Model Output Discussion - The final stretch to Christmas

[ItNeverSnowsInWindsor]

Not the most festive charts today. Merry Xmas everyone and hoping to see some more cheery charts tomorrow..

[stewfox]

So you didn't read it? I think it is irrelevant what the charts look like, either there is some missing or there isn't.

Experts?

Any one can Google the facts re airlines some routes New York to London down 30 per cent for one day ie today gobal max 3 per cent down. Comes up every year and clutters the model thread . We can now leave it for another year re blaming lack of data for high Shannon entropy or poor model forecasting. Edited December 25, 2014 by stewfox

[Harsh Climate]

Interesting pressure chart from the met office for sunday night, could produce some snow across the spine of the country from that occlusion.

 

 

 

 

[bradymk]

Just a last on the model data issue. "ECMWF DATA 24/12 18Z = 177831 total obs. ECMWF DATA 25/12 12z = 49240 total obs." This should clear up the topic, whether it vastly affects the runs I do not know, but clearly a lot less data on today's 12z compared to yesterday.

Edited December 25, 2014 by bradythemole

[Blizzardo]

There actually is a lack of data Frosty, read Retron's post on TWO

I've not read his post but this debate is now a Christmas tradition. A few years ago on here someone posted all the data collected prior to the Christmas holiday period and then during it and the comparison showed that although there was a reduction in data collected it was a relatively small decrease. My recollection is that some flight data was missing.

[Chris D]

Just a last on the model data issue. "ECMWF DATA 24/12 18Z = 177831 total obs. ECMWF DATA 25/12 12z = 49240 total obs." This should clear up the topic, whether it vastly affects the runs I do not know, but clearly a lot less data on today's 12z compared to yesterday.

Link to this http://old.ecmwf.int/products/forecasts/d/charts/monitoring/coverage/dcover/ :smiliz64:

Edited December 25, 2014 by Chris D

[Paul_1978]

So, from a trop viewpoint it looks pretty grim. If (and big if) I've understood the signs from the strat thread the future looks pretty positive as we go into Jan. Both can't be right so we are at in interesting fork in the road.

Yes there are certainly some interesting developments strat wise, but are the models picking these signals up yet?

[johnholmes]

re the missing data

An annual red herring. Not getting involved, some years ago I posted the response from NOAA which said it had little if any effect and was 'filtered' at the start up I think was the phrase they used. Write to EC and MET and see what their response is. Data gets missed daily for a variety of reasons hence the comment from NOAA.

It makes good folk lore on here though every Xmas.

[East_England_Stormchaser91]

With a warming stratosphere, I for one do not expect anything like the super mobile pattern we saw this time last year.

2012/13 saw outputs like this and did not pick up the cracking snow event on the 18-20th January until a few days out. With the heights set to be in place over the pole the whole time, I expect subtle changes to happen with the outputs over the coming week. Plenty of opportunities could happen with the heights present over the pole.

Anyway, hope everyone has had a blessed Christmas Day.

Thankyou to everyone for your inputs to all the topics it's been a pleasure!

[fergieweather]

With a warming stratosphere, I for one do not expect anything like the super mobile pattern we saw this time last year.

2012/13 saw outputs like this and did not pick up the cracking snow event on the 18-20th January until a few days out. With the heights set to be in place over the pole the whole time, I expect subtle changes to happen with the outputs over the coming week.

Possibly so, albeit the strat issues and ultimate effects remain highly uncertain. Of the current (12z) EC suite, only 7 members offer blocking (to E in this case) by d15. Westerly mobility into the trend period does remain the form horse for now, with risk of deep lows especially into NW (a consistent signal in EC-EPS), but on the other hand, divergent signals re temperature regime post-Jan 1st remain noticeable in EPS site plumes. Thus, whilst the bias towards a resumption of westerly mobility (with periods of deep cyclonicity possible, but also spells of ridging especially to the S) must remain most likely based on current output (including for that matter across GFS OP and HRES), it has to be viewed with due caution at least *for now*. We've been here before...!

[Freezing-Point]

Merry Christmas to all.

 

There has been a gradual cooling trend since the start of December. Will it continue or will the Atlantic storm in as usual and leave many forecasts in tatters?  Nobody knows for sure. 

 

Here's to the cold trend continuing and all of us seeing a decent spell of cold in the next 6 weeks

[bluearmy]

The ECM ens bring some pretty low heights into the n Atlantic which will no doubt spawn some 'runners' along the base of the upper trough. This is a consistent signal and cool/cold zonal looks to be the way we're headed. That's assuming that the strat doesn't throw a curveball and change the trop polar profile with a marked split in week 2. There are signs that some weak upper ridging will be in the east Greenland area which could divert the jet away from its normal recurve back ne as it reaches the east Atlantic.

Looks pretty assured (as Ian's info that only 15% of the ecm ens support blocking hanging on to our east) but in thus game things are seldom that straightforward.

