Model Output Discussion - 1st February Onwards 12z--->

[knocker]

Sorry week 3 is yonks away.

It also goes against most of what I have read on here during the last few days, which is also yonks away.

All models have to be written about, but how about something more useable like the next week, which is also yonks away in reagrds to model accuracy.

 

You appear to be mixing up analogs and 500mb anomalies, that basically are looking for trends, with detailed analysis in the short term. It actually doesn't go against all that's been written on here either. In any case it's not a competition between one or tother.

[kumquat]

A good chart for coldies.

 

18z GFS 192hrs

 

 

The usual reasons why. WAA into Western Greenland. Heights also exploiting that space as the Azores ridges, being coerced by the lower heights shallow trough that is being pushed there *today*. The slightest energy under the block that will go on to extend our winter and provide all of those seeking winter warmth and early suntans a bit of a dog as it ruins winter getaways in the Costa Del Sol and Canaries.

[knocker]

Like Wsi energy showed a huge neasterly and prolonged Feb cold back in Jan...proceed with caution

 

I wasn't intending to proceed anywhere. I merely posted in case anyone was interested, particularly the more detailed ECM. I should no better by now. As for the February cold........................

Edited February 4, 2015 by knocker

[fergieweather]

Jeez - when you put but like that, i think I'm going to become a mildie ................

the 18z continues with an amplified pattern and e Europe is the beneficiary of the repeated cold surges (as well as the ne states). Looks quite a set pattern but would be quite odd this season for weeks and weeks of mobility to become a stagnant trough followed by an endless block?

Well, circa 20% chance of significant high cell retrogression towards the end of next week... the downward trend in mean EPS 850hPa temp and GPH shows very well in 12z EC plumes (e.g. For Reading or Exeter), with some markedly colder members in an ever-widening ENS spread by then... so, can't *yet* discount further colder outbreaks of Pm/Am air into next 10-15D on. It's not the favoured f'cast outcome into medium range, but for now can't be discounted either.

[shaky]

Well, circa 20% chance of significant high cell retrogression towards the end of next week... the downward trend in mean EPS 850hPa temp and GPH shows very well in 12z EC plumes (e.g. For Reading or Exeter), with some markedly colder members in an ever-widening ENS spread by then... so, can't *yet* discount further colder outbreaks of Pm/Am air into next 10-15D on. It's not the favoured f'cast outcome into medium range, but for now can't be discounted either.

fergie any news on potential snow for some places tomorrow? Gfs has a band of snow around east mids/west east anglia? !!

[winterof79]

Well, circa 20% chance of significant high cell retrogression towards the end of next week... the downward trend in mean EPS 850hPa temp and GPH shows very well in 12z EC plumes (e.g. For Reading or Exeter), with some markedly colder members in an ever-widening ENS spread by then... so, can't *yet* discount further colder outbreaks of Pm/Am air into next 10-15D on. It's not the favoured f'cast outcome into medium range, but for now can't be discounted either.

I will raise you your 20%.........

 

ECM looking good today.

[Argyle1980]

Looking good.

I know it's only one run but this could be the start of something special , mabe a split of the vortex and a long drawn polar flow.

Have a good day all

[chris55]

Yep, after those 12z GFS ensembles yesterday we have new trend developing towards the end of next week, retrogression of the high with ridging up towards Greenland!

Certainly looks a possibility and with some very cold air tied up on the Easter side one to watch :0

Edited February 5, 2015 by chris55

[bluearmy]

I will raise you your 20%.........

ECM looking good today.

the ECM op taken from the 20%. Like you say, that could be a bit higher on the 00z suite. Certainly a chance of retrogression given the flow of systems coming off the eastern seaboard and the splitting vortex as some gefs members showed yesterday. even retrogression doesn't guarantee the pattern backing far enough west to deliver notable wintry conditions as far as here but at least it would be more interesting to watch the NWP than the sluggish block.

Chris - don't want to wait until Easter!

Edited February 5, 2015 by bluearmy

[Duane S.]

ECM showing a huge amount of promise this morning.

And as I posted yesterday, GEFS continues to spew out the odd very cold run, both in the mid term and the long.Although in the minority, they are not going away...

[nick sussex]

The ECM looks like its starting another " pot of gold at the end of the rainbow scenario"!

 

More amplified upstream at T168hrs than the GFS, its set up though would still need some changes as the high is aligned more nw/se and too close, I think it would need a shortwave to head south at T264hrs.

 

Putting the latest ECM tease aside good agreement for high pressure to head east so likely to turn colder once again as the flow goes round to the se.

