Model output discussion - 1st December onwards

[Nouska]

21 minutes ago, Singularity said:

I'd love to know what the Met Office make of the UKMO modelling but Fergie seems to have gone AWOL since things got a bit less friendly for a time two weeks ago. I vaguely recall UKMO going a bit nuts with the MJO earlier this year and the actual outcome turning out to be about halfway between it and GEFS.

Courtesy of my saved images from summer posting on here ...

   

Your memory serves you well.

[Singularity]

7 minutes ago, IDO said:

I understand that, what I mean is that you cannot then go to the MJO composites and expect the same scenario as if this was MJO forcing. This Kelvin Wave may just lead to a MLB over the UK and that is pretty bad if you want some wave 2 response to the strat. Of course it may lead to a Scandi/Euro ridge but I would not be getting too excited till we get some consistency.

Duly noted. I am prepared for the scenario in which some more settled weather with the chance of it being chilly for once as being the best we can hope for... but for the time being I'm going to enjoy chasing the dangling carrot wearing a cloak of cautious optimism 

GFS 12z det. out to +168 or so, nothing much to report so far. Still showing 15*C in my locale tomorrow afternoon and again on Saturday, remarkable to say the least. The possible addition of Tuesday 22nd to the mid-teen club seems to have been lost, though - but only just. 

 

Edit: thanks Nouska, good to know the grey matter files are loading correctly 

Edited December 16, 2015 by Singularity

[bradymk]

45 minutes ago, IDO said:

I am still going with Dr Ventrice who mitigates this with his latest tweet:

He is one of the leading lights in this type of developments.

Fair enough, but I think the important thing here is that even if it isn't the MJO that is going to start forcing/dicatating the pattern, it is more the fact that the forecasted pattern for day 10+ at the moment reflects what the MJO phase 4 composite would normally be, which is a good wave 2 pattern? I maybe wrong however.

[radiohead]

Christmas flooding a real possibility on the GFS. Horrendous.

 

[knocker]

22 minutes ago, IDO said:

I understand that, what I mean is that you cannot then go to the MJO composites and expect the same scenario as if this was MJO forcing. This Kelvin Wave may just lead to a MLB over the UK and that is pretty bad if you want some wave 2 response to the strat. Of course it may lead to a Scandi/Euro ridge but I would not be getting too excited till we get some consistency.

I agree with that assessment. I don't think this ridge is a done deal by any means.

[The PIT]

26 minutes ago, radiohead said:

Christmas flooding a real possibility on the GFS. Horrendous.

 

Thankfully deep FI at the moment so unlikely to verify.  The only thing that is verifying is the Euro high and until that gets a vacation ticket we will be stuck with what we got.

[nick sussex]

I think the chicken and the egg analogy comes to mind re the MJO and Kelvin waves however I'd rather see the MJO moving even if its a faux one. And its clear from the outputs upto T144hrs that they're responding to something because the jet is already more amplified than that shown a few days back.

The Kelvin Wave v MJO is complex because they're both interconnected.

 

[Nouska]

1 hour ago, IDO said:

I am still going with Dr Ventrice who mitigates this with his latest tweet:

MJVentrice
A strong atmospheric Kelvin wave will superimpose onto the El Nino standing this week. This will fool MJO tools. https://t.co/I0QZoLLsuU
16/12/2015, 13:28

MJVentrice
@tombo82685 Both RMM and space-time filtered products will show this as an MJO wave due to the nature of the pattern.
16/12/2015, 14:47

He is one of the leading lights in this type of developments.

Indeed he is and a great person to follow if interested in tropical weather. My question would be .... the wave replicates MJO as far as model parameters are concerned; it is a genuine movement of convection through the ocean basin, why would the atmospheric response be any different to the composites for MJO when they are built from response to a convection signature?

[knocker]

True. So much so it's blown away the Scandinavian ridge although the faithful European high takes it's place at the 250mb table. Just a bit of fun.

 

[Geordiesnow]

16 minutes ago, The PIT said:

Thankfully deep FI at the moment so unlikely to verify.  The only thing that is verifying is the Euro high and until that gets a vacation ticket we will be stuck with what we got.

