Model Output Discussion 1200 hrs 15/11/14

[chionomaniac]

are we getting to the stage where all routes seem to lead to something wintry? it seems that even the runs which deliver mobility evolve into a seasonal scenario.

This may be a bit premature but I'm taken at the way many runs which seem to bring back the Atlantic big time, soon amplify (or would do if they went further) again. (Ops and ens)

Now Tony and I have finished the winter forecast, I can start looking at the charts again.We need the Atlantic to come in enough so that any amplification gets in around the back. It is unlikely to be just yet, by my reckoning that scenario starts to evolve around the middle third of December.

 

Does anyone want to suggest what the next scenario following on from these ensembles would be?

 

 

Hmmm.

[blizzard81]

Now Tony and I have finished the winter forecast, I can start looking at the charts again.We need the Atlantic to come in enough so that any amplification gets in around the back. It is unlikely to be just yet, by my reckoning that scenario starts to evolve around the middle third of December.

 

Does anyone want to suggest what the next scenario following on from these ensembles would be?

 

get_orig_img.gif

 

Hmmm.

That would be the heights over north east canada joining up with the scandi heights and the low dropping into central southern Europe - Result = Easterly mid December. Am I correct ?

[Severe Siberian icy blast]

Now Tony and I have finished the winter forecast, I can start looking at the charts again.We need the Atlantic to come in enough so that any amplification gets in around the back. It is unlikely to be just yet, by my reckoning that scenario starts to evolve around the middle third of December.

Does anyone want to suggest what the next scenario following on from these ensembles would be?

get_orig_img.gif

Hmmm.

Chiono I may barking up the wrong tree here , in distribution of low and high pressure terms would be , I would say the Greenland trough pushing South of the uk , the Azores high drifting up towards Greenland , and the Scandi high driving North And west , pushing into the polar regions but linking up with the sister high pressure over Greenland , with the main trough over Southern Europe becming cut off ??? Please tell me how I'm doing there ! Edited November 23, 2014 by Severe Siberian icy blast

[Thundery wintry showers]

For the coming week, a dry sunny start appears likely but a shallow trough will move up from the south around midweek which is likely to result in rather grey and damp weather establishing for most of England and Wales.  In Scotland dry and sunny weather is more likely to persist.  The latest FAX charts show up the trough quite well.

http://www.wetterzentrale.de/pics/brack2.gif

 

There is significant divergence for the first week of December, with the GFS and ECMWF (including the ensembles) suggesting a significant build of pressure from the south-west resulting in high pressure settling close to the British Isles.

https://max.nwstatic.co.uk/gfsimages/gfs.20141123/18/216/h500slp.png

https://max.nwstatic.co.uk/ecmimages/20141123/12/ecm500.240.png

 

...but the longer-range guidance from the NOAA is suggesting low pressure to the west and north-west playing a significant role:

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

 

I get a sense that high pressure may become quite prominent around Scandinavia as we head towards mid-December, either way.  But I don't foresee anything snowy arising before around 10 December given the way the atmospheric circulation patterns are evolving, nor anything particularly warm for the time of year.

[summer blizzard]

Yet another run suggesting a lovely area of high pressure over the UK..

 

 

Parallel is even better..

 

[Nouska]

Right at the end of the PGFS 18Z, a fair representation of the Z500 anomalies presented with the OPI winter forecast.

 

 

 

 

[The Eagle]

No one wants to discuss the 00z runs? I'm not surprised. It is all rather grim right now for coldies. 

[Johnp]

No one wants to discuss the 00z runs? I'm not surprised. It is all rather grim right now for coldies.

That's an odd post, because my eyes have been drawn to the Arctic high coming into view on both the GFS and UKMO this morning.

In fact I'd say they're the most promising runs I'd seen fit several days now.

* typically the GEM has gone belly up though!

[Mucka]

No one wants to discuss the 00z runs? I'm not surprised. It is all rather grim right now for coldies. 

 

The 00z runs show some exciting developments I think?

 

 

Signs the block is finally getting the upper hand with an interesting NH split. That should very likely lead to an Easterly further down the line.

Probably the most promising output for sometime IMO but we wil see what others make of it and who knows if the trend will continue through the day.

 

EDIT:

 

JohnP beat me to it.

