Model Output Discussion - 31/10/2014 and Beyond

[winterof79]

The more i look in to the Aleutian Low and its presence during our cold spells the more intriguing it gets.Whats more is, once it sets up shop it takes some shifting...

 

http://modeles.meteociel.fr/modeles/reana/1986/archivesnh-1986-11-28-0-0.png

http://modeles.meteociel.fr/modeles/reana/1986/archivesnh-1986-12-31-0-0.png we know the rest.

 

http://modeles.meteociel.fr/modeles/reana/1978/archivesnh-1978-12-8-0-0.png

http://modeles.meteociel.fr/modeles/reana/1978/archivesnh-1978-12-31-0-0.png not a bad rest of that winter!

 

http://modeles.meteociel.fr/modeles/reana/2009/archivesnh-2009-11-20-0-0.png

http://modeles.meteociel.fr/modeles/reana/2009/archivesnh-2009-12-20-0-0.png

 

Probably just me though....

http://modeles.meteociel.fr/modeles/reana/2010/archivesnh-2010-11-30-0-0.png

Edited November 5, 2014 by winterof79

[bluearmy]

Just an obsevation that the 06z GEFS seemed to be reducing the alaskan ridge and aleutian low somewhat as week 2 progresses. im sure the 12z will drift back

[Barry12]

The GFS is so confusing, especially now it's got a parallel that is also different from the old GFS. Which one do you believe? The fact it has 4 runs that are all different makes following it rather pointless. Definitely easier if you stick to following the ECM, even if the ECM shows us something we don't want, and the GFS shows us a bitter easterly, I'd still believe the ECM. While the GFS may be right some of the time, usually the GFS is playing catch up to the ECM.

 

Heres an example, comparing the GFS and The GFS P at just day 6, which should be the semi-reliable:

 

 

Massive differences.

Edited November 5, 2014 by Barry95

[Met4Cast]

The GFS is so confusing, especially now it's got a parallel that is also different from the old GFS. Which one do you believe? The fact it has 4 runs that are all different makes following it rather pointless. Definitely easier if you stick to following the ECM, even if the ECM shows us something we don't want, and the GFS shows us a bitter easterly, I'd still believe the ECM. While the GFS may be right some of the time, usually the GFS is playing catch up to the ECM.

 

Well, the GFS Parallel has been upgraded so in theory it should be performing better than the current operational GFS. Until we see some verification stats though we wont know, it's still very much in its testing phase so their could be some issues with it causing it to produce inaccurate outputs. Until it goes fully operational it's best to use it in conjunction with other models and treat it as a separate entity from the operational GFS.

 

The current trend is for heights to build across into Greenland with a slightly weaker signal for a Scandi High too. The Northern Hemisphere is primed for cold but with low pressure systems continuing to not undercut, it could be a few more weeks before we really manage to tap into any cold air.

[winterof79]

I only drifted in The the model output discussion very rarely this summer.My brief flirtations with the GFS output throughout summer led me to believe it was the trendsetter when it came to spotting high pressure and its whereabouts in our location well In advance.

How it copes through the winter is another debate

Edited November 5, 2014 by winterof79

[Barry12]

I only drifted in Ti the model output discussion very rarely this summer.My brief flirtations with the GFS output throughout summer led me to believe it was the trendsetter when it came to spotting high pressure and its whereabouts in our location well In advance.

 

If it set the trend within day 10 fair enough, but you can't say it saw the trends first if it started after day 10, as obviously the ECM doesn't go out after day 10.

[Barry12]

Some of the professional weather forecasters (Liam Dutton) can see us getting some cold weather as well by looking at  the jet stream models.

Edited November 5, 2014 by Polar Maritime
To remove deleted quote and off topic comment,

[Mucka]

Great read from Snowking, thanks.

 

I was going to post that I couldn't understand why anyone would be in the least bit despondent with this mornings output, I mean even the most optimistic among us can't expect any chance of any cold until the last 3rd of Nov at the very earliest and all that has been said is that the possibilities of seeing and early wintry spell are currently greater than normal and there is absolutely nothing in this mornings output that diminishes that possibility but Snowking has provided the where, what and why far more eloquently than I would of done.

 

As for Steve M's post talking of the possibility retrogressing high from Scandi to Greenland area, he is talking about time-frames just beyond the models scope so we should be looking for conditions to set up to allow this retrogression rather than the actual retrogression itself. 

There is currently no way to know but the possibility is there because, despite what some people have posted, there are signs in the output for it.

 

Take another look at the ECM/GFS 7-10 day height anomaly charts

 

 

 

Clear signs on the ECM that heights are attempting to retrogress.

So what is the difference between the ECM anomalies and GFS  in the context of what we should look for in the MO over the next few days?

Transfer your attention to the negative anomalies and compare the alignment and depth of the trough to the West of the UK.

You can see that the ECM anomaly screams undercut of scandi heights with the trough digging right through Western Europe on NW/SE axis while GFS is a shallow trough with much more westerly aligned jet - little to no undercut of heights over Scandinavia.

A huge difference for 10 day anomaly charts.

 

How might that translate into the MO? Well look at this mornings operational runs of GFS and ECM day 7 and it is a perfect illustration of how differently they handle the pattern in FI. ECM on the left in tune with its anomaly charts GFS on the right in tune with its own anomaly charts regarding depth and orientation of the trough. (Do not look for retrogression as that won't come until further down the line and only if we get the ECM undercut.)

 

 

So out of chaos comes order. 

Although we are seeing a lot of variance in the charts, because of the models often touted lack of ability when dealing with large positive polar height anomalies, there is actually only one significant thing to look out for if you really want to see an early wintry blast (If GFS is correct don't get upset, the potential will still be there - patience grasshopper.) and that is the nature of the trough to the West of the UK. Of course the nature of that trough is dependent on earlier factors and developments upstream which is another post but for the sake of considering whether we may get a cold NE blast before the end of November via retrogressing Scandi heights it is a significant part of the puzzle that we can see modelled run to run.

