Model Output Discussion 1200 hrs 15/11/14

[Captain Shortwave]

Good consensus between the ECM and GFS ensembles for heights to become positions somewhere in the northern Europe/Scandinavia region.

GFS

Week one looks near normal until later in the week where temperatures could rise to above or well above average. Week 2 sees the Azores high build over the top of a cut off low and then positions itself similar to now. This potentially could see a rather chilly south easterly develop which could end November on a rather cold note. Not cold enough for snow but cold enough to bring widespread frosts in any clearer spells. We will have to see what type of high sets up. Certainly hoping for a sunny one.

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY SUNDAY NOVEMBER 16TH 2014.

NEXT UPDATE MONDAY NOVEMBER 17TH 08:00

THE CURRENT GENERAL SITUATION. Slack low pressure continues to lie close to Southern England with a trough moving West over England and Wales tonight.

MODELS-2 WEEK HEADLINE  Becoming generally less unsettled with a lot of dry and bright weather with just occasional rain. Temperatures near or a little above average. Perhaps becoming somewhat colder later


THE JET STREAM ENSEMBLE FORECAST The GFS Jet Stream Ensemble forecast shows a very complex and uncertain pattern over our part of the Northern hemisphere over the coming two weeks. In general there will be a tendency for there to be a split flow, one flowing East over the Arctic while a complex Southern arm undulates and disrupts towards the west and SW of the UK. Later in week 2 the flow simplifies to a single flow, blowing strongly across Greenland and Iceland before travelling SE over Scandinavia.

GFS OPERATIONAL The GFS operational this morning indicates High pressure becoming the dominant force affecting the UK weather over the two weeks. This starts the period over Eastern Europe extending a ridge across Scandinavia and the UK later this week before being reinforced by a new centre close to NW Brirain slipping South later. This wards off any major Atlantic attack though some fronts will make inroads from the West at first and the North later with a little rain. Temperatures will remain close to or a little above average to begin with but will probably fall off with time as the incidence of clearer skies permits more in the way of frost and fog at night to develop, slow to clear by day.


THE GFS PARALLEL RUN The GFS Parallel run shows a similar evolution in the short term with a gradual transition towards High pressure based dry if rather cloudy weather for most once this weeks weakening troughs move out of the way later. In Week 2 High pressure forms a new centre close to the UK drifting NE and allowing a colder feed of Easterly winds later which coupled with lower pressure developing brings rain to the South eventually extending to all areas later as the High to the East recedes away.

THE GFS ENSEMBLES.  The GFS Ensembles show slightly less domination from the High over Europe this week with a slack if rather mild SE flow for many and occasional troughs moving North over the west of the UK maintaining ccasional rainfall here while the East stays largely dry. Then a more concerted push of rain and attendant Low pressure clears East and allows a new High to form over Northern Britain setting up a large UK based High pressure system for much of the rest of the run with colder and perhaps frosty and foggy conditions developing thereafter.


UKMO. UKMO today shows a slack SE flow later this week strengthening later as Low pressure and fronts approach the UK from the West by next weekend. East is best being the motto this week as weak fronts continue to affect these Western parts at times especially at first and again later while the East sees a lot of dry and cloudy, benign type conditions in temperatures overall close to if not a little above average.

THE FAX CHARTS  The Fax Charts show the current complex Low pressure near Southern britain slowly giving way and filling as a benign ESE flow develops around High pressure to the East. Troughs continue to afflict the West at times even late in the week with occasional rainfall here whereas many Eastern areas become largely dry after tomorrow.

GEM  GEM this morning shows a more simplified pattern reolving around High pressure over Europe and/or over Scandinavia. A SE flow will develop across the UK over the coming days and persist through to the end of the run. With pressure rising substantuially this week a lot of dry if rather cloudy weather is likely before pressure falls again towards the end of the run as Low pressure edges in from the west to bring rain back slowly East late in the period.


NAVGEM NAVGEM shows a very similar pattern with the UK under SE winds with the driest and brightest weather in the East while weak troughs continue to affect the West at times with occasional rain spreading further east towards next weekend.

ECM  ECM this morning shows High pressure taking over control of the UK weather though it might take a while for the full effects to be shown to all areas as weakening troughs through this week continue to buffer the West of the UK at times. Later on High pressure shifts from being to the East to being to the North of the UK with cooler and frosty air developing in situ under clear skies in the North and a freshening NE breeze across the South where cloud and rain from Low pressure over East France and Switzerland could threaten the SE for a time.

THE ECM ENSEMBLES   There is strong support for a shift towards High pressure based weather to develop across the UK around a centre of High pressure which is most favoured to end up centred close to Scandinavia. Weather at the surface will depend on how much cloud is trapped within it's circulation but with a light Easterly drift we have to look towards somewhat cooler conditions with a risk of frost and fog by night in places.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend continues to grow towards rising pressure across the UK with a shift towards drier conditions and though possibly cooler never cold.

MY THOUGHTS   The models have really shifted away from the unsettled and Atlantic dominated wet and windy pattern shown a few days back to show a cross model agreement on High pressure to the East of the UK affecting all areas with time, though changes in the far West will be slow and erratic and hiccups could give a little rain at times to all areas too as the High pressure shuffles around. there also is some support for a new centre develop near Northern Britain with perhpas more in the way of frost and fog for us if that pattern evolves. However, in the short term a benign east or SE flow will maintain average if not slightly above temperatures but with a lot of cloud likely frost and fog by night looks limited in the short term. The one thing of note this morning is that despite a lot of High pressure around the UK and the NE there is little cold air to tap into but the caveat being that with High pressure in the positions shown a slight drift further North of the High pressure could allow something cold to drift South over Europe and advect West towards the UK. This is hinted at by some output but doesn't develop on this occasion but this could become a feature of the output over coming days if the High pressure support continues to grow between the models. So in the short term some relief from the wet pattern of stalled Low pressure to something not exciting but different in weather terms to look forward to with dry and rather cloudy weather likely to form a large part of many forecasts later this week in temperatures close to or a little above average before falling off somewhat later. At least the water table should start to fall slowly with the impact of less new rainfall becoming significantly welcome.

[mushymanrob]

Alot of talk of easterlies and sliders, not sure why the excitement at that as things stand, a glance at any of the upper air profiles on any current run shows that its not particually cold.

however many great cold spells of the past came after a benign anticyclonic spell and as long as theres high close by then a cold evolution might happen in the future.

but for now the anomaly charts suggest some sort of easterly high ridging north, atlantic low stalled to our west  is the likely general pattern for days 6 - 10.

 

 

it appears the ecm anomaly is off on one, it has no support from anywhere else that i can see. and although statistically the ecm is the best performing model, it is prone to some pretty dramatic wild changes. it isnt always right, even after a spell of consistency, exactly like the gfs or ukmo.

so on the face of it this morning, its looking like we might slowly dry out (that must suit everyone but ducks!) or at least become less wet after midweek as a rather gloomy spell (as overnight temps dont look frosty im guessing there is likely to be alot of cloud = gloomy) as the euro-high becomes dominant. theres a possibility of a mild southerly depicted on some runs recently, and no cold evolution yet although others have suggested a possible path to it.


 

Edited November 16, 2014 by Polar Maritime
To remove off topic reverences.

[Paul]

I know we cover this quite regularly but for new people, and those who have maybe forgotten just wanted to quickly remind everyone the difference between this thread and the model ramps/moans and banter thread. 

 

In short, this thread is for more reasoned discussion of the models, that doesn't mean there can be no emotion or excitement etc, but as people come to this thread to read model discussion it's things like these which need to be posted into the other thread:

 

"OMG this run is great, time to dust off the sledge"

 

"This run is rubbish"

 

"All the runs show cold next week, I can't wait for it to snow"

 

"Ignore the models, I bet it's going to get cold anyway"

 

"I want it to be hot/cold/wet/dry/snowy, when will the models show that?"

 

"The models have all shown cold in 10 days time for 3 days now, but now they're not [insert generic moan/groan here!]"

 

So please take a moment to think about where the best place is to make your post, and if your post isn't model related in the slightest don't forget there are dozens of other active threads to use across the forum as well

 

The model ramps/moans/banter thread is here:

https://forum.netweather.tv/topic/81281-model-banter-moans-and-ramps-autumnwinter-2014/

[johnholmes]

For what is may be worth I have just written this regarding the 500mb anomaly charts. Below is the link to both outputs, someone may wish to see if that from NAEFS is similar?

 

Sun 14nov

Ec-gfs

Well both show more ridgy over uk today than troughy!. Ec especially so. When fairly marked changes occur I never like to jump in with this until at least 2 preferably 3 days consistency between each of the models. Currently nooa shows not much inclination to join this idea, not yet seen its idea last evening so will now pull their charts out.

 

Noaa

6-10 and the far west look about the same as does the n Canadian trough into the atlantic towards the eastern atlantic, however this is being type AFTER seeing the Sunday output from ec-gfs. Looking more closely and the +ve area has shifted further west into the uk from its ridge centred axis towards Svalbard. So in fact there is some continuity within the past 24 hours os so for this idea on all 3. However, to be convinced this is a change in emphasis if not a major change I need to see similar outputs from all 3 over the next 2-3 days.

