Model Output Discussion 12z 04/12/2012

[Ian Brown]

The ECM does seem to have stalled that shortwave in northern Germany which does seem a little strange.

We really need that to clear se otherwise the high orientates less favourably, this would effect the angle of any Atlantic attack.

I don't normally just bin outputs unless they're the NOGAPS but I'm happy to shred the later output from the ECM. I don't think I've ever seen a shortwave behave like this.

Maybe its the CPS Couch Potato Shortwave!

Yes it looks a little strange, the worry is that heights are already retreating at Northern latitudes between T168 and T192 and this is the second ECM run to really crank up the PV at the end of the run.

Thankfully the ECM at T192-240 has been as inconsistent as any other output over the last few weeks, but as Dave says, what is being shown by the NWP overall is a fair way from an unstable easterly flow spreading West across the UK.

[nick sussex]

Silly question but the ECM shows a mass of cold coming from the NW, could it be that is what will happen instead?

Maybe we are looking in the wrong place for our cold?

No chance it looks all cold and mean but if you want cold under the current NH pattern it has to come from the east or ne initially.

[chris55]

At day 10 this charts is as good as one showing "snowmagedon" for parts of the UK,

http://www.wetterzentrale.de/pics/Recm2402.gif

Small tweaks either way in the broad pattern at this range could result in a milder flow or a serious battleground scenario. Just because day 10 shows us on the milder side, really makes little difference IMO.,

[Ian Brown]

Silly question but the ECM shows a mass of cold coming from the NW, could it be that is what will happen instead?

Maybe we are looking in the wrong place for our cold?

We would not want that T240 to verify, the Atlantic would come in, block to the NE retreats/sinks and the Azores High would ridge NE. T268 onwards would be +ve NAO charts.

[EML Network]

just spewed my words re 162 back up !!!

[Ian Brown]

At day 10 this charts is as good as one showing "snowmagedon" for parts of the UK,

http://www.wetterzen...cs/Recm2402.gif

Small tweaks either way in the broad pattern at this range could result in a milder flow or a serious battleground scenario. Just because day 10 shows us on the milder side, really makes little difference IMO.,

It isn't Chris because the energy is going North, milder air would get ahead of the PPN. You would need an Atlantic attack to be negatively tilted or at worst vertical to get widespread frontal snow.

Anyway, hopefully academic and not happening !

[Jupiters Winter]

I think it is not a worry about the PV and that out to T240. Models have juggled T120 as many times. Overall It is one run which we would call FI if it was showing positivity for the UK.

Edited December 4, 2012 by Jupiters Winter

[nick sussex]

Yes it looks a little strange, the worry is that heights are already retreating at Northern latitudes between T168 and T192 and this is the second ECM run to really crank up the PV at the end of the run.

Thankfully the ECM at T192-240 has been as inconsistent as any other output over the last few weeks, but as Dave says, what is being shown by the NWP overall is a fair way from an unstable easterly flow spreading West across the UK.

Ian any thoughts on why the SW would just sit there for days? Funnily do you remember last February when we saw that small shortwave developing under the Russian high, almost out of nowhere as the frigid air moved in from the east.

I agree regarding the unstable easterly, this has a way to go to produce that. At least we survived the 168hrs timeframe, it could have been worse so not a bad evening so far.

[ITSY]

remember what Matt Hugo said the other day. As long as the PV sets up shop in Greenland, the block will inevitably come under pressure at some point. It is this that COULD prevent a major cold spell. The question is the speed with which it develops as compared to the potential scandi high. if the high sets up shop first then we could have a battle scenario and lots of cold. If it is forced to play second fiddle because of the lows spewed out of the PV then we will struggle to get the cold air. A lot rests on the speed with which the HP develops across scandi as compared to the speed of the PV to the West of Greenland

[SMU]

The surface flow for the SE at 240 would JUST ABOUT support snow- however as Ian as said, vertical advection or negative tilted trough is the way forward for undercutting-

On balance very happy tonight- in this current pattern we would only need -3/-4 uppers off the continent & a SE surface feed to get a widespread snow event- as the near continent will be perishing by then with substantial snowcover-

The ECM at 240 is a lifetime away- so lets not worry. & concentrate on things closer to hand- more snow tonight & a higher risk of snow thurs/friday-

S

[Radiating Dendrite]

The outcome of the ECM at the end cranking up the PV seems to be completely at odds with what we are hearing from Matt etc regarding the ECM 32 day run showing good northern blocking.

Presumably these models are completely seperate?

