Winter Model Discussion 06Z 10/01/13>

[Iceberg]

The GFS is being consistant in that at T72 to T96 it takes baby, but important steps towards the other models, after this time it revert to type.

at some point maybe either tonight or tomorrow morning it will reach the tipping point where it can nolonger revert to type as the baby steps have taken it too far.

All good points made above re jet position and angle etc.

[Catacol]

Yep - at 78 GFS is sending the energy SE.

Nope - its gone pear shaped again. Sticking to its guns - truly amazing. Will ECM 12z and GFS 12z do the same? 5 hours to find out... :-)

[Methuselah]

[Harsh Climate]

6z run looks worse than the 00z run to me, didn't think that was possible!

The high we need to retrogress towards greenland is about to sink over us preceding a mild atlantic flow..

Have to save to say that I am now very worried regarding these gfs runs, the consistency been shown know is very clear. If anything the ECM has moved away from an easterly overnight and only looks good due to us having an undercutting low. Very risky route to cold/snow that.

Edited January 10, 2013 by Harsh Climate

[SnowBallz]

https://twitter.com/...3845120/photo/1

To be honest, going by that graph, Matt got the rate of warming totally wrong; he predicted it would take into the later parts of January to warm to that degree, whereas - in reality - it only took a matter of days. One could argue hyper critique, but it's a solid obversation if one is proposing their forecast is/was right, and I think in terms of sheer punch - the rate of warming is just as important as the degree itself.

[TEITS]

Im still shouting for the CMA.

You do realise that if it was only the GFS showing these E,lys it would back down towards the other models. Now it would be sods law we see the reverse.

To show how bad it is im viewing the latest NOGAPS to help clear the mist.

[Ian Brown]

The GFS refusing to backdown.

I think whats a bit frustrating is that if its going to not take that shortwave near Iceland se/s then it might aswell take it east and prolong the initial easterly.

Here its the middle ground solution which shortens the cold advection from the east and still wont deliver what the UKMO suggests.

Yes, this is even quicker with the Atlantic moving in. Just using past experience of these situations, I would be astonished if the GFS is wrong.

[Nick F]

I'm thinking that the models are having issues with the upper flow over the NW Atlantic. Both the 00z ECM and UKMO show a 500mb trough extending SE across the NW Atlantic from the vortex over Baffin/NE Canada toward NW Europe - which allows height rises to build NW across Iceland and Greenland. While 00z/06z GFS doesn't entertain this trough extension SE at all.

Until they resolve this area, the divergence will continue.

Edited January 10, 2013 by Nick F

[BLAST FROM THE PAST]

briefly...

Next week's forecast looks horrid and complex. I would go below average and becoming increasingly cyclonic. That brings an attendant snowfall hazard.

Ironically, day 10+ might be less problematic to get a broad view on.

Tendency in relative angular momentum is very likely to spike in the next few days. That will shoot the Global Wind Oscillation towards high amplitude phase 4. That teleconnects with the core of the +ve height anomalies in a triangle between eastern Greenland, Svalbard and northern Scandinavia.

GEFS has trended this way in the last 24 hrs, as has ECM. Also trending is the development of some energy off the residual pv over Canada into the North Atlantic, which most likely to reinforce the blocking signal further north and NE. Low pressure signal over Europe still very strong. Interestngly this perhaps resolves CPC's teleconnective issues w/r/t Greenland and Pacific blocking structures.

So period 14-21 Jan looking cold and unsettled with wintry mix. Thereafter, signal for renewed push of Arctic air from the NE.

Thanks GP for those thoughts and indeed I tend to agree very much as below are a run down of my musings, note dates and set up seem to lock in nicely and we use very different methods

.

Posted by BLAST FROM THE PAST on 02 January 2013 - 23:43 in Model Forum Archive

THE EYE IN THE SKY, on 02 January 2013 - 22:43 , said:

Well the difference between the 18Z and 12Z is laughable especially from +240 onwards. This is why at the moment its pointless to be disappointed or elated with the model output because they are simply clueless what is going to happen from mid month. We often see disagreement from the models beyond +240 but this level of uncertainty is increased in my opinion due to what is occurring in the Stratosphere.

The ECM tonight is very poor but based on recent output im not worried due to its poor consistency.