Edited November 24, 2014 by Mucka

[Captain Shortwave]

Nice little bit of Arctic ridging going on

UKMO

GFS

GEM

All three show this, but again given a very unfavourable upstream pattern, our wait for cold will continue for now. 

Best run so far is the GFS parallel

More of an easterly chance here which shows up later in the run as the Azores high has more gusto and develops a fresh and cool easterly on it's southern flank.

Still thinking a quiet frosty spell will be the more likely at this present time than true snow bringing cold.

GFS ens show some transient ridging into the south before the later stages bring us back to square one, Atlantic/UK trough and a ridge to our east.

Edited November 24, 2014 by Captain shortwave

[ITSY]

looks like improvements on the GFS Op, P, Control and the ECM op on the 00Z. not bad progress for the start of the week - look at the GEFS suite, a noticeable increase in colder ones on any of the previous days. Lets portray as it is guys, not as we wish it to be!

 

ens for holland

 

http://modeles.meteociel.fr/modeles/gens/runs/2014112400/graphe3_1000_494_76___.gif

Edited November 24, 2014 by ITSY

[Duane S.]

No one wants to discuss the 00z runs? I'm not surprised. It is all rather grim right now for coldies. 

 

??? 00z suite the most encouraging of the year to my eyes. Great viewing compared to recent 00z outputs.

 

As for the the GFS control, an interesting ending... !

 

[Snowman.]

Nice little bit of Arctic ridging going on

UKMO

GFS

GEM

All three show this, but again given a very unfavourable upstream pattern, our wait for cold will continue for now. 

Best run so far is the GFS parallel

More of an easterly chance here which shows up later in the run as the Azores high has more gusto and develops a fresh and cool easterly on it's southern flank.

Still thinking a quiet frosty spell will be the more likely at this present time than true snow bringing cold.

GFS ens show some transient ridging into the south before the later stages bring us back to square one, Atlantic/UK trough and a ridge to our east.

Wouldn't say square one the PV lobe nw is a whole lot weaker

[Nick F]

So, strong signal now from all model guidance for a mid-latitude high pressure belt to build in across northern Europe as the Azores and Russian high link up. This all develops once the increasingly high amplitude trough moving in across western Europe late this week disrupts into a closed upper low over Iberia this Saturday.

 

However, the GFS op quite progressive in pushing in an Atlantic shortwave upper trough and surface low from the NW early next week, whilst the low over SW Europe quickly fills. Whilst ECM keeps high pressure maintained across the UK and upper low over SW Europe shifts east allowing a chilly easterly to develop, GFS P actually more simialr to ECM than its own op.

 

However, we do see the Scandi HP eventually develop on GFS op, as the flow amplifies uptream allowing a ridge to build NE and with help of an arctic high on the op pushing deep cold air down in across NE Europe, which eventually advects SW towards the UK.

 

All in all a good set of runs, with optimism levels surely on a high after some seemed resigned to the idea that a mobile Atlantic low conveyor would take over. Still a long way to go and many obstacles to overcome to get any deep cold our way, but there is increasing chance of a chilly easterly at least.

Edited November 24, 2014 by Nick F

[IDO]

The control and op are total outliers at the end of FI according to the London temp graphs (Control also on uppers and pressure):

 

 

So at the moment one to watch as the hi-res may have spotted something. GEM as expected is back on track with a similar run to the GFS and ECM. All push some WAA towards the Arctic this week but all succumb to the Canadian vortex sending low heights over the MLB near the UK and blocking off anything developing further.

 

D8:   

 

ECM does it's usual tease at D10: 

 

Though that has some merit within the pattern, it is probably overdoing the heights per usual. 

 

The mean GEFS chart for 7th December just suggests the repeating pattern with the three players jockeying for positions leaving the UK in no mans land:

 

 

The Azores and sceuro high look like keeping the Atlantic to our north so although no real cold, at least it will be dry and seasonal. How long this pattern continues for is anybodies guess as an SSW before next year is finely balanced we probably need the trop pattern to change for UK cold in the medium term.

[knocker]

Before we get to the chilly easterly perhaps a chance for pleasant weekend with this lovely SE fetch.. Nick Sussex  could even indulge in country walks.According to the GFS and P.