Well the Euro high influence will be out of the way by the weekend with the weather only slightly cooling down but then the focus will turn to potentially how stormy it could get, far too early to put any detail on it at this stage mind

Mid teen temps in December is not unheard of and nor is this type of set up but what is more unusual is just the sheer persistence of it, I mean the really mild air has arrived widespread across the UK from Tuesday onwards(although Scotland was a touch cooler) and its look like it could last into Saturday/Sunday at least.

It does look like the maximum temp won't be broken as the mildness has been downgraded a tad but the night time minimum is under threat I feel, tonight and perhaps Friday night is the best for that. 

[Glacier Point]

22 minutes ago, Nouska said:

Indeed he is and a great person to follow if interested in tropical weather. My question would be .... the wave replicates MJO as far as model parameters are concerned; it is a genuine movement of convection through the ocean basin, why would the atmospheric response be any different to the composites for MJO when they are built from response to a convection signature?

Quite.

If it smells like a dog, barks like a dog and growls like a dog, it is a dog.

The MJO, Kelvin Wave and other forms of intraseasonal tropical modes share measured parameters. The most useful is upper level velocity potential. The only thing that differentiates Kelvin Waves from the MJO is the speed, with Kelvin Waves showing much faster propagation.

Taking Mike Ventrice's plot:

He states Kelvin wave projection for next week. Beyond that, the week 2 forecast shows a classical signature of +ve velocity potential around 120E and negative velocity potential around the Dateline. That would imply a strong convective anomaly around the Dateline consistent with tropical forcing centred in what would equate to MJO phases 7 and 8.

The CFS forecast shows more MJO component, and low level forcing becoming sustained just east of 180 degrees.

Note the similarity to September and October in terms of where positive and negative velocity potential anomalies lie. That  strongly suggests that the atmospheric forcing is becoming solely Central and East Pacific with positive velocity potential through the Maritime Continent. Whether this is the MJO, Kelvin Wave or other tropical mode is somewhat irrelevant. It is the reinforcing of an El Nino atmospheric pattern and lack of destructive interference from Indian Ocean convection that is key. The really crucial point here is that tropical forcing is getting into a position where angular momentum will be raised and in doing so, the hemispheric circulation will become more amplified. We continue to see this with excellent and eye taking intra and inter model run consistency. 

What that tells me is the Arctic Oscillation is beginning to loosen its grip, and tropical convective activity, in all its forms, is responding. Composites for high angular momentum velocity potential for January are consistent with an MJO phase 7 and 8 type solution.

Note the relative positioning of positive and negative velocity potential. Now, phases 7 and 8 >

Arguably, early / middle of January looking phase 7ish. But, this will be transposed across a pattern that is thus far robustly +AO, so there will be inevitably be a degree of adjustment that we need to make (turning around the super tanker).

Edited December 16, 2015 by Glacier Point

[mb018538]

Looking like the 12z is following on from previous runs of the last few days in painting a stormy outlook with plenty of wind and rain in the week up until Christmas, with things gradually settling down between then and new year. It'll be one hell of a turnaround if things don't change now with the amount of runs showing high pressure!

[phil nw.]

We can see looking at the 2 images from the GFS below the uptick in expected Tropical convection from today and day 5

i am not over familiar with this area but i would think the MJO phase 4 signal is the rain area around Indonesia which is forecasted to move only slowly east by the GEFs.

The picture is clouded(excuse pun)by the other areas of convection spread across the Pacific further east, so no wonder the MJO forecast is uncertain,indeed other agencies show a stronger MJO wave moving further east as Nick S alluded to in a post above.

The point is with such a strong nino state and warmth spread across the Pacific forecasting the MJO is more difficult than in other times methinks.

Just my take on things and maybe a bit of background on why this Scandi/Euro ridge modeling is taking on different forms run to run.

To my untrained eye and looking at the composites for the MJO in January we need that movement to phase 7  to really change things although i am happy to be corrected on this.

