Model Output Discussion - The final stretch to Christmas

[johnholmes]

one is amused, as a certain person might say, at the thought of a computer 'losing the plot'

 

We still wait for certainty on the track of the low although the odds seem to be shortening on being in the southern N Sea by the end of the weekend, how cold and how much if any white stuff on its NW'ern flank for low lying areas has yet to be decided?

[Blue max 90]

UKMO ends with a UK high at day 6 giving some hard frosts with cold uppers trapped in its circulation.

 

Could be good going forward as well.

 

UW144-21.GIF

Roll on the ECM - come on Europe!

What tells you that the UKMO output would be good going forward please? (Learner alert!)

Thanks

[SW Saltire]

Please give your reasoning... thanks dragan

Exactly.

As Nick did earlier, let's reverse the situation.

GFS and it's sister GFS (p) develop easterly and cold at 120 but UKMO and (we shall have to see the 12z ECM) the 00z ECM showing milder conditions.

What would we be saying?

Now of course, there is a chance the GFS is right but if (it's a big if) the ECM broadly backs the UKMO then I know where my money is.

Edit: as noted below, the GFS (P) does show promise with an attempt at an easterly. The trend (highlighted by Snowking, Bluearmy et al) continues to grow, as Jason M has been noting for the past few days

Edited December 23, 2014 by SW Saltire

[ItNeverSnowsInWindsor]

About the best chart we could hope for at this point. I think I will leave at this point as still huge model disagreement.

 

UKM 120hr

 

That would be a perfect post-Xmas treat!  Hope the ECM follows suite....

[johnholmes]

Ok so enlighten me to the differences?

several hundred miles perhaps?

[Downpour]

the GFS  parallele  is doing its best at setting up a easterly

but surley it aint possible with a huge mass of PV moving back in to eastern canada and greenland it doesnt look possible to me has it lost the plot

A truly extraordinary chart from GFSp – which manages to carve a cold solution even in the most incongruous circumstances. As much as I hate to say it I suspect this chart is one for the fabled shredder. 

[karlos1983]

My bet would be we end up with heights rising over Scandi. I've seen it pop up a few times now, in fact the GFS(P) has hinted at it on it's last 2 consecutive runs, just a little trend to keep an eye on. The UKMO also wants to build heights over us, but that could easily evolve

 

I certainly don't expect raging south westerlies in the near future.

 

GFS(P) Height rise examples as mentioned 

 

UKMO at +144 

Wouldn't take much to get the same sort of Heights over Scandi that the GFS(P) suggests fro this chart.

Edited December 23, 2014 by karlos1983

[Neilsouth]

That would be a perfect post-Xmas treat!  Hope the ECM follows suite....

 

I put my guarantee it will look nothing like that on the day as UKMO fail at long range low pressure's diving into europe through UK

[johnholmes]

A truly extraordinary chart from GFSp – which manages to carve a cold solution even in the most incongruous circumstances. As much as I hate to say it I suspect this chart is one for the fabled shredder. 

 

why is it as you suggest, 'the most incongruous circumstances' I am puzzled by the meteorology in this post-genuine question please?

 

Just had a look on Meteociel and to me IF it has it right then the idea of movement of the low, rapid deepening due to upper air factors, the upper trough (short wave) well deescribed by Nick F this morning, with a subsequent build of upper heights behind this, again due to upper air factors, seems fairly logical meteorologically to me?

Edited December 23, 2014 by johnholmes

[Cheshire Freeze]

A truly extraordinary chart from GFSp – which manages to carve a cold solution even in the most incongruous circumstances. As much as I hate to say it I suspect this chart is one for the fabled shredder.

There have been numerous occasions in history where an Easterly has set up despite a raging Greenland/Canadian PV. On my phone and can't post charts but I'm sure someone else will post up an example. There's a few to choose from!

[Dr. Astro]

The UKMO 120hr is a good chart. Get the established UK High, followed by inversion = cold & icy conditions. Albeit it's usually dry, it can also be key in getting colder air to the UK in the long term.