8-14 and it continues with most aspects troughs/ridges, -/+ve about as its last issue and does seem to support, on closer inspection, the ridge idea from n Europe/Russia west towards greenland

 

links

ec-gfs

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

noaa

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

And before someone jumps in and says noaa have no forecast staff to amend, the pattern shown by noaa has been along similar lines back to Friday and Thursday so there is NO weekend effect. Not that it exists in fact anyway.

 

I would add IF the anomaly charts turn out to be correct or close to correct then the surface high would be somewhere N, ? NW rather than NE of the UK I would think. Why? Because within the 3 dimensional meteorology that governs how the atmosphere behaves, surface centres tend (not always) but often, tend to develop under the axis of the upper ridge.

As to what the actual surface will be, cold, less mild, cloudy, bright etc is not the use of 500mb charts on their own exspecially 6-10 days out to give that detail. Again IF they turn out to be correct then looking at the synoptic models that most closely mirror the 500mb charts will probably be the best guide.

Edited November 16, 2014 by johnholmes
Just edited a repeated line. To save you doing it John ;-)

[bluearmy]

the ECM ens are again happy to send low anomalys into europe to our south beyond next weekend. this means there is an average chance of advecting some low uppers from the east into the mix of any blocking. Thereafter, we have signs on both gefs and extended ECM ens that there is a decent chance of heights rises Iceland/Greenland (not Northern Greenland). without having spreads available on extended ECM, it's tricky to work out any direction of travel but I would end this post by saying that the ens no longer preclude winter arriving by months end.

[Cloud 10]

An unusually precise ECM day 10 ensemble mean this morning with the high centered just NE of the UK feeding in an increasingly cool continental flow.

 

I wonder what those 00z dutch ensembles look like?

 

 

Plenty of activity on Moscow ensemble watch as well.

 

[skadi]

An unusually precise ECM day 10 ensemble mean this morning with the high centered just NE of the UK feeding in an increasingly cool continental flow.

 

I wonder what those 00z dutch ensembles look like?

 

EDM1-240.GIF

 

Plenty of activity on Moscow ensemble watch as well.

 

MT8_Moskau_ens (1).png

 As you can see, there's an increasing amount of members going for colder weather.

Yesterday evening:

 

Compared to the one this morning:

[blizzard81]

the ECM ens are again happy to send low anomalys into europe to our south beyond next weekend. this means there is an average chance of advecting some low uppers from the east into the mix of any blocking. Thereafter, we have signs on both gefs and extended ECM ens that there is a decent chance of heights rises Iceland/Greenland (not Northern Greenland). without having spreads available on extended ECM, it's tricky to work out any direction of travel but I would end this post by saying that the ens no longer preclude winter arriving by months end.

Hi BA, am I correct in saying that it was the ECM that teased us with the promise of lower heights into Europe last winter, only for it never to come to fruition ?

[Nick F]

A very strong westerly jet stream emerging out of NE Canada/New Foundland by day 10 on 06 GFS op, which tends to flatten out any attempts of a ridge over NE Atlantic/N Europe as it pushes east.

 

Interestingly, the 00z GFS Parallel had a similarly strong jet emerging oout of NE Canada around day 10, but with the Euro block/ridge north further west over the UK, the jet is bifuricated well away from the UK.

 

Difficult to get one's head round where the block will position and how this will displace the upper westerlies energy coming off the North Altantic. Block too far east or southeast and UK at the mercy of the Atlantic energy, or block just north and northeast and the jet goes up or under or both away from the UK. NWP never great at handling blocks IMO, so lots of rollercoasting to come!

Edited November 16, 2014 by Nick F

[bluearmy]

Hi BA, am I correct in saying that it was the ECM that teased us with the promise of lower heights into Europe last winter, only for it never to come to fruition ?

Dont recall but the difference here is blocking in our vicinity which we didn't see last winter - modelled or actual! The point I'm making is low heights to our south raise the chances of western advection of any cold that drops into the block over to our east. At the moment, there is no deep cold in any blocking although late November under a continental flow will feel decidedly chilly.

I suspect there are many clusters at the moment in week 2 and we need to wait a few days for the primary one to cone to the fore.

[Nouska]

At first glance, the model output may not look as good as last night but a look at the De Bilt temps shows a strengthening signal for colder options. I've used max temps rather than minimums as we know nights will be cold under high pressure - the days can be variable.

 

12Z    

 

00Z   

 

 

[blizzard81]

Dont recall but the difference here is blocking in our vicinity which we didn't see last winter - modelled or actual! The point I'm making is low heights to our south raise the chances of western advection of any cold that drops into the block over to our east. At the moment, there is no deep cold in any blocking although late November under a continental flow will feel decidedly chilly.

I suspect there are many clusters at the moment in week 2 and we need to wait a few days for the primary one to cone to the fore.

Thanks BA. Well, after viewing the GFS 06z parallel, I am as confused as the models right now! Hope this jet streak from GFS at day 10 that nick f alludes to is a red herring.

[IDO]

Thanks BA. Well, after viewing the GFS 06z parallel, I am as confused as the models right now! Hope this jet streak from GFS at day 10 that nick f alludes to is a red herring.

 

 

Last week GFS and other models over done the Atlantic, then they went towards a middle ground of a SW to NE jet, yesterday and on the 0zs then went with MLB-HLB. Shannon Entropy in all her splendor. It is apparent the models are struggling with the current setup. Logic says the Atlantic should barrel through with maybe some initial fight from the sceuro high; and if they have overdone the Azores ridging then this will happen. The 06z's show repeated attempts at the Atlantic/Azores ridge to build NE but it succumbs each time to the lower heights to the NW. The timing and the phasing of those lower heights maybe the determining factor but it's a multi faceted jigsaw puzzle so pure guesswork at the moment. The T180 mean of the 06z shows that the suite has flipped on the Azores ridging to mid-latitude:

 

 

I am not a fan of the 06z so a watching brief from me.

[knocker]

I'm not a fan of posting odd charts from one run but a couple from the GFS 06 perfectly illustrates why one shouldn't

 

[bluearmy]

 

not much explanation needed 

 

pretty dry and calm aswell.  just like a seventies november should be !

Edited November 16, 2014 by bluearmy

[heath]

Noticed yesterday evening that an easterly drift had come to my location - and that is pretty close in timing to what ECM first showed on 6 November for 9 or 10 days out.  So kudos to ECM's model for that - remarkable consistency in the uncertain circumstances.

[Duane S.]

Very pertinent post by Nick a bit further back in this thread this morning.

 

There does appear to be a more than just a hint that at around D10 a very strong looking jetstream will be emerging off the NE seaboard heading directly East. The point of resistance will lead to it becoming dissipated and more meridional but exactly how/where/% split etc will likely help shape whether or not we get our first cold spell of the winter at the end of the month.This is going to lead to some 'interesting' charts in the coming days I supect, from one end of the eye candy spectrum to the other. The rollercoaster is just leaving the station!

Edited November 16, 2014 by s4lancia

[fergieweather]

As others rightly highlight, it's simply impossible to be bullish about outcome into trend period (beyond D 10)... albeit a weak signal to resume mobility shows beyond D13, the inconclusive prognosis shown collectively through MOGREPS-15 and EC DECIDER products into next fortnight is well summarised by the UKMO Dep. Chief: "…the dominance of anticyclonic S-SE’ly or neutral-cyclonic S-SW’ly remains undecided, with implications for a possible drier, and colder spell."

[damianslaw]

Very pertinent post by Nick a bit further back in this thread this morning.

 

There does appear to be a more than just a hint that at around D10 a very strong looking jetstream will be emerging off the NE seaboard heading directly East. The point of resistance will lead to it becoming dissipated and more meridional but exactly how/where/% split etc will likely help shape whether or not we get our first cold spell of the winter at the end of the month.This is going to lead to some 'interesting' charts in the coming days I supect, from one end of the eye candy spectrum to the other. The rollercoaster is just leaving the station!

 

Yesterday I mentioned all attention should be on events on the other side of the atlantic as this is key to shaping longer term developments over our neck of the woods. In the short-medium term we have an amplification of the long wave trough across the western atlantic seaboard which will have the knock on effect of propping up heights to our east and allowing them to advect westwards and crucially feedbacking warm air advection to the west of Greenland, but for the chance of a colder evolution setting up thereafter, much depends on the interaction, position and strength of the Jetstream - there are differing scenarios here, we either maintain a split jet flow which would probably result in high pressure sitting overhead or just to the north of the UK and we are then at the mercy of its power, if more energy is transferred into the southern arm of the jet, this would enable heights to retrogress NW resulting in a major cool down of eastern and northeastern Europe, with scandi trough formation, more energy in the northern arm and it all depends on the position, this could result in a long draw easterly, or it could simply result in a collapsed high and a return to westerly airstream, another scenario is that we see a meridional jet streak flow with energy in the northern arm, but if heights are strong enough over and to our NW, forcing the jet to take a more northerly looped path could thereafter result in major scandi trough formation and a cold attack from the NE this would happen if we continue to see a weak PV lobe across western Greenland and continuation in an amplified flow.