Dave

I think we should start taking notice. I think ECM and GFS are now showing signs of what i think will be stark change. dats of interest 8-10 [cold block to start showing to north?] and 16-22 [block in place atlantic push?] cold to win and a notable winter event

BFTP

To me GP, Arctic air to to push in from NE suggests High Pressure over Greenland extending across Iceland and Northern Scandinavia with a trough over Northern Europe bringing in a long draw NE'ly flow.

GFS - actually a slight improvement as we head later into the run, I wouldn't be surprised to see further movement appear on this model over next day or so. It is very odd it more or less holds firm and MUST be considered as a concern.

ECM - that LP over Iceland I mentioned yesterday at t96 - t112 now [yest t105-120] , it does move it a tad further East but then drops it sharply ESE and thus the run is essentially the same which equals cold and snow and cold winning out. IT IS NOT THE RIDICULOUS 'WELL DONE GFS' ECM has jumped on board run.

UKMO - for prolonged cold the best run upto 144, strong block becasue it drops that LP over Iceland sharply S / SSE

So which is going to be correct?

GFS and UKMO really at odds of each other. ECM more of middle ground......tell you what, I'll go for that

BFTP

Edited January 10, 2013 by BLAST FROM THE PAST

[bluearmy]

the shortwave either comes se or it doesnt.

thereafter, although ecm mean looks excellent, there is a large spread evident to the west. given the dispuptive implications of the ecm op verifying next week, the met office have a real headache in issuing guidance when a model such as gfs high res is churning out consistent runs out to day 7.

[Frosty.]

It's so unusual for the gfs to be on it's own like this but if it's right, the pendulum will have to change, but stick with what GP says and all will be well, cold cyclonic snowfest next week then a big arctic push from the Northeast the following week, stick that in your pipe and smoke it gfs

[SMU]

For those that are watching & are now bewildered-

The 06z has made subtle changes in the 84-120 timeframe- the downstream pattern is the same - so we see the upper air cold pool move west over europe to effect the SE-

Upstream to the NW this is the first run where the GFS is sending the energy & small low over greenland SE towards the UK through the UK as opposed to EAST through the block-

it starts this process & indeed gets some energy over the UK hence this PPN band-

http://modeles.meteociel.fr/modeles/gfs/runs/2013011006/gfsnh-2-108.png?6

however it does lose the signal so continues with moving the rest of the atlantic jet & subsequent energy over the top still...

so we have a move to the euros in the gFS but not enough to sway the whole pattern YET-

its a bit like when you have a ridge to greenland with a small shortwave in the flow projected to move north with it- if on the models it starts in a northerly direction & goes up the west coast of greenland the greenland ridge builds -

Then the next run that shortwave is modelled a little further east- the margin of error gets thinner- but it still makes it up the west of greenland- then the ridge survives-

Do it again on another run the ridge just survives-

On the 4th run it edges east again- & goes east of the greenland tip & now recurves east- you have no greenland ridge & suddenly the whole pattern is different.

what we have here on the 06z is the same but the first step towards the euros with the energy dropping a bit further south insteand of EAST-

another step south at 12z may not make a difference, but do that on the 18z then come the 00z the whole pattern is different- hopefully to reflect the euros-

we are talking about small margins of error with the models speed & amplitude of the jet making LARGE differences at 144-

No model should be really criticised the are not that far apart.........

S

[TEITS]

Yes, this is even quicker with the Atlantic moving in. Just using past experience of these situations, I would be astonished if the GFS is wrong.

One positive from the 06Z is I feel the medium range is going to be better than the 0Z.

[garbagebags]

6z run looks worse than the 00z run to me, didn't think that was possible!

Not at all, the low tracks further south. Its not enough granted but its deffinately a "better" run.

[andy_leics22]

The 06z looks as flat as a pancake! I know the models are all over the shop at the moment but the consistency of the GFS in the last few runs cannot be ignored. In my opinion i think the other models eill now start to fall in line with what the GFS is predicting. I expect by tomorrow afternoon we will have agreement across the models on a return to zonal weather by wednesday next week.

[johnholmes]

What a bewildering (but fascinating) time for a newbie to start chart watching! Anyway, I have GFS/ECM/UKMO open in 3 windows and as I step through I can see the divergence emerge after T48.

At T72, ECM begins to do its own thing, but GFS and OKMO are still close (to my novice eyes).

