Model Output Discussion 12z 07/11/2012

[snowking]

Just using this chart purely for conjecture, and not expecting it to verify like this for one minute, but I wonder if this is the sort of pattern the EC 32 Dayer & Meto outlook our suggesting for the months end;

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=384&code=0&mode=0&carte=1

Nice easterly taking shape there. Does go to show the varying differences between GFS FI output though.

I've only got access to the control run of the ECM 32, but that's not a million miles away from what that has shown for the last couple of runs.

Not sure whether the full EPS suite mean may have placed heights differently

SK

[ITSY]

I've only got access to the control run of the ECM 32, but that's not a million miles away from what that has shown for the last couple of runs.

Not sure whether the full EPS suite mean may have placed heights differently

SK

would you mind posting the ECM32 control run?

[snowking]

Unfortunately I am not able to. The companies that provide this data have to pay upwards of €80k for it, and both ECMWF and the licencees therefore restrict any republishing of such data

Sorry about that

SK

Edited November 11, 2012 by snowking

[Robbie Garrett]

I am not sure about end of month as much as I was now. I am really just not sure, I think we might have a December 2009 type snowfall event in the early-mid parts of December, with any cold pool slightly less prolonged.

I do think as we go forward, though the following pattern the MetOffice have summarised

UK Outlook for Sunday 25 Nov 2012 to Sunday 9 Dec 2012:

As is usual, there are uncertainties in the forecast for this period, but there are signs that the changeable conditions will continue through the start of this forecast period. There is also a signal for temperatures to be close to or just below the seasonal average. Into December, although there are no strong indications that any particular weather type is going to dominate, on balance colder, drier conditions than at present are favoured, rather than milder, wetter weather, especially across the southern half of the UK.

Will breakdown as we head towards Christmas, but winter won't really start going till we enter January/February which looks extremely tasty on the CFS 9 monthly.

We are now in a neutral state NAO, and it ain't exactly warm or pleasant out. Looks very likely that next week the BBC temperature haven't firmed up yet and it could go either way, either pretty chilled under a NW/W flow or slightly warmer with the W/SW flow.

Looks likely to return negative, as forecasted.

AO showing some hints of change.

Pattern change date on the models at the moment looks likely to appear on the 15-19th November, for a change during the last week of November. I'd say the models are struggling slightly with firming up on the positioning of the Northern Hemisphere especially in our position. The options are coming, which is what happened in 2010 so caution needs to be exercised in this.... and also if you have already looked at the GFS archive for that year and month, you'd notice that it dropped the idea of snow/cold a few times before correctly firming up on that pattern, even then it never really showed the longevity of such spell that evolved.

The MetOffice have pretty much summed it up for me: As is usual, there are uncertainties in the forecast for this period. A signal for temperatures to be close to or just below the seasonal average. Into December, although there are no strong indications that any particular weather type is going to dominate, on balance colder, drier conditions than at present are favoured.

However I am rather skeptical of their wording, their wording seems to say to me they can see some colder conditions but have no confidence in their system. That's just my opinion!!

[Mark Neal.]

Unfortunately I am not able to. The companies that provide this data have to pay upwards of €80k for it, and both ECMWF and the licencees therefore restrict any republishing of such data

Sorry about that

SK

That is understandable given the price which has to be paid to access this data.. Just a quick question... Given how much has to be paid can we assume this is a trusted model run?

Interesting watching model runs recently after a cooler period of weather recently looks set to become a little bit more milder this coming week, as ever at this stage any colder solutions look at being out in FI, lets hope over coming days ahead we get to see some more interesting pattern changes starting to show up in the models..

[bluearmy]

That is understandable given the price which has to be paid to access this data.. Just a quick question... Given how much has to be paid can we assume this is a trusted model run?

Interesting watching model runs recently after a cooler period of weather recently looks set to become a little bit more milder this coming week, as ever at this stage any colder solutions look at being out in FI, lets hope over coming days ahead we get to see some more interesting pattern changes starting to show up in the models..

The ECM control is the highest resolution model run to 14 days. Doesn't make it right though.

[summer blizzard]

I think that modelling could be a lot worse, the vortex is still been periodically attacked by wave breaking from both the Atlantic and Pacific as the 18z run showed.

Compared to last year this is much better.

[tcc]

Yes in the far reaches of FI (I know) there is a lovely example of a split Vortex:

Which could explain why the AO forecast says it's going to tank negative:

Not sure where this sits with the forecasted Strat temps? All very confusing and will be very difficult to forecast too far ahead!

[Severe Siberian icy blast]

Yes in the far reaches of FI (I know) there is a lovely example of a split Vortex:

Which could explain why the AO forecast says it's going to tank negative:

Not sure where this sits with the forecasted Strat temps? All very confusing and will be very difficult to forecast too far ahead!

The thing is the models have been showing vortex splits in fi for some time now, but each time it's a different type of split, and each time it's in the back end of fi ,so although its nice to see, I think there is no strong signal either way at the min, which is how the meto sees it, maybe there are signals the gfs picks upon , but a false dawn at the min, I think we may well see a very Atlantic driven nov , still time for the change at the end of the month , but maybe it will be the last few days of it into dec.

[bluearmy]

Despite very cold temps, there are stirrings afoot in the strat forecasts which will no doubt cause ed to make some further informative input today. However, the relationship between the strat and trop should have a lag so what we see developing over the next 2 weeks should be affecting us on the surface in December. current modelled splitting of the trop vortex ( caution urged as this remains consistent but still in week 2) should not be a reflection of the current cold strat but given that we still remain in relative infancy re understanding the strat/trop mechanics, I suppose anything is possible!

This is one of those days when you really want to see the ECM op go beyond day 10. Looking scarily like it could be tightening up a decent vortex and would love to know if it would be able to drive those travelling ridges into the arctic thereafter.

[Nick F]

So it's a waiting game to see when the large polar vortex over Greenland and environs will implode. Certainly no time soon, so looks like we are stuck with southwesterlies for a while, even southerlies during the second half of this coming week, as an Atlantic trough disrupts to the SW.

After tomorrow's rain moving through most areas, it looks like much of England & Wales will become dry for the rest of the week and mild too, thanks to the influence of high pressure on the near continent. Always the threat of cloud and rain at times for Scotland and N Ireland.

An Atlantic trough arrives in the west on Friday, which shows signs of disupting over Wern Europe as it encounters the block to the east. So although GFS sugguests it turning unsettled everywhere next weekend from the west and turning cooler, as Pm air is ushered in - I think there is some uncertainty over the trough disruption and hence how far east the unsettled weather will advance.

Edited November 11, 2012 by Nick F

[Gibby]

Good morning. Here is the morning report on the output from GFS, UKMO, GEM and ECM for today Sunday November 11th 2012.

All models show a weakening showery Westerly pr North-westerly flow across the UK today with some early showers in the far West and North. As pressure rises through the day these die away as a weak ridge crosses East. Tomorrow sees a warm front swing NE across the UK followed by a mild and rather cloudy SW airflow for the following couple of days. As winds die out in the South by midweek fog may become problemmatical in the South though as long as it clears the slack winds will make for mild and pleasant afternoons. Further North will see a continuation of the more unsettled weather with rain at times in mild air from the SW. Towards the end of the week a cold front inches it's way slowly across the UK with a band of cloud and occasional rain spreading East with a slight fall in temperatures over Southern Britain as a result.

GFS takes us through the weekend with a trend to more unsettled weather in the North as Low pressure encroaches closer in with more general rain at times. The South sees a new ridge off the Azores High bring in a nother mild SW flow by the start of the new week with some drizzle possible on exposed hills to the SW. Into FI the trend is for Low pressure to gradually take command of the UK weather with showers or longer spells of rain for all in stronger South or SW winds. It will never be very cold though as the UK stays on the milder side of the Lows. Towards the end of the run the weather turns cooler briefly as a NW flow extends across the UK from off the Atlantic before a ridge introduces a return to milder South-westerlies at the end of the run.

The GFS Ensembles show and maintain a fairly typical pattern for this time in Autumn. A very mild few days are shown through this coming week before a gradual decline in uppers return us into near normal temperatures at the surface with rain at times for all after some dry days in the South this week. There is absolutely no sign of anything remotely cold trending in the 850's this morning nationwide.

The Jet Stream currently backs a continuing milder phase as the flow steadily becomes flatter moving NE over the British Isles and over the Northern flank of the European Anticyclone in the week to come.

UKMO for midnight on Saturday shows Low pressure to the NE of Iceland with an associated trough moving gently eastwards over the UK in a mild and moderate Southerly flow. Rain would spread from the East in the day that followed.

GEM shows a slightly more unsettled phase in its latter stages as the potentially calm and misty weather in the South late this week gives way to rather chillier and unsettled conditions as Low pressure drags down some colder North Atlantic air with rain at times in air just about cold enough for snow on the Northern mountains.

ECM too shows a trough crossing East over the weekend period with a spell of dank and drizzly conditions in the South as the front dispels some of the mild, misty conditions of previous days. As we move into the latter stages of the run the Euro High takes control once more with troughs just to the West and a very mild Southerly flow wafting North from Southern Europe.

In Summary the pattern is for a rather mild and slightly changeable period of weather to come through the next few weeks. The Euro High will remain in control keeping Low pressure away to the North and NW with a mild feed from the South or SW for much of the time. A gradual trend to nearer to normal temperatures look likely as we move towards the second week with a trend towards more rainfall for all areas and not just the North with time but in general it looks like a gentle conclusion to a rather chilly Autumn is looking likely if this morning's output is anything to go by with no sign at all of the projected cold spell progged by some at this point in the model output's time frame.

[latitude]

I know its FI but the PV is consistantly being shown in pieces:

[johnholmes]

to AWD in your apology last evening, there is no need to apologise, all any of us are doing is trying to understand what the medium term models, 6-20 days ahead are suggesting.

Indeed your comment about mild air is looking more like happening than it being normal to below at the surface.

Looking at how the NOAA ouput has shifted over the past 48 hours and the other two also moving to show a more south of west orientation along with, again, all 3 showing height rises over the UK, then normal to rather mild may be the main feature.

All of you know I am never very confident when the anomaly charts are not showing the same thing or changing by more than a slight amount each day. Currently we have about the same and all 3 changing, not erratically, but by rather more than a 24 hour movement might suggest.

I am unsure just what the end of November is going to show in the upper air but perhaps the odds are shifting in favour of mild rather than cold in VERY broad terms. Unsettled is perhaps the phrase to use with cold levels only featuring for a small % of the time.

Nope after all I've gone on for in this post uncertain sums me up!

[Cloud 10]

Just using this chart purely for conjecture, and not expecting it to verify like this for one minute, but I wonder if this is the sort of pattern the EC 32 Dayer & Meto outlook our suggesting for the months end;

http://www.meteociel...&mode=0&carte=1

Nice easterly taking shape there. Does go to show the varying differences between GFS FI output though.

If you like easterlies,the BOM is the model of choice this morning!

http://modeles.meteo...nh-0-240.png?00

http://modeles.meteo...nh-1-240.png?00

[bluearmy]

Thanks ian - that reflects the general 'standard autumn' we have seen the models churning out over the past weeks or so. I rather think we may get a bit of a split second week whereby the euro heights edge into the southeast of the uk with a slack continental feed and subsequent cooler temps. Unlike JH I see a trend to strengthen and retrogress those heights to our east and north east last third nov with the danger we sit firmly under a trough of sorts which becomes cooler as time progresses.

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

Edited November 11, 2012 by bluearmy

[snowking]

Despite very cold temps, there are stirrings afoot in the strat forecasts which will no doubt cause ed to make some further informative input today. However, the relationship between the strat and trop should have a lag so what we see developing over the next 2 weeks should be affecting us on the surface in December. current modelled splitting of the trop vortex ( caution urged as this remains consistent but still in week 2) should not be a reflection of the current cold strat but given that we still remain in relative infancy re understanding the strat/trop mechanics, I suppose anything is possible!

This is one of those days when you really want to see the ECM op go beyond day 10. Looking scarily like it could be tightening up a decent vortex and would love to know if it would be able to drive those travelling ridges into the arctic thereafter.

I can't help you out with the op I'm afraid but I've got the main ECMWF control out to +360.

What I would say is that by +240 they are looking very different in their long wave patterns and so I would urge caution here, however by +348 (the last two frames didn't update this morning) which places us at 25th November, its back to cool zonality, with some PM air well in the mix across the UK, but interestingly the vortex still not especially organised, one large segment down through Svalbard and into Scandinavia, and the other out towards the pacific. Two main ridges either side of the USA, and an Azores trending mid Atlantic HP too. Deep depressing heading up the western flank of the ridge between Greenland/Newfoundland too and signs of southward ridging from this HP towards the mid Atlantic HP.

Obviously usual caution is the be exercised, this is every bit as much FI as the GFS at such a range. Not to mention its only one run AND very different synoptically from the deterministic run.

So I guess all this does is really ramp up the uncertainty factor in the longer range NWP output at present

SK

[bluearmy]

SK, the ens mean and spreads didn't really support the concerning parts of the operational too much so I wasn't so bothered after I saw that. Thanks for the insight - we really are being spoiled with what is usually restricted info at the moment.

[IDO]

A mild week coming for most, as usual favouring the south; normal caveats apply as to cloud cover, etc.

From then its all as clear as dishwater:

http://cdn.nwstatic.co.uk/ensimages/ens.20121111/00/t850London.png

The graph shows a variance from 17th November in 850s temps (GFS 0z). Members varying between 10-15c, with no apparent clustering. I would imagine that they cover numerous possibilities, and the panels confirm this:

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=6&ech=384

At the end of FI however over 60% of members have some sort of trough disruption over the US. The 40% that dont have us back in a cool/average zonal setup whilst the amplified majority have us under a trough or HP influence depending on the ampllification upstream.

Anything beyound T168 is of very low confidence but the way November has been going I suspect that continuation of the current zonal pattern maybe the call.

[BLAST FROM THE PAST]

So how close are we now to the block to east, trough just to our west/NW and a mild to very mild flow. Timing builds from mid month [new moon/perigee coincide on 14th hence I said last 12 days to 3rd of Nov for mild set up as pattern/set ups generally take a few days to build and set] but models seem keen to usher in milder set up fairly quickly. Nothing is set in stone as we are still 3-7 days off but if it does develop as models show now that isn't a disaster as it could easily develop into what MetO have suggested for end of month. However, i sense their resolve on that is weakening.

BFTP

Edited November 11, 2012 by BLAST FROM THE PAST

[SMU]

Posted by Steve Murr on 06 November 2012 - 23:00 in Forecasting Model Discussion

evening All-

Yes im here- Always here in fact-...

Its been a frustrating 24/36 hours for many a coldie.

In the interest of honesty I expected the Scandi block to be another 5 / 10 degrees West after the overnight runs - hence the post- expect an overnight change.

whats developed today is that the first Scandi ridge ISNT retrograding back far enough west to halt the westerly flow over the UK, so fair play to John on the assessment around the UK remaining in some form of westerly flow out to day 10- that appears to be correct.

What we see in the 18z which is supported by the ECM 16 day ensembles is at day 7 & 8 a low amplitude high east of Scandi thats just starting to back the pattern up, however its not enough for the UK, however with Scandi blocks they can work their way back retrograding west over 2 / 3 cycles as they wain & rebuild eventually seeing some form of undercutting -

This is what the GFS has done on the 18z, 3 retrogrades with the final one at day 16 sends the cold all the way to the UK-

The trouble we have at the moment is to expect large varience in the outputs - WHY?

* Downward propergation from the stra cooling is now beginning to filter to 30 HPA & that is effecting the zonal Mean- so the modality & mode of the teleconnections are changing sharply-

EG- + PNA to a strong - PNA ridge-

NAO negative to positive...

* Interseasonal model variability increased due to strong phase changes in the teleconnects as mentioned above-

* Quasi stationary Scandi High oscillating South & east then back North & west- this then drives the model accuracy down for the UK as the models will ALWAYS pitch to far south & east with the jet in these flows...