[Fred Sykes]

Unlike so many people on here, I don't take each run as gospel, but look at the overall pattern. It seems quite clear to me that high pressure will rise over Scandinavia over the next couple of weeks, which means there is a chance of easterly winds and therefore cold temps and risk of snow.

The building blocks are nearly in place, detail will come later

I am hoping to see a bit of the white stuff tomorrow am

Edited December 4, 2012 by Rybris Ponce
Increased font size.

[Met4Cast]

It might be worth remembering that the ECM often has an Eastern bias, in 2010 it placed everything too far East, given the background signals for blocking I'd expect to see the pattern corrected Westwards placing the UK under the cold air and pushing the Atlantic back.

The 12z GFS Ensembles have gone COLD

Edited December 4, 2012 by Daniel AKA WMD

[nick sussex]

This is the rather strange looking chart from last February:

If I remember rightly this was picked up late by the models, this shortwave formed ahead of that exceptionally cold air moving west.

This was a problem for you guys in the UK as this diverted some of that deep cold to the ne.

[Duane S.]

Unlike so many people on here, I don't take each run as gospel, but look at the overall pattern. It seems quite clear to me that high pressure will rise over Scandinavia over the next couple of weeks, which means there is a chance of easterly winds and therefore cold temps and risk of snow.

The building blocks are nearly in place, detail will come later

I am hoping to see a bit of the white stuff tomorrow am

Any chance you could make that a little smaller? (I agree with what you say though)

[BLAST FROM THE PAST]

This is the rather strange looking chart from last February:

If I remember rightly this was picked up late by the models, this shortwave formed ahead of that exceptionally cold air moving west.

This was a problem for you guys in the UK as this diverted some of that deep cold to the ne.

Nick

wasn't there an exceptional cold pool at that locale that formed this SW?

BFTP

Edited December 4, 2012 by BLAST FROM THE PAST

[Frosty.]

Surely it's the ensemble mean trend we should be happy with right now since the op run charts will continue to show different solutions, good and bad. The cold block is coming but it's true identity is still out of focus, the really good charts are beyond T+168 hours and just minor changes in the pattern will have a big impact later, still all to play for now I have erased that awful 6z from my mind.

Edited December 4, 2012 by Frosty039

[Methuselah]

Guys...

Are we not getting a tad too preoccupied with things that don't actually exist yet? Does it really matter if this or that model is showing an Atlantic attack on day 10 or 14?

We don't even have the BFTE anywhere near 'nailed on' yet. So why give ourselves myocardial infarctions over its eventual demise?

Enjoy the ride?

[camiscool]

when do the ecm esembles come out?

[Country Boy]

I dont post on here very much just read all the interseting comments. , but I came across this chart ..it shows high pressure to the east bringing a south easterly air flow, a long way off but the set up is there, what would this airflow bring just before christmass

I keep reading F1.. can you please explain what this means

[Jason M]

To see charts like these in early December is fantastic. Forget the ECM 240, it might as well be 2400 hours in the future for its accuracy at that range.

My main concern has been around a mid lat uk high setting up, and that threat has receded somewhat tonight. Expect the outlook to ebb and flow though as there is no chance that model consistency will be strong at 7-10 days out.

A good sign is that the easterly threat is starting to come forward now through the time frames.

Jason

Edited December 4, 2012 by Jason M

[Rob K]

A question about the PV: I thought the signals were meant to be that it was going to head to the Siberian side of the pole, so why have the models over the past 24 hours seemingly ramped it up over NW Canada?

[Radiating Dendrite]

Formula One Gaz - car racing.

No, in all seriousness FI means fantasy island. Charts that can look amazing, but will never actually materialise.

[Mucka]

I dont post on here very much just read all the interseting comments. , but I came across this chart ..it shows high pressure to the east bringing a south easterly air flow, a long way off but the set up is there, what would this airflow bring just before christmass

I keep reading F1.. can you please explain what this means

Hi, the term is FI as in "Fantasy Island" used as caveat when describing charts that are outside the hi res section of model runs or outside a timeframe that can be reasonably predicted. To know conditions on the ground you would have to take into account previous charts but I would generally expect conditions to be very cold but mainly dry, perhaps a little milder in the far NW.

Edited December 4, 2012 by Mucka

[Fozfoster]

Unlike so many people on here, I don't take each run as gospel, but look at the overall pattern. It seems quite clear to me that high pressure will rise over Scandinavia over the next couple of weeks, which means there is a chance of easterly winds and therefore cold temps and risk of snow.

The building blocks are nearly in place, detail will come later

I am hoping to see a bit of the white stuff tomorrow am

Hi Fred,

the snow chances for my area are about as small as your post!................................!