Model Output Discussion

[Guest North Sea Snow Convection]

Wish I could be enthuasiastic because the GFS Operational & GEFS Ensemble Mean suggest a 24-36 hour severe blizzard for all of Ireland..

However, the UKMO run, especially towards T+144 is very disappointing and if you compare the UKMO run @ T+144 with the overnight ECMWF @ T+168, they are certainly not a million miles apart...

If GFS were to verify then brilliant short term but we need a very good short term and long term ECMWF Operational tonight to restore confidence.

Hi, yes I agree, much of my own caution is based on the fact that the trends this evening mirror the ECM this morning . Hopefully I am very wrong (lol!), but I think there may be more of the same this evening. I'm beginning to think that that trough over Norway is not going to shift quickly enough and is going to prevent a full reload of the cold

Edited December 26, 2009 by North Sea Snow Convection

[Snowaddict]

If it's any consolation, GFS 12Z Control is a lot better than the operational to T+192, with a greater intermediate easterly feed, an initial snow event and a snow event @ T+192..

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=0&mode=2&runpara=0

SA

[nick sussex]

I'm just going to have to start keeping my own records to back up my theory. How many times towards the end of last week did the UKMO at T144 show the cold spell ending before Xmas with milder 850s flooding the country ? At least three times. Did the fax charts ever back up their own model during this time ? I don't think they did.

I'm not disagreeing with you on last week, the point i'm making is that somehow it verifies better than the gfs and gem over the last month, it could well be wrong this time but the fact it churned out that output is cause for concern. Just so people know where i stand here i think it's wrong and also think the gfs operational run is wrong and neither will be backed by the ecm.

[Harsh Climate]

Don't take it personally, the weather doesn't care a hoot what we think and hope for. Seems like the downgrades are taking place already which perhaps already makes today's meto update obsolete as I type this. Where has the northely arctic flow gone between friday and early the following week?

lol just logged on and cant believe the huge dissapointment on here at the last couple of runs :lol: :lol:

I though we'd have all learnt our lesson by now, me included! The charts were constantly downplaying this weeks cold spell and trying to break it down from the south west, which is certainly not going to happen anytime soon. Not the bartlett high that a few runs earlier this week were showing.. And for many this coldspell has been up there with the best! plenty of widespread snow, very low maxima/minima and still know end in site in the medium term..

Yesterday morning for example showed northenmost parts of england/scotland getting hammered by snow on tue/wed, then this morning it showed the midlands getting hammered, when the models are guna struggle so much wi that even, theres no point really looking too much into what happens after as the positioning of tue/wed low is everything! The further south the better I would think as that should allow an easterly to follow on a much better axis..

Even if this is a classic cold/snowy winter coming up the charts will allways throw wobblies up and mild breakdowns will never be too far awa but with a strongly negative NAO/AO expected through january, I think most unlikly!

nao

http://www.cpc.noaa.gov/products/precip/CWlink/pna/nao.mrf.gif

ao

http://www.cpc.noaa.gov/products/precip/CWlink/daily_ao_index/ao.mrf.gif

No coincidence that this current blocking to the north has coincided with negative nao/ao

[john w]

I would love to bin the meto 144 and before with the low North, but I actually think it is more likely to come off purely on the confidence of the meto in our bespoke forecasys received from them....unfortunately I cannot disseminate them outside of work.

Can someone pls explain the polar vortex...would like to know more about it,

Also I note the warm pool of anomolous warmth off the NE coast of US. As that migrates west I suspect that will bring the end to any real blocking potential.

Owing to the met-offices over confidence on this...im going to say their awful rain fest may come off.

Like the warm being pushed back for an end to the cold spell just recently, I think for the South the next cold spell may actually never arrive. However, hops I am wrong

Edited December 26, 2009 by john w

[Snowyowl9]

I wasn`t going to post today but after seeing last night`s outstanding charts.

which really gave a late christmas preasant.

That is the trouble with looking at too many models/charts just take a break from model watching.

over the christmas holidays.

Cold will dominate this January. :lol:

:lol:

Last post until the blizzard next week.

Edited December 26, 2009 by Snowyowl9

[Mark Bayley]

As already mentioned the Control run from the GFS is fantastic!

