Model Output Discussion 1200 hrs 15/11/14

[Tom Jarvis]

Evening All-

 

Its been a decent steady day looking at the models making small pidgeon steps forward in the hunt for cold.

 

Theres something that I meant to add into my posts of late, & that is there is ALWAYS 1 trend of the day, If you take the UKMO, GFS, GFS (p),ECM, GEM & the NAVGEM JMA all the runs of the day you get around 18 runs.

 

The trends noticed in the last 2 days including today.

 

Saturday 22 Nov. - Low digs further south-

What I saw Saturday, mainly in the Euros & JMA was the propensity to angle the atlantic low further & further south throughout the day, so what first looked like an overrunning pattern from the GFS with little in the way of disruption started to display more & more of those displaced charactoristics--

 

For example-

Heres tonights ECM 96 Mean, neg tilted low centred west of Portugal-

http://www.meteociel.fr/modeles/ecmwf/runs/2014112412/EDH1-96.GIF?24-0

 

On Saturday 00z would have been the 156 chart - for todays 12z 96 Mean above.

ECM

http://www.meteociel.fr/modeles/ecmwf/archives/2014112200/ECH1-144.GIF?00

Not enough energy moving SE & not enough depth to the low over Iberia - ECM trying to lift it out quickly.

UKMO

Coming into range at 144 on the 00z was the most southerly & acute solution.

http://www.meteociel.fr/ukmo/archives/2014112200/UN144-21.GIF?22-00

GFS

http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2014112200-0-144.png?0

was poor, with little extension of the jet, Also when Myself & a few others say the GFS cannot separate energy we see here the GFS just trying to move east rather than allowing energy North & south.

 

By 12z

ECM

http://www.meteociel.fr/modeles/ecmwf/archives/2014112212/ECH1-144.GIF?12

Excellent Close low over Iberia, & a fair neg tilt over the UK

 

UKMO-

The best !  CLOSED LOW OVER IBERIA..

http://www.meteociel.fr/ukmo/archives/2014112212/UN144-21.GIF?22-12

 

GFS

http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2014112212-0-144.png?12

Very poor again, no closed low, minimal energy sent North as a split flow - everything moving EAST.

 

JMA-

http://www.meteociel.fr/modeles/jma/archives/2014112212/JN144-21.GIF?24-12

Pretty good, southerly extension of energy good,, however no closed low....

 

Then 18z GFS

http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2014112218-0-138.png?18

More energy south but the balance was still very orientated towards the North... not a 50/50 split.

 

So Saturday summary was whilst everyone 'thought' that things looked bleak, the UKMO / ECM blend was fast arriving on the correct solution, since then even more energy has move south & recurved back North up which props up the block & strengthens the easterly flow-

 

For reference this is where the final solution roughly sits

http://modeles.meteociel.fr/modeles/gem/runs/2014112412/gemnh-5-120.png?12

& the GFS 12z from Sat-

http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2014112212-5-168.png?12  POOR- wheres the split of the amplified Northern Arm-

 

 

Sunday 23rd November Trend.... The Arctic high & sliding low.

The first model to pick this up was the GEM here

http://modeles.meteociel.fr/modeles/gem/archives/2014112212/gemnh-0-168.png?12 - look over Svalbard see the low spinning East & sending the cold SOUTH on its Northern & western flank & the arctic high 1045 MB....

Look at the same timeframe that day for GFS 12z & ECM 12z

http://www.meteociel.fr/modeles/ecmwf/archives/2014112212/ECH1-168.GIF?12 ECM yes-

http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2014112212-0-168.png?12 GFS fail.

http://www.meteociel.fr/modeles/jma/archives/2014112212/JN168-21.GIF?24-12 JMA yes

 

Now move onto Sunday 144 12z for the same area over Svalbard

http://www.meteociel.fr/modeles/ecmwf/archives/2014112312/ECH1-144.GIF?12 ECM yes

http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2014112312-0-144.png?12 GFS yes halfhearted

http://www.meteociel.fr/modeles/jma/archives/2014112312/JN144-21.GIF?24-12 JMA yes- looks good

http://www.meteociel.fr/ukmo/archives/2014112312/UN144-21.GIF?23-12 UKMO Yes

 

what changed Sunday was the modelling of the slider low & its orientation towards the SW, this is also effected by any forcing exerted on it, the GFS keeps piling lows into it so it slides the cold away SE, where as SOME runs steer it south & SW

( notably the GEM & NAVGEM)

 

So across Sunday, whilst the GFS firmed up on the negative tilted low but still tried to push east overall, so the other models were probably 24 hours ahead of it with the closed low over Iberia nailed & were moving on towards the interaction between this slider low/ arctic high feature & what the amplification of the scandi high looked like.

