Model Output Discussion - The Start Of Winter

[Banbury]

Someone must have heard you and given it a kick as its out to 180 hrs now.

eh? It finished a while ago on my pc

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014121212/gfsnh-0-384.png?12

[IDO]

Very flat and zonal GFS op from the 12z for the Christmas period:

 

  

 

Some PM and TM shots in the lead up with the former the more dominant on this run. The models are beginning to firm up on the handling of the PV in week 2. In week 1 weak polar heights are both evident on the gFS and GEM:

 

 

 

These are enough to divert the Canadian PV from the east (week 1 it was on the move east) back towards the Greenland area in the D7+ period. This recycling on the GFS keeps our locale in a very flat pattern right out into FI. GEM at D10 would also go that way:

 

 

This ties in with the week 3 CFS anomaly: 

 

I noted from the more amplified 06z GEFS that the polar heights are instrumental in any ridge formation, they aided that development. The control is an example where the polar heights migrate towards Alaska and mix with the MLB and amplifying the upstream...

 

control:

 

...sending a trough to the eastern seaboard and the resultant wave amplifies the Atlantic. This signal is repeated in the GEFS, and this is looking a promising cluster, with the best of the ens:

 

 

This is probably what has been showing in the EC and the UKMO output and good to see the GEFS trending that way. We now need consistency going forward.

Edited December 12, 2014 by i'm dreaming of...

[ukpaul]

eh? It finished a while ago on my pc

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014121212/gfsnh-0-384.png?12

 

That's the soon to be binned version. The upgrade has been running for a while now (greater resolution etc,)

 

Can anyone explain what the bias corrected run does on the ensembles, what sort of bias is it correcting?

[Mucka]

There is certainly nothing I can see using whatever models cover the next 2 weeks to suggest any real change in the overall westerly pattern of weather. Possibly even a touch less cold (bit milder than the past few days) by Christmas?

Will do a summary of anomaly charts and other factors some time tomorrow along with links.

 

Are you including ensembles?

10 days I would agree but definitely a signal building for changes into last week of December.

 

 

Signal probably too weak to show up in anomaly charts at that range as yet but it is there.

[bluearmy]

The 12z gefs follow on from the 06z by again building a mean upper ridge in the greenland area in two weeks. it seems we will have to wait that long for the upstream amplification we require. it arrives via the alaskan ridge which drives an e american trough. that in turn seems to drive the ridge ahead of it. at this stage, its unclear how transient any greeny upper ridge would be as the run ends.  i suspect the condition and locale of the vortex at that timescale will dictate the answer. the question of how efficiently heights may drain from  our south and soutwest is also to be answered. as some of the members posted above by mucka show, we could see the core of any cold headed a bit to our e if the heights hang on.

[Buxton Codge]

The 12z GFS & UKMO suggest another week of mobile westerly weather but slightly milder than the last week. The CET is currently bang on average but I expect this to steadily rise over the next 7-10 days. More hints of a return to settled weather after the 27th and hopefully colder too.

[ukpaul]

I don't usually take much from long range means but they can sometimes give an idea of the direction of travel.

 

240h

 

 

312h

 

384h

 

[nick sussex]

Big differences upstream at T120 and T144hrs between the ECM and the GFS's and UKMO, the ECM is more amplified and phases those lows which helps to pull some of those low heights nw away from Greenland.

 

Theres still that shortwave complication in the Atlantic but the T168hrs on the ECM given its T144hrs I would have thought would look a bit more interesting than the GFS's.

 

Sadly it all goes downhill pretty quickly at T192hrs, the shortwave in the Atlantic is a real irritation and doesn't help matters.

Edited December 12, 2014 by nick sussex

[gottolovethisweather]

There is certainly nothing I can see using whatever models cover the next 2 weeks to suggest any real change in the overall westerly pattern of weather. Possibly even a touch less cold (bit milder than the past few days) by Christmas?

Will do a summary of anomaly charts and other factors some time tomorrow along with links.

