Model Output Discussion 18th Nov.2013-12z onwards.

[bluearmy]

ECM fi has a little depresion breaking through off the eastern seaboard at T168/T192. if that doeant get through the canadian block then the atlantic ridging will be a day quicker and that has other ramifications. similarly, the end of the run releases a depression from kamkatchka to n of alaska. this removes the impressive n alaskan block from the 00z run. until these bundles of energy are resolved, we have no detail to hang on the developing amplification. they could easily derail it completely.

[tinybill]

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=204

 

evening all f1  is looking very wintry  from  5  DEC  at  the  moment  i dare  say  it  will  change!!!

[tight isobar]

Models getting a hold perhaps (relate, going into DEC...much for opptimise, cold viewers..

[The PIT]

Surprising good agreement in deep fi between GFS and ECM at T240. Interesting but unlikely to happen like that.

[nick sussex]

Good agreement between the ECM and GFS for the NH pattern at T240hrs. That's not something that we can often say! Overall there are still quite a few hurdles to overcome to remove those low heights to the north.

 

If we don't see a delay in these evolutions then D-Day looks to be around the 5/6 December, the whole pattern has to play out and theres not a fast track to get there so for coldies its a case of hoping that this trend doesn't get derailed.

[cooling climate]

ECM and the GFS are not that different really and at this stage as we know

its just about trends at least until we are within t168 or so and thats three or

four days away yet. So yes plenty of time for it to go Pete Tong.

[tight isobar]

Q, the pitt with all regards to yourself. Amp/ jet hpa, and further aligned would,(at least) hold a revert in suggests to NH, euro upsurge different ..thus convert to a differed agree on hp ultimate on both UK and euro,..It's ref" something that needs an eagle eye in! .

[Summer Sun]

Latest from Gibby on the 12z models

 

All models tonight show High pressure still in control of our weather as it centre currently over NW Britain slipping further South and flattening out to allow a milder flow of winds from the North Atlantic to move down across the UK midweek. Then late in the week a cold front crosses all areas from the NW with a spell of rain, weakening as it moves SE across the UK to be followed by colder and breezier weather for the weekend with some wintry showers possible in the North and East and some frosts for all.

 

GFS then shows things turning milder soon into the new week with Westerly winds bringing cloudier skies once more. Through the middle and end of the week conditions deteriorate from the North as High pressure to the South finally dissolves away South. Things turn colder with some wintry showers for a time with some sharp frosts then as a transient ridge crosses West to East. The run ends with cloud and rain extending NE across the UK with milder air returning East over the South and west at least.

 

UKMO shows a very uninspiring chart for weather watchers in general as the large High to the SW is positioned such that a rather cloudy NW flow brings benign conditions with temperatures recovering to average again by Sunday.

 

GEM shows a steady deterioration in conditions next week as Low pressure gradually gains a stranglehold on conditions over the UK, moving down from the North. The end of the run for next Thursday shows strong to gale force WNW winds and heavy and frequent showers with hail, thunder and sleet and snow over Northern hills.

 

NAVGEM shows a mild WSW flow over the UK early next week as High pressure maintains it's position over France bringing mild and moist conditions with a lot of cloud across the UK.

 

ECM tonight shows a dry start to next week with fine and bright weather in the South while the North clouds over with a trough moving SE across the British Isles bringing a little rain which in turn is followed by a dip into much more unsettled weather with rain and strong SW winds sweeping East across Britain followed by sunshine and squally showers, wintry on hills by the second half of next week.

 

The GFS Ensembles show a tale of two halves tonight with Week 1 generally unexciting with High pressure cloudy based weather with average temperatures while Week 2 shows a strong trend now for the weather to turn colder and unsettled with rain at times with snow over the hills as a period of cold zonality looks likely to develop.

 

The Jet Stream shows the flow to the North of the UK with a plunge South of the flow over Britain on the weekend before a return to where we are now. Then later in the run it looks like the flow will trend towards a NW to SE axis across the UK as the weather turns more unsettled and chillier.

 

In Summary the weather still shows only slow changes over the coming week or so as the Azores High pressure remains displaced further NE close to SW Britain delivering an extended spell of dry and rather cloudy weather with a few brighter interludes with patchy frost and fog if these breaks occur overnight. A brief colder interlude is likely at the weekend with a few wintry showers in the North and East before milder weather returns once more. However, next week sees a steady change to more unsettled and windy weather moving down from the North and NW and while some models tend to exaggerate the severity of such changes a trend is well set that by the middle and end of next week a pattern change is most likely to have occurred and whilst it may not be a change to raging cold and blizzards a more unsettled and volatile pattern will offer something other than Anticyclone Gloom to talk about.

 

http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm

[phil nw.]

A pretty quiet and mainly dry setup continues for the next few days with the high never far away.

Looking beyond there does seem a growing trend for the block to be eroded from the north.

 

Both main models look similar tonight with that Alaskan ridge pushing the vortex this way next week.

http://modeles.meteociel.fr/modeles/gfs/runs/2013112512/gfsnh-0-240.png?12

http://www.meteociel.fr/modeles/ecmwf/runs/2013112512/ECH1-240.GIF?25-0

 

A burst of colder cyclonic conditions would develop as the jet moves south- if this was to verify.

A chilly looking day 10 GFS mean

http://modeles.meteociel.fr/modeles/gens/run/gens-0-0-240.png?12

 

The GFS ens graph showing the falling 2mtr temps reflecting the change.

 

Early days yet but promising for a colder than normal outlook.

If we can't achieve Arctic blocking yet then this would be a consolation for cold lovers with more polar air coming south across the country.

[Mucka]

BOM continues the general trend.

