Model Output Discussion - The Run In To Christmas

[Mair Snaw]

MORNING GANG ,gfs normal [old ] is not updating on my computer its still showing 00hrs ,or am i missing something ,dont want to miss a good run ,cheers .

missed it mate....its a stunner in the end...

[EML Network]

I'm just glad that it's flip flopped back toward a colder solution, and not moved further toward a milder one.

 

I don't recall another time when the models have gone cold, mild, cold, mild and back to cold again, it's a shame the ECM doesn't go past 240 as I'd love to have seen the next frame. 

 

Not very often you get a uk snow fest showing up on a GFS chart even in FI.

 

WOULDN'T THAT BE A GREAT WAY TO END THE YEAR 

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014121906/gfs-2-300.png?6

 

[offerman]

Mild Christmas yet again! (down here anyway!)

 

I`m a cold snow lover for this time of the year.

[karyo]

It may be nice to see but the cold spells are always after the 144 hour range. This is because shortwaves are not picked up well at this range. 

[Banbury]

It may be nice to see but the cold spells are always after the 144 hour range. This is because shortwaves are not picked up well at this range.

That would imply we never get any cold .

[mushymanrob]

well ive not read through the last 6 pages since i was on, so apologies if this point has already been made ...

 

Recm2402.gif Rtavn2402.gif

 

reasonable agreement out to day 10 over the general unsettled, often mild, pattern to continue with the previously expected post crimbo freeze now all but gone. so no white crimbo is on the cards on this mornings op runs, in fact theres hardly anything cold at all.

but this is where things from my eyes get interesting... i deliberately posted charts from day 10 above, to highlight the conflicting message this appears to be sending

814day.03.gif

this noaa 500mb anaomaly chart to me (please correct me if im wrong...john?...)  doesnt suggest a large greenland high ridging into the mid atlantic, and an upper mean trough to our east . it doesnt suggest high pressure over france, nor a southwesterly jet.

so theres a huge conflict going on... and itll be interesting to see which data source becomes reality, the current ops with their mixed, unsettled, average - mild, or the anaomaly which suggests a much colder,  blocked and very cold wintry spell the sorth the gfs has been championing from the post crimbo period.

this might surprise some of you, but im going to back the noaa 500mb anomaly solution and expect their colder outcome to 'win' out, because (as jh says ) when in agreement and consistent they are right c70% of the time. tbh i expected them this morning (didnt view last night) the 8-14 dayer to have backed down from the blocked/cold option, but it appears to have amplified.

so no, i havnt turned into a cold ramper, i just think that (assuming my interpretation of the anoms are correct) a cold solution is more likely then the milder one later next week going off current data.

 

...i should have waited half an hour, the above post would be redundant!

THIS chart is what id expect to see

 

off THIS anomaly chart

 

but hold on, its the gfs 06z.... isnt that the one that was suggested we ignore?

 

IF these charts verify, itll give very strong backing to johns findings that when in agreement and are consistent, the noaa anomaly charts DO pick up long term upper trends better then the ops and are therefore more reliable.

Edited December 19, 2014 by mushymanrob

[LomondSnowstorm]

It may be nice to see but the cold spells are always after the 144 hour range. This is because shortwaves are not picked up well at this range. 

The key is that the shortwaves phase into the UK low, allowing the pattern to shift further east and ridging to develop to the west of this:

Far better Parallel run too, big GH developing. 

Edited December 19, 2014 by LomondSnowstorm

[BLAST FROM THE PAST]

GFS(P) is UGLY!

It isn't, just for Xmas day it is,

 

 

 

Just needs a couple of bites

 

 

Perfection

 

 

 

Longevity or one week wonder?

 

BFTP

Edited December 19, 2014 by BLAST FROM THE PAST

[Banbury]

GFS(P) is UGLY!

http://modeles.meteociel.fr/modeles/gfsp/runs/2014121906/gfsnh-0-204.png?6

 

Looks to be fairly similar to me

[karyo]

That would imply we never get any cold .

