Model output discussion - 7th January onwards

[karlos1983]

11 minutes ago, Lloyds32 said:

Hm. I think today's ECM run isn't as good as yesterdays. Today's looks like the ridge is having more influence on the UK, where it has moved (sunk?) more over the UK stopping the strongest flow from the east. Which in turn pushes the low pressure further south into Europe. I'm looking for a stronger ridge and up further to the NE. I have feeling the ridge is going to sink more on the next ECM run keeping the easterly flow more towards northern France. Therefore the deep cold being pushed further south into Europe. That's just my take on the way I think it will pan out. Europe into the freezer with snow, with the UK missing out with the ridge sinking over us. I think the operational run was cold outliner.

 

 

That's interesting.. other than gut feeling, do you have any charts to back that rather sweeping statement up? nowhere on this mornings output have i seen the ridge sinking over us in the way you are suggesting.

UKMO - nope

ECMWF - nope

GFS - Nope

GEM- Nope

If youn refer back to for example, some of @Catacol or @lorenzo 's posts (hope you don't mind me tagging you), you might understand why uk a high is pretty unlikely anytime soon. Take the time to take on board what the more technical posters are saying and you might learn some cool stuff, gut decisions don't usually end well in most situations, definitely not in nwp.

Edited January 18, 2019 by karlos1983

[East_England_Stormchaser91]

1 minute ago, kold weather said:

ICON 06z has moved back towards it's 18z setup with the low not separating as well come 120hrs. 00z was a good step forward but 06z definite step back again with the heights remaining more stubborn over Iceland.

Charts? I’ve yet to see any pictures to back up this negative implicit. 

Its coming across as deceiving and somewhat confusing to newer members. 

The weather in a nutshell is set to turn much colder with a risk of snow anywhere in the country in the next 5 days. Unless you can provide charts that suggest otherwise? 

[TEITS]

Wow what an exciting time at the moment.

Putting aside the details i.e snow/how cold, which personally I cannot be bothered with. The fact remains the models are suggesting a trough in the Med with high pressure between Iceland extending into Scandi. The end result is below average temps in the UK. However it is inevitable you will see details change with regards to temps/precip. You simply cannot expect -15C upper temps, constant streamers in every run!

The pick of the day for me is the GEM. Absolute classic old school 1947 style cold spell. For anyone who didn't know the classic old school cold spells had alternating N,lys&E,lys as high pressure alternated between Greenland/Scandinavia. Worth mentioning that if the GEM is correct then during that switch from E,lys to N,lys then you will see a brief increase in the 850hpas. I mention this for those looking at the ensembles.

[Catacol]

16 minutes ago, Lloyds32 said:

Therefore the deep cold being pushed further south into Europe. That's just my take on the way I think it will pan out. Europe into the freezer with snow, with the UK missing out with the ridge sinking over us. I think the operational run was cold outliner.

 

 

No problem having a feeling - we are all interpreting the data for ourselves....but actually there is no model evidence for this interpretation at the moment. All ensemble data indicating the main height anomaly to the north and trough to the south. In this scenario, even if the high did drop a bit further south, we would still be very much in the general European freezer. Given the trend for arctic heights and ongoing impacts of downwelling ssw it also isn’t an interpretation that runs alongside strat teleconnections....and if you go and read David’s post from yesterday that very accurately sets out the next Pacific spike in momentum it would also fly against that forcing.

Most bets I think would remain attached to the UK being more under the influence of the trough than the block....though obviously north/south location will be relevant. This isn’t a pattern that suggests a sinking block. (For once....!) 

Edited January 18, 2019 by Catacol

[kold weather]

7 minutes ago, East_England_Stormchaser91 said:

Charts? I’ve yet to see any pictures to back up this negative implicit. 

Its coming across as deceiving and somewhat confusing to newer members. 

The weather in a nutshell is set to turn much colder with a risk of snow anywhere in the country in the next 5 days. Unless you can provide charts that suggest otherwise? 

