Model Output Discussion - The Start Of Winter

[Mucka]

isnt it?

 

1.gif a chilly couple of days, nothing too cold away from scotland

 

2.gif followed by three days of wet windy and mild

 

3.gif three days of 'average' cold before

 

4.gif mild mobile wet and windy weather returns throughout fi...

if the gfs 00z is anything to go by, then the cold pm incursions have been reduced in their potency, and the general trend is for more mild weather as we progress into december. now that looks pretty dominant to me ! so the 00z looks average - above average.

these arent cherry picked charts, i went through the gfs 00z and chose a chart to emphisise the ever changing outlook we have each mild/cold spell. there appears to be a tendancy here to play down milder options because its not what most appear top want. but denying their existance wont change the fact that there are milder options.

 

 

Unfortunately I can only comment on output being discussed at the time of writing. If you lend me your time machine and issue a diktat which particular/specific output/chart I should comment on in the future I will try to do better. 

 

We already put that to bed and Teits stated he wasn't emphasising the mild and even now it is still not the dominant theme over the next 8 days.

 

 

Currently GFS wants to have the AH ridge in pre Christmas and bring in milder weather for a time but that may change. ECM pretty much continues the current theme with the possibility of an Atlantic ridge around Christmas.

A forecast of predominantly mild for the next 10 days would be inaccurate but for the 8 to 12 day range it may be milder (Xmas period)

But it may not be... 

Edited December 14, 2014 by Mucka

[draztik]

Baby steps...

The ECM EPS 0z & GEFS 6Z both trending towards a -NAO & -AO by 26th Dec, with the control for both models sharply negative, esp GEFS. We will wait and see if this trend can be continued and enhanced.

 

 

Edited December 14, 2014 by draztik

[IDO]

As others have said the MJO moving out of the circle of death late December so it may become more of a driver again, and I am assuming that there will be no SSW until at least mid-Jan:

 

 

The composites are for phase 4 and 5:   

 

May head into phase 6 & 7 in the second half of January so maybe a pattern change from then?

 

With regard to the cold for this month, the current CET is -0.1c so average would be spot on. I cannot see that changing too much in the next two weeks so a very ordinary start for Winter. Of course a lot better than last year, but that was a one off extreme (like comparing it with December 2010, another once in a 100 year event), and I doubt it will be repeated for sometime (hopefully).

[nick sussex]

Mild  or cold Christmas ?

 

Either is possible this morning and will be determined IMO by what happens in that circled red area over the central USA.

 

 

The pattern upstream over Europe will be dictated by the amplitude of that USA troughing, this more amplified wave is likely to work its way east, as it does so it will likely pull some of those low heights away from Greenland closer to Hudson Bay, at this point a proper Greenland high is unlikely however the interaction upstream might leave the southern part of Greenland open to some retrogression of the Azores high.

 

A northerly could develop if that occurs and then its really whether we can hold troughing over Scandi with low heights developing further south and the upstream pattern remaining amplified whether this turns into  cold snap or a longer colder spell.

 

We are reliant on the upstream pattern playing ball, in nutshell if the upstream pattern doesn't reamplify sufficiently then a more average/ milder Christmas is likely.

 

In terms of the GEFS that's somewhat disappointing but we need to factor in the flat bias of that so I'd tend to factor in the operationals more than the GEFS especially at this stage.

 

 

 

 

[snowking]

As others have said the MJO moving out of the circle of death late December so it may become more of a driver again, and I am assuming that there will be no SSW until at least mid-Jan:

 

realtimemjo ( .png

 

The composites are for phase 4 and 5:  JanENMJOphase4all500mb.gif JanENMJOphase5all500mb (1).gif

 

May head into phase 6 & 7 in the second half of January so maybe a pattern change from then?

 

Just FYI with regards to the CFS MJO forecast. I did take a look at this yesterday but chose to disregard it as it is rather a long way out of sync with current NWP, which suggests the emergence of a new wave in around 10 days time - that CFS forecast is not predicting the new wave to emerge until the first few days of Jan (current OLR forecasts have it in towards phase 6 by this stage)

That would bring tropospheric changes forward a little compared to your suggested timescale and the timescale suggested by that CFS forecast

SK

[Nouska]

So yet another run that hints at a pattern change towards the end of the year with the interest starting from around the 28th Dec onwards.

 

As some of you know I like to look at the Iceland SLP ensembles when blocking to our N is hinted at. However keep an eye on the Madrid SLP mean also.

 

http://max.nwstatic.co.uk/ensimages/ens.20141214/00/prmslMadrid.png

 

Should blocking develop then you would expect low pressure systems to take a more S,ly route and the SLP mean will drop. A few 0Z GEFS members hint at this.

 

Finally as many know my forecasting is based on instinct. Until today I haven't seen anything of interest but my word my mind has now changed towards a mega cold spell arriving at the end of the year.

 

Meteociel now offer a global map to create ensemble graphs for anywhere.

 

http://www.meteociel.fr/modeles/gefs.php?carte=2

 

Within this, there are pressure, temperature, wind direction, ThetaE and precipitation options at the bottom of the graph.

 

Azores     Faroes 

 

The ECM ensembles for Madrid and Rome are not showing any signs of low pressure influence as yet.

 

http://www.meteo24.fr/fr/home/meteo-france-et-europe/passion-meteo/ensemble-de-previsions.html?eps=rome

 

http://www.meteo24.fr/fr/home/meteo-france-et-europe/passion-meteo/ensemble-de-previsions.html?eps=madrid

[Blue max 90]

CFS model still giving this picture of a cold easterly come January! I know it's well into FI but the constant signal is there.

