Model Output Discussion - The final stretch to Christmas

[frosty ground]

Its because the GFS op has been consistent with regard to the pattern flattening whilst the GFS P goes from 0z Scandi High to 06z Greenland High. How can you take that seriously:

 

gfsnh-0-336 (1).png  gfsnh-0-348.png

 

The GFS op is also consistent to the mean where the GFS P is on its own. Its a new model so until it shows consistency and or some verification of its seemingly outlier height bias it is best ignored.

Well I must have miss read a few of the last few runs and even your post in which you highlight the run is an outlier and does not sit with the ensemble mean for either temperatures except this run which is now an established trend..... I find it rather puzzling.

[IDO]

Well I must have miss read a few of the last few runs and even your post in which you highlight the run is an outlier and does not sit with the ensemble mean for either temperatures except this run which is now an established trend..... I find it rather puzzling.

 

 

At T132 compare the mean 850s with the GFS P and it is clear that it is no way representative of the mean. It will have best a small cluster support:

 

 

 

I am not saying it is wrong as statistically it has a chance of verifying, but at the moment it is a very low risk.

[BLAST FROM THE PAST]

 

The most accurate chart yet... :w00t: 

 

What this demonstrates is the very unclear path forward and an exciting model watching time ahead.  Its Christmas which is exciting so for me a bonus of great model watching and a seasonal feeling Xmas.  Happy Days.

 

 

BFTP

Edited December 22, 2014 by BLAST FROM THE PAST

[Hocus Pocus]

Can anyone call anything after +120 though, I've never seen such chaos at such short timescales. There's some conflicting signal that is causing such madness within the output, just what though I've no idea as it can't just be down to the track of the low on the 27th as we've seen plenty of those features over the years.

[SLEETY]

gfs(p) has got it right for the whole run.awesome.bitter ne winds moving south ,then low pressure moving in,engaging the cold air.and bang.easy really .Scotland to be buried by blizzards ,.cairngorms the new spitzbergen

[IDO]

The Control supports the op:  

 

   Mean: 

 

 

 

 

[shaky]

Unbelievable changes this morning which i have never seen in a long time of model watching!! The fact that it's all happening at just 4 or 5 days out gives me no faith in amy output at the moment! ! Ecm is just ridiculous and does what it normally does!! Anyway for coldies things are looking up again and lets see if the 12zs produce a stellar set of beasterly runs and build on the scandi high signal! !

[Mark Bayley]

Certainly a confusing picture from the models this morning. I note, upstream, the ECM and GFS are keen on ramping up the PV, with low heights over Greenland and +AO/NAO. Given the predicted warming of the strat with further wave breaking (and easterly QBO), plus re-excitement of the MJO, i don't subscribed to that prediction, or at least in the long term. The GFS (P) may have been on the drink, although of the state  PV in FI seems a little more believable as we progress into and through January. 

Edited December 22, 2014 by Mark Bayley

[offerman]

Problem we have which shows in all the charts that everybody has posted is the Azores high is very strong and stubborn and its oval positioning just seems to be blocking or deflecting any attempt at colder incursions. If that can shift out further west or south and perhaps change its orientation then we would have a better chance. Thats just my take on it as i see it.  

Edited December 22, 2014 by offerman

[frosty ground]

At T132 compare the mean 850s with the GFS P and it is clear that it is no way representative of the mean. It will have best a small cluster support:

 

gfs-1-132.png gens-21-0-132.png

 

I am not saying it is wrong as statistically it has a chance of verifying, but at the moment it is a very low risk.

I am rather lost now, I am not saying the GFS(P) run will happen, indeed I have made no statement about what will or will not happen. You have, and your reply is not consistent with the points I raised, it's on a tangent. 

So the GEFS Ensembles mean is not exactly the same as the GFS(P) Operational run , I think that would be expected considering the the complete Chaos in the models, with this storm the driver of any chances....... But I have seen Operational lead Ensembles and Ensembles lead operational's.

Posting a chart @ 336 hours and saying we are back to reality is both misleading and misses completely the complex nature of events for this weekend, it also misses that previous runs espically from the ECM have picked up and droped this signal before. 

[Barking_Mad]

30th December:

 

[Fred Sykes]

Where are you Fergie?? What are your thoughts on the latest model runs?

[london-snow]

It'll be interesting to hear from ian f as i note he hasn't posted in a few days. Obviously no doubt shannon entropy i would have thought would feature if he does give us a update. However it will be insightful as to what the thinking is from the meto.

Personally i have a gut feeling that we could see a cold spell appear within the medium period from the ne just a few hints over the past few days although nothing concrete.

The output being so laughable atm (no clear trends) also leads me to feel something is about to happen. Could be strat related who knows but very interesting viewing nonetheless.

[A.J]

Hello, I'm a Numerical Weather Prediction Model...

 

....and I'm a alcoholic   

 

 

 

 

sums up my feelings on the current outputs!

[Gowon]

Certainly a confusing picture from the models this morning. I note, upstream, the ECM and GFS are keen on ramping up the PV, with low heights over Greenland and +AO/NAO. Given the current warming of the strat with further wave breaking (and easterly QBO), plus re-excitement of the MJO, i don't subscribed to that prediction, or at least in the long term. The GFS (P) may have been on the drink, although of the PV in FI seems a little more believable.