Look at Meteociel, its updates most models faster, ICON 06z only runs to 120hrs but its 100% out, take a look!

Edited January 18, 2019 by kold weather

[Singularity]

While it's true that we can't guarantee an easterly that's unstable enough for snow, there's no reason to expect one outcome over the other. The presence of stratospheric downwelling offsets the usual climatology of ridges struggling to gain enough latitude to bring us vigorous convective streamers so the door is wide open for all manner of outcomes from benign to jaw-dropping.

Regardless of what happens with the easterly spell, odds are we then see a bit of an attempt by the Atlantic troughs to break through sometime around D8-D11, but there's a good chance it will be up against some cold air at least at the surface and possibly aloft as well, and - most crucially - the MJO movement back across the Pacific should take the sting out of the Atlantic before long. That could work out pretty well from a snowfall perspective unless, of course, the Atlantic never makes it in, in which case we likely see some exceptionally low temperatures instead. Experience tells me, though, that the low temps tend to prove harder to achieve than the modelling indicates at mid-long ranges, and the snow less so... i.e. it usually turns out less 'clean' with disturbances in the flow.

[Lloyds32]

40 minutes ago, karlos1983 said:

That's interesting.. other than gut feeling, do you have any charts to back that rather sweeping statement up? nowhere on this mornings output have i seen the ridge sinking over us in the way you are suggesting.

UKMO - nope

ECMWF - nope

GFS - Nope

GEM- Nope

Hi Karlos. You always reply to every post I make. Its a forum, many posters make a predication based on the output. The ECM at 168 and 192 today has a weaker flow from the east. At 192 the pressure the NE seems further south, pushing the stronger flow into France etc. That's how I see it panning out, just an opinion. No need to get so upset.

Edited January 18, 2019 by Paul

[kold weather]

6 minutes ago, Singularity said:

While it's true that we can't guarantee an easterly that's unstable enough for snow, there's no reason to expect one outcome over the other. The presence of stratospheric downwelling offsets the usual climatology of ridges struggling to gain enough latitude to bring us vigorous convective streamers so the door is wide open for all manner of outcomes from benign to jaw-dropping.

Regardless of what happens with the easterly spell, odds are we then see a bit of an attempt by the Atlantic troughs to break through sometime around D8-D11, but there's a good chance it will be up against some cold air at least at the surface and possibly aloft as well, and - most crucially - the MJO movement back across the Pacific should take the sting out of the Atlantic before long. That could work out pretty well from a snowfall perspective unless, of course, the Atlantic never makes it in, in which case we likely see some exceptionally low temperatures instead. Experience tells me, though, that the low temps tend to prove harder to achieve than the modelling indicates at mid-long ranges, and the snow less so... i.e. it usually turns out less 'clean' with disturbances in the flow.

I think regardless of what happens with the easterly, there looks like to be a trend for the jet to keep spltting between 50-30W and this should help to keep us on the cold side of things regardless of whatever happens.

The ECM ensembles certainty hint at an attempt to break the pattern down BUT there is also a clear signal for heights to drop to our east again and for the flow to start swinging more to the north again. There IS a chance of the HOLY grail, AJKA a late December 62 set-up wit hthe easterly running out just as the flow bends northerly, end result is the frontal zone stalls out and huge falls of snow...Its exceptionally rare, but possible in this set-up if the stars align! (I've seen it maybe 2-3 times total on the archive charts of all winters since 1900!)

Edited January 18, 2019 by kold weather

[Lloyds32]

4 minutes ago, Catacol said:

No problem having a feeling - we are all interpreting the data for ourselves....but actually there is no model evidence for this interpretation at the moment. All ensemble data indicating the main height anomaly to the north and trough to the south. In this scenario, even if the high did drop a bit further south, we would still be very much in the general European freezer. Given the trend for arctic heights and ongoing impacts of downwelling ssw it isn’t also an interpretation that runs alongside strat teleconnections....and if you go and read David’s post from yesterday that very accurately sets out the next Pacific spike in momentum it would also fly against that forcing.