Edited December 14, 2014 by Blue max 90

[Frosty.]

I agree with teits about the very wintry further outlook but just to add, there has already been plenty of interest in the model output for the north of the UK in terms of wintry weather but diddly squat for the south so far, however, I think the cold incursions will extend further south by Christmas with a higher risk of snow. There has been no downgrade to the rather cold zonality although it's fair to say we are in for some slightly milder air in the week ahead, at least across the southern half of the UK.

[bluearmy]

Nouska, I don't see a desire to bring lower heights to Central Spain or s Italy within two weeks. The week 2 ens modelling heading cold has the Scandi trough slowly expanding South and west. It's precipitation influence may not get as far as these two capitals though week 3 direction of travel clearly unknown as yet.

[tinybill]

http://www.meteociel.fr/modeles/gefs_cartes.php?code=16&ech=192&carte=&mode=0

 

looking  deep into fantasy world   there certainly  some tasty weather heading to us from over the pond later December

[meathead]

The fact that the met office are hinting about a pattern change to potentially prolonged cold at the end of the year is huge. They have been pretty accurate so far this winter. I wouldn't worry too much about what the models are saying right now. 

[Team Jo]

Afternoon folks, just a gentle nudge back into the model discussion please... There's a separate thread for met office & lrf musings..

Thanking you!

Edited December 14, 2014 by Team Jo

[Winter Cold]

Good agreement with GFS, GFS(P) and UKMO this evening for another cold blast from the NW hopefully next Saturday. Im looking forward to getting the mild muck midweek behind us and start seeing this again:

 

 

UKMO looks better for snow/wintry showers as it keeps the low closer. GFs's more keen on settling things down from the west.

Edited December 14, 2014 by Winter Cold

[Mucka]

GFS 12z is a bit of a horror show in hi res (<=8 days) really, though thankfully out on its own with the parallel being a little more coldie friendly in that time-frame.

 

 

Of course, transient moderate cold shots aside, people will be more interested in Christmas period and the bigger picture that develops.

 

[Eugene]

Good agreement with GFS, GFS(P) and UKMO this evening for another cold blast from the NW hopefully next Saturday. Im looking forward to getting the mild muck midweek behind us and start seeing this again:

 

 

UKMO looks better for snow/wintry showers as it keeps the low closer. GFs's more keen on settling things down from the west.

 

 

Yeah me too but unfortunately after a brief clearer cool snap next weekend the mild muck looks like returning hopefully not for long.

[bluearmy]

Promising week 2 greeny ridging is being complicated by cut off troughing in the Western Atlantic on Gfs and gfsp

Once the models get to grips with this, I expect a smoother transition to the post xmas set up will become clearer.

[stratty]

 

..........I'm dreaming of a .........

[Summer Sun]

Bingo!

 

 

 

[Tim Bland]

 

..........I'm dreaming of a .........

Dear Santa,

Please can the 12z GFS be correct! Snow to the south coast from that! http://www.meteociel.fr/modeles/gfse_cartes.php?ech=222&code=0&mode=0&runpara=1

[Jason M]

Increasing trend today for -NAO to set up, albeit we will still not benefit if it's west based. This has been a repeating scenario in the GEFS.

I really hate these set ups! Lots of water to pass under the bridge before we get to this though....

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=384&mode=0

Edited December 14, 2014 by Jason M

[Mark Bayley]

What do we have here? 

Certainly the strongest warming so far predicted. A definite trend towards renewed disruption of the PV and increasing heights over Greenland towards new year. Not strong, but certainly interesting. A more notable cold spell as we progress into new year? One to keep an eye on i think. Snow again shown for xmas day in north western regions    

[snowking]

Promising week 2 greeny ridging is being complicated by cut off troughing in the Western Atlantic on Gfs and gfsp

Once the models get to grips with this, I expect a smoother transition to the post xmas set up will become clearer.

 

Absolutely the standout feature for me from the last few runs:

 

GFS:

 

 

We should of course be a little cautious and remember over the past few years the over-tendency to evacuate low heights from Greenland in the extended timeframe, however with ensemble support in the most recent suites all eyes should be peeled on this for now.

 

SK

[johnholmes]

Most folk on here already know the tide is turning in favour of cold. Heck, I have posted enough charts to back up this view..coldies at last have something to look forward to apart from pressies, mince pies and Turkey. :-)

 

most folk 'hope' the tide is turning, there is a difference, and to me it is not ye sufficiently strong to punt for it. Currently I would asses it as a 30% probability byt about/soon after Xmas. As data is updated so my % probability may change, up or down.

[Jason M]

GEFS rolling out, going to be a very interesting set this evening methinks! A good set might even bring a visit from the big man this evening :-)

No, I don't mean Santa, I was thinking of Steve Murr!

[IDO]

Promising week 2 greeny ridging is being complicated by cut off troughing in the Western Atlantic on Gfs and gfsp

Once the models get to grips with this, I expect a smoother transition to the post xmas set up will become clearer.

 

I think that boat sailed a while back. The push from the US of heights comes in two packets and they slide between the jet to the south and lower heights to the north:

 

 

 

So although that prevents any WAA in the medium term it does allow heights to migrate to Greenland without sinking. Of course that means in FI we need the Atlantic to ridge to sustain those heights. The GFS op fails:

 

 

 

But with the GFS over progressive nature that is no surprise. The GFS P keeps recycling the heights in Greenland so we get two Northerly's; one before Christmas and one before the New Year:

 

Later one: 

 

I think we can see the mechanics and it is all plausible for Greenland heights for at least a week. It's how much amplification we can get between the phasing of lower heights that is the difference between the GFS Op and P. GEM at D10 is hinting at that type of setup as well: