Model output discussion - 1st December onwards

[bobbydog]

13 minutes ago, Daniel* said:

No,

Ian F has used the term multiple times over the years, some of his insight would be welcome.

im not talking about shannon entropy, its the myth that the models pick up an idea, drop it then show it later. we think they do but they show many scenarios. if the one we like reappears, we notice it above any other - the myth is born...

[nick sussex]

In terms of the MJO in the last ten days the UKMO forecasts have been better in terms of reliability than both the ECM/GFS/GEFS.

The worst were the GFS/GEFS which were reluctant to amplify the MJO and were forecasting it to go back into the COD even before it got into phase 5.

At this point we need all the help we can get so really need the MJO to make progress into phase 7 at least at a decent amplitude.

Edited December 21, 2015 by nick sussex

[Interitus]

Anyone with an information theory or data compression background will find it bizarre to see the phrase "Shannon entropy" cropping up occasionally - strictly speaking it's not, it's thermodynamic entropy or just plain entropy.

Edited December 21, 2015 by Interitus

[Eskimo]

Well the GFS Parallel is predicting blizzards for the south associated with a very deep low and intense snowfall rates at 364h. 

[bobbydog]

whats the new GFS parallel all about? the old 'parallel run' became the new GFS operational, so is the new GFS parallel to become the improved Op?

[MR EXTREMES]

3 hours ago, nick sussex said:

Yes for a convective easterly you generally need 850 values much colder. Frontal snow however is a different scenario, values just below freezing can produce that with an east/se flow set up.

Its been a long time since we saw a 5 star convective easterly, we have seen some cold easterlies however its been the infamous snow grains set up or ones with little convection.

For this reason the perfect easterly set up is a rarity.

feb 2008 was cracking for southern england from convective easterly but i like northeasterlies better.

as to the models its a fair reflection to say that easterlies and northern blocking in one form or another have been popping up in the runs for fair amount of time but nothing ive seen has really concreted the chance of anything exciting.

the ukmo ecm and gfs are all different jma if correct would be a peach but then i think that was lastnights run as you can see though the vortex is firmly in control need a serious wave 2 attack to really mess with the mighty monster.

el nino is also a pain in the ass as for the mjo still low amp nothing really going on that dramatic that could throw the atmosphere into a real pattern change i fear theres atleast a couple more weeks of the mild average alternating.

jma would lead to something more exciting but no support at all

 

[Liam J]

7 minutes ago, bobbydog said:

whats the new GFS parallel all about? the old 'parallel run' became the new GFS operational, so is the new GFS parallel to become the improved Op?

Yep, April/May 2016 it will become operational, the parallel running just recently was an improvement to the GEFS which has now been implemented. 

Edited December 21, 2015 by *Sub*Zero*

[Daniel*]

52 minutes ago, bobbydog said:im not talking about shannon entropy, its the myth that the models pick up an idea, drop it then show it later. we think they do but they show many scenarios. if the one we like reappears, we notice it above any other - the myth is born...

I will not blabber on but I've observed it on here quite a rarity it ain't no myth mate not a carbon copy but a shift to of old...let us hope the 12z is on the Buck's Fizz, I sense pendulum will sway back to 18z of yesterday....or I'm hoping. 

[nick sussex]

MJO forecasts have updated. The UKMO is the most amplified in terms of signal with it going into phase 6, the direction of travel looks to be headed towards phase 7.

[johnholmes]

1 hour ago, nick sussex said:

 At the moment there doesn't look like much Shannon Entropy because basically they're all crxp bar some GEFS ensembles. Even when the Euro high was shown to ridge north we didn't have a single operational solution within T240hrs delivering proper cold to the UK.

 

the actual definition of Shannon Entropy is given here, no idea just what the exact meteorological view is! For sure it is like a number of other formula/definitions=quite often wrongly used!

https://en.wiktionary.org/wiki/Shannon_entropy

 

[Interitus]

41 minutes ago, Interitus said:

Anyone with an information theory or data compression background will find it bizarre to see the phrase "Shannon entropy" cropping up occasionally - strictly speaking it's not, it's thermodynamic entropy or just plain entropy.

Hmm, unless IanF was referring to something like the statistical verification of NWP output and the entropy growth in error ranges I suppose....

[swilliam]

ECMWF forecast with a model based climatology updated and goes into 7 in F1 albeit at a rather low amplitude. 

 

[Eskimo]

Can someone tell me what the MJO is, and how it works? Thank you!

[bobbydog]

5 minutes ago, PerfectStorm said:

Can someone tell me what the MJO is, and how it works? Thank you!

its the Madden Julian Oscillation.

cant seem to post the link but wiki has a good explanation

[Gael_Force]

14 minutes ago, nick sussex said:

MJO forecasts have updated. The UKMO is the most amplified in terms of signal with it going into phase 6, the direction of travel looks to be headed towards phase 7.

It's like groundhog day in here, same discussion about MJO at this time last year .....

Same phasing (red line) as last year, give a week or so .....did it do any good then?  

 

[karlos1983]

UKMO Certainly looks more amplified than the GFS @ 120

[karlos1983]

I'm pretty happy with this chart from UKMO

 

Some nice warm air shooting up poleward. would love to see the next couple of frames 

[booferking]

Yep sure does tides are changing again.

[Eskimo]

Well, well, well....

[Allseasons-Si]

Oooh!!!

some may wake up to a white Chrimbo.

Edited December 21, 2015 by Allseasons-si

[booferking]

A nice tilt to the UKMO on that 144hr chart looks like going under if you fast forward a few days.

[radiohead]

No shortage of amplification the GFS. Though whether this will actually amount to anything interesting later down the line remains to be seen.

[karlos1983]

3 minutes ago, radiohead said:

No shortage of amplification the GFS. Though whether this will actually amount to anything interesting later down the line remains to be seen.

Well it's backed up by the UKMO,  

albeit slightly different in terms of where, how and when, if we can get some sort of agreement from the ecm, I might even become an optimist.

Edited December 21, 2015 by karlos1983

[Captain Shortwave]

Another set of runs and to be honest there seems to be no real route to bring cold air in from the east.

At this point the high will likely slide away towards Svalbard and leave us in an unsettled south westerly pattern. To be honest the UKMO would probably go the same way. Not to say that the introduction of high pressure into the Arctic won't do some good in terms of potential as we head into January.

GEM showing a even more pronounced Euro/Scandi ridge.

 

Edited December 21, 2015 by Captain Shortwave

[bobbydog]

now thats a disturbance in the force.....