Most bets I think would remain attached to the UK being more under the influence of the trough than the block....though obviously north/south location will be relevant. This isn’t a pattern that suggests a sinking block. (For once....!) 

Thank you for your response, much appreciated.

[Singularity]

 

For what it's worth, ICON 06z is very similar to ECM 00z at +120 and it still has the shortwave on the western flank of the trough by Canada that serves to re-focus the trough in that area rather than letting it move quickly NE and flatten the Azores ridge before it can make the link with the Arctic High.

That shortwave needs watching out for on future runs by the way; it won't help matters if it disappears.

[Methuselah]

Gordon Bennett!

So, I get up (on my first snow-day of the season) to find that the anticyclone has already collapsed...What anticyclone? I ask myself...Oh, that one! The one that was there in nine-days' time! Forgive my lack of a TARDIS, but how can a weather-feature that's yet to exist have already met its demise?

I know it's still early doors, but adjusting from real time to a 'day-nine was yesterday' mindset has come as something of a shock to the system!

PS: Model-runs look okay to me...

[Catacol]

4 minutes ago, kold weather said:

I think regardless of what happens with the easterly, there looks like to be a trend for the jet to keep spltting between 50-30W and this should help to keep us on the cold side of things regardless of whatever happens.

The ECM ensembles certainty hint at an attempt to break the pattern down BUT there is also a clear signal for heights to drop to our east again and for the flow to start swinging more to the north again.

Yes - exactly. In the medium term we might appear to run the risk of marginal situations via inroads from the atlantic....but these are the patterns that bring the most snowfall and models will tend to underestimate resistance of residual wedges of higher pressure embedded in the cold. It’s a very good setup for snow rather than cold/dry.

 

Offline for a bit now. Job interview.....

Edited January 18, 2019 by Catacol

[bluearmy]

no one should think that the overnight runs have downgraded anything .....they are merely fluctuating within an envelope - some parts are better for cold some are worse for snow .... it’s normal 

if anything, the T2’s are tending colder in the 6/11 day period and no sign of the cold period relenting 

[shaky]

Hmmm low pressure digging slightly further south in the atlantic on gfs 06z i think!!could be a beauty this one!!

[kold weather]

4 minutes ago, Singularity said:

 

For what it's worth, ICON 06z is very similar to ECM 00z at +120 and it still has the shortwave on the western flank of the trough by Canada that serves to re-focus the trough in that area rather than letting it move quickly NE and flatten the Azores ridge before it can make the link with the Arctic High.

That shortwave needs watching out for on future runs by the way; it won't help matters if it disappears.

There is ONE big difference, and that is the frontal extension on the ICON just SW of Iceland from the shortwave, that is going to be putting pressure on any formative block and also keeps heights lower over Iceland, a key zone where the two LP vortexes seperate. As it is I think the ECM was probably only just a hit in terms of the connection as well.

Otherwise, they are very similar it has to be said!

Edited January 18, 2019 by kold weather

[East_England_Stormchaser91]

7 minutes ago, kold weather said:

Look at Meteociel, its updates most models faster, ICON 06z only runs to 120hrs but its 100% out, take a look!

120 hours out. That looks pretty darn cold to me, and there’s heights building above the sinking low heights between Iceland and Scandinavia.

It paints a much different picture as what you have been portraying it to be in the form of text. 

[karlos1983]

9 minutes ago, Lloyds32 said:

Hi Karlos. You always reply to every post I make, and usually pretty aggressively. Its a forum, many posters make a predication based on the output. The ECM at 168 and 192 today has a weaker flow from the east. At 192 the pressure the NE seems further south, pushing the stronger flow into France etc. That's how I see it panning out, just an opinion. No need to get so upset.