With 2 trains of thought still unresolved-

 

the TOTAL vertical advection was 1

http://modeles.meteociel.fr/modeles/navgem/archives/2014112400/navgemnh-0-168.png?24-06

Or the partial push through over the North of Scandi was the other

http://www.meteociel.fr/modeles/ecmwf/archives/2014112312/ECH1-168.GIF?12

 

The summary of yesterday was though more & more heights ahead of the low over scandi & an increasingly negative tilt - with still unresolved areas of advection towards the pole. Finally on the 18z the GFS started to catch on.

http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2014112318-0-114.png?18

 

 

Monday 24th Nov trend-

More energy as a SPLIT flow as opposed a sinuous flow due to even better resolution of the forcing over Scandi-

This afternoon has seen ALL models align into a recurvature of the jet NE over spain ( which is symmetrical to the bend SE over Scandi) - this forcing increases the easterlies over the central continent.

 

seen below

http://modeles.meteociel.fr/modeles/gem/archives/2014112400/gemnh-5-156.png?00 GEM see Spain- correct but perhaps not amplified enough

http://www.meteociel.fr/modeles/jma/archives/2014112412/JN156-102.GIF?24-12 JMA yes- lots of energy pushing back up NE

http://modeles.meteociel.fr/modeles/navgem/archives/2014112412/navgemnh-5-144.png?24-17 NAVGEM yes-

http://modeles.meteociel.fr/modeles/gfs/archives/gfsnh-2014112412-5-156.png?12 GFS well, to far east aimed at Italy.

 

Todays clear trend with the recurvature NE of the jet supports lower heights extending Eastwards through Southern Europe,

with the JMA finding a good even balance of energy

http://www.meteociel.fr/modeles/jma/runs/2014112412/JN144-102.GIF?24-12

 

It would seem the southern side is fairly well resolved now, however there will be residual energy in the Northern arm - the JMA finds the PERECT split

http://www.meteociel.fr/modeles/jma/runs/2014112412/JN144-21.GIF?24-12

this is supported by the NAVGEM

http://modeles.meteociel.fr/modeles/navgem/archives/2014112412/navgemnh-0-162.png?24-17

 

ECM & UKMO just slide through.

http://www.meteociel.fr/ukmo/archives/2014112412/UN144-21.GIF?24-12

 

So for today strong trending towards the recurvature of the southern arm that supports the easterly over Europe, whats the trending for Tuesday, can we get better amplification at 144 like the JMA - that has the biggest shot of deep cold coming through Europe or will we see consolidation of the slide through which still supports the easterl over Europe but cuts off the cold feed from the PV lobe over Western Russia.

 

either way its clear that the GFS has taken to the 18z to reach the correction point that the main models had at either 18z the night before or at the very least on the 00z.

expect the 18z GFS to fall into line with all the other models, or at least move to the rest of the model suite with a sharp correction to a more amplified flow of the jet exiting NE through Spain...

 

regards

Steve

Great post Steve. After a few years of model watching I have also been able to see the traits that the models have in these sort of situations. The last few days I have seen people posting charts with the pv surposadly ramping up and getting rid of the block. Which has been in fi for the past two weeks. What I would say to people is don't bother to look at the charts pas fi as thing within t144 can change the outlook dramatically!!!

[SMU]

So blink & you will miss it changes on the GFS at 102 means larger changes at 144-

 

T108 12z JET

 

circled are where it will be wrong

 

 

& now the 18z 102 JET

 

S

 

PS Cheers Tom.

Edited November 24, 2014 by Steve Murr

[damianslaw]

Late November - early December traditionally the most stormy atlantic driven period of the year, and what are the models showing a continuation of a very weak ineffectual atlantic with a Jetstream buckling to our south.

 

Watching the models over recent weeks and the most common theme has been the propensity for them all to continue to prop up heights to the NE and be forced to hold the atlantic back time and time again. The GFS has always been less keen to do this, ECM more bullish. This theme continues this week, a surface high looks like developing over the weekend and with more energy going into the southern arm of the jet rather than the north we could be looking at quite a chilly outlook for the start of December - nothing especially cold, but with an ever cooling continent frost and fog could become very stubborn features. At this time of year you don't necessarily need low uppers and polar air to deliver appreciably below average mean values - a surface high can do the business when combined with clear skies and light winds. Take tomorrow, parts of the midlands could struggle to get up to 5 degrees with lows of 0- -2 degrees producing an average mean of 1.5 degrees, notably cold for late November. Some call such conditions 'faux cold'.. I just call it cold.