UKMO

http://www.meteociel...72-21.GIF?10-06

GFS

http://modeles.meteo...fs-0-72.png?0?0

It's then that things begin to really change, but it seems a shame to me that neither UKMO nor ECM provide the 6h or 12h updates at that stage as GFS does so you can really watch the evolution in detail. So the question it leaves me is, leaving the models aside, are there any compelling physical reasons why that low would track E/NE rather than SE?

many thanks for that post-welcome to Net Wx, please keep that kind of informative post coming

[Timmytour]

Hazard a guess here...but GFS pushing Atlantic high a little bit further west......this could be epic! i want to see the Atlantic Swan flying north west!

Hazarded a guess....and I was wrong. The Swan was a seagull and it's heading the wrong direction...towards us instead of away

from us

Edited January 10, 2013 by Timmytour

[That ECM]

GFS consistent but not perhaps correct. Like I tell the good lady often!!! Lets not lose sight of the shorterm whilst the mid term is so uncertain. Much of interest to many.

[NO LONGER POSTING]

To be honest, going by that graph, Matt got the rate of warming totally wrong; he predicted it would take into the later parts of January to warm to that degree, whereas - in reality - it only took a matter of days. One could argue hyper critique, but it's a solid obversation if one is proposing their forecast is/was right, and I think in terms of sheer punch - the rate of warming is just as important as the degree itself.

I agree, but it is how quickly it warmed up that is a wow factor

[Severe Siberian icy blast]

Looking at the gfs I think we are about to see high pressure gaining strength over Greenland , I think the fi will show the SSW implications.

[Wayneywoo]

It appears all three models differ due to the way they handle the jet.

Am I correct in thinking that the Jet dictates where the LP's go? The UKMO and ECM both have the Jet head SE taking the undercutting LP with it whereas the GFS has the Jet heading towards Scandi, taking the LP E?

[Southender]

For those that are watching & are now bewildered-

The 06z has made subtle changes in the 84-120 timeframe- the downstream pattern is the same - so we see the upper air cold pool move west over europe to effect the SE-

Upstream to the NW this is the first run where the GFS is sending the energy & small low over greenland SE towards the UK through the UK as opposed to EAST through the block-

it starts this process & indeed gets some energy over the UK hence this PPN band-

http://modeles.meteo...snh-2-108.png?6

however it does lose the signal so continues with moving the rest of the atlantic jet & subsequent energy over the top still...

so we have a move to the euros in the gFS but not enough to sway the whole pattern YET-

its a bit like when you have a ridge to greenland with a small shortwave in the flow projected to move north with it- if on the models it starts in a northerly direction & goes up the west coast of greenland the greenland ridge builds -

Then the next run that shortwave is modelled a little further east- the margin of error gets thinner- but it still makes it up the west of greenland- then the ridge survives-

Do it again on another run the ridge just survives-

On the 4th run it edges east again- & goes east of the greenland tip & now recurves east- you have no greenland ridge & suddenly the whole pattern is different.

what we have here on the 06z is the same but the first step towards the euros with the energy dropping a bit further south insteand of EAST-

another step south at 12z may not make a difference, but do that on the 18z then come the 00z the whole pattern is different- hopefully to reflect the euros-

we are talking about small margins of error with the models speed & amplitude of the jet making LARGE differences at 144-

No model should be really criticised the are not that far apart.........

S

Exactly what I was thinking Steve.

You can see some energy heading SE over the UK clearly by that PPN chart.

Not enough to impact the overall outcome yet, but a very very small shift towards the EC and UKMO train of thought.

As you say something to clutch on to as we view the later outputs (with more data) later today.

[Glacier Point]

The key developments around t96 so we still could go for another 24 hs before final resolution.

Key things fo me, the 06z GFS has begin to adjust a positive tilt to the jet towards a negative tilt angled south of the UK. Also, main lobe of pv is becoming detatched from west of Greenland and the field vacated is seeing some signs of a divergent flow.

Edited January 10, 2013 by Glacier Point

[Methuselah]

[R.P. McMurphy]

Yes, this is even quicker with the Atlantic moving in. Just using past experience of these situations, I would be astonished if the GFS is wrong.

Ian,

Not sure about astonised, as only 11 members are going with this Run.