Model Output Discussion 1200 hrs 15/11/14

[fergieweather]

Due to it's bias towards over amplification to our north west, I wouldn't be surprised to see a bit of a climb down on tonight's ECM. Pressure is much lower to our west on 12z GFS & UKMO.

Sorry, but where exactly has this supposed ECMWF bias of over-amplification been cited? UKMO colleagues say no such bias known to them. Moreover, citing NOAA:

"Compared to the other 2 operational models described above (GFS & UKMO-GM), the ECMWF does the best in predicting mid/upper tropospheric heights during the colder part of the year(such as October through April). The ECMWF tends to perform quite well in predicting amplitudes of planetary-scale regimes such as the Pacific/North American teleconnection (PNA). This model can also perform outstandingly during low to high planetary-scale wavenumber transition events, and northern hemispheric-scale regime transition

.Outperforms the other medium-range forecast models during shallow cold air situations."

(NB: The citation re UKMO-GM was written prior to operational introduction of ENDGAME).

[bluearmy]

Ian, it's been noted on here over the past couple years that ECM fi is prone to amplifying towards Greenland which invariably doesn't verify. At the same time, GFS is prone to shoving everything East. Now the evidence for the ECM amplification is a combination of anecdotal plus a couple of instances that some will be able to post. Of course, the guys at Exeter have the evidence which may not agree!

[That ECM]

Sorry, but where exactly has this supposed ECMWF bias of over-amplification been cited? UKMO colleagues say no such bias known to them. Moreover, citing NOAA:

"Compared to the other 2 operational models described above (GFS & UKMO-GM), the ECMWF does the best in predicting mid/upper tropospheric heights during the colder part of the year(such as October through April). The ECMWF tends to perform quite well in predicting amplitudes of planetary-scale regimes such as the Pacific/North American teleconnection (PNA). This model can also perform outstandingly during low to high planetary-scale wavenumber transition events, and northern hemispheric-scale regime transition

.Outperforms the other medium-range forecast models during shallow cold air situations."

(NB: The citation re UKMO-GM was written prior to operational introduction of ENDGAME).

Does it not depend on what T plus charts one is looking at? If I remember correctly, they rarely look past T 120 where Blizzard may have been looking past this time. Just curious.....

[Jason M]

Purely for fun (as taken from an ensemble at plus 300 hours)!!

No worries about 850 cold pools here :-)

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=372&code=10&mode=0&carte=0

http://www.meteociel.fr/modeles/gefs_cartes.php?code=10&ech=384&mode=1&carte=0

Jason

[blizzard81]

Sorry, but where exactly has this supposed ECMWF bias of over-amplification been cited? UKMO colleagues say no such bias known to them. Moreover, citing NOAA:

"Compared to the other 2 operational models described above (GFS & UKMO-GM), the ECMWF does the best in predicting mid/upper tropospheric heights during the colder part of the year(such as October through April). The ECMWF tends to perform quite well in predicting amplitudes of planetary-scale regimes such as the Pacific/North American teleconnection (PNA). This model can also perform outstandingly during low to high planetary-scale wavenumber transition events, and northern hemispheric-scale regime transition

.Outperforms the other medium-range forecast models during shallow cold air situations."

(NB: The citation re UKMO-GM was written prior to operational introduction of ENDGAME).

Hi Ian, just years of seeing over amplification from ECM - Especially in Iceland and southern Greenland area. Many other posters on here have noticed this too. I may sound thick here but what do mean by ENDGAME ? Edited November 16, 2014 by blizzard81

[phil nw.]

nicely illustrated there phil with a sequence showing a similar outcome for the same date. That method is well worth bearing in mind with any model output. It can go wrong but far less often than taking each model output as being correct.

Indeed not an exact science for every occasion but they do normally show the way that the 500hPa pattern is trending,same with the NOAA forecast anomalies.

On those i posted i guess as we countdown from day 10 we see stronger anomalies showing as the spread in the ens members narrow but what is interesting is the movement of the block closer to W.Europe and the diminishing extent of the Atlantic push off the Eastern seaboard.

[Nouska]

Hi Ian, just years of seeing over amplification - Especially in Iceland and southern Greenland area. Many other posters on here have noticed this too. I may sound thick here but what do mean by ENDGAME ?