Hi L 

I'm sorry you feel that way. Aggressive reply? Not at all, I'm not an aggressive person in anyway shape or form. But you are correct this is a forum and there is Nothing wrong with you having your opinion, so I've taken the time to reply to your post to just give a more balanced view (in my opinion), based on what the models are actually showing rather than "gut feeling". Part of Forum life is people may not agree with you and therefore a debate will take place. So I'm far from upset, I reply often to your post as they do tend to contradict the actual pattern being modelled more often than not. Sorry if you took my reply in the wrong way. 

Cheers

Karl

 

Edited January 18, 2019 by karlos1983

[bluearmy]

4 minutes ago, shaky said:

Hmmm low pressure digging slightly further south in the atlantic on gfs 06z i think!!could be a beauty this one!!

It’s a little less amplified and therefore further east by day 4 - certainly not the correction that we wish to see 

[Rocheydub]

4 minutes ago, shaky said:

Hmmm low pressure digging slightly further south in the atlantic on gfs 06z i think!!could be a beauty this one!!

Seriously? On every run pre 96 you comment upgrade/downgrade all the time. Will you let it run it’s course until at least 120? The early nuances rarely have big impacts on the overall picture.

 

sorry if this sounds cranky, I’m tired and emotional!

[kold weather]

1 minute ago, bluearmy said:

It’s a little less amplified and therefore further east by day 4 - certainly not the correction that we wish to see 

Interestingly having just done my high tech 'finger test (very high tech here!!) the LP is actually a touch further west at 96hrs, though there isn't much difference it has to be said. However it does look a little flatter as you say, so swings and roundabouts!

 

[shaky]

4 minutes ago, Rocheydub said:

Seriously? On every run pre 96 you comment upgrade/downgrade all the time. Will you let it run it’s course until at least 120? The early nuances rarely have big impacts on the overall picture.

 

sorry if this sounds cranky, I’m tired and emotional!

All good dont worry!!ermm looks similar to 00z so far!

[Ben Sainsbury]

7 minutes ago, Rocheydub said:

Seriously? On every run pre 96 you comment upgrade/downgrade all the time. Will you let it run it’s course until at least 120? The early nuances rarely have big impacts on the overall picture.

 

sorry if this sounds cranky, I’m tired and emotional!

Conversely, the pattern is extremely volatile within the 4/5 day time frame and will lead to differences thereafter and it is model discussion so why not comment pre 96? No malice intended I just don't see a problem!

Safe to say I think GFS 6z will get there, just appears to be a slower evolution. Less amplified as others have noted too!

Also the GFS is painting an extremely snowy 24 hours from T90 onwards.

Edited January 18, 2019 by Ben Sainsbury

[winterof79]

Cactol has posted what I was enquiring 

Edited January 18, 2019 by winterof79

[kold weather]

Trough isn't quite digging as well by 108hrs on the 06z GFS, and as BA said, the flow is a little flatter. Should still make it but that gap isn't as large as I'd like to see it in the mid atlantic. Will be interesting to see whether the HP sets up closer to the UK on this run due to it all being a touch further east again and flatter.

[Singularity]

2 minutes ago, kold weather said:

There is ONE big difference, and that is the frontal extension on the ICON just SW of Iceland from the shortwave, that is going to be putting pressure on any formative block and also keeps heights lower over Iceland, a key zone where the two LP vortexes seperate. As it is I think the ECM was probably only just a hit in terms of the connection as well.

Based on current guidance, the shortwave I refer to looks more significant... in fact it also digs down west of the Azores as well, further aiding proceedings. A frontal extension is easily split by ridges building north in response to a supportive trough behaviour upstream.

BUT it is plausible that the frontal extension may consolidate its own small low, which we'd then need to see slide SE into the Euro trough. It'd be a classic drama-inducer as if it didn't slide it'd leave us reliant on the Arctic high drifting in the right direction (a bit risky!), but if it did, we'd probably see an area of high snow potential crossing part of the UK. I've been through enough of those in the past to know that you're right to keep a close eye on that area.