 

Lots of options, but many do point to the chances of a colder evolution occurring as higher than average.

[nick sussex]

Rather than the mist clearing this morning the reverse has happened with a fog bank of uncertainty!

 

The output upstream is all over the place, and even at T96hrs we have disagreement with how west the ridge extends, the differences being in terms of phasing or not phasing of some low heights with the troughing over Greenland.

 

So a little mini battle here between the GFS/UKMO against the ECM.

 

We do know that some de-amplification will occur upstream but how quick this happens and whether its a case of just less amplified rather than flat is still open to question, comments from NCEP suggest they are going for a slower de-amplification:

 

WPC MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500 MB PROGS ARE
PRIMARILY DERIVED FROM A BLEND OF 70% 12 UTC ECMWF ENSEMBLE MEAN
AND 30% 18 UTC GFS ENSEMBLE MEAN. THESE REASONABLY CONSISTENT
MEANS OFFER DECENT CONTINUITY COMPARED TO RUN TO RUN VARIABILITY
ISSUES INHERENT TO THE LATEST DETERMINISTIC MODELS AT MID-SMALLER
SCALES. THIS WPC SOLUTION THOUGH SEEMS TO OFFER ABOVE AVERAGE
PREDICTABILITY WITH THE MID-LARGER SCALE FLOW EVOLUTION OVER THE
NEXT WEEK AND LEANS ON THE SLIGHTLY SLOWER SIDE OF THE FULL
ENVELOPE OF SOLUTIONS WITH RESPECT TO LATER WEEK TRANSITION FROM
HIGH AMPLITUDE GIVEN UPSTREAM WATER VAPOR LOOPS AND RECENT PATTERN
HISTORY.

 

I think a sticking point in terms of a quicker and less stressful route for cold lovers here is the output at T144hrs and what happens to that shortwave in the Atlantic which sits between the ridge to the west and higher pressure to the east, we really wanted to see this forced se but we lack the upstream amplification that would help here, the UKMO although most amplified blows this shortwave up and the tilt of this is not condusive to the undercut, however given the volatility of the output we should assume that this will probably change by this evening!

 

Overall a confusing picture, you can make a case for different scenarios from mid latitude block to cold east/ne flow.

 

Show me an undercut at T144hrs and I'd go for the colder scenario, as it is it looks like this route to possible cold might well take the scenic route with quite a few steps along the way!

 

Or maybe not, who knows what tonights outputs might deliver....
 

[MR EXTREMES]

you could not make it up last night everyone was getting rather excited but as a few top posters suggested watch out and although most certainly no alantic onslaught there is some very mild air coming up from africa going to feel balmy but at night if skys clear fog and frost is a feature and if fog sicks around then could be cold.

 

tbh its a stale mate colder air is getting into europe but its not enough just yet across the board theres south easterly and southerly flow but its a big difference from last nights charts and daytime temps will be fairly balmy at time judging on the southerly flow shown on almost all the models. 

Edited November 16, 2014 by Polar Maritime
To remove the term as to avoid confusion..

[Jason M]

Nothing wrong with enjoying the good charts that were on show but as they were all ten days away, nobody would expect them to verify.

Looking through the 06Z ensemble suite, nothing really has changed since last night. There is potential for a pretty cold easterly around the end of the month, but its only potential. I wouldn't also be too quick to assume that we are due 'balmy' weather. Remember that the wind flow doesn't follow the isobars exactly, so what actually looks like a deep draw southerly could be bringing some coolish air off the near continent as we are now into the 2nd half of November.

Edited November 16, 2014 by Polar Maritime
To remove deleted quote.

[Banbury]

you could not make it up last night everyone was ramping and rather excited but as a few top posters suggested watch out and although most certainly no alantic onslaught there is some very mild air coming up from africa going to feel balmy but at night if skys clear fog and frost is a feature and if fog sicks around then could be cold.

 

tbh its a stale mate colder air is getting into europe but its not enough just yet across the board theres south easterly and southerly flow but its a big difference from last nights ramps and daytime temps will be fairly balmy at time judging on the southerly flow shown on almost all the models. 

The charts the 18z threw out were more than realistic with HP being forecast by more than one model and it was eye candy we haven't seen for nearly two winters. I think people on here are sensible enough to know they might be gone in the morning.....and they were BUT the trend is still there for HP to around our area and as we know that could move anywhere in time

Edited November 16, 2014 by Polar Maritime
To remove deleted quote.

[Polar Maritime]

Can we please continue to discuss 'Model Output', There are other threads for Met further outlook.

 

Many Thanks, PM