 

Yes John, certainly quite a strong trend for something drier over Southern UK in the D5 to D7 timeframe right now, a signal which has undoubtedly grown stronger over the last few days. However, it could yet simply be a blip in the overall repeating pattern and the projected uppers on some outputs of 4c - 8c could easily get moderated downwards as, in fact I suspect they will. The overall trend is for a Westerly/Northwesterly based regime for most parts of the UK over the coming 7 to 10 days and beyond that, I for one won't be placing any confidence in any forecasts surrounding actual surface synoptics, as I'm sure you would attest to yourself. A case of as you were for coldies, no deep cold and also nothing remotely mild in the reliable. Brief opportunities for wintry showers with a bit of snow thrown in for those located in the usual favoured places. Regarding your updates, as ever, I like many others, will look forward to seeing them tomorrow.

Edited December 12, 2014 by gottolovethisweather

[Eugene]

Great to see both ECM and GEM 12Z limit that mild sector mid next week to just Wednesday, back to lovely clear PM air on Thursday, lets hope they are correct

[Recretos]

Dont forget that CFSv3 is already in the workshop, getting ready to see its dawn, somewhere down the line

[nick sussex]

Yuk! At T240hrs its colder in Crete than in Scotland, ghastly later output from the ECM. It would be better if the high was further north to at least get some surface cold off the Continent.

 

Not sure if this operational run will have much ensemble support as its been overdoing the Azores high in its recent later outputs and these have tended to want to keep the high more displaced to the west.

 

Overall a chance for a cold blip before the ridge flattens and then its crud to be honest.

[gottolovethisweather]

Great to see both ECM and GEM 12Z limit that mild sector mid next week to just Wednesday, back to lovely clear PM air on Thursday, lets hope they are correct

 

Hence my reference to a blip above, still a case of watch this space though and we will know more by the end of the weekend. 

Edited December 12, 2014 by gottolovethisweather

[Barry12]

The mild weather has continuously been pushed back over the last couple of weeks on the models, and any mild weather that does verify is very short lived, before a return to a cold PM airflow. This might be because the Azores high has continuously been forecast to push in, but as we get into the reliable it is pushed further west. My prediction is that the pattern change will involve the Azores high trying to push in, but will end up being forced N/NE, resulting in a cold Easterly flow. If this does happen, then hats off to Tamara and others for predicting the end of December pattern change, which now has some support from the Glosea5 and ECM clusters.

 

The chart below maybe?

 

 

 

 

[bluearmy]

No Idea about the accuracy of the bias corrected gefs on Meteociel but I would question the mean Asia Pacific jet in week 2.

[blizzard81]

No Idea about the accuracy of the bias corrected gefs on Meteociel but I would question the mean Asia Pacific jet in week 2.

Why BA? Is it showing it to be strong?

Just had a look and yes, looks to be strong and flat.

There is no doubt that the output has taken a turn for the worse to day

with regards to Christmas week in terms of cold synoptics. What struck me most

about the GFS & ECM 12z runs is the diminishing heights over the pole.

Edited December 12, 2014 by blizzard81

[legritter]

Evening all ,well certainly tonights ECM was a bit of a let down for me especially in its later 3 frames .ok we have high pressure modeled too the s east of us but it would be totally wrong to accept this at this range ,could be that high could be many hundreds of miles in another location .PLenty of talk about a pressure change later this month perhaps this is the first sign appearing on our charts .i would have thought that the models would soon start sniffing at something and we are only 12 days into winter so gang be patient and No writing off winter ,   cheers 

[phil nw.]

The 12z runs all very underwhelming for any significant cold after this weekend tbh.

 

The best chances of any snow look  increasingly confined to northern elevations next week as the pattern starts to flatten from mid week, restricting the move south of the colder air.

The Azores high is beginning to show it's hand more in the charts from mid week and this will push less cold conditions more into the mix as time goes on,especially further south.

 

The warm sectors from Atlantic lows to our north will become more expansive and the colder air behind the fronts modified by the warmer sea track.

The GFS mean at day 10

 

which is very close to the ECM op.

 

Without some changes upstream to the flat NA pattern it's difficult to see any change across the Atlantic soon.

 

We continue to hope that background factors may come into play but that area of low heights spread between Greenland and Scandinavia coupled with the omni present Azores High is our normal Winter pattern and can take some shifting - a solid +ve NAO picture.

At least with the mean jet not pushing too far north it doesn't yet promise to evolve into a overly mild set up.In fact we could see some noticeable temperature differences between north and south over the next 2 weeks as the jet oscillates across our latitude, 

[blizzard81]

The 12z runs all very underwhelming for any significant cold after this weekend tbh.