Not never but that's how most of our cold spells fail.

[Harsh Climate]

Gfs 06z parallel on the money two!

 

[nick sussex]

So we're now onto yet another solution from both the GFS and GFS P.

 

This time the low in the Atlantic develops a shortwave but crucially this gets ejected ene and separates.

 

You'll then see how the output develops much more favourably, we don't want to see a long train of shortwave energy stuck to the nw because its so much more difficult and takes much longer to develop anything interesting.

 

Lets hope we can at least manage this type of scenario because frankly I'm losing patience and don't want a long drawn out affair because this just allows more variables to pop up!

[IDO]

So the GFS now pushes back the cold spell 2-3 days. And the great charts are now back in FI. Lets hope its not another false dawn, where the signal keeps getting mistaken as we get close to the reliable. All to familiar. Again the GFS P offers 3-4 days (after D9) of cold uppers before the pattern collapses . I am sure nothing can go wrong this time!

 

 

ECM D9-10 off it's rocker again with a massive 2m temp outlier: 

 

I would expect the ECM to change tonight to more like the GFS 06z but you never know with the ECM!

 

 

[Weathizard]

The issue is, initially we were looking at Christmas Day, the mouth watering charts always seem to be at t240, I do think we will eventually end up with a cold spell of some sort but I'm not sure it will be severe.

I've noticed in the ENS suites this is also an issue, the really tasty charts never come into reliable timeframe and keep getting pushed back, the good thing is they are still there on the table as an option though I guess. Knife edge stuff.

[snowy weather]

I'm just glad that it's flip flopped back toward a colder solution, and not moved further toward a milder one.

 

I don't recall another time when the models have gone cold, mild, cold, mild and back to cold again, it's a shame the ECM doesn't go past 240 as I'd love to have seen the next frame. 

 

Not very often you get a uk snow fest showing up on a GFS chart even in FI.

 

WOULDN'T THAT BE A GREAT WAY TO END THE YEAR 

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014121906/gfs-2-300.png?6

 

Oh lord please let that happen. That would be amazing.

 

I am not an expert on model reading but surely if the outputs are consistently showing the the same trend for cold weather then some cold weather is nailed on?

There can be expected to be milder outputs and huge swings and variations because at the end of the day it is a stochastic random process.

[Kentspur]

http://modeles.meteociel.fr/modeles/gfs/runs/2014121906/gfsnh-0-228.png?6

 

Great shout

Call me an amateur IMBY and I know it's only showing 9 days away but until we see any charts involving easterlies the vast majority of the countries southern population will surely only remain dry with a N or NW flow?

[nick sussex]

This is now the biggest point of interest, this gap so we're now on gap watch!

 

You can see the shortwave circled red, this gets ejected from the main low:

 

 

Now at T180hrs you can see the clearance and the gap:

 

 

This is a big departure from the 00hrs runs but certainly is welcome, so its basically " mind the gap"! sorry for that feeble attempt at bringing London Underground into the equation! lol

 

In terms of importance if you're a coldie this separation of energies means a massive difference to how quickly any cold could develop for the UK so IMO:

 

Gap- 80% chance of cold and snow within T240hrs

No gap and lows stuck to the nw 20% chance within T240hrs.

Edited December 19, 2014 by nick sussex

[terrier]

So once again were looking towards fi on the gfs and gfsp. Thinking back to what was said last night stick to t96 and avoid the disappointment.

[ItNeverSnowsInWindsor]

It may be nice to see but the cold spells are always after the 144 hour range. This is because shortwaves are not picked up well at this range. 

There will be colder charts appearing inside 144 hrs soon as long as the Greenland high builds as it is being shown across the models today firstly from the ECM and now GFS.

[Staffordshire]

Whilst I agree with the point big snow made regarding GFS picking up a trend, ECM and UKMO joining the party just when GFS drops it and then the GFS picks it up 24,48 hours later. This was a seemingly common pattern a year or two ago I feel this could be what we are seeing this year.