 

http://www.metoffice.gov.uk/barometer/science/2014-08/ENDGame

[blizzard81]

http://www.metoffice.gov.uk/barometer/science/2014-08/ENDGame

Thank you Nouska

[IDO]

The previous 10 days height bias for ECM for D7 from the 0z's: 

 

 

 

 

[Cloud 10]

http://www.metoffice.gov.uk/barometer/science/2014-08/ENDGame

 

Can't wait for the GungHo!

 

"In a sense ENDGame finishes the work that New Dynamics started, but the story doesn't end here. Research has already started on the next-generation dynamical core (named GungHo) which we expect to replace ENDGame in about 10 years. GungHo will be part of a completely new model that will deliver the step change in scalability required to continue to exploit future generations of computers. This will ensure that, together with our collaborators, we can continue to improve our weather and climate services into the next decade and beyond."

[nick sussex]

Quite a lot of differences upstream and the new problem is the shortwave near the UK at T144hrs, yet another phasing drama. If that shortwave isn't going to head se then we may aswell hope the GFS trend is correct by pulling it further north.

 

Theres still also the differences at T96hrs between the earlier ECM and the GFS/UKMO, the 00hrs had the ridge the furthest west compared to those.

[knocker]

Indeed not an exact science for every occasion but they do normally show the way that the 500hPa pattern is trending,same with the NOAA forecast anomalies.

On those i posted i guess as we countdown from day 10 we see stronger anomalies showing as the spread in the ens members narrow but what is interesting is the movement of the block closer to W.Europe and the diminishing extent of the Atlantic push off the Eastern seaboard.

 

Following on from that then Phil the last three 12z from GEFs. no sig. change in 24 hours/

[SMU]

Afternoon All-

 

We are traversing along nicely along the provisional pathway laid out - which is a continued continental feed this next week oscillating between Chilly Easterly & possible warm southerly-

Im quite content that if we do get the warm feed it could be a real nice weekend coming up- one of those- 'last garden' weekend where you cut the grass & know its not likely to grow much more now this year.

However a word of caution- the ECM have been the most correct & has been giving the undercut energy a little more weighting so that warm air may be sheared away westwards on more of a Easterly / South easterly wind signal.

 

Post this then the probabilities are increasing towards a cold feed from the East, all the while we are getting the warm southerly the heart of Europe is steadily getting colder & come next weekend typical sub 5c surface values will be observed- which is below.

 

As I alluded to over the past few days the main absence of cold into Europe has been the fact that theres been zero energy feeding south out of the pole-

the slider lows or even small pulses of energy cutting through the block do introduce the first pockets of sub-5c air & as these drop into Europe so they expand & also change the flow over the UK from Southerly to Easterly-

 

if your wondering what that looks like then this GFS run illustrates this process perfectly all but being ( for us ) about 200 miles to far east)

 

remember how I kept posting the location of the slider low on the GEM etc-

Heres it highlighted at 96 now

 

 

follow its path from T96 to 276 - it does 1 full orbit of Scandi !!!

http://www.meteociel.fr/modeles/gefs_cartes.php?code=20&ech=6&carte=1&mode=0

 

Lots to resolve- mainly for the GFS as its hopeless at splitting energy- remember I said the ensembles would be on the page from today-

Expect these to drop off now as from the 12z suite!
S

Edited November 16, 2014 by Steve Murr

[nick sussex]

Differences between the ECM/UKMO and GFS over the eastern USA at T120hrs.  Comments from NCEP might help to explain this:

 

IN THE EAST...THE UNCERTAINTY RESULTS FROM THE PROJECTED
CONFLUENCE---OR LACK THEREOF--- OF ARCTIC/POLAR JET STREAMS ALONG
40N-45W EAST OF 90W LONGITUDE.
THIS IS MOST EVIDENT AROUND DAY 5...WHEN THE LAST DEFINITIVE LOBE
OF ARCTIC AIR DESCENDS ACROSS THE GREAT LAKES AND MIGRATES
EASTWARD INTO THE NORTHEAST.

 

The ECM at T168hrs manages to separate the key shortwave away from the mothership! Interesting.....

Edited November 16, 2014 by nick sussex

[SMU]

ECM out to 168 with a good size system ready to dive SE over iceland & good allignment of the deep cold over svalbard ( pointing SW)

Could be an epic run

[shaky]

Oh boy interesting ecm run! ! High pressure much further west earlier in the run aswell!!lets see where it goes from 168 hours! !