 

Precisely.. After  looking at the NH maps on both runs.. I'd have to say GFSP is more indicative of what is happening in the stratosphere and regarding the latest tweet from MH?

[IDO]

I am rather lost now, I am not saying the GFS(P) run will happen, indeed I have made no statement about what will or will not happen. You have, and your reply is not consistent with the points I raised, it's on a tangent. 

So the GEFS Ensembles mean is not exactly the same as the GFS(P) Operational run , I think that would be expected considering the the complete Chaos in the models, with this storm the driver of any chances....... But I have seen Operational lead Ensembles and Ensembles lead operational's.

Posting a chart @ 336 hours and saying we are back to reality is both misleading and misses completely the complex nature of events for this weekend, it also misses that previous runs espically from the ECM have picked up and droped this signal before. 

 

I post charts that far out to highlight that even the variation from the 0z and 06z op will make little difference to the long wave pattern as we go forward. I was saying that the collapse of the Pacific Ridge is more of a driver for the medium term than the variation on the track of the weekend's storm. Of course if the GFS P goes in a different direction then all bets are off, but at the moment this is a low risk, it has three ensemble members supporting it on the 06z (16%).

[Chris D]

Hello, I'm a Numerical Weather Prediction Model...

 

....and I'm a alcoholic   

 

 

 

 

sums up my feelings on the current outputs!

 Aye, in fact the GFS(p) was so drunk this morning it was unable to produce a cloud cover output past +252hrs. lol

 

http://www.wetterzentrale.de/pics/Rpgfs2643.gif

[Mark Bayley]

Precisely.. After  looking at the NH maps on both runs.. I'd have to say GFSP is more indicative of what is happening in the stratosphere and regarding the latest tweet from MH?

 

Any effects of the predicted warming would take time to influence tropospheric patterns, so a temporary strengthening of the PV is possible. However, longer term, the charts shown by the ECM and GFS would seem unlikely to be sustained (IMO) as the PV continues to come under increasing pressure (e.g. > )

 

http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2014122200&var=HGT&lev=100mb&hour=300

Edited December 22, 2014 by Mark Bayley

[frosty ground]

I post charts that far out to highlight that even the variation from the 0z and 06z op will make little difference to the long wave pattern as we go forward. I was saying that the collapse of the Pacific Ridge is more of a driver for the medium term than the variation on the track of the weekend's storm. Of course if the GFS P goes in a different direction then all bets are off, but at the moment this is a low risk, it has three ensemble members supporting it on the 06z (16%).

Well it's not quite that simple, and it's not quite what you said either but alas this has now run its course......

Small point it's more than 3 runs, and there are plenty of runs that keep heights higher over Greenland while not being as could as the GFS(P).

Edited December 22, 2014 by frosty ground

[IDO]

Well it's not quite that simple, and it's not quite what you said either but alas this has now run its course......

Small point it's more than 3 runs, and there are plenty of runs that keep heights higher over Greenland while not being as could as the GFS(P).

 

Yes we will agree to disagree but looking at the D13 means, GFS P -v- GEFS it really does show how out of kilter the P is:

 

  

[Mark Bayley]

Anyone for perturbation 1? :smiliz19:

 

[Jason M]

I post charts that far out to highlight that even the variation from the 0z and 06z op will make little difference to the long wave pattern as we go forward. I was saying that the collapse of the Pacific Ridge is more of a driver for the medium term than the variation on the track of the weekend's storm. Of course if the GFS P goes in a different direction then all bets are off, but at the moment this is a low risk, it has three ensemble members supporting it on the 06z (16%).

Although GFS(P) runs at higher res out to 240. Whilst still clearly there is little support the 16% figure doesn't reflect this fact. Whether the new GFS is better than the old one out to 192 is difficult to say, but it should be better from 192 to 240. All of that said, it would clearly help if the GFS opp and GFS P looked similar at 192 so we can see what happens!!

As I posted this morning I think the GEFS will be largely useless for a day or so tbh. If a cold spell emerges it will be opp run led as GEFS will just keep churning out zonal runs. This may ultimately prove correct (and I wouldn't bet much against it tbh) but it won't be down to the GEFS leading the way, more just them reverting to the climatic norm.

[Trom]

Entropy is a measure of informational content within a data set.  So in the context of models it is typically a used as a measure of uncertainty rather than certainty.  Shannon is just one particular measurement of entropy.  A high level of Shannon entropy means low levels of predictability or put in the context of the models, that they have low levels of predictive informational content.  Very certain outcomes still have entropy values (the more certain the closer to zero).   I only mention it as it seems to be a buzz word on here.

[Mapantz]

GFS UV index looks quite consistent..

[ukpaul]

Output this morning looks very much like the models look when they are transltioning from one presumption to another. As of yesterday there was no possibility of a blocking High beyond day 8. no signal at all as each model tried and failed with ridging to allow for it. 

 

Today, we see the possibility through a large undercut -

 

 

- giving up the effort and pushing height rises into Scandi instead -

 

 

- plus, if you look at the ensembles, the PV splitting in the latter stages of  the run in a number of different ways. Nothing fixed as of yet but moving forward looks a much better prospect than the entrenched and fierce PV of yesterday looked set to allow. I presume there was some sort of signal that has since disappeared. as the strat warming suggests something more akin to what we are seeing today.