Model Output Discussion 18/11/2012 12Z onwards

[weather eater]

Everything starting to come together nicely now and we are getting agreement on how the very early stages of this blocking are going to develop. Although we have good pointers to how the blocking starts to form, the models quickly disagree on the positioning of the block, with the GFS having it much closer to us before sinking, the ECM has the block further north and keeps it there.

Personally I wouldn’t look much beyond 144hrs for now, and I certainly find it strange that some are already fretting about when it may breakdown, at this stage of the winter it would be surprising if it didn’t. It rather reminds me of my youth in the 60s and late 70s an early cold period with the expectation of something more potent after Christmas. And please let’s not start agonising about snow, when, where, how much, if this turns out to be part of a stepping stone to something better later in the winter, does it matter.

[SMU]

Last one from me-

IGNORE THE 06Z.....

Enjoy the rest of the day & I will join in the discussion later this eve,

S

[bluearmy]

the way this is trending, i am heading into the 'concerned where the cold uppers are coming from' camp' within the next fortnight. its looking cold at the surface as we look to be influenced by a fairly slack euro trough. that may well suffice with a fairly weak flow. i think it will be borderline for snow for the period. the influence of an increasingly significant scandi trough may well do the trick in a couple of weeks time. if we do require a couple of goes at this, lets hope the blocking remains in the right place as it could well drift a little west accroding to the recent naefs trend.

what has been clear watching the 850 spreads is that there has been little sign of any push of cold right out to the end of week 2. i guess that has been due to the wide spread on heights and lack of any particular solution being favoured at that range. i note this mornings naefs run brings colder uppers south later in week 2 and then a possible further drop in uppers across the southern half of the uk at the end of the run. early days but this may reflect the possible influence of that scandi trough as it spits shortwaves out. thats what will be needed to drag low uppers across us.

Edited November 20, 2012 by bluearmy

[swfc]

06z looks a poor run so far.Amplification is poor .

[The Northern Ramper]

The Gfs is in its dropped the signal phase, my advice is to follow the ECM and Ukmo and wait for the Gfs to come back into line in 24/48 hrs time.

[January Snowstorm]

Yeah the 06z run is very poor tbh, though still cold.

Hopefully as Steve says it's just a blip and the 12's will strengthen the Greeny high

[weather eater]

The GFS 00z and o6z are really demonstrating why is foolish to look too far ahead, they are similar early and out to the mid range, but from mid range to beyond, the 06z starts to go off at a completely different tangent. My advice is ignore beyond 144hrs and view even the output before that point with a degree of caution.

Edited November 20, 2012 by weather eater

[MKN]

A very similar run to the 0z in the later stages. The gfs is highlighting the importance of the Greenland high, atm it isn't showing and the potential for blocking to our north breaks Down. 4 poor runs in a row now from the gfs. It can't be ruled out that its onto something however at such a long way out im sure at least one or two runs over the next few days will switch back to something that looks much better

Edited November 20, 2012 by SnowTornado

[offerman]

O/T...

Edited November 20, 2012 by Paul
PM's are a great facility for this type of thing :-)

[Liam J]

3 poor GFS runs in a row now, the signal being flattened out quite quickly. Not a disaster though as things remain cool/cold throughout the run but more unsettled. Thankfully all this is still in FI, BUT, we cannot dismiss this outcome altogether given the last few runs have been consistent. I hope this isn't a new trend to be seen across the 12z suite later on....

The GFS looking very similar to yesterdays CFS output which isn't pretty for December either - http://www.meteociel...&carte=0&run=10

Stick with the ECM & also the ECM32 day which has been very bullish with the cold & blocked signal for some time now.

Typical GFS here when the model picks up a trend, looks good for a few days, then drops the idea at the same time the ECM picks up the trend only for the GFS to then play catch up.

Edited November 20, 2012 by Liam J

[No Balls Like Snow Balls]

Below is the GFS 6z chart for T144.

What's wrong with the 06Z?????? to me this chart oozes potential.

When you have professionals from the meto coming out and saying long range charts are not worth the paper they are written on so to speak, does it then cause so much stress to so many when it all goes pete tong in FI LOL. Listen to the professionals they know more than any of us can ever dream of - FACT. :-)

Edited November 20, 2012 by No balls like Snow Balls

[Frosty.]

Below is the GFS 6z chart for T144.

What's wrong with the 06Z?????? to me this chart oozes potential.

When you have professionals from the meto coming out and saying long range charts are not worth the paper they are written on so to speak, does it then cause so much stress to so many when it all goes pete tong in FI LOL. Listen to the professionals they no more than any of us can ever dream of - FACT. :-)

Looks good to me, trending colder next week and cyclonic with growing risk of wintry ppn, compared to how mild it is now, it's a much better set up...FACT

Edited November 20, 2012 by Frosty039

[Paul_1978]

If there's one word model watchers need be keep aware of it's "trends".

So we still have the trend of a mid Atlantic ridge, and a north easterly is now well within the T+144 timescale.

Following that the low still sinks south (again a continuing trend) to bring an easterly of sorts, which is still in place at T+252.

So overall no complaints from me and plenty to be happy about.

I personally wouldn't worry about anything after this.

[Robbie Garrett]

Just emailed the MetOffice regarding this and there view for the week after this weekend.

Below is the GFS 6z chart for T144.

What's wrong with the 06Z?????? to me this chart oozes potential.

When you have professionals from the meto coming out and saying long range charts are not worth the paper they are written on so to speak, does it then cause so much stress to so many when it all goes pete tong in FI LOL. Listen to the professionals they know more than any of us can ever dream of - FACT. :-)

[UV-RAY]

Some worrying that the uppers won't be cold enough, well stop worrying lots of time for upgrades, lets get the Synoptics established first .

