Model Output Discussion - 10th Jan Onwards

[Weathizard]

Pressure rising over Italy has quashed any chance of cold, needed lower pressure over that area otherwise there is no 'pull' to slide underneath. Unfortunately with scenarios like this, as always minor changes have massive effects and we've got unlucky this time, I think we'll have a westerly zonal type restart before we get another shot. The 168 chart is pretty complex, looks prime for weather from the west, probably of the more unsettled type though unfortunately for coldies.

Chin up lads and lasses!

Edited January 10, 2014 by Weathizard

[Trom]

Yep a measure of certainty or uncertainty, bit like scatter or not on the GFS ensembles.

 

I'm not sure the scatter point is correct. I think that would be captured by standard deviation.

 

I think this is looking at variability in the variables from one model run to the next so time is a factor.

Edited January 10, 2014 by Trom

[Eskimo]

To be fair, the difference between the GFS, ECM & UKMO is substantial, so therefore they must be struggling with the low around the 15th. ANYTHING can happen from that point. 

[Captain Shortwave]

JMA similar if not even more progressive than the ECM

This has been a bitter pill to swallow, what we will actually get in 5 or 6 days time is still up for debate, but the cold train seems to have hit the buffers big time.

Still nothing a few beers can't solve 

[Stuie]

Ahh some cold air plunging into eastern europe, that`s better.

[The Northern Ramper]

NW/WNW/N flow towards end of run with low heights to north. Average temps in anomalies. But given high Shannon Entropy even by end next week, very low confidence second half Jan. MOGREPS call to spike any cold chance next week appears to have been well-founded... it was the only model keen on mobile, less cold outcome.

MOGREPS the trouble causing relative you never meet but is a blight on our lives.

[TSNWK]

NW/WNW/N flow towards end of run with low heights to north. Average temps in anomalies. But given high Shannon Entropy even by end next week, very low confidence second half Jan. MOGREPS call to spike any cold chance next week appears to have been well-founded... it was the only model keen on mobile, less cold outcome.

Fair play then to MOGREPS, looks like we have another box to tick then going forward during the next hunts for cold...

[The PIT]

Hi Ian, what does 'high Shannon Entropy' mean? Thanks

http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Entropy_%28information_theory%29.html

At one time I would have understood such things but my mind is clay these days.

I see Steve M's favourite model is getting even worse. ECM not  a pleasant run totally loses any cold uppers in deep FI although the diving low may re-introduce colder air again.

[weatherguy]

Shannon Entropy, in lehman terms, basically means the models don't have a clue of what will happen - A large spread in the data output essentially. 

[Stuie]

Well the ECM keeps the candle alive, albeit in FI but back on the colder wagon.

[Gaz1985]

Ahh some cold air plunging into eastern europe, that`s better.

 

Looks similar to the JMA, overall the JMA is devoid of any substantial cold for the UK in it's 12z run.

 

[carinthian]

Our own forecast Raw Data sources are still a million miles away from what is being shown this evening from particuarly the GFS and UKMO models who both seem to sink the Scandinavian High and cold away from Western Europe rather quickly. The problem still seem to be the handling of the low forming out in the Atlantic, these models want to push away any cold chance in a short pulse,  whereas we send lower heights into Europe with cold block holding on further to the Northeast.

 Maybe ECM may come to our rescue? Still time for a change again this weekend.

C

Well no rescue there from ECM latest offerings. That run would send most ski- resorts into melt down with no snow on offer, only snowdrops spouting !

 C

[TSNWK]

Well the ECM keeps the candle alive, albeit in FI but back on the colder wagon.

Really.. Happy to be proved wrong when the 240 panel comes out..

[Stuie]

Looks similar to the JMA, overall the JMA is devoid of any substantial cold for the UK in it's 12z run.

 

 

It may look similar but the ECM has much more colder air coming in, a vortex snippet whereas the JMA is just blowing in the wind.

 

Edit: yes it is true to a point.

Edited January 10, 2014 by StuieW

[MR EXTREMES]

it looks like if the ecm went out any futher we could have well above average

[Summer Sun]

High pressure edging in closer at t240

 

[IDO]

Its typical, most of the op runs are now singing from the same hymn sheet; they never do that when an easterly is forecast.

 

ECM is a variation on the GFS and GEM upto D7; different timing leading to the trough more east or west, the Scandi high sinking or sliding slower or faster (the wrong way), but they are close enough to call it:

 

No Easterly next week.

 

ECM develops a cold pool that props up the Scandi high and stops it sinking a la GEM/GFS; probably due to the pattern being a bit further west (trough):

 

 

So at T240 the ex-Scandi high is more of a player and we don't get a return to zonal, another trough digs through the UK:

 

 

More transitional seasonal fare than the GFS at that juncture, cooler and more interest up north wintry wise short term. No support from other models so probably just another FI option.

 

[pip22]

Despite the 12z misery North America at least warming up at last. Also Eastern Europe is cooling down too. That means weaker low pressure systems. Don't give up coldies the cold will show on the models any time from now on. This failed easterly is just the start.

[Stuie]

Really.. Happy to be proved wrong when the 240 panel comes out..

[SMU]

http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Entropy_%28information_theory%29.html

At one time I would have understood such things but my mind is clay these days.

I see Steve M's favourite model is getting even worse. ECM not  a pleasant run totally loses any cold uppers in deep FI although the diving low may re-introduce colder air again.

 

 

Getting worse in what respect? - Not sure what your moaning at really.

 

The shred of comfort tonight which has been apparent in the ECM for the last 2 days is no return to a resterly regime, & whilst the Scandi block comes back it does begin to reassert itself later on ( circa 9/10)

 

At the end of the day 99.9% of people on this forum will be here again in 10 days time so its worth pointing out- it may not amount to anything, but its a whole lot better than the ECM showing the high sinking into oblivion to be replaced by zonal westerlies-

 

S

[Cecil Hogmanay Melchett]

The deep cold over Greenland is not a precursor to cold anytime soon across our latitude i wouldn't have thought.

Apparently there are more signs of a warming in the strat but we really need something soon IMHO or the effects (if not immediate) will be too little to late for my money...

http://www.wetterzentrale.de/pics/Recm2401.html

ECM 240h chart shows a pretty big block to the North east,but it also shows a stinking PV sat like a limpet to the North west.

[tight isobar]

Well no rescue there from ECM latest offerings. That run would send most ski- resorts into melt down with no snow on offer, only snowdrops spouting ! C

from day 1 of model cross materialisation, of possible change of current, the lps hovering in the pond(Atlantic) has been the biggest headache.and for NW Europe not discounted upstream develops at usa, but when some quote the bigger picture ie northern hem as a whole, it will almost always come down ultimately to our own small window development. (Reiterate) any single shortwave, patch of energy, lps call it what you will can and will have MASSIVE consequence for our pin head maritime island. This isn't a done deal.im expecting a flip once more.,, and within the reliable. See you tomorrow.

[TSNWK]

Getting worse in what respect? - Not sure what your moaning at really.The shred of comfort tonight which has been apparent in the ECM for the last 2 days is no return to a resterly regime, & whilst the Scandi block comes back it does begin to reassert itself later on ( circa 9/10)At the end of the day 99.9% of people on this forum will be here again in 10 days time so its worth pointing out- it may not amount to anything, but its a whole lot better than the ECM showing the high sinking into oblivion to be replaced by zonal westerlies-S

You bet 99.9 will be here in 10 days. If it don't break ya it makes ya and its worth all the pain when one lands.. Onwards and upwards to the next chase... Edited January 10, 2014 by TSNWK

[cooling climate]

What do you mean CC?

I thought we had a good run then judging by your comments?All i see is the high getting shunted off east and a more mobile setup waiting in the wings...

You get the feeling the ECM is on a wind up by dangling the carrot so to speak. Looking at the UKMO

and GFS you think that is it games up then out comes the ECM again and backs everything further

west again plus the Scandi high looks a lot stronger and better shape at t120-t144 regardless of where the run goes after that.