Edited November 24, 2014 by damianslaw

[Barry12]

It will be a cold start to December, if the GFS verifies.

 

 

[knocker]

So blink & you will miss it changes on the GFS at 102 means larger changes at 144-

 

T108 12z JET

 

circled are where it will be wrong

 

T10812z.png

 

& now the 18z 102 JET

T10818z.png

 

S

 

PS Cheers Tom.

 

These larger changes do you mean the jet pushed north by the upper ridge extending into the UK?

[shaky]

The Parallel gfs looks a beauty!! Everything pushed west at 162 hours! Cold incoming from the north west and the east!!

[blizzard81]

This is a good link for the actual synoptics of all ECM ensembles upto T120hrs, it used to go upto T168hrs before the ECM powers that be stinged out.

 

http://old.ecmwf.int/samples/d/inspect/catalog/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa%21168%21pop%21od%21enfo%21enplot%212009112700%21%21

 

Many thanks for that Nick, I was a lurker on here for many years and I do indeed remember the good old days when these went out

to T168hrs and I remember your good self posting those charts back then.

[Captain Shortwave]

Both the GFS and parallel show a much weaker and shallower low over Iberia in the mid-range, this is crucial to developments further on regarding an easterly. Simply the GFS shows nothing but a southerly veering back to the west in some form or another. In fact the south turns very mild with highs of 14C on Friday and Saturday and minima just dropping into single figures.

The issue here is previous experience has show the Euro models to over do low heights over Europe, even at the earlier timeframes. Given there isn't much margin for error at the moment with the ECM/UKMO at days 5/6 then this could easily disappear on the morning runs. 

Still an easterly or something else won't probably matter further down the line where the rewards will be much greater and snowier

Edited November 24, 2014 by Captain shortwave

[nick sussex]

Will the shortwave circled red still be there tomorrow and if it is will it eject se'wards further west?

 

 

This shortwave whilst attached to the troughing upstream will keep trying to pull this east, as soon as this separates you'll have a chance for ridging to back further west, its a race against time because you want the ridge to back west and stop the east and ne momentum of the troughing.

Edited November 24, 2014 by nick sussex

[SMU]

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=6&code=0&mode=0&runpara=1&carte=1

 

If you look close the GFS (pub) is the best run yet with nearly full on vertical advection.

 

compare with the NAVGEM 12z

http://modeles.meteociel.fr/modeles/navgem/archives/2014112412/navgemnh-0-156.png?24-17

 

GFS p

http://modeles.meteociel.fr/modeles/gfsp/runs/2014112418/gfsnh-0-174.png?18

 

Close....

[SMU]

These larger changes do you mean the jet pushed north by the upper ridge extending into the UK?

 

 

Yes, however the 18z whilst has corrected with a sharper jet still hasn't quite resolved the rest of the phasing issues at 168 etc-

 

However you can see the 'COL' move west from the 12z to the 18z

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014112418/gfs-6-144.png?18 18z is over central Europe

http://modeles.meteociel.fr/modeles/gfs/archives/gfs-2014112412-6-150.png?12 12z further east

 

18zp FWIW

http://modeles.meteociel.fr/modeles/gfsp/runs/2014112418/gfs-6-144.png?18  MUCH further west.

S

[nick sussex]

After an Autumn of model watching that's been like watching paint dry we finally have some more interesting output.

 

This could go one of several ways as the PV is now armed and dangerous and determined to throw everything at the blocking, looking ahead to tomorrows output if theres to be some major drama you won't have to wait till FI.

 

It's likely to happen within T144hrs with a likely shortwave being the catalyst ejected from the upstream troughing, the odds however still currently favour the ECM/UKMO solutions but because of the GFS P tonight which has done well since it started this does leave that element of doubt.

[Jason M]

I actually quite like the GFS P. Wouldn't grumble too much if this chart occurred!! 

 

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

[ITSY]

haha -14 upppers for the SE. I'll take that from GFSP thank you very much!