 

If we get the undercut and good trough alignment then we will start to see heights extending from Scandi toward Greenland and from there hopefully low pressure sinking down its Eastern flank so that eventually the current high pressure is replaced by low pressure in the region. Of course even if we get the undercut and retrogression the upstream pattern still has to play ball for the UK to benefit with a cold Arctic blast. 

 

So heads up and chins up and all that.

Edited November 5, 2014 by Mucka

[carinthian]

Looks like the latest update from the UKMO does not give any hope for undercuts during the rest of this month. They indicate the rain next week transfers from the SW to the NW and during the following week a rise in temperatures across the board. The longer outlook confirms no imminent cold spell during the latter end of Nov and early December. Until, the UKMO charts start to hint at cold, it looks as though we will have to wait some time yet and not get too excited . Looking at their latest outlook,it would seem low pressure it staying out to the NW and high to the SE, which is not what us cold lovers are looking for.

C

Edited November 5, 2014 by carinthian

[Yarmy]

Well, the GFS Parallel has been upgraded so in theory it should be performing better than the current operational GFS. Until we see some verification stats though we wont know, it's still very much in its testing phase so their could be some issues with it causing it to produce inaccurate outputs. Until it goes fully operational it's best to use it in conjunction with other models and treat it as a separate entity from the operational GFS.

 

The current trend is for heights to build across into Greenland with a slightly weaker signal for a Scandi High too. The Northern Hemisphere is primed for cold but with low pressure systems continuing to not undercut, it could be a few more weeks before we really manage to tap into any cold air.

 

I *think* the new GFS is the pink PRX line here:

 

 

It's a bit misleading at the moment though because it only has 4.5 days compared to the full month for the others.

[Polar Maritime]

I have deleted and edited some posts, Can we please only discuss what the Models are showing. There are other threads for Meto outlooks and maybe even one to discuss "likes"..

 

Many Thanks, PM.

Edited November 5, 2014 by Polar Maritime

[Mark Bayley]

Marked differences between the runs (zs), however the broader hemispheric patterns remains the same (i.e. disrupted PV). Normally you'd expect the PV to strong and organised, so such pattern shown by the GFS, and other models, is unusual, and good for coldies (regardless of the immediate weather). Minor wave breaking and warming events in strat will ultimately prevent PV from garnering too much strength. However, nothing substantial is currently forecast. In terms of the UK, for the next few weeks, i'd suggest unsettled, as low pressure systems try to track south east. I would not expect anything notably wintry in this period. The last 1/3 of the month and into December, for me,  holds some interest.

Edited November 5, 2014 by Mark Bayley

[Polar Maritime]

The cool/wet N/W flow draws in even stronger by the 19th, Maybe even stormy on a strong Jet.

 

Edited November 5, 2014 by Polar Maritime

[radiohead]

Deep in FI, but the 12Z GEM is showing a nasty looking storm approaching from the southwest.

 

 

12Z GFS(P) also showing a deep low at the same time.

 

Edited November 5, 2014 by radiohead

[phil nw.]

A reminder to please keep to model discussion in here please.

One post has been removed-no discussion on the charts- and one moved to the other Model thread which accommodates more general views.

 

thanks.

[phil nw.]

We can see from the 12z runs continued pulsing of heights into the vortex,particularly over the Canadian side mid-range.

So signs of continued warmings but not enough to break the current set up as the transient ridges move around the NH.

The UK image is typical of all the models over the next week or so.

 

For us then it looks like an ongoing pattern of mainly west/south westerly action with a slow moving  Atlantic upper trough nearby with attendant fronts interspersed with some brief drier spells. 

[summer blizzard]

Euro makes some more progress tonight at day 8 and 9, again though we really need the eastern side of the low to deepen.

 

[Snowy L]

JMA and ECM both going for heights building to our Northwest towards the end of their runs. I keep thinking it's too early for all this but then I remember the best cold spell in my memory occurred in November.

[Man With Beard]

Latest NOAA 8-14 dayer... lots of heights through Scandi to the Pole and some form of troughing to our west, seems to have been this way for months now. So rain likely to be a feature for some time - temperatures will be very dependent on whether the source of the weather is southerly (mild) or with an easterly aspect (chilly regardless of the 850s).

p.s. whisper it ... deep troughing over Aleutian Islands...

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

[Captain Shortwave]

Day 8 mean from the GFS/ECM and GEM

 

ECM

 

GEM

 

All fairly similar to be honest, cyclonic with winds varying but becoming more south/south easterly with time. Rainfall looks above average for the west but drier in the east. Temperatures look near normal.

As hopeful as the ECM is, it does look like it will be a long road to cold, if we continue to see the building blocks develop of course.

Edited November 5, 2014 by Captain shortwave

[shaky]

Big differences in the 18z gfs already!!stronger heights back all of a sudden across the arctic and also a more amplified Atlantic!!

[Weathizard]

Look at the state of the vortex at the time it should be strengthening significantly, this chart screams potential in future:

 

[pip22]

Is that me or is the cold air mass over N America gonna come to us?

 

 

 

I think its something to keep an eye on it.

Edited November 5, 2014 by pip22

[Banbury]

Is that me or is the cold air mass over N America gonna come to us?

 

 

 

I think its something to keep an eye on it.

The Atlantic will lift the temps for sure

Edited November 5, 2014 by Banbury

[Polar Maritime]

Yes the GFS continues to show a stronger N/W flow into the run. With the PV finding it's way home maybe?

 

Edited November 5, 2014 by Polar Maritime