[Jason M]

This is the interesting point IMO. It just begs for a high pressure cell to pop up over Scandi. Not going to happen now at 60 hours out though...

 

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=60&mode=0

[DAVID SNOW]

re the missing data

An annual red herring. Not getting involved, some years ago I posted the response from NOAA which said it had little if any effect and was 'filtered' at the start up I think was the phrase they used. Write to EC and MET and see what their response is. Data gets missed daily for a variety of reasons hence the comment from NOAA.

It makes good folk lore on here though every Xmas.

 

If there is missing data? how could you filter it?

[Mucka]

The ECM ens bring some pretty low heights into the n Atlantic which will no doubt spawn some 'runners' along the base of the upper trough. This is a consistent signal and cool/cold zonal looks to be the way we're headed. That's assuming that the strat doesn't throw a curveball and change the trop polar profile with a marked split in week 2. There are signs that some weak upper ridging will be in the east Greenland area which could divert the jet away from its normal recurve back ne as it reaches the east Atlantic.

Looks pretty assured (as Ian's info that only 15% of the ecm ens support blocking hanging on to our east) but in thus game things are seldom that straightforward.

 

 

The ensembles could just as easily "flip" back, we have seen it often enough. Usually it is from cold to mild unfortunately rather than the other way around but it can work both ways.

 

FI is well inside hi res output IMO so I don't take this seemingly good model agreement at face value as I normally would.

I must admit I didn't expect ECM to be so progressive this evening but I still expect a slow move back toward the block being more resilient than is currently being modelled and can still see an eventual turn around with block being modelled further NW out to about day 5 and with the pattern backed West somewhat and the high at a better latitude it wouldn't take big changes in the upstream pattern for us to see some undercut being modelled once more day 6 through day 7 looks like a good opportunity for a legendary turn around and that isn't the Christmas spirit talking.  :w00t:

 

Whatever happens I just can't see this fast-track to zonal that has appeared in most of the output today but obviously with cross model and ensemble support it is hard to be so bullish about a backtrack over the next couple of days.

 

If the worse happens we will just have to hope the jet digs south quickly and gives us another shot at building a block.

 

If I get some decent snowfall over the enxt couple of days my snow lust will be satiated for some time anyway.

Edited December 25, 2014 by Mucka

[Carlrg]

HP hanging on for grim death at T120 on the GFS 18z. Still rolling out.

[bluearmy]

The extended ens picks this cold spell 14/12 when there was title apparently to look forward to on the modelling mucka. Of course they could be wrong but they don't often 'flip' with the long wave pattern.

[Weathizard]

This is just a hideous chart, it hurts my eyes.

Edit: at least the Atlantic is fairly blocked out though.

Edited December 25, 2014 by Weathizard

[Eskimo]

This is just a hideous chart, it hurts my eyes.

Really? Surface still very cold with the potential for ice days. 

[I remember Atlantic 252]

New years day still cold on the parallel (south) not so on operational, could op backtrack to keep us cold and dry? similar to 2002 one of my coldest new years day's

[Geordiesnow]

Really? Surface still very cold with the potential for ice days. 

 

I think he means in terms of the general trend overall to be fair PS. Weatherwise, if you can't have cold with snow then cold and dry with frosty mornings will do me although the trend is for things to less turn from the West as we head through the week. 

 

Regardless if there is a lack of data or not, the trend has been for the PV across to Canada to get much stronger and the Atlantic to regain strength, although detail will be subject to change, these less complicated set ups do tend to mean predicting the overall trend is easier than it is if there was a cold and blocked set up to occur. 

[Carlrg]

Is that shortwave going to undercut and have no decent cold to tap into. Ruddy typical. T186 GFS 18z.

 

Can anyone please explain why it disappears at T192H. Thanks Carl.

Edited December 25, 2014 by Carlrg

[bluearmy]

Any thoughts on latest Cohen blog u could share with us Ba?

They seem to base a fair bit on the output of one gefs run week 2. I assume they checked it to make sure it's well supported but the current extended ens look a bit different to the forecast he used so not really sure about it.

It might sound sacrilegious but over the past few weeks, that blog appears to be reacting to the output rather than predicting it which is what one might expect.

[swilliam]

The end of the high res GFS Op looks pretty weird to me  - nothing seems to be happening - just a few small lows dotted about in the large PV

 

 

 

Maybe the weather is in on its hols as well

 

Edit

 

Soon fires up in the low res though

Edited December 25, 2014 by swilliam

[shuggee]

Here's tomorrow's (Boxing Day) chart modelled by GFS at T+72 (i.e. only two days ago - Tuesday 12Z)

 

 

How things change.  Look at the mid Atlantic compared to how it's modelled now.  

 

 

For those worrying over today's T+168 (which is a full week away) - I'd say chill with a wee sherry and a mince pie  :smiliz19: