Model Output Discussion - 31/10/2014 and Beyond

[knocker]

It has to be said that this mornings GEFS isn't as bold as the young pup. Looking at the difference between the 12 and 00 anomalies does show at what was being hinted and that is an increase of heights from the SW/S but that's all it is at the moment with the low pressure to the NW remaining and just the south effected.

 

At T168 the main difference is the removal of the trough to the SW of the UK to be replaced by the SW/NE orientated ridge. Thus at T240 the HP has some influence vis a vis the UK but the Canadian Atlantic trough is still the main player.

 

It continues with the removal of the east Pacific block and has a strong zonal jet between the two Atlantic systems.

 

Charts courtesy WxBell

Edited November 14, 2014 by knocker

[winterof79]

That's a long way out isn't it ? The reality is wet windy and mild I think ! 

It is a very long way out.Worth a mention this year i feel.Model output all the same.Agreed ther is some pain to go through, as there always is, to gain i have found in past winters.

Edited November 14, 2014 by winterof79

[IDO]

An update on the GFS P. At D5 it's verification is the same as the GFS op, so at the moment treat it as another hi-res run (along with the control) in the GEFS suite. Its output this morning is not an outlier as height rises near the UK has had a cluster of 20-25% for many runs. However overwhelming support for the Atlantic train to drive through. D10 mean:

 

 

GEM, notorious for over doing heights was the main lone voice yesterday (not including yesterday's ECM's take it as given D10 bias chart). However GEM has come on board with the current consensus:

 

 

There remains considerable timing issues and it is usually the case the GFS is too progressive with the Atlantic and GEM/ECM too reluctant. ECM this morning has moved a lot closer to the GFS timing and I expect GEM to move in that direction tonight. GEM's mean from last night did not back its op and was similar to GFS:

 

 

So wet and windy is the tagline for the next 2-3 weeks. A relatively slack upper flow from Saturday-Tuesday, so inland (showers coastal regions) a chance to dry out before the next cold front arrives. Then we get the zonal flow with LP systems, warm & cold fronts and generally miserable weather. Deep in FI there remains the signal for heights to build in the Atlantic.

 

GFS tries to split the PV at around D7 but this fails and by D10 that signal has been lost:

 

 

 

Warming is present at 10hPa till about D14 and then it fades. No pattern developing on the trop PV so difficult to be confident at this time how the displacement would effect our sector of the NH. Above my pay grade so I will leave that to the experts.

[gottolovethisweather]

Signs of a change upstream over the east Pacific looking at the models, with the large scale upper pattern that brought the high latitude block formed from wavenumber 1 breaking down and a more active Pacific jet firing up across the Pacific northwest, this ties in with EPO forecast to go from a -ve phase to a +ve one.

 

ftp://ftp.cdc.noaa.gov/Public/gbates/reforecast2/teleconn/4panel.png

 

This has the implication of the cold vortex eventually relaxing its grip over Canada, central and eastern USA. The model operationals and ens seem to gather on the idea of pushing the core of low heights/cold vortex  over E Canada out across NW Atlantic and Greenland, which may seem like bad news, but if blocking over northern Europe holds it could amplify a trough over the mid-Atlantic with WAA helping strengthening blocking to the east further, perhaps creating a block over Scandi.This is one possible outcome of the pattern change coming upstream in next 11-15 days ... not to say it will pan out like that.

 

But wouldn't bank on a prolonged bout of Atlantic lows coming our way.

 

Many Thanks for your analysis Nick, I think I touched on these changes in my post about the forecast NH Jetstream profiles, although I didn't know where any changes might have come from. According to you at least, it IS the pacific region where we might want to set our eyes in the not too distant future.

 

However, you've explained the signal for a potential pattern change much more clearly.

Edited November 14, 2014 by gottolovethisweather

[gottolovethisweather]

That's a long way out isn't it ? The reality is wet windy and mild I think ! 

 

Kim, do you have any input yourself that you could provide us with, I'd like to hear your thoughts. Near-term discussion or FI charts, albeit near on next month are still relevant in this thread as it follows the thread title "Model Output Discussion" 

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY FRIDAY NOVEMBER 14TH 2014.

NEXT UPDATE SATURDAY NOVEMBER 15TH 08:00

THE CURRENT GENERAL SITUATION. A large depression covers the Atlantic ocean with the centre filling slowly and drifting towards SW England over the weekend. An active trough will slowly clear NE to lie over NE Scotland tomorrow.

MODELS-2 WEEK HEADLINE  Remaining largely unsettled with rain at times, heavy in places, especially later in the NW and coupled with spells of strong winds in near to average temperatures for all.

THE JET STREAM ENSEMBLE FORECAST The GFS Jet Stream Ensemble forecast is shown to weaken over the coming days splitting as one arm blows East across the Arctic while the other remains diffuse to the South of the UK. The Southern arm then becomes the dominant force again later next week, crossing the UK before moving further North around our neck of the hemispher to lie North of the UK at the end of the run.

GFS OPERATIONAL The general message from the GFS operational this morning is for mild and changeable weather maintained across the UK after a quieter chillier period early next week as Low pressure becomes slack across the South. A much stronger Westerly flow develops thereafter with gales in the North and West with rain, heavy at times too for all though as pressure is shown to build to the South for a while at the start of Week 2 the South could see drier and mild conditions for a time.

THE GFS PARALLEL RUN The GFS Parallel run is shown to become much more dominat across the UK in Week 2 as after a week of unsettled and sometimes wet and windy weather replaced by dry and fine weather in light winds. A warm High is shown to engulf the UK in Week 2 with cloudy and misty conditions likely at the surface. Then very late in the run more unsettled and colder weather looks poised to come down from the North with rain and wind in tow moving North to South.

THE GFS ENSEMBLES.  The GFS Ensembles are very similar to the operational run in sequence and trend with the run ending in High pressure having built across the UK with some frost and fog patches replacing the wet and windy Atlantic based weather in the preceding days.

UKMO. UKMO today continues to show another Low pressure out to the West through the middle of next week filling slowly again as winds stay largely light and from a mild Southerly quarter. Rain will occur on occasion but with some drier spells too especially over the East where some parts could stay dry with some fog at night.

THE FAX CHARTS  The Fax Charts show a gradually slacker airflow developing across the UK as a parent Low to the West drifts towards the South of the UK and fills by the start of next week. Troughs to the NE persist and showery ones near the coasts of the South will continue to blight the far South in slowly less mild weather with fog in places.

GEM  GEM also shows a sustained period of slacker winds as Low pressure areas to the West fill as they move SE towards the SW of the UK with a light South or SE flow likely with rain and showers more restricted to near an old trough close to the NE at first and the far South throughout. Late in the run the Atlantic ratchets up a few gears with stronger winds and rain spreading steadily East across the UK by Day 10.

NAVGEM NAVGEM shows changeable conditions over the coming week as the High pressure block to the NE collapses later with a shift in distribution of rain and wind moving more towards the NW later as a SW flow develops across the UK in fairly mild conditions.

ECM  ECM this morning has again shifted from it's last run with the unsettled and slack pressure gradient over the UK through much of next week being replaced by a real bullseye of a storm system over the UK by next weekend delivering severe gales and heavy rain for all as a result, all this following the collapse of the High pressure block to the NE by then. This then sets up a strong Westerly flow thereafter with further troughs carrying rain and strong winds quickly East over all areas at times in average temperatures.

THE ECM ENSEMBLES   The Ensembles point to a strong chance of a deep depression lying close to SW Iceland in 10 days time with a strong SW airflow covering the UK in what would produce rain at times for all in relatively mild conditions.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend continues to show variations on a theme of basically mild and changeable weather in a largely Westerly flow with rain at times, the emphasis of which shifts more towards the North and West with time.

MY THOUGHTS   The main message delivered from the models this morning continue to suggest that the UK will see little if any particularly cold conditions over the next few weeks as the basic flow of winds remain from either Southerly or Westerly latitudes. In the short term the High pressure block still dominant to the NE prevent deep Low pressure areas crossing the UK from the West with attendant fronts and rain stalling over the UK and delivering the most unsettled conditions toward the South and West. Later in the period most output suggests the block to the NE collapses and pressure may become higher towards a position South or East of the UK shifting the emphasis of rain towards the North and West but also permitting more mobility across the North Atlantic as a stronger Jet flow is likely to lie across the UK by then powering up deep Low pressure areas to the NW with rain and gales for all at times as a result. The position of any higher pressure to the South of the UK will be indicative of how much of the wind and rain from these Lows affect the South but a more certain fact is that if High pressure does develop there it will be mild for all and once developed can become a real fixture for a sustained period but as for now this is a minority view. My own personal viewpoint is that it will stay relatively mild for the foreseeable future with many ingredients for cold becoming increasingly displaced with time shifting the emphasis of concern towards how much rain will be falling on already saturated ground over the period. I think what we are lacking this season is cool High pressure which can sometimes develop at this time of year introducing early Winter cold to our shores in the shape of frost and fog failing to clear by day rather than cold weather from any other source this early on. However, as things stand apart from the risk of cool fogs this weekend in some parts there is little sign of any significant chill for the UK shown from any source today.

[BLAST FROM THE PAST]

Mmmm. Long way out but nice to see

http://modeles.meteociel.fr/modeles/gfsp/runs/2014111400/gfsnh-0-384.png?0

 

Reminds me of something a few Decembers ago.The vortex completely shifted east

Indeed mate, another one.  I realy think we'll be seeing interest start shooting through the roof soon as imo more and more charts like this will appear as we move forward this month.  It is deep FI but again shows what sort of idea is there.  I am so far away fro the camp that have posted that we'll be westerly well into December.  Not to get carried away I'm not pronouncing a Dec10 here but definitely more wintry than early Autumnal

 

 

BFTP 

Edited November 14, 2014 by BLAST FROM THE PAST

[Polar Maritime]

Can we please discuss what the Models are showing.

Thanks, PM

[Duane S.]

That's a long way out isn't it ? The reality is wet windy and mild I think !

Why do you think that? It would be nice to have a bit of meat to the bone from time to time instead of the same one liners on both this and the Strat thread. You don't plant a seed in the evening and expect a potato in the morning.

Anyway, it may be a long way out but any major change is not going to come in the next 2 weeks, so far FI is where we need to start looking for any developing trends. That omnipresent scandi ridge is probably going seem more of a hindrance than a help right now but I can see it playing a role at the end of the month / start of December, with a large slice of luck. The jet moves south, energy starts to undercut said high slips west, reinforces growing midatlantic high and we see a strong shot of WAA up into the Greenland area. Simple! :-)

[swfc]

pressure to the ene slightly stronger on the 6z and carries on from what SM was saying yesterday.Not to say the atlantic wont win out but interesting none the less

[knocker]

I know the ECM monthlies are considered of little interest by the aficionados so I'll keep the update short.

 

Atlantic

[Newberryone]

The position of any higher pressure to the South of the UK will be indicative of how much of the wind and rain from these Lows affect the South but a more certain fact is that if High pressure does develop there it will be mild for all and once developed can become a real fixture for a sustained period but as for now this is a minority view.

A quote from Gibby above which both the Gfs, GfsP and its ensembles have been toying with on and off over recent days. Seems to be a widely held view here that a displaced/disorganised PV may enhance our chances of introducing something colder down the line. However, I would say one of the knockon effects of this would be a greater chance of height rises from the south becoming more of a player. Not even the slightest hint of PM incursions should the latter stages of the Gfs gain momentum in the coming days.

[fergieweather]

06z NCEP seems to follow same emerging notion of recent MOGREPS-15 EPS (since 12z yesterday), with pressure build to S/SE of UK into end of Nov. Some cautious hope, perhaps, of the cyclonic pattern relaxing at least for S'rn districts.

[Nick F]

Many Thanks for your analysis Nick, I think I touched on these changes in my post about the forecast NH Jetstream profiles.

 

However, you've explained the signal for a potential pattern change much more clearly.

 

Looking at the northern hemisphere H500 charts from GFS and ECM this morning, still very meridional over the next 8 days or so, then the flow beocmes much less amplified over NE Pacific and N America as the block over Alaska and Yukon collapses and the Pacific jet powers up to bring a much more zonal flow across N America with the cold easing towards the east. This tying in with the forecast transition to a +ve EPO, as I mentioned last night.

 

Question is, will this be a temporary relaxtion of the block that was created by Nuri to redevelop later this month or early December, certainly no strong hints from GFS or longer range CFSv2 this morning for this to happen, though with a blocky October and early November, the SAI and OPI pointing to blocking reappearing, perhaps we will just have to sit back and ride out a spell of zonal Altantic low dominated weather before the blocking re-appears.

 

Having said that, even though the core of low height shifting over Greenland turns it zonal downstream over the Atlantic and perhaps the UK too, still uncertainties over how long the block over eastern Europe will hold out. Indeed, it could be further reinforced, if the an Atlantic trough amplifies upstream of the block as per 00z GFS parallel. Though the 00z ECM deter seems to have backed away from this idea to join GFS op and collapses the block by day 10. Still way to go until we see whether or not the block to out E or NE completely goes away.

Edited November 14, 2014 by Nick F

[Blessed Weather]

The trend that is catching my eye at the moment is the drift east of the west Russia block that has been so persistent over the last several weeks. Not only has this block been the cause of the stuck trough just to the west of the UK, but to my eyes it’s also been the reason why, with the PV so disrupted and lobes looking for somewhere to go, they’ve not been falling into a position to benefit the UK.

I nearly posted such back at the start of the week but in the end didn't. The ECM chart I didn’t post for 12 Nov :

 

So the indication from this morning’s ECM and GFS P output that the block may move further east is IMO good news. And although deep FI, the GFS P shows how this may open the door for a PV lobe to finally drop down into a position that brings a blast of artic air into northern Europe.

 

22 Nov block still there 30 Nov block finally starts to move east 

[IDO]

pressure to the ene slightly stronger on the 6z and carries on from what SM was saying yesterday.Not to say the atlantic wont win out but interesting none the less

 

 

Looking at the 06z the upper ridge is showing a continued trend to redirect from it's EuScandi flow of WAA more towards the UK. So I would say that this will be the death knell of the Scandi ridge rather than a resurgence:

 

 

 

That should favor at least some of the UK for maybe less torrid weather, though the Atlantic still driving the weather. This would also mean a quite mild spell from around D10 with little sign of any cold till way out in FI:

 

 

[gottolovethisweather]

Looking at the northern hemisphere H500 charts from GFS and ECM this morning, still very meridional over the next 8 days or so, then the flow beocmes much less amplified over NE Pacific and N America as the block over Alaska and Yukon collapses and the Pacific jet powers up to bring a much more zonal flow across N America with the cold easing towards the east. This tying in with the forecast transition to a +ve EPO, as I mentioned last night.

 

Question is, will this be a temporary relaxtion of the block that was created by Nuri to redevelop later this month or early December, certainly no strong hints from GFS or longer range CFSv2 this morning for this to happen, though with a blocky October and early November, the SAI and OPI pointing to blocking reappearing, perhaps we will just have to sit back and ride out a spell of zonal Altantic low dominated weather before the blocking re-appears.

 

Having said that, even though the core of low height shifting over Greenland turns it zonal downstream over the Atlantic and perhaps the UK too, still uncertainties over how long the block over eastern Europe will hold out. Indeed, it could be further reinforced, if the an Atlantic trough amplifies upstream of the block as per 00z GFS parallel. Though the 00z ECM deter seems to have backed away from this idea to join GFS op and collapses the block by day 10. Still way to go until we see whether or not the block to out E or NE completely goes away.

 

Cheers Nick, it is all these linkages between what happens with any Pacific heights or lows for that matter and how it in turn affects NW Europe which muddy my brainstorming abilities.   Good to know that no set pattern can truly be determined as we head into late November and that D10 hemispherically speaking is well up for grabs. Ultimately nothing initially cold at the surface but a small chance of something drier would suffice for now, given the higher propensity for Frosts and Fog developing. As long as teh Blocky patterns remain and the PV doesn't do a 2013/2014   on us, there is much to be excited about, assuming one does not want to see another Winter season like the last.  

 

I personally believe a pattern change is a heading our way by the final third of November as you also pretty much allude to, along with several other folk in here.

Edited November 14, 2014 by gottolovethisweather

[Nick F]

Cheers Nick, it is all these linkages between what happens with any Pacific heights or lows for that matter and how it in turn affects NW Europe which muddy my brainstorming abilities.   Good to know that no set pattern can truly be determined as we head into late November and that D10 hemispherically speaking is well up for grabs. Ultimately nothing initially cold at the surface but a small chance of something drier would suffice for now, given the higher propensity for Frosts and Fog developing. As long as teh Blocky patterns remain and the PV doesn't do a 2013/2014   on us, there is much to be excited about, assuming one does not want to see another Winter season like the last.  

 

I personally believe a pattern change is a heading our way by the final third of November as you also pretty much allude to, along with several other folk in here.

 

I suppose it's difficult to contemplate how any changes upstreamin 10 days can have an affect later downstream, but when the flow turns much less amplified and more zonal over N America, the models will tend to flatten out the flow downstream over the Atlantic too. But with a block in the equation to our east, how well do the models do at handling the flow over the Atlantic as it hits the block?

 

But, at the end of the day, it seems unlikely the block will work in our favour now to get cold, particularly as the UK will end up on the warm side now it looks like Greenland will be covered in low heights. The best we can hope for is HP over the UK and inversion cold for now. But, still plenty of time this winter for blocking to work more in our favour, plenty of good pointers to blocking re-appearing again in next few months.

Edited November 14, 2014 by Nick F

[phil nw.]

Glancing through the ens outputs this morning and 2 main features still show up to day 10 and they are the Atlantic trough and those Scandinavian heights, although somewhat reduced.

A look at the NAEFs and ECM at t240 hrs do show a similar picture.

 

 

as the Alaskan ridge starts to fail around day 6 the jet flow starts to flatten out and the downstream Canadian trough loses it's sharpness.This starts to spill eastwards into the Atlantic and this injection of cold upper air adds to the Atlantic vigour.

This gear change can be seen if we look at the difference between the t144 and t168hrs on the ECM and onwards as the surge comes through.

http://www.meteociel.fr/modeles/ecmwf/runs/2014111400/ECH1-144.GIF?14-12

http://www.meteociel.fr/modeles/ecmwf/runs/2014111400/ECH1-168.GIF?14-12

 

with the remaining heights to our NE this simply re-enforces the nearby trough angle which continues to drive SE near the UK bringing continuation of the unsettled and rather mild outlook.

 

It seems much of W.Europe and indeed parts of Scandinavia remain rather mild into week 2.

Some 2m temp.ens graphs for various locations show this.

 

 

the result of being on the wrong side of the block, such as it is.

 

It's difficult to see any change up to month end in the 500hPa pattern.

 

The one positive as we look towards the start of Winter though are the +ve height anomalies across the Polar region which indicate the weakened state of the vortex.

At the moment those heights are not strong enough to push the cold air far enough into mid-latitudes on our side of the hemisphere until we see renewed pressure from wave breaking.

Bearing mind it's only mid November then we still have all Winter to look for this.

[Summer Sun]

Deepest FI so don't take it seriously but the PV on the GFS para just clips northern Scotland, although not overly cold at that stage the fact that the PV is still not forming like last year remains a positive

 

[nick sussex]

Still not convinced the models are to be trusted and how far east or ne the Atlantic gets is subject to some uncertainty.

 

You'll see even within T144hrs theres not agreement with that low to the west and after this point comments from NCEP throw another variable into the mix. We do know that there is going to be some flattening out upstream but are we looking at a flat as a pancake scenario or something just less amplified?

 

The ECM dropped its tease last night and replaces it with a mini-tease!

 

Firstly to the NCEP comments, to elaborate the flatter the upstream pattern the more likely that we'll see the PV chunk ejected further east, there will be less nw/se tilt to the jet near the UK, we also have to factor in what high pressure does to the ne.

 

...GUIDANCE/UNCERTAINTY ASSESSMENT...

PREFER AN OVERALL PATTERN SOLUTION ON THE MORE AMPLIFIED SIDE OF
THE FULL ENVELOPE OF MODEL AND ENSEMBLES GIVEN AMPLIFIED UPSTREAM
FLOW OVER THE PACIFIC/HIGH LATITUDES AS PER WATER VAPOR LOOPS.
MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500 MB PROGS HAVE
ACCORDINGLY BEEN PRIMARILY DERIVED FROM A COMPOSITE BLEND OF
REASONABLY COMPATABLE/CLUSTERED GUIDANCE FROM THE 18 UTC GFS/GEFS
MEAN AND 12 UTC ECMWF/ECMWF ENSEMBLE MEAN DAYS 3-6 MON-THU. LEANED
AWAY FROM DETERMINISTIC MODELS AND MORE HEAVILY UPON THE ECMWF
ENSEMBLE MEAN AND TO A LESSER EXTENT THE 18 UTC GEFS MEAN INTO DAY
7 NEXT FRI IN A PERIOD OF INCREASING UNCERTAINTY/FORECAST SPREAD.

 

I don't think we can avoid an assault by the Atlantic, its really the nature of this that still has room to change, for newbies I'd advise looking at the outputs from a NH perspective rather than just Europe, if you're wanting to learn about just how much upstream events effect the UK .

 

So the uncertainty going forward is really the angle of attack into the UK which will be effected by the amplitude upstream aswell as higher pressure near Svalbard.

 

On the face of it just too much energy is spilling east out of Canada to allow the UK to get on the polar side of the jet however theres still a small chance we may see more undercutting near the UK helped by higher pressure to the ne.

 

[johnholmes]

The post by Nick F about what happens when, as looks pretty likely on 500mb anomaly charts, a more westerly flow spreads across N Ameica into the Atlantic. The block to the NE is shown to still be around. The 'normal' occurrence is for the Atlantic flow to be deflected NE over the top of the upper ridge, but it is possible over time for the ridge to be pushed east.

I have no means of knowing what will happen say from early December. However, I would think the most likely way to cold is not going to be from an easterly point but from the N-NW. Just my own feeling for how signals are showing in the 1 month plus areas. The whole set up for winter is fascinating, UK Met, ECMWF models both showing mild rather than cold as the headline with other teleconnections used on web sites suggesting either a more variable winter (still possible on both Met and EC) or a cold bias. No one on here whatever their experience can predict what will happen so I hope we can read each others thoughts and be polite to one another and not let any cold bias make us tetchy with one another.

[carinthian]

Another day and still we hunt for the cold. Yes, I like many other on here have a cold bias. Presently, the models do not hold much hope in the next 10 days and that's the frustrating thing about model watching, the cold  always seems out of reach. I should know better than get frustrated, but I do. Anyway, as others have mentioned on here , signs that a colder period could have a better chance of working out later. A winter like 13/14 again would be unbearable for UK cold lovers.

 C

[legritter]

Its great being a part of the Net Weather forum ,being able to view many different charts and Data and also the input of knowlegable members .Looking back about thirty or so years ago it was a case of having synoptic charts posted to me 3 or 4 times a week from the local Weather centre at a small cost delivered in a standard brown envelope ,when they arrived in the winter they were the first thing i did when getting home even before tea .the other tools were shipping forecast and late night further outlook on radio 4 about midnight 30 ish .what a great array of information we have .forecasts Have improved ,but still the weather his still full of twists and turns .Current charts still point towards mild unsettled and rather seasonal weather for next week or so But December could be totally different ,but what ever the outcome i will personally enjoy this top of the charts Forum ,i will probably drop a few toys out of the Pram [ but i am getting better ]So bring it on   STellas all round ,

[carinthian]

Its great being a part of the Net Weather forum ,being able to view many different charts and Data and also the input of knowlegable members .Looking back about thirty or so years ago it was a case of having synoptic charts posted to me 3 or 4 times a week from the local Weather centre at a small cost delivered in a standard brown envelope ,when they arrived in the winter they were the first thing i did when getting home even before tea .the other tools were shipping forecast and late night further outlook on radio 4 about midnight 30 ish .what a great array of information we have .forecasts Have improved ,but still the weather his still full of twists and turns .Current charts still point towards mild unsettled and rather seasonal weather for next week or so But December could be totally different ,but what ever the outcome i will personally enjoy this top of the charts Forum ,i will probably drop a few toys out of the Pram [ but i am getting better ]So bring it on   STellas all round ,

Nice one legritter. It was those same charts you mentioned that our geography teacher used to put up and display outside the class room every day during the 60s. When class started, he always looked outside the window  and viewed the heavens and gave the class a weather forecast. Great guy, he got me interested in the weather bug and eventually, I ended up drawing up those same synoptic charts !

 C