Charts courtesy weatherbell.com

Edited November 24, 2014 by knocker

[Nick F]

Quite a difference ECM vs GFS in the 8-10 day H500 00z comparison this morning over Europe. But what is encouraging, from a cold/wintry down the line aspect, is the arctic high building - which will help shunt cold air south across NE Europe.

 

 

The cross polar +ve height anomaly was already a feature on the CPC 8-14 day H500 chart issued last night, with two distinct upper vortices over N Canada and Siberia:

 

[bluearmy]

Not many gefs members you wouldn't take for the 8/12

Things beginning to take shape. Possibility of a coldiah snap witiin next two weeks aswell.

The fi ecm continues to get the Asian vortex South of the Siberian high which has morphed into a general Arctic high in the locale. That would provide plenty of ammunition should a - AO appear ............

Edited November 24, 2014 by bluearmy

[ITSY]

Not many gefs members you wouldn't take for the 8/12

Things beginning to take shape. Possibility of a coldiah snap witiin next two weeks aswell.

The fi ecm continues to get the Asian vortex South of the Siberian high which has morphed into a general Arctic high in the locale. That would provide plenty of ammunition should a - AO appear ............

I'm not entirely with you here.i think these runs give cause for optimism, and given the interest in strat changes and the GEM yesterday add to the sense that something may be coming, but it seems a push at this point to suggest that things are shaping up for a cold spell within the next 2 weeks. We need the ECM ens first and more GEFS backing before things start gathering pace. Remember we had a larger amount of cross model support a few weeks for a cold spell about now; we're just at the beginning of stage 1! Still, better there than not.

Maybe just being pedantic and overly cautious. Justifiable optimism for now

Edited November 24, 2014 by ITSY

[knocker]

Quite a difference ECM vs GFS in the 8-10 day H500 00z comparison this morning over Europe. But what is encouraging, from a cold/wintry down the line aspect, is the arctic high building - which will help shunt cold air south across NE Europe.

 

gfsec_00.gif

 

The cross polar +ve height anomaly was already a feature on the CPC 8-14 day H500 chart issued last night, with two distinct upper vortices over N Canada and Siberia:

 

CPC814day_03.gif

 

But I think caution as the GEFS isn't quite as bullish with this.

[johnholmes]

Quite a difference ECM vs GFS in the 8-10 day H500 00z comparison this morning over Europe. But what is encouraging, from a cold/wintry down the line aspect, is the arctic high building - which will help shunt cold air south across NE Europe.

 

gfsec_00.gif

 

The cross polar +ve height anomaly was already a feature on the CPC 8-14 day H500 chart issued last night, with two distinct upper vortices over N Canada and Siberia:

 

CPC814day_03.gif

 

Yes I never have a great deal of faith in the anomaly charts when they do not show consistency with themselves and one another.

The difference between them, ec-gfs this morning is quite large. EC builds the ridge back into the UK from the E/N while GFS builds it in from another source, S/W from the Atlantic, bit like chalk and cheese. NOAA has been consistent with its pattern, shown by Nick in the post above. I tend to accept its charts more than EC-GFS which do seem more changeable shall we say. If NOAA shows its similar pattern this evening then probably the EC-GFS outputs may revert back. Not too much confidence in any suggested change at the moment.

[SLEETY]

certainly worth taking note of fergieweather said about no clear signals yet of what lies ahead,and they rarely look beyond 5-7 days .

[blizzard81]

I quite like the ECM tonight. It should bring some nice seasonal weather with frost and fog - always a good precursor to a cold outbreak. I still think the 120 to 144hr time period has some resolving to do. This applies to all the models as I don't believe any of them will have the south east diving atlantic trough modelled correctly. They will not get to grips with the track of this low until it comes in to the 72 to 96hr range. We can see by the JMA and GEM just how negative this low tilts can have major ramifications thereafter.

Just going on from my post last night and I am very happy with this mornings output with regards to something colder around the corner. Every run I have seen this morning has adjusted the atlantic trough at 96hrs to a much more favourable negative tilt which means the azores high has less influence thereafter and the air is sourced from the continent.

[BlueHedgehog074]

The operational models do show some amusing scenarios for cold conditions this morning.