I see even at the end of the run its hinting their may be a second bite of the cherry. Of course the ECM is a NWP model the same as the rest and may have picked up on something the other models

haven't due to its higher resolution. Then again the adjustments west could be gone on the next run.

[Vorticity0123]

For the time being, I'll give a comparison of previous model output for today and the real output today (Johnholmes had some excellent pdfs about this comparison and forecasted pressure in the in depth model thread BTW), and the general trend in model forecasts for the far future.
 

Verification of ECMWF and GFS

 

It appears that the block over Scandinavia has been modelled somewhat too agressively during the past few days. For comparison, the ECMWF T168 from the third of January (this is today 12Z) and the analysis at the same time today is shown below:

 

ECMWF 03 january T168

 

The model run showed a pronounced block over northern Scandinavia, and therefore easterly winds over the UK.

 

ECMWF 10 January 12Z T0

 

As can be seen from the comparison, the block ended up much weaker than forecast at the same timeframe. Moreover, there also appeared no opportunity for the high pressure area north of Scandinavia to build between the lows moving eastward to the north of the UK.

 

Note that the general pattern wasn't very far away from reality, with a trough over Spain (though it appeared to be weaker than originally forecast) and low pressure south of Finland (configuration was once again slightly different, which can be expected 7 days out).

 

Also the GFS from the third of January is shown below:

GFS 3 January T144 

 

Note that the output from the GFS is one day earlier than the output from the ECMWF above.

 

The difference is that the GFS at that time modelled the lows over the south of Scandinavia better compared to the ECMWF. However, the pattern over the US appeared to be less well forecast. Moreover, the GFS also had the trough over Spain right (though it was slightly too west)

 

I have to admit that I don't have a reason for the differences in model output and result. Does anybody have a clue?

 

Future general trend

 

First, I'll start with the 500 hPa charts, as analyzed by the NOAA.

The chart shows the 500 hPa heights (green lines) and anomalies (blue and red lines) forecast by NOAA in 6-10 days.

 

What can be seen is a mainly diffluent pattern over Europe (the lines of equal geopotential are diverging over that area). Moreover, there seems to bea signal of a  ridge over or to the north of Scandinavia, though the signal is weak. A stronger signal exists for a deep trough to extend over the UK toward Spain.

 

Next, an analysis of the surface charts (comparison of the ECMWF and GFS) will be given. This will be at 8 days, to compare with the 500 mb chart above.

 

First, the ECMWF:

ECMWF 12Z T192 (8 days out)

 

What can be seen is a trough (as well as a surface low) over Spain. This agrees with the 500 mb charts as analyzed by NOAA. High pressure is forecast to be located over eastern Scandinavia, which also agrees somewhat with the anomaly charts. The high pressure is located more to the east than anomaly charts would suggest (also the 500 hPa ridge).

 

Next, the GFS:

GFS 12Z T192 (8 days out)

 

Looking at the chart shows that the GFS also agrees with the trough (low 500 hPa heights) and low surface heights between Spain and Italy (slightly more to the east than the ECMWF). However, the high heights at 500 hPa (as well as the surface high) are located much more to the east than on the ECMWF. 

 

Of a final note is that the troughing signal to the south and over the UK is also visible in the stratosphere (100 hPa) showing generally markedly low heights over that area.

 

Concluding, there does seem to be a general agreement over the next couple of days, with troughing near the UK and the Iberian Penninsula. This will most likely lead to changeable and possibly wet weather over the UK, though no details can yet be given. The high pressure area appears to be too far east to provide cold air, along with easterlies, over the UK. The disconsistency in the exact position of the high will be worth watching, though, as it might provide more settled conditions if the exact position appears to be more to the west than shown by for example the GFS.

 

I hope the post is of some value. However, because I'm still a beginner, there could be some mistakes in the post. Sorry for the possible inconvenience. 

 

Sources:

http://www.wetterzentrale.de/topkarten/fsecmeur.html

http://www.meteociel.fr/

http://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

Edited January 10, 2014 by Vorticity0123