In Summary, I was slightly premature with the scandi assessment, however its there, nowts changed- the models always want to push it away south but as we edge along to reality it will bounce back & rebound towards us-

The thinking would hopefully be west west then MAYBE NW towards greenland- however that process may span 10-18 days..

thanks for the comments- the usual rollercoaster is full steam ahead!

S

Morning All- it feels like its been a bleak few days model watching,- So Ive been just on a break before we head into the peak time-

We are now on the cusp of what I would say is our 16 / 17 week period of where the availabilty of snow falling over the UK becomes significant as opposed to an outside chance.

Whilst things remain on the mild side I feel nothing has changed since 7 days ago-

The scandi block ( also possibily name current the sceuro high) is oscillating around a point, flattening off south east then rebuilding NW- each time though not enough to carve out the cold air we want to tap into to-

we will get a break in the pattern & things will start to happen, so patience is required- in the mean time relax & enjoy whatever weather comes our way.

Lovely & sunny here this morning.

Steve

PS I will take todays BOM at 240 thanks- exactly what may well happen at day 11- 14

http://modeles.meteociel.fr/modeles/bom/runs/2012111100/bomnh-0-240.png?00

Edited November 11, 2012 by Steve Murr

[Frosty.]

The Gfs 00z ens mean finally gets there, but it's in a very unreliable range of over 2 weeks away, eventually we get the azores high ridging northwards and we get the trough far enough to the northeast to tap into genuine polar maritime air (yes it sounds a bit desperate) but for the next few weeks it's a struggle and this week ahead brings a very sluggish pattern with light winds from midweek and probably a lot of misty low cloud, probably the best of the sunshine will be tomorrow but it will also be turning milder, the initial burst of milder air sweeping in tomorrow as wet and windy weather spreads into the north and west, but for most of the week it looks dry and mild apart from the far northwest where unsettled weather clings on, eventually reinforced by a fresh wave of unsettled weather later in the week from the northwest but the south and east becoming very benign in the coming days, a kind of limbo period, the ecm 00z mean builds a stronger ridge from the anticyclone over the near continent at T+96 hours but it's more half hearted from the gfs at that range. Thereafter, the southeast stays dry for longest but turning gradually more unsettled to the north and west, the further outlook is then dominated by low pressure to the northwest but occasionally drier and milder in southern areas as pressure rises to the south, the north and west mild at first but trending back towards near average.

A lovely tribute to the brave fallen by netweather community forums

Edited November 11, 2012 by Frosty039

[EML Network]

The Variance in the ensembles suite is very split as soon as the 15th, and when this happens it screams out "Were not sure where were headed".

I've seen this happen many times before and it tends to lead something quite different to what the models were suggesting a week or a few days previously.

So in my view, were either going to take the path leading to something exciting in terms of cold and snow prospects, or were going to go the complete opposite way, I'm struggling therefore to see a middle ground this morning , which worries me , because looking at the trends, the likely outcome is the later.

But ...it's not a done deal, this morning I feel better about the chances of a colder outbreak at the end of December, than I have since talk of it began, largely due to the quick and large split amongst the various runs

Edited November 11, 2012 by EML Network

[BLAST FROM THE PAST]

Well done Mods...nice to show the respect for our fallen ones.

Now let's hope these models are showing a temporary set up and there'll be no 'fallen' early winter.

Now to view the 06z as just was teaching my sonof 7 on how to observe the 2 minute silence, which he did by not crunching his biscuits but letting them melt in his mouth!!!

Sorry off topic but a bit of light humour in the gloomy model thread

BFTP

[nick sussex]

Not much change in todays output but whats becoming more evident is that whilst the operationals are trying to work out where any troughing sets up this CPC map may well be closer to the money.

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

Broadly speaking high pressure to the east and low pressure anchored more to the west. This could bring some mild conditions in connection with a southerly flow but where does the pattern go after that?

This depends on whether that troughing sinks or a portion splits and edges into Iberia forcing a change in the flow more towards the se, also how much energy continues to run over the top towards Scandinavia.

As yet too early to say here but given the current state of the stratosphere if you're looking for colder weather its more likely to be coming from the east at least initially.