[Eugene]

http://www.wetterzentrale.de/pics/Recm1682.gif - Hot Plume of air next weekend on ECM 12Z, I can bet you though it will not feel anything like it looks

[johnholmes]

Does it not depend on what T plus charts one is looking at? If I remember correctly, they rarely look past T 120 where Blizzard may have been looking past this time. Just curious.....

 

where on earth do you get the idea they rarely look beyond 120h from?

That is as far their Fax chart goes but of course they look further out. Where does the 6-15 day and 16-30 day outlook come from then please?

 

It does amuse when someone with inside knowledge posts quotes from within there and others start to question it. Of course there will be instances where EC is wrong but even we can see how far it out performs GFS, even the new version currently on test as far as 500mb heights go. link to this check run by NOAA incidentally

http://www.emc.ncep.noaa.gov/gmb/STATS/STATS.html

 

anecdotal is never a substitue for fact in my view.

[nick sussex]

Not enough amplitude in the upstream troughing, we need this to dig further south at T168hrs.

 

 

We do at least get the separation of the shortwave which is crucial otherwise this will just pull the troughing too far east.

 

 

 

 

[phil nw.]

Following on from that then Phil the last three 12z from GEFs. no sig. change in 24 hours/

There does appear to be a trend towards the Atlantic trough to dig further south and east starting to undercut the block at T192hrs Knocker.

Sign of the jet being split in mid-Atlantic and a bit more energy going south towards Iberia.We can see the low hts appearing there on the T192 hrs chart.

[blizzard81]

Hi Ian, just years of seeing over amplification from ECM - Especially in Iceland and southern Greenland area. Many other posters on here have noticed this too. I may sound thick here but what do mean by ENDGAME ?

I know I keep banging on about this but tonight's ECM 12z is a perfect opportunity to test this out. If you go from 144 to 168, you will see pressure rise suddenly up towards the Iceland/east Greenland area. None of the other 12z runs go with this. Lets see if it verifies over the next few days.

[IDO]

ECM has also moved towards the GFS output this evening and has the ridge of warmer uppers hitting the UK next weekend as well:

 

 

 

 

[snowking]

There does appear to be a trend towards the Atlantic trough to dig further south and east starting to undercut the block at T192hrs Knocker.

Sign of the jet being split in mid-Atlantic and a bit more energy going south towards Iberia.We can see the low hts appearing there on the T192 hrs chart.

 

Indeed, very visible on the 0z ECM EPS mean too even out to day 15:

 

 

Also using the very handy tool you guided towards yesterday, you can see the swing in the EPS over the last 24 hours towards this:

 

12z Yesterday

 

0z Today

 

The suites at this range are far from infallible, but offers the best NWP insight available to us mere mortals.

 

SK

[knocker]

There does appear to be a trend towards the Atlantic trough to dig further south and east starting to undercut the block at T192hrs Knocker.

Sign of the jet being split in mid-Atlantic and a bit more energy going south towards Iberia.We can see the low hts appearing there on the T192 hrs chart.

 

Noted

[nick sussex]

where on earth do you get the idea they rarely look beyond 120h from?

That is as far their Fax chart goes but of course they look further out. Where does the 6-15 day and 16-30 day outlook come from then please?

 

It does amuse when someone with inside knowledge posts quotes from within there and others start to question it. Of course there will be instances where EC is wrong but even we can see how far it out performs GFS, even the new version currently on test as far as 500mb heights go. link to this check run by NOAA incidentally

http://www.emc.ncep.noaa.gov/gmb/STATS/STATS.html

 

anecdotal is never a substitue for fact in my view.

Maybe the UKMO were talking more of upto T144hrs where the ECM performs best.

 

As this thread is most interested in colder synoptics we're probably more microscopic about it when it shows more amplitude past T168hrs, the ECM gets away with its odd AWOL moment because it remains ahead of the rest upto T144hrs.

 

I have to disagree with what the UKMO have put out, I've seen 99 percent of every single operational output from the NWP for the last ten years of winter months and more especially in recent winters the ECM has been often just as useless past T168hrs as the GFS.

 

We're not saying it will always over amplify past that point but just that we will obviously notice more because generally its overamplification is in relation to cold synoptics.

 

The GFS on the other hand is too flat so both models IMO need to improve.