I also feel a lot of us are getting caught up on the ops more so than the ens, seeping into a pit of despair or a state of euphoria over the op is only going to result in sleepless nights and very long days (which we've all had before).

It is apparent in the GFS 6Z that there has been yet another swing in the model and I'm sure by the 12z there will be a stonking easterly coming from Yaktusk but then by the 0z southerlys from Mali will be giving us a 25c Xmas day, this is the case every year (okay not as extreme) but we all, myself included, never seem to learn.

I do feel we will have a cold spell between XMAS and the NY as the general cross model trend suggests, but patience is needed as we know how models can deviate when a pattern change is incoming

Let the snow commence!

[inghams85]

So the GFS now pushes back the cold spell 2-3 days. And the great charts are now back in FI. Lets hope its not another false dawn, where the signal keeps getting mistaken as we get close to the reliable. All to familiar. Again the GFS P offers 3-4 days (after D9) of cold uppers before the pattern collapses . I am sure nothing can go wrong this time!

 

gfsnh-1-240 (1).png

 

ECM D9-10 off it's rocker again with a massive 2m temp outlier: ensemble-tt6-london (10).gif

 

I would expect the ECM to change tonight to more like the GFS 06z but you never know with the ECM!

The difference this time is a very cold spell has been forecast with background signals to happen around this time for a good few weeks.

 

Christmas week was just a bonus on the charts and built around too much amplification and not on solid background signals.

 

As has been stated many times buy Tamara etc this is the period we expect a very big cool down.

 

Watch the charts build the consistent signal for an east based -NAO and also look to the second week of January for when the asian mountain torques adds further spice. Patience grasshopper

[karlos1983]

It isn't, just for Xmas day it is,

 

 

 

Just needs a couple of bites

 

 

Perfection

 

 

 

Longevity or one week wonder?

 

BFTP

 

Yep my bad! Should know better than to comment on an unfinished run 

[JoeShmoe]

To be honest we are trying to predict shortwaves here at 144, which is pointless.

 

This is the key, said this yesterday, until the ECM starts to model the shortwave at T+96 and under, and pick up any additional ones closer to the time predicting any evolution to cold is a lottery ticket

 

One small shortwave, that appears that T+48 or less has ruined countless cold spells since i've been on these forums (since '96)

 

Indeed i seem to recall SteveM having a rant about shortwave spoliers at some point back in time (sorry Steve :-) )

[london-snow]

The difference this time is a very cold spell has been forecast with background signals to happen around this time for a good few weeks.

 

Christmas week was just a bonus on the charts and built around too much amplification and not on solid background signals.

 

As has been stated many times buy Tamara etc this is the period we expect a very big cool down.

 

Watch the charts build the consistent signal for an east based -NAO and also look to the second week of January for when the asian mountain torques adds further spice. Patience grasshopper

Whilst i very much appreciate the effort who base their lrf's around factors as previously mentioned because it does statically aid and improve chances of the pattern painted becoming a reality it does not mean however it will happen as projected.

There have been past examples where we have had all the *key ingredients* however something has scuppered our chances for example being on the wrong side of favourable blocking synarios when the pv has been disjointed following a strat and continued strat warming.

As i say in my view its a aid and a big aid of that and to have such great input from those in the know is invaluable however it is not a decider and we still require a high element of luck to produce the goods. This is why i am always very sceptical of people using the phrase 'Another bite of the cherry should do it' before you know it another week ot two have passed.

Grab every opportunity what arises..

[bluearmy]

I would throw this out there

'Does the behaviour of the shortwave(s) prevent the onset of the broad long wave pattern for nw Europe completely or just delay it?

Sort of 'all roads lead to Rome' situation but are we going via the A roads or the motorway . (Seems the flight got cancelled !)

It's a potentially complex answer but maybe only as complicated as the higher res models want to make it ........