 

It just shows the importance of the lobe of HP that could migrate up to scandi. that's stage 1. stage 2 is getting it to the arctic. stage 3 is migrating it back to greenland and then back again (stage 4) to scandi. That evolution is pretty much as good as it gets for Winter synoptics - at least for the bulk of the British Isles. Really worth seeing the ensembles - I wonder how the KMNI ECM ensembles looked this evening

Edited November 24, 2014 by ITSY

[Midlands Ice Age]

GFSP mayhem at the end.

Galeforce easterlies and -14 uppers flooding straight from Moscow.

 

Hold the express!!!!

 

MIA

 

Edit that should read straight from Peking  via  Siberia.

Edited November 24, 2014 by Midlands Ice Age

[lorenzo]

24th of November and we have our first decent pub run screamer of a run.

 

Double hit of WAA to kick December off.. equivalent of steroids for the Arctic High which blooms to 1050mb.

 

Chaos ensues..

 

 

Always fun to see what else is the pub run for

 

Edit : RE JMA verif stats within that link from Ian F is a great loop showing the model bias , good to play through for those who appreciate the visual side of things http://www.wis-jma.go.jp/ddb/errormap/index.html

 

Edited November 24, 2014 by lorenzo

[Polar Maritime]

Yes some lovely charts out in the GFSP run showing a very cold Easterly with widespread snow showers over the UK. Very nice to see..

 

Edited November 24, 2014 by Polar Maritime

[Jason M]

I'll wager that it has support once the GEFS runs out fully. I'd imagine this would be the coldest option possible but the general evolution is credible looking across the output today.

 

 

Edit: Imagine the snow showers with -14C uppers streaming across the very warm North Sea!! All just good fun, but nice to see!

Edited November 24, 2014 by Jason M

[Jason M]

Yep, GEFS out to 192, some good un's already.

 

http://www.meteociel.fr/modeles/gefs_cartes.php?code=4&ech=192&mode=0&carte=0

[SMU]

I'll wager that it has support once the GEFS runs out fully. I'd imagine this would be the coldest option possible but the general evolution is credible looking across the output today.

 

 

Edit: Imagine the snow showers with -14C uppers streaming across the very warm North Sea!! All just good fun, but nice to see!

 

PTB 3,4,9 ,15 & poss 19 is the answer in the ensembles. Not to mention GFSP.

 

all have the Scandi high pressure lobe at 144- the signal trend 'should' increase tomorrow .....

 

S

[Midlands Ice Age]

I'll wager that it has support once the GEFS runs out fully. I'd imagine this would be the coldest option possible but the general evolution is credible looking across the output today.

 

 

Edit: Imagine the snow showers with -14C uppers streaming across the very warm North Sea!! All just good fun, but nice to see!

 

Jason,

I cannot imagine a  colder option than the GFSP in any sceario for us. The other thing is that it looks to have set in for a long time. It is shown for the last 3 days of the run and could go on some while.

 

Ramp over...

 

Sorry it won't happen though!

 

MIA

[Jason M]

Yep, Steve

 

People need to not get hung up on the opp runs though as at days 9 plus they should just be treated as honoury ensemble ptbs. Lets see if we can get some decent charts into the high res section over the next few days.

 

Got to laugh at the old GFS run though. If you ran it forward to April it would still be zonal.

Jason,

I cannot imagine a  colder option than the GFSP in any sceario for us. The other thing is that it looks to have set in for a long time. It is shown for the last 3 days of the run and could go on some while.

 

Ramp over...

 

Sorry it won't happen though!

 

MIA

 

Colder is certainly possible, but not so early in the season. This would be a once in a 100 year chart so early on, so I agree its just for a bit of fun.  

[Nouska]

The 18Z GFS has developed a bit of a reputation on weather communities - not wholly deserved IMO - it has sometimes been the first to pick out runs that verify in the long range.

Mr Holmes is a proponent of comparing like for like runs: so let's do that. Dates and times slightly different but the theme is what matters. 

 

Yesterday PGFS 12Z left and todays on the right.

 

  

 

 

 

Same for the PGFS 18Z runs.

 

  

 

 

Now, I've been following charts a long number of years and to my mind that is quite a signal of continuity - it has been seen before at such a long lead - Dec 2010 and Christmas day/Boxing day of last year are just a couple of examples.

 

Edited to add the trend from the NAEFs - chosen Paris as it indicates if low heights are moving south at that time scale.

 

00Z   12Z 

 

 

Edited November 25, 2014 by Nouska

[lorenzo]

Good point Nouska and it has some good stats to back that performance up.

 

 

 

[dallas]

When does the upgraded GFS become operational please