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=6&runpara=0&mode=1

[snowking]

On the very latest verification stats update (may be necessary to hit F5) - ECMWF is a long way ahead of the pack by almost 10%..

http://www.emc.ncep.noaa.gov/gmb/STATS/html/graphics/acz5.gif

Therefore, the ECMWF evolution is extremely important tonight in my opinion..

Maybe at day 5, but at day 6...

http://www.emc.ncep.noaa.gov/gmb/STATS/html/graphics/acz5.gif

A very different picture with the GFS every bit as good as the ECMWF

But thats if you look at it on just a one day scale....to get a proper picture of model verification your better following the averaged monthly correlation values - which do, indeed, place the ECMWF in the lead on both days 5 and 6....but you have to notice in both cases the UKMO is second placed

And this is where people need to wake up and smell the roses - there is such uncertainty at the present time in the output that we can't be looking at the specific details such as will it snow in carlisle on wednesday at 7pm because it will not be for a few days yet that we know the exact track of the LP system

Take monday for example, despite the Met Office's claims in their press release their forecast of the snow that hit the SE was some of the shoddy-est i've seen this decade

We are still being spoilt with some of the synoptics shown currently and that is a good trend, especially the right side of the usual FI boundary (even though one could argue FI is actually at a very short range currently), lets settle for that for now and then look at specifics a little later

SK

[Stu_London]

Anyone reading this, please just look at all the 12z charts tonight and make your own mind up. This sort of post is just putting less informed members who don't necessarily understand the models away.

Obviously anyone is free to look at the output.

I would suggest if they have extra to look at the last 4 runs also and the ensembles - so they can clearly see a progressive downgrade of a cold spell to a cold snap

[rich1]

Brian over on TWO has mentioned there are some issues with the data collected for the 12z. Though there have been full datasets for the most part, the xmas/boxing day output has been known for throwing the odd wobbly in its time

I think the one thing to bear in mind is that there isnt full agreement in the setup for next week across the models, while there are discrepancies like that then it makes no sense to write it off

though have to say, would really irritate me if all we get is a week of rain down here but sense we could see things improve over the next couple of days all the same

ECM will be of interest, could do with a colder run to help build a bit more optimism for those south of the M4. GFS does go cold in the long term though, at least for a while

for those in the north, its a decent picture generally, but already fed up of this milder weather down here with all this northern blocking it would be hugely annoying if it all goes to waste

[phil nw.]

The further north that the low tracks, and the more that the trough over Norway impedes the colder air - then the more that the timeframe for colder weather is pushed further out. In turn, more time for further things to go wrong.

The ECM will complete the 12's and then we can see fully. However, there is still time beyond the mid week period for changes, and further changes are almost inevitable, despite rather unencouraging output so far this evening.

I can see your concens Tamara regarding the impeded flow.

We are on the Eastern edge of the block with the Trough disruping over us causing complications,this is why we won`t get a clean North Easterly,here,

http://www.meteociel.fr/modeles/ecmwf.php?ech=144&mode=1&map=1

I posted 00z ECM as i think that looks like the middle ground amongst all the changes.

It`s not ideal for everyone i know but unless the Block re-orientates it`s the one we are stuck with for now.

[Guest North Sea Snow Convection]

I don't agree Tamara. What are these things that 'can go wrong' when you have a dominant Greenland High ?

The only thing that can go wrong is if you end up with a too West based NAO ansd even if you take the UKMO at T144 as fact, then you wouldn't have that set-up at T168 .

Obviously people in the SE want a Channel low followed by an easterly. Why not just say so ?

It isn't just the track of the low that is an issue, that is what I keep endlessly repeating. The low over Norway is preventing the properly cold advecting fully southwestwards. In that respect the high over Greenland is redundant, at least to a degree. If the coldest air is tracking westwards only over northern most parts (not southwards or south westwards to the majority of the UK)) courtesy of the blocking to the north of the Uk that doesn't qualify as a cold spell for the majority. There are similarities, thus far, with Feb 2001 imo. But there is plenty of time for that to change.

Edited December 26, 2009 by North Sea Snow Convection

[nick sussex]

At 144hrs no major model agrees on the set up so far, the GFS, UKMO and GEM are all different. My advice bin all the output past 96hrs and wait for the ecm to deliver the final deciding verdict, in all the time i've been on the net i can only remember one time when it's been badly wrong at the T-96hrs time frame. Upstream NOAA favoured the ecm and ecm ensemble mean this morning and theres a reason for this.