Edit,Just seen your post GP-thanks.

 

 

Edited December 16, 2015 by phil nw.

[nick sussex]

GP In terms of the artist formerly known as the MJO but now to be called the confused MJO who isn't sure whether its Kelvin  or Rosby etc the ECM monthly has really clustered around the phase 7 destination.

I've noticed over the last few days an underestimation of the amplitude of the MJO, I've also noticed an increase in upstream amplification, the T144hrs outputs today are more amplified that that suggested a few days back. In your opinion is this a slowness of the NWP to pick up on the increase in MJO amplitude? Its interesting that the UKMO has been most bullish about driving the MJO into that higher amplitude.

[Glacier Point]

Nick, I posted a little while back about the pattern over the next day or so over the Pacific and North America as being ripe for amplification through mountain torques. That I suspect has a role to play, as does the lagged impact of spikes in angular momentum tendency 21 days ago. The beautiful choreography of the atmosphere as other elements of tropical forcing come together ! But you're right, there has been a trend for tropical forcing to become more coherent.

Edited December 16, 2015 by Glacier Point

[bluearmy]

both the ecm eps and gefs are settling an impressive high anomaly over the Baltic states by the end of week 2.  at least we now have agreement on a starting point quite a distance away.

Edited December 16, 2015 by bluearmy

[chionomaniac]

Great post @Glacier Point regarding MJO and Kelvin waves. I questioned exactly the same last month with the IO walker cell convergence and MJO similarities. In that case the dog barked and we had the toppler. 

[Captain Shortwave]

Whilst of course we are quite fair away from this, the anomaly from the GEFs is rather impressive.

A very strong signal for a large  ridge east of the UK, whether it is a chilly continental flow or a monster blowtorch from the south west remains to be seen. To ignore this would be a little unwise at this point.

Of course an anomaly like this wouldn't appear in summer would it. 

Edited December 16, 2015 by Captain Shortwave

[Cloud 10]

21 minutes ago, Captain Shortwave said:

Whilst of course we are quite fair away from this, the anomaly from the GEFs is rather impressive.

 

 

More black holes on the GEFS individual members than you can shake a stick at,a small selection included below.

Gonna be some fun model watching over the next couple of weeks.

 

 

[Summer Sun]

ECM shows +4 and +5 850's in parts of the south and south east on Christmas day whilst further north its -3's, -4s & -5's

[Bullseye]

5 minutes ago, Summer Sun said:

ECM shows +4 and +5 850's in parts of the south and south east on Christmas day whilst further north its -3's, -4s & -5's

Based on that chart, does this lose the mild SW and replace it with W/NW at least for northern half of country? Maybe a bit more seasonal than current conditions.

[Cloud 10]

10 minutes ago, Greenland1080 said:

Perb 19 looks like a sharks head coming through water to swallow the pv...slightly less technical than GP post

 

[Summer Sun]

16 minutes ago, Bullseye said:

Based on that chart, does this lose the mild SW and replace it with W/NW at least for northern half of country? Maybe a bit more seasonal than current conditions.

The wind is shown turn more westerly yes (for the north) so temps not as high as what we are experiencing this week

 

Moving onto boxing day we have a very deep low west of Ireland giving the potential for gales in the west

Edited December 16, 2015 by Summer Sun

[The Enforcer]

36 minutes ago, Cloud 10 said:

More black holes on the GEFS individual members than you can shake a stick at,a small selection included below.

Gonna be some fun model watching over the next couple of weeks.

What are the verification stats for the GEFS at T+384?

Edited December 16, 2015 by The Enforcer

[Grimsby Snow Lover]

34 minutes ago, Greenland1080 said:

Perb 19 looks like a great white sharks head coming through water to swallow the pv...slightly less technical than GP post

 

34 minutes ago, Greenland1080 said:

Perb 19 looks like a great white sharks head coming through water to swallow the pv...slightly less technical than GP post

Can I just ask what the black holes are on the charts posted above. Thanks

Edited December 16, 2015 by Grimsby Snow Lover