[asjmcguire]

Before the 06z GFS Friday here has been fairly consistently progged to be very wet and windy - the 06z has changed that completely - it's now forecasting temperatures several degrees above what it has been saying previously, the rain has gone from being likely flooding to almost no rain at all and the wind doesn't look terrible. I somehow suspect something has gone very wrong with the run.... TD10 region.

[bluearmy]

Some worrying that the uppers won't be cold enough, well stop worrying lots of time for upgrades, lets get the Synoptics established first .

only wrt the initial troughing. thereafter, we need to retain the pattern and then colder uppers will definitely arrive.

[snowmadchrisuk]

Some worrying that the uppers won't be cold enough, well stop worrying lots of time for upgrades, lets get the Synoptics established first .

The question on everybodys lips is really , will the blocking become established over Greenland , or will the last 3 GFS FI runs be correct and send to much energy over the top of the block , powering up the PV , leaving not enough time for any real Cold air to get to the UK. My gut feeling on the matter is Blocking will become established and will be a lot harder to move than the GFS currently thinks and energy will be sent underneath the block instead. You can't rule out a slightly Milder spell mid December as The High will likely drift with time , but then you have to ask your self what state will the PV be in by then, I also think it is likely we will see some warming's in the Strat soon ,, With all that Warm air being pushed up into Greenland.

[johnholmes]

Is this not a cold enough set up for some of you. This has been consistent for 10 days now suggesting this type of pattern at 500mb.

I really cannot understand how so many hang on to each GFS run in its further reaches, and be either on cloud 9 or down in the dumps after each run.

For new folk please do read the guide I placed in the Guides area which will help you to follow the models with less ups and downs. That is unless you enjoy the see saws of the GFS and to a lesser extent the ECMWF synoptic models?

Following this set of charts, (the 500mb anomaly charts), all 3 +the NAEFS have been solid in predicting this pattern as I have just commented for 10 days.

It will happen, the detail as in ANY forecast will not be known until probably 72 hours prior to each day.

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

[Methuselah]

http://nwstatic.co.u...c6cc3698c45ab5;

To my way of thinking, the above chart represents a pivotal point regarding any future developments...and all model-solutions after that point are subject to wide variability. But, I don't believe that the model uncertainty (ensemble-/run-divergence) has anything at all to do with either 'missing data' or the fact that the GFS reverts to 'low res', at around that point: I believe that it comes from the chaotic nature of the equations themselves...

We must now be approaching the point where (and there must be myriad alternative ways of putting it) the background noise-signal overwhelms whatever it is that the models are trying to say. And, IMO, until quantum computers become available, the Law Of Diminishing Returns will ensure that future improvements will be slow indeed...

So no, there is nothing 'wrong' with the GFS itself - just how some folks want to read it!

Edited November 20, 2012 by Rybris Ponce

[Robbie Garrett]

Definitely.

We only achieved -5/-8*C uppers end of November 2010. -10 as we got into early December. We definitely don't need any colder, as that was cold enough.

Some worrying that the uppers won't be cold enough, well stop worrying lots of time for upgrades, lets get the Synoptics established first .

Edited November 20, 2012 by Robbie Garrett

[Glacier Point]

GEFS 06z mean has Europe going into the chiller week 2 FWIW and the ECM 00z has us not far behind at around 4C below normal over mainland Europe. At that range it doesn't take much to shift that cold pool further north. ECM 00z mean also depicting a half decent cross polar flow. This is the 06z however, but you get my point - anything beyond t144 (more especially when hemispheric pattern change is occuring when mode performance drops off) should be ensemble mean / spread based first. The operational GFS means didly squat beyond this time.

The key players here, stable ridges over the North Pacific and North Atlantic, should be your guidance here.

[chionomaniac]

GEFS 06z mean has Europe going into the chiller week 2 FWIW and the ECM 00z has us not far behind at around 4C below normal over mainland Europe. At that range it doesn't take much to shift that cold pool further north. ECM 00z mean also depicting a half decent cross polar flow. This is the 06z however, but you get my point - anything beyond t144 (more especially when hemispheric pattern change is occuring when mode performance drops off) should be ensemble mean / spread based first. The operational GFS means didly squat beyond this time.

The key players here, stable ridges over the North Pacific and North Atlantic, should be your guidance here.

Exactly GP.

The vageries of each run is highlighted by the amount of energy that each daughter vortex receives following the split. There is no way the GFS, ECM or any other model will possibly have the correct evolution of what is likely 10 days out in these or other scenarios.

I think with the general position of the split is the only thing that we can guess at for now. And that is from Pacific to Atlantic.

The 6Z GFS has this split on the east side of Greenland whereas the previous run had the split on the west side.

We would be extremely unlucky not to get some significant cold air once this split has occurred.

[January Snowstorm]

History tells me that when the gfs shows something like this in FI it can be an indicator that change is backtracking just a little.

Of course the mean and trend is what is important but the operational run cannot just be swept aside.

[Frosty.]

Exactly GP.

The vageries of each run is highlighted by the amount of energy that each daughter vortex receives following the split. There is no way the GFS, ECM or any other model will possibly have the correct evolution of what is likely 10 days out in these or other scenarios.

I think with the general position of the split is the only thing that we can guess at for now. And that is from Pacific to Atlantic.

The 6Z GFS has this split on the east side of Greenland whereas the previous run had the split on the west side.

We would be extremely unlucky not to get some significant cold air once this split has occurred.

Exactly Ed,

Let's hope we can turn that garden hose on soon , I especially enjoy reading the posts from yourself GP and steve as you all look at the much bigger picture and the knock on effect that has on our weather, fascinating model output and our first meaningful cold spell is not far away.