For the first few days, though, the models are in general agreement for this High Pressure spell to break down from the West or South-West around mid-week onwards as Low Pressure to the West tries to bump up against the block to our East. This of which will usher in spells of rainy/showery weather for places, but with the West likely to see the most unsettled conditions. This will probably just be temporary, however, as the trough slips to the South of the UK along with the Azores ridge extending towards us. But the sinking trough looks as though it will take a vacation over around the Spain or Italy area. Some models such as the 00Z ECMWF and 00Z GFS Paralell have the trough showing quite a negative tilt as it slips South/South-East underneath the block to our East or North-East. As some have mentioned on here in the past, this is often good for seeing undercutting opportunities and to help draw in an Easterly feed. And interestingly, the GFS Parelell and the ECMWF have the blocking to the North-East putting up a strong fight against the Atlantic right to the end of the run. It does however get help from the Azores High as this links up with the block over Scandinavia and builds to the North with low heights to the South/South-East of the UK. A chance of some wintry showers in the form of rain, sleet, hail or possibly hill snow (most especially towards Eastern coasts) as the Easterly feed draws in increasingly colder 850 hPa temperatures towards the 240 hour mark of both the ECMWF and GFS Parelell runs.

(Quick example from ECMWF at 240 hours)

The GEM, though, generally keeps the UK under influence from the Azores High with generally settled conditions, and while the trough to the West does show a bit of a negative tilt to it before it slips to the South/South-East, the UK doesn't quite pull in an authentic Easterly flow. Probably also thanks to the fact the blocking to East gets flattened somewhat by vigorous Atlantic Lows to the North/North-West of the UK.

The non-Parelell GFS is only really one of the beyond-144-hour models that shows the Atlantic breaking through from the West with Westerly winds returning for the UK. But even this doesn't last long as High Pressure amplifies to the West and transfers towards Scandinavia in response to Lows dropping down towards mainland Europe.

While the models do show some varying scenarios, what does seem evident is that some kind of blocking to the East or North-East still seems quite possible and could still prove to be a tough fighter against the Atlantic. This could be particularly true if the Azores High Pressure system steps in and helps deflect Atlantic Lows away from us, or just keep 'em to our North/North-West.

The 00Z ECMWF ensemble mean generally keeps the worst of the cyclonic conditions away to the North-West, but not much confidence at all that a Greenland High will develop sometime soon. (Also backed by what many of the operational models show this morning with, again, High Pressure more likely to the East or North-East of the UK, possibly with us being influenced by the Azores High at times).

(would add some extra charts, but really should be working now).

Edited November 24, 2014 by DiagonalRedLine

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY MONDAY NOVEMBER 24TH 2014.

NEXT UPDATE TUESDAY NOVEMBER 25TH 08:00

THE CURRENT GENERAL SITUATION A ridge of High pressure over the UK currently will become weaker as a warm front moves North over the English Channel tomorrow.

MODELS-2 WEEK HEADLINE Generally uncertain conditions seem likely with the East vs West battle lines drawn. Some rain at times for all but a fair amount of dry and benign conditions too. While not warm it won't be especially cold either.

THE JET STREAM ENSEMBLE FORECAST The GFS Jet Stream Ensemble forecast shows the weak flow around the UK at present persissting until later in the week when the flow strengthens across the UK with the flow moving South late in the period to a point South of the UK.

GFS OPERATIONAL The GFS operational this morning shows High pressure to the East and later NE continuing to dictate the UK weather pattern. Disrupting Low pressure to the West of the UK later this week allows a strengthening Jet flow to ride over the Northern flank of High pressure over Europe around a week from now with a period of windier and wetter weather as a result before new High pressure builds across the UK towards Scandinavia later and brings a return to dry and cold weather briefly to the North and East while the South and West become under the influence of Low pressure moving SE to the SW of the UK with strong and chilly SE winds and rainfall as a result.

THE GFS PARALLEL RUN The GFS Parallel run also keeps High pressure to the East and NE well incontrol of the weather around the UK throughout it's morning run. The South of the UK in particular remains under threat of Low pressure at times either feeding up from the South or down from the NW with some rain at times here. Towards the very end of the run High pressure transfers to mid Atlantic and with an Azores Low pressure then a cold North flow for the UK could be just around the corner from the term of the run.