 

A great chart for coldies to start off with.

Edited December 23, 2014 by Dr. Astro

[mulzy]

Not the best model but NAVGEM is quite a nice evolution...

 

 

 

[shotski]

several hundred miles perhaps?

LOL, I'm glad your not a taxi driver John, you'd cost me a fortune.

[karlos1983]

Not the best model but NAVGEM is quite a nice evolution...

 

 

 

 

That'll be 3 models showing an easterly and or an attempt at a Height rise to the NE.. Trends our friend

[Downpour]

There have been numerous occasions in history where an Easterly has set up despite a raging Greenland/Canadian PV. On my phone and can't post charts but I'm sure someone else will post up an example. There's a few to choose from!

Yes, I probably over-egged the post slightly. It's far from a common scenario but you are no doubt right that there are examples of it happening. Apologies. 

[johnholmes]

LOL, I'm glad your not a taxi driver John, you'd cost me a fortune.

 

Did I slightly exaggerate?

[mulzy]

There have been numerous occasions in history where an Easterly has set up despite a raging Greenland/Canadian PV. On my phone and can't post charts but I'm sure someone else will post up an example. There's a few to choose from!

 

[Captain Shortwave]

Day 5 charts

GFS

Northerly, main low tracking east with the secondary feature pushing south towards Italy

 

Parallel

Main low tracks south east down the east coast of the UK.

 

UKMO

Similar track to the GFS(P) but much quicker, cold easterly flow across the south eastern third of the UK

 

GEM

Another bizarre evolution from this model.

 

The GFS remains the odd one out with the main drive of that low, though there are plenty of options on the south/south easterly track of the low. A cold block remains the favour solution near the UK, though again the chances of snowfall remain limited. 

Edited December 23, 2014 by Captain shortwave

[karlos1983]

 

oh god, just a 23 year wait then   (tongue in cheek)

[shotski]

Did I slightly exaggerate?

Possibly, I'll give you a couple of hundred.

[Downpour]

oh god, just a 23 year wait then   (tongue in cheek)

Feb 91.

 

BANK!  :w00t:

[Cloud 10]

Roll on the ECM - come on Europe!

What tells you that the UKMO output would be good going forward please? (Learner alert!)

Thanks

 

Going forward there looks to be a good chance of Low Pressure going under the High to prevent it form slipping away South East,therefore extending any potential cold spell.

 

 

 

Where's Nick Sussex when you need him to provide a more elegant explanation. :smiliz64:

Edited December 23, 2014 by Cloud 10

[mushymanrob]

GFS's operational track over last few runs has little support from the 51 00z ECM/EPS members, the majority and ens mean take the low SSE or SE across mainland UK something akin to 00z UKMO. Mind you little support from 06z GEFS for the ECM op or even UKMO, with most taking the low SE down the North Sea. Be interesting to see if there's still a stand off on the 12Zs and if there is, what the t+96 and t+120 faxes coming out later this evening make of the low.

 

I do think the GFS, like others, is too quick to flatten the high that builds once the weekend low clears, I would expect the next Atlantic S/W upper trough to slow and amplify mid-Atlantic more towards the Euro solutions, though it's hard say at this juncture how long the resultant MLB will hold on. Really need to see some energy undercutting such a high centred over NW Europe for it stay in place.

 

i understand that nick, but does it totally mean the gfs is wrong? i see the 12z and again its sticking to its exit and flattening out the ridge.

mr cynical here is thinking that maybe people dont want the gfs to be right because quite frankly its a horror show for those searching for cold. im not suggesting it is right, but surely it has to be a possibility.

[Blue max 90]

Going forward there looks to be a good chance of Low Pressure going under the High to prevent it form slipping away South East,therefore extending any potential cold spell.

 

UW144-21.GIF

 

 

Where's Nick Sussex when you need him to provide a more elegant explanation. :smiliz64:

Ahh yes thanks for that; therefore potentially trapping heights NE of us to allow continued easterly?

Cheers

[Ali1977]

GEFS has some good set ups for easterly potential at 162