Edited December 26, 2009 by nick sussex

[Geordiesnow]

UKMO could be better this evening it must be said, it still has the low that bit far too the North, therefore not as much cold across the UK as the GFS is showing.

Meanwhile, the GFS is a decent run and i feel some got sucked into what the charts were showing yesterday. It has the low further South than the UKMO and most places apart from Southern counties are at least in the -5 or below air. Whoever is on the Northern edge of the front would recieve alot of snow if this run came off. Meanwhile Northern and eastern Scotland and perhaps NE England would recieve quite a few convective showers which would more than likely to be snowy. The only time where it goes "dodgy" is around the 168 hour mark where we start seeing the charts get a bit messy but there is alot of potential for height rises in Scandi on this run.

It's funny though because the last easterly we had, it was not as good for Scotland whilst it was good for the further South and east you were - funny how the mood shifts when the risk gets transfered Northwards.

I'll accept the comments that the UKMO is not as good as the GFS but all it takes is a shift of around 100-200 miles and then things might look better.

[swilliam]

Very annoying - it sunk our high - but it seems to be showing up on the all runs now including the METO T144

Still there on the control but this time it does not sink the high - what a difference!

[Cecil Hogmanay Melchett]

Bitterly disappointed with ukmo this evening.

I think the meto/bbc are going to do some serious backtracking tonight/tomorrow unless ecm pulls a rabbit out of the hat.

ukmo is just rain,and more rain,totally flies in the face of bbc calling cold next week.

[Snowstorm1]

Ive been posting on this forum for 2 years and can understand some of the charts but im really confused with the posts on here ? Upgrade/downgrade can someone give people like me and other amateur model watches an accurate assesment of what is going on please

[chapmanslade]

I've posted last night's ensembles again for the south together with tonights for Wiltshire which nicely demonstrate the vanishing 'hump'! Virtually no support for the warmer hump in the 850's that had almost total support a few days ago - for this reason anything more than 5 days away really is to be taken with a pinch of salt and isn't worth argueing over !

Edited December 26, 2009 by chapmanslade

[Optimus Prime]

Obviously anyone is free to look at the output.

I would suggest if they have extra to look at the last 4 runs also and the ensembles - so they can clearly see a progressive downgrade of a cold spell to a cold snap

As you've shown numerous times before you go through more mood swings with the models then Jesus had disciples.

In a nutshell the outlook is fantastic. what the models are showing is for a progressively colder week (or remaining cold if you're in Scotland) and getting even colder as January starts up.

[Geordiesnow]

Bitterly disappointed with ukmo this evening.

I think the meto/bbc are going to do some serious backtracking tonight/tomorrow unless ecm pulls a rabbit out of the hat.

ukmo is just rain,and more rain,totally flies in the face of bbc calling cold next week.

UKMO is a cold run but it transfers the cold northwards and have the milder air further northwards. Too me, the UKMO looks fairly similar to this morning's UKMO, low was further South than last night's 12Z but not as far South as we would like.

[Barb]

Why are people putting so much faith in the UKMO? Same thing happened last night (though not as bad) and the Met Office dismissed their own model and put out completely different Fax charts.

[Guest North Sea Snow Convection]

It's absolutely nothing like Feb 2001, we relying on the Arctic High back then and as usual it failed to come into play bacause of the jet. This is wholly different.

This too has everything to do with the jet, does it not?? And we again have high latitude blocking profiles.. I have repeatedly said there is time for change, I am just trying to give an objective view as well as some concerns of the models as they stand, not predicting that what we see will happen! It's funny, I always was suggested to be Mrs Optimist whatever the models say. Can't seem to win!

[Barb]

GFS ensembles backing the GFS op out to 3rd Jan.

[snowmadchrisuk]

I think your all over looking the fact that from +96 to it's +144 chart the UKMO is showing a massive Greenland high , and I have never known a Greenland high of that shape to give mild weather across the UK. I am getting very excited by the charts shown , does any of the level headed people agree ?

Chris .

[Cecil Hogmanay Melchett]

GFS control shows what we need to happen here.We get the link and the pressure rise across Scandy.

Frankly if we dont get the link between Greenland and Siberian its looking like the Atlantic will slip in and all that fantastic northern blocking will go down the toilet.

I really hope ecm delivers this evening.