THE GFS CONTROL The GFS Ensembles take the operational run's route through Week 1 before a High pressure build across the UK based from the Atlantic crosses further NE later to Scandinavia at the same time as deepening Low pressure moves across the Atlantic towards Southern Britain. Colder air having moved West from Europe then is shown to engage with milder Atlantic air near Southern Britain to form an intense Low complex over Southern Britain and Northern France late in the run with gales and heavy rain the result and with moderately cold air close by sleet or snow could result in places

THE GEFS ENSEMBLES The GEFS Ensembles end this morning with the UK lying in a trough stretching from an Atlantic Low South of Greenland and down towards the Meditteranean indicting little overall change from the current pattern.

UKMO UKMO today shows a complex syoptic pattern late next week as High pressure to the East remains resilient and possibly realigns itself further North at the end of the run. Disrupted Low pressure to the West late in the week fails to cross the UK with rain held out to the West before a new ridge of High pressure next weekend keeps things dry if rather cloudy with some fog and frost patches in the South especially should skies clear overnight.

THE FAX CHARTS The Fax Charts continue to show High pressure out to the East holding up the natural West to East progression of troughs and Low pressure across the UK. Instead we lie in nomansland with decaying fronts either to the West or over the UK decaying in situ as winds slowly warm and freshen from a Southerly quarter later in the week.

GEM GEM this morning likes the idea of the disrupted Low pressure system to the West of the UK later this week developing it into a cut off Low to the South at the weekend. At the same time a UK ridge slips South in response to an increased Jet flow crossing the North Atlantic and into Northern Europe gradually strengthening a mild SW flow later with occasional rain spreading progressively South and East across the UK with time early next week.

NAVGEM NAVGEM shows a complex synoptic structure across the UK next weekend between High pressure to the East and SW and Low pressure up to the NW and SE with no one system having overall control. The resultant surface conditions would be variable as a result with all areas at risk of some rain but drier spells too in average temperatures overall.

ECM  ECM this morning also shows a cut off Low feature over Spain at the weekend while the UK in centre ground to a ridge from an European High to another one over the Atlantic. Fairly quiet if rather cloudy conditions are likely as a result with patchy fog an frost at night possible. Then through next week the Spanish Low moves North and High pressure to the West ridges across to Scandinavia strengthening an Easterly flow across the UK. Though chilly no real cold air is available to tap into at this stage so with thick cloud for many and a strong breeze it will feel chilly and uninspiring with rain at times for many especially towards the East and South.

THE ECM ENSEMBLES The Ensemble run shows Low pressure still close to Southern Greenland all the way down to the Meditteranean Sea with High pressure based over Eastern Europe and Scandinavia. The UK lies in nomansland with indeterminate conditions but not especially cold.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend is steadily returning to High pressure remaining the driving force to UK weather over the period with the positioning of such instrumental in determining air source and weather type which is currently variable between the models today.

MY THOUGHTS A day off from the models yesterday has done nothing to alleviate the pattern that we are at currently and may stick with for some time to come. The main focus of attention is still the persistence and strength of the High block over Europe warding off attacks of Low pressure from the West and sending a cut off Low down to Iberia later in the week. This leads the UK in a slack ridge both from the High to the East and a new one out in the Atlantic. It's the movement of this one which could prove interesting as some output take it through Scotland to Scandinavia and sets up an Easterly flow over the UK. With pressure forced towards the South and SW of the UK because of this pattern would normally introduce a real risk of heavy snowfall and very cold weather being that we are now entering December soon. However, with a few exceptions due to the orientation of High pressure over Russia very little deep cold lies over Europe at the moment and as a result just chilly weather with rain is still the more likely option rather than snow. There are some exceptions to this general rule of thumb though and these in themselves have increased in number over the last few days. No one can doubt that the synoptic pattern is fascinating at the moment and it is a mile away from the pattern of last Winter with this early season standoff between East vs West very marked albeit and although meaning nothing to the UK currently in weather terms I believe that as the season deepens it is only a matter of time before things become better orientated to bring the UK at least a shot of cold weather soon. I think there is one word which is going to have to be adhered too though while all this drama unfolds and that is 'patience' but at least we have a whole Winter season in front of us still so with the synoptics as they are I feel we couldn't be better placed.