 

[Panayiotis]

A bit of a simplistic view of the NH but from the GFS,ECM ,GEM and BOM, the trend at 240hrs is for the PV to be placed to the N/NE (important part its not over Greenland!). This is promising because of two things: It allows heights to build into Greenland and the second point is that colder air is closer to the UK so given that a N/NW/NE/E occurs the mass will be cold! The charts below are outlined for 512dam or deeper.

As others have said the +PNA is giving us a hand as this applies pressure to the PV, which in turn moves it towards Scandi, its something we want to see if we want to salvage something from December....

Edited November 25, 2013 by Panayiotis

[chris55]

With winter fast approaching, these GFS ens are certainly heading in the right direction as e move into the beginning of December.

 

 

,

After our anticyclonic gloom (which aint a bad thing at this time of year IMO, at least its dry) we could be heading for something more interesting.

[East_England_Stormchaser91]

I wouldn't like to bet on what it will be like even in a week or so's time!

Its a bit like trying to Pin the tail on the Donkey...

[Frosty.]

GEFS 12z mean turns into a BEAUTY.......for coldies..a much more amplified upstream pattern which is what the 12z op run showed, a cold and wintry outlook has taken a step closer since yesterday's output, when the mean looks this good it suggests to me that a cold blast of some type is going to happen, nice strong Greenland high building, deepening scandi trough and the arctic gates are blown wide open with wintry weather for all areas through early to mid December. In the meantime, the mean shows friday's cold plunge followed by a chilly saturday after a widespread frost, then a less cold blip before the fun begins. the high is then banished and a possibly sustained wintry spell arrives.

Edited November 25, 2013 by Frosty.

[Ali1977]

I wonder what the Mets take on possibilities of cold are, any hints Ian F?

The daily express has been quiet for a few days so maybe cold really is coming.

[Matty M]

I wonder what the Mets take on possibilities of cold are, any hints Ian F?The daily express has been quiet for a few days so maybe cold really is coming.

Just looked at 10 day ECMWF ensembles and nothing that would alarm the MetO in the offing.

 

We are a long long way from a significant cold outbreak. Just getting some tentative signs at day 10.

[Ian Brown]

Just looked at 10 day ECMWF ensembles and nothing that would alarm the MetO in the offing.

 

We are a long long way from a significant cold outbreak. Just getting some tentative signs at day 10.

 

Yes, the pattern simply looks to fluid to sustain HP between the Atlantic and Greenland to get anything other than transient NWrlies.

[andymusic]

I wonder what the Mets take on possibilities of cold are, any hints Ian F?The daily express has been quiet for a few days so maybe cold really is coming.

 meto's text forecasting up to 24th Dec now say "a mixed bag" - a little wintry - but nothing exceptional for early winter - models we are seeing are hinting at something colder and wintry at the beginning of December - but again nothing concrete - so patience is the word!!!!!!!!!!!

[Frosty.]

The GEM 12z is still bang on track for an increasingly cold and unsettled outlook, expect snow eventually, initially for northern hills and then more widely as the much colder T850 hPa digs south into the uk, i'm quietly confident that there will be wintry fun and games between early and mid dec.

[Frosty.]

Coldies should be happy with how the Ecm 12z ensemble mean is trending towards T+240 hours, really we have seen significantly better charts for a colder outlook than in recent days, looks good to me, as does the gem 12z and gefs 12z mean.

[fergieweather]

 

Just looked at 10 day ECMWF ensembles and nothing that would alarm the MetO in the offing. We are a long long way from a significant cold outbreak. Just getting some tentative signs at day 10.

Yes, last I saw (based on 00z suites) they merely hint at a possible cold 'turn' later in 10-15d trend period but tone of way they worded assessment suggested transient phases as we continue an oscillation in temps average-cold-average (& sometimes above) for forseeable reliable(reliable-ish) range. I agree, nothing too troubling or out-of-kilter with seasonal norms in current output. We'll leave Express to scare the horses.

[damianslaw]

Not surprised to ECM discarding its suggestion from yesterday of heights building east into europe, developments to our NW are not going to favour such an outcome = the key player at the moment appears to be the aluetian/Alaska high - which is projected to intensify and put pressure on the PV over west greenland. The result is likely to be a shift in the main core of the PV away from west greenland and towards siberia/north scandi. The displaced azores high is thus most likely to ridge back west and north towards greenland and the end result is what ECM and GFS are showing i.e. a meridional flow with a NW-SE aligned longwave trough and a more southerly tracking jet.

 

I said yesterday all eyes on the position and strength of the PV over west greenland and how it interacts with the high pressure to its west. An amplified pattern has been desperately trying to establish itself over the last 7-10 days, we may be about to see a more concerted attempt as we enter December. Such developments would promise wintry goods especially for the north, but nothing too extreme it has to be said, as the flow still looks a fluid one.

[Frosty.]

Check out these mouth watering GEFS 12z perturbations, there are quite a lot of them..it's been a GOOD day for cold and wintry trends into next month, hoping this is the beginning of something wonderful.

[Jonathan Lang]

Check out these mouth watering GEFS 12z perturbations, there are quite a lot of them..it's been a GOOD day for cold and wintry trends into next month, hoping this is the beginning of something wonderful.

 

Ah yes! It's the first time I've seen those darker blues on Britain since March! Too bad its still FI. Hopefully I will be watching those charts pull themselves into the present! A cold winter would nicely tick all the boxes for this year's weather in terms of British variety! Especially after the summer we had!

 

Now to contribute something to this thread!

 

The GFS Ensembles for West Yorkshire which is essentially slap bang in the middle of Britain CLEARLY show the trend towards colder conditions!!!

They also show a dumping of precipitation, just as the temperature drops!

Edited November 25, 2013 by Jonathan Lang

[Mucka]

Eh up.looks like a proper pub run, not had one of them for a while