 

I'd urge people to not get too excited about the ECM , even NCEP think its been overamplifying the upstream patterns and has had generally a poor winter.

 

We need to see backing and that amplified troughing shown within T144hrs.

 

Going by the expected upstream pattern high pressure is likely to pull nw, the issue is how much amplification occurs at that point.

 

This is the difference between the ECM and GFS, if you look at the NCEP update its quite positive for downstream:

 

 IN GENERAL, A DEAMPLIFICATION
OF THE NORTHERN STREAM IS INDICATED THROUGH MID-PERIOD, WITH A
COMMENSURATE PROGRESSION OF THE MODERATE-AMPLITUDE LONGWAVES IN
THE SOUTHERN STREAM ACROSS THE UNITED STATES. BY THE END OF THE
FORECAST, THE NORTHERN STREAM IS PROGGED TO AMPLIFY ONCE AGAIN,
DELIVERING COLD AIR INTO THE MIDWEST AND NORTHEAST

Edited February 5, 2015 by nick sussex

[KyleHenry]

ECMWF 0 z at 216 hours

http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=0&map=1&type=0&archive=0

Is what most people have been waiting all winter. It's the first time all winter that the -20 C 850 hPa line has moved into Eastern Europe.

No over excitement yet but it's 9 days away.

Good N Hemisphere agreement between UKMO ,GFS and ECM at 144z

[Ali1977]

I have a feeling the next cold spell could evolve quickly, more interesting model watching ahead. Ian Fs future posts giving the METOs ideas may be safer to follow though, rather than cherry picking.

[snowking]

Whilst the pattern shown by the ECM is exactly what I was talking about yesterday with regards to MJO phasing and MLB over the UK not proving to be a particularly bad holding pattern in years gone by, here's an interesting article to counter-balance this point of view:

http://fb.me/1Zak4RxsD

The biggest thing to note at the end - both GFS and GEM out score ECM out to day 10 on a hemispheric scale, and when we are looking at overall longwave patterns that is significant.

SK

[knocker]

If the ECM run doesn't do anything else it does  illustrate the vagaries of the 850mb temp in these fairly mobile HP situations. At T132  plus 8C and T240 Minus 10C. But it is just a passing comment as the next run likely to be quite different

[nick sussex]

Whilst the pattern shown by the ECM is exactly what I was talking about yesterday with regards to MJO phasing and MLB over the UK not proving to be a particularly bad holding pattern in years gone by, here's an interesting article to counter-balance this point of view:

http://fb.me/1Zak4RxsD

The biggest thing to note at the end - both GFS and GEM out score ECM out to day 10 on a hemispheric scale, and when we are looking at overall longwave patterns that is significant.

SK

Great article thanks SK.

 

The other day NCEP also criticized it for being overamplified especially in relation to this winter and ne storm developments. Is it a problem do you think with its 4D data assimilation.

 

http://www.met.reading.ac.uk/~ross/Documents/BkErrProp.html

 

It's quite complicated but am I right in thinking the ECM is different from other NWP in that it takes the observation and projects that forward to the initialization start so for example the ECM gather balloon data at say 10:30 am, this is not simply inputted but varied so that its tweeked forward to cover a change from 10.30 am to Midday, this then is what goes into the operational run.

 

Does that make sense?

 

The reason that this winter may be worse for the ECM is that many of those upstream storms have been quite complicated with northern and southern streaming phasing/interactions/timing, perhaps because of the background chaos its 4D data is overly complicating the issue.

Edited February 5, 2015 by nick sussex

[Weather-history]

There are a couple of outrageous ensemble runs on GFS 0z

http://www.meteociel.fr/modeles/gefs_cartes.php?code=20&ech=228&mode=1&carte=0

http://www.meteociel.fr/modeles/gefs_cartes.php?code=10&ech=348&mode=1&carte=0

[TEITS]

Well as Nick has done an excellent summary (as per usual) on this mornings outputs I shall refrain from adding anything.

 

Instead I am going to focus on the GEFS ensembles following a post last night on the E Anglia/SE regional thread. Somebody posted that they were giving up on this winter and shall return in November. I replied to this by saying that even in mid Feb we can see -15C upper temps. Hey presto an ensemble member shows -15C.

 

http://max.nwstatic.co.uk/ensimages/ens.20150205/00/t850Aberdeenshire.png

 

So the point I am making is we have plenty of winter left. Whilst day time temps might be higher at this time of year with upper temps below -10C this does not rule out heavy snowfalls, ice days.

 

At least with this mornings output we have something to keep an eye on rather than a slug of a HP sitting across the UK.

[joggs]

I wont be taking too much notice of the ecm atm until when or if mo updates show similar.

[nick sussex]

Well as Nick has done an excellent summary (as per usual) on this mornings outputs I shall refrain from adding anything.

 

Instead I am going to focus on the GEFS ensembles following a post last night on the E Anglia/SE regional thread. Somebody posted that they were giving up on this winter and shall return in November. I replied to this by saying that even in mid Feb we can see -15C upper temps. Hey presto an ensemble member shows -15C.

 

http://max.nwstatic.co.uk/ensimages/ens.20150205/00/t850Aberdeenshire.png

 

So the point I am making is we have plenty of winter left. Whilst day time temps might be higher at this time of year with upper temps below -10C this does not rule out heavy snowfalls, ice days.

 

At least with this mornings output we have something to keep an eye on rather than a slug of a HP sitting across the UK.

Yes the slug looks like it might be undergoing some transformation! I can understand people getting frustrated with recent events but essentially people giving up on winter at this point is like giving up on hot weather in early August.

 

The hottest temperature I've ever recorded down here at just over 40c came right at the end of August a few years back, so its not really a case of the unusual not being possible. Of course the later you get you tend to need higher quality synoptics but I've known many very cold second half of Februaries.

 

Theres been a marked improvement in the NWP over the last two days, originally it was the high slug stuck to the west, now that's moved east so after a less cold interlude its likely to turn somewhat colder with a se flow, now theres a good chance of more upstream amplification so high pressure more centred nw of the UK.

 

The uncertainty today is really down to the extent of the amplification over the eastern USA.

[IDO]

No change this morning from the GEM or GFS or GEFS. HP dominating till D16 and looking like staying around even longer on the GEFS mean:

 

GEM D10:  GFS: 

 

The GEFS mean at D13:  D16: 

 

So for the south dry and average temps: 

 

Background noise showing a very small cluster going cold at one point or other but no clear signal for that yet. Where as the GFS op rarely throws in one of those colder clusters you can count on the ECM op sitting in one of the more amplified and therefore colder clusters. If only horse racing was so predictable I would be a wealthy man. It did the same thing a few days ago and eventually came in line with the GFS and I expect the same this time even if it has support from its ENS. As Snowking points out the ECM has been poor this winter and I have been dissing it for a lot longer than that with respect to it's over amplification after D7. Anyway it has no support from its mean as is expected:

 

 

 

[snowking]

Great article thanks SK.

 

The other day NCEP also criticized it for being overamplified especially in relation to this winter and ne storm developments. Is it a problem do you think with its 4D data assimilation.

 

http://www.met.reading.ac.uk/~ross/Documents/BkErrProp.html

 

It's quite complicated but am I right in thinking the ECM is different from other NWP in that it takes the observation and projects that forward to the initialization start so for example the ECM gather balloon data at say 10:30 am, this is not simply inputted but varied so that its tweeked forward to cover a change from 10.30 am to Midday, this then is what goes into the operational run.

 

Does that make sense?

 

The reason that this winter may be worse for the ECM is that many of those upstream storms have been quite complicated with northern and southern streaming phasing/interactions/timing, perhaps because of the background chaos its 4D data is overly complicating the issue.

It is indeed a very complicated read!

That is my take on it too - I'll try and reply more in depth at the weekend when I can find some time (currently hopping between wifi at stations on the underground!)

The interesting thing I'll need to look in to is when the 4d-var method was implemented, because up until the December 2012 debacle I would have trusted it as much as Leighton Baines with a penalty...then it went and became all Kevin Mirallas on us.

It's actually more surprising that it's taken this long for meteorological organisations to pick up on the over-amplification that we have all been noting for the previous 2 years or so. And as we enter the next solar minimum over the next 5-8 years, and the likely resultant increase in split jet scenarios that is usually associated with this, you suspect the problem may only get worse yet.

SK

Edited February 5, 2015 by snowking

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS

THE CURRENT GENERAL SITUATION A large anticyclone will move slowly towards NW Britain with a cold and freshening ENE flow across Southern England tomorrow.

MODELS-2 WEEK HEADLINE A lot of benign and quiet weather is expected across the UK with light winds and plenty of cloud but some sunshine or clear spells with some frosts at night especially in the South. Daytime temperatures close to average.

THE GFS JET STREAM ENSEMBLE FORECAST The Jet Stream Ensemble Forecast shows the flow now climbing North of the UK and weakening the European trough as High pressure near the British Isles ensures it stays North of or over Northern parts of the UK for most of the period.

GFS OPERATIONAL The GFS operational today shows High pressure domination throughout the duration of it's run. The centre drifts around, over or close to the UK throughout the run providing a very variable set of weather at the surface impossible to predict. Dry weather is guaranteed with few places seeing any rain or snow. Cloud amounts will be much harder to predict with some clear or sunny spells leading to overnight frosts and fog while daytime temperatures should reach average levels especially over the North but it could be rather chilly in the South at times if a drift of wind from Europe develops.

THE GFS CONTROL The GFS control run offers nothing any different with no real trend away from the UK based High pressure shown from this run either.

THE GFS CLUSTERS The GFS Clusters show an amazing 90% support for High pressure to lie close to SW England or just to the SW of that point in 15 days time. This means Northern areas will see the strongest breezes from the west or NW and the frost risk becomes restricted towards the South. The remaining 10% of support a UK trough with High pressure well out in the Atlantic.

UKMO UKMO this morning shows High pressure close to NW Britain slipping slowly South to Southern ireland by the end of the weekend before moving it slowly East across the UK next week. Quiet and benign conditions look likely for all with a few breaks allowing a little sunshine by day or frost at night while the general theme will revolve around light winds, cloudy skies and temperatures not far from average.

THE FAX CHARTS The Fax Charts are replicated from the raw data showing the UK under slack winds revolving arouns a large and intense High settling near to Ireland by early next week cutting off the cold feed of East winds over the South to begin with.

GEM GEM shows High pressure domination too with the same tricky mix of conditions at the surface revolving around cloud amounts and temperature values overnight dependent on cloud cover. Pressure falls slack for a time later next week as the High declines for a time but returns later to put us back to square 1 in 10 days time.

NAVGEM NAVGEM holds High pressure just to the West for a while before it drifts slowly across the UK and away to the SE declining slowly later next week. Winds will be light and variable throughout. Some sunshine is possible under a generally rather cloudy period with patchy frost and fog patches where skies clear by night.

ECM ECM offers the most interest this morning if its a return to cold weather your looking for as it too shows High pressure drifting across the UK and away to the SE next week but linking then to a build of pressure to the NW and opening the door somewhat to another cold plunge from the North late next week and the weekend.

ECM 10 DAY MEAN The 10 Day Mean this morning indicates that High pressure will most likely lie close to the South of the UK next week and beyond. Conditions will slowly recover to fairly average temperatures and rather cloudy weather overall with patchy rain at times in the North.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend from all models remains focused on anticyclonic weather being dominant over the UK for the foreseeable future.

MY THOUGHTS Not a lot to be said about this morning's output as all models are agreed upon a sustained dry and bright period of weather with a lot of cloud and temperatures not far from the seasonal average though frosts and patchy frosts at night will be possible almost anywhere at anytime. Amounts of cloud will determine whether there is frost or not and this will be the forecasting nightmare for the whole period as the High drifts over from the Eest and away to the SE later next week. The positioning of the High later next week may give rise to a greater chance of more sunshine as winds turn towards the SE and this could draw colder and clearer air into the South and East of England later next week. We also have to touch upon the ECM model this morning which although agrees on a declining High to the SE by the end of next week shows an interesting rise of pressure up to the NW late in it's operational run which could open the door to an arctic surge from the North again by next weekend although this is poorly supported from within it's ensembles at the moment. However and in Summary High pressure is sometimes more difficult to predict than Low pressure as they don't tend to follow any particular rules about movements and this can be poorly handled by models but what can be said this morning is that there will be very little if any rain or indeed snow over the next 10-14 days with a lot of quiet and settled weather with the main focus likely to be how much cloud determines how things will be at the surface in regards to sunshine by day and frost and fog by night.

Issued at 08:30 Thursday February 5th 2015

[Jason M]

Ecm opp is supported within the GEFS. Trouble is that the Ecm 240 is the same outcome as most of the similar GEFS runs.

All of that said, at days 8 to 10 there are going to be lots of changes yet.

Tend to agree with teits post. Late Feb is often the point at which the deepest cold pools of the winter are floating around mid latitudes. From mid Feb onwards the sun ramps up quickly but the two often counterbalance until we reach March. The main issue tends to be in direct sunlight snow will generally melt much more quickly or evaporate if cold enough.

Edited February 5, 2015 by Jason M

[nick sussex]

Heres more about the ECM 4D data assimilation:

 

http://nwmstest.ecmwf.int/products/forecasts/guide/The_four_dimensional_data_assimilation_4D_Var.html

 

Theres also a link there to the Early Delivery System, its quite complicated! My advice put the Espresso machine on, you'll need it!