 

The best chances of any snow look  increasingly confined to northern elevations next week as the pattern starts to flatten from mid week, restricting the move south of the colder air.

viewimage.png

The Azores high is beginning to show it's hand more in the charts from mid week and this will push less cold conditions more into the mix as time goes on,especially further south.

npsh500.144.png

 

The warm sectors from Atlantic lows to our north will become more expansive and the colder air behind the fronts modified by the warmer sea track.

The GFS mean at day 10

viewimage (5).pngviewimage (6).png

 

which is very close to the ECM op.

 

Without some changes upstream to the flat NA pattern it's difficult to see any change across the Atlantic soon.

 

We continue to hope that background factors may come into play but that area of low heights spread between Greenland and Scandinavia coupled with the omni present Azores High is our normal Winter pattern and can take some shifting - a solid +ve NAO picture.

At least with the mean jet not pushing too far north it doesn't yet promise to evolve into a overly mild set up.In fact we could see some noticeable temperature differences between north and south over the next 2 weeks as the jet oscillates across our latitude, 

Yes, the pressure patterns into Xmas week are very reminiscent of the Meto contingency planners outlook for winter,

very positive NAO at least for the first part of winter.

[phil nw.]

Yes, the pressure patterns into Xmas week are very reminiscent of the Meto contingency planners outlook for winter,

very positive NAO at least for the first part of winter.

Yes it's all pretty average at least for the next 2 weeks but that's as far as we could reasonably go with our limited data.

I wish i could be more upbeat but it is what it is.

Considering the overall picture it doesn't promise to be as mild as it could be- and has been in many Winter past-the jet much further north on those occasions.

Edited December 12, 2014 by phil nw.

[johnholmes]

Are you including ensembles?

10 days I would agree but definitely a signal building for changes into last week of December.

 

 

 

Signal probably too weak to show up in anomaly charts at that range as yet but it is there.

nope don't use them, although I do look, but what you suggest is shown on ? 5 out of how many? Nothing can be discounted which is why my post said what it did re any/all models.

[Mucka]

nope don't use them, although I do look, but what you suggest is shown on ? 5 out of how many? Nothing can be discounted which is why my post said what it did re any/all models.

 

5 out of 20 with a few others showing similar traits. It was just that your statement was quite definitive of no sign of a pattern change within that time-frame which is why asked if you would be taking ensembles into account. I'm not trying to be contrary, it was a genuine question.

Yes it is a weak signal but then I stated as much.

Thanks for the clarification.

 

We will see if it strengthens in the coming days or disappears.

Edited December 12, 2014 by Mucka

[ANYWEATHER]

The Ebb and Flow of  milder and colder incursions continue in tonights runs from gfs and ecm.  Looks like little change to the run up to Christmas and beyond, but the normal caveats apply. I know many on here are looking for deep cold from the East , early days yet and as the past and stats will prove ,the meatiest part of Winter is yet to come in January and February! Its a very fine looking December, as regards Seasonal weather, the Uk has seen gales, High Waves, rain, sleet, Snow, sunshine , frost, hail and thunder, who can ask for more?!!!  Perhaps we may squeeze a normal or slightly below average month in terms of temperature.....

[The Enforcer]

1. Forecast Charts for around T+ 2 weeks will rarely remain consistent between outputs and verify as presently indicated.

 

2. The N-W winter forecast anticipates that January will be the coldest month, so a lack of sustained cold before then should not be a surprise.

 

3. Don't lose sight of the wood for the trees - an occluded front shown on the models, which is moving south over the UK tonight bringing wintry precipitation seems to be largely ignored.

[winterof79]

1. Forecast Charts for around T+ 2 weeks will rarely remain consistent between outputs and verify as presently indicated.

 

2. The N-W winter forecast anticipates that January will be the coldest month, so a lack of sustained cold before then should not be a surprise.

 

3. Don't lose sight of the wood for the trees - an occluded front shown on the models, which is moving south over the UK tonight bringing wintry precipitation seems to be largely ignored.

Agree with most of what your post says however the occluded front is fizzling out and is not expected to produce much as the northerly component sets in.

http://expert-images.weatheronline.co.uk/daten/proficharts/en/euro4/2014/12/12/basis12/ukuk/prty/14121218_1212.gif

http://expert-images.weatheronline.co.uk/daten/proficharts/en/euro4/2014/12/12/basis12/ukuk/prty/14121300_1212.gif

regards

Edited December 12, 2014 by winterof79