the game. 

Ian, if this is correct,and I'm sure it is,it begs the question, where did the front loaded winter come from?Bearing in mind a strong PV generally speaking is not a precursor to UK cold?Apologies if the front loaded winter snippet was not related to the met office..

[Frosty.]

Again, any unsettled weather looks brief with a return to benign anticyclonic conditions from boxing day thru to the new year according to the Gfs 00z.

Edited December 15, 2016 by Frosty.

[Chris.R]

 I would just like to say something here. Are we sure that front loaded cold was actually  what was being predicted, or front loaded blocked? If the latter then that certainly has happened; the block has just not been in the right place for cold, but was it ever predicted to be or is that just something where blocked has been interpreted as cold. 

[Frosty.]

Just now, Chris.R said:

 I would just like to say something here. Are we sure that front loaded cold was actually  what was being predicted, or front loaded blocked? If the latter then that certainly has happened; the block has just not been in the right place for cold, but was it ever predicted to be or is that just something where blocked has been interpreted as cold. 

Good point, I think front loaded MLB winter sums it up bar the occasional unsettled blip.

[fergieweather]

1 minute ago, northwestsnow said:

Ian, if this is correct,and I'm sure it is,it begs the question, where did the front loaded winter come from?Bearing in mind a strong PV generally speaking is not a precursor to UK cold?Apologies if the front loaded winter snippet was not related to the met office..

This "front loaded" winter thing isn't a phrase ever used in any UKMO assessment. They talked about a higher *risk* of cold weather in 1st part of winter, due to background signals (weak SPV initially; blocking which could result in increased E/NE flow). Whilst we've seen both blocking and recent E'ly phases, the probabilistic risk of *prolonged* cold weather was never high in previous diagnosis and in very latest seasonal update this week, any such signal is lacking anyway. So in summary: yes, there was a clear potential for cold weather into early winter, which was flagged to contingency planners and public; however the caveat re this not manifesting was also made very clear (eg in Adam Scaife's UKMO blogs).

[Seasonality]

Seasonality's brief Xmas summary 

Both ECM and GFS showing troughing pushing down over the uk. As you can see though with ECM the blocking is further east and not as robust allowing a better draw of colder air across Europe. GFS 2m temps seasonal for Europe but not amazing. We then end the run folks with another variation on blocking. I suspect we're drawing closer to a cool unsettled NW'ly regime for the big day for the UK, and some seasonal cheer for the Scottish ski resorts, Northern Island and higher ground in the north at least.

PS Just for all the pedants on the forum, all of this *may* happen 

Edited December 15, 2016 by Osbourne One-Nil
Be nice!

[northwestsnow]

Just now, fergieweather said:

This "front loaded" winter thing isn't a phrase ever used in any UKMO assessment. They talked about a higher *risk* of cold weather in 1st part of winter, due to background signals (weak SPV initially; blocking which could result in increased E/NE flow). Whilst we've seen both blocking and recent E'ly phases, the probabilistic risk of *prolonged* cold weather was never high in previous diagnosis and in very latest seasonal update this week, any such signal is lacking anyway. So in summary: yes, there was a clear potential for cold weather into early winter, which was flagged to contingency planners and public; however the caveat re this not manifesting was also made very clear (eg in Adam Scaife's UKMO blogs).

Thanks-

[mb018538]

1 minute ago, Chris.R said:

 I would just like to say something here. Are we sure that front loaded cold was actually  what was being predicted, or front loaded blocked? If the latter then that certainly has happened; the block has just not been in the right place for cold, but was it ever predicted to be or is that just something where blocked has been interpreted as cold. 

I think this is the crux of the problem - people just take blocked as automatically meaning it'll be cold and/or snowy here. Of course this doesn't have to happen at all.

[Summer Sun]

Well last night the beeb said the deep low to the NW was a low probability looks like they were right

Whilst still unsettled at times in the far northwest we've lost the really deep lows of last night

 

 

[Paul_1978]

4 minutes ago, Seasonality said:

Err, yes, I know that, would you stop taking things so literally and let people narrate a run without having to field sarcastic little quips. We all know 384 charts don't verify, calm down dear.

So now that ECM has Xmas day in view, a little round up of the output if I *may*  

Seasonality's brief Xmas summary 

Both ECM and GFS showing troughing pushing down over the uk. As you can see though with ECM the blocking is further east and not as robust allowing a better draw of colder air across Europe. GFS 2m temps seasonal for Europe but not amazing. We then end the run folks with another variation on blocking. I suspect we're drawing closer to a cool unsettled NW'ly regime for the big day for the UK, and some seasonal cheer for the Scottish ski resorts, Northern Island and higher ground in the north at least.

PS Just for all the pedants on the forum, all of this *may* happen 

Sarcasm is the lowest form of wit.

But overall I can't argue with your summary.