Model Output Discussion 1st January 2014-06z onwards.

[stewfox]

A very good trend from the ECM, its not a big deal if we don't see a deep cold easterly here, the key is the earlier timeframe. If you take the GFS out of the equation then overall a positive evening for coldies.

 

If we can manage even more dig south and a more elongated troughing set up to the west then the Scandi high should land.

 

 

What would that have been on the old NS score card for cold for those of us that dont have time to read through pages of contradictory comments but just want a high level non bias knowledgeable opinion.

[IDO]

The ECM mean still supports ridging of upper heights at T168 towards Scandi and also a surface high heading  towards that region:

 

 

The trend afterwards appears to suggest that more members compared to the 0z, sink the surface high further south and/or east, so by T240:

 

 

So still a good signal though clearly not as good as this morning's mean; a less cold cluster likely for London.

 

Early days to worry about that. Lets get GFS on board before we worry where the high will set up.

Edited January 5, 2014 by i'm dreaming of...

[SMU]

.............can we play the game with two charts from the same time rather than 18hrs apart please Steve? Just easier to see

use the 132 then as theres half a circulation there-

 

1:00 11 Jan.

 

S

 

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.php?run=12

extended ECM shows 5/7 ice days from the control

Edited January 5, 2014 by Steve Murr

[nick sussex]

What would that have been on the old NS score card for cold for those of us that dont have time to read through pages of contradictory comments but just want a high level non bias knowledgeable opinion.

The score for cold with the better dig south and elongated troughing would be 8.5/10, with the current ECM operational 7/10 but I am hard to please! the GFS gets a 3/10, UKMO 6/10.

[Matty M]

use the 132 then as theres half a circulation there-

 

1:00 11 Jan.

 

S

 

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.php?run=12

extended ECM shows 5/7 ice days from the control

 

Good to see a good cluster heading below zero. About time, very few times that has happened this winter.

[draztik]

Its important to point out that the extended ensembles from ecm are still keen on a mean westerly thru days 10-15, with troughing to our nw and heights to our ne being shunted further and further east!

So, a zonal reset is still the favored route, if you take it at face value. Day 12 & 15 mean pressure charts attached.

[bluearmy]

The ECM mean still supports ridging of upper heights at T168 towards Scandi and also a surface high heading  towards that region:

 

EDM1-168.gif

 

The trend afterwards appears to suggest that more members compared to the 0z, sink the surface high further south and/or east, so by T240:

 

EDM1-240 (2).gif

 

So still a good signal though clearly not as good as this morning's mean; a less cold cluster likely for London.

 

Early days to worry about that. Lets get GFS on board before we worry where the high will set up.

 

the ecm mean drifts the battleground a bit east again. same general story though. the trend post day 10 is for the euro low heights to hold and the high anomlys to our north to slowly fade and those to our ne pull away a little also as the east canadian vortex cranks up again. are we headed back into the strong zonal mire again  as we reach the final third of jan ? 

 

we could well see a good few days of battleground scenarios as the depressions running in from the wsw run into the frigid blocking to our ene. 

[nick sussex]

Its time for me to bore you all with upstream news,this from the State forecast for Kansas:

 

The ECMWF model is forecasting a more amplified upper level troughmoving east into the plains on Monday. Rain may develop on Mondaythen change to snow through the day and into Monday night. The GFSmodel is less amplified and much farther north with the upperlevel trough.

 

That's a week on Monday, the disagreement between the ECM and GFS is important re amplification and movement of the PV. If you're going on recent events then you'd side with the ECM upstream as the GFS made a pigs ear of the inland runner low, also factor in NOAA comments from the end of last week in terms of some outputs not following the normal teleconnection correlation between the pattern in the Pacific and that expected over the CONUS, the sum total was that they thought the models might eventually settle on the deeper colder trough over the central USA.

 

 

[bluearmy]

Its important to point out that the extended ensembles from ecm are still keen on a mean westerly thru days 10-15, with troughing to our nw and heights to our ne being shunted further and further east!So, a zonal reset is still the favored route, if you take it at face value. Day 12 & 15 mean pressure charts attached. 

 

mean pressure charts at that range are not too helpful though. the heights much more informative. they would show the canadian vortex appearing top left.  i would say days 10 to 15 are very uncertain at the moment. we know how strong a cold block can prove to be once in situ. a recharged jet could be just what we need to drive an undercut !!  i wouldnt be reading too much into those charts yet. anyway, as many have said before, 'its the euro heights stupid' !!

[Vorticity0123]

For the 12Z output of the models, I'll try to make a comparison between the ECMWF and the GFS and where I think the crucial difference lies upstream. 

 

First, GFS at T96

 

GFS T96 (12Z)

 

Look at the low heights near Greenland (the purple colors) and not the surface pattern. The GFS shows the low heights edging toward the east slightly, which results in some low pressure areas moving toward that direction.

 

Next, the ECMWF (T96)

 

ECMWF T96 (12Z)

 

Compared to the GFS, the ECMWF forecasts the low heights near Greenland (residual of the Polar Vortex) to edge more to the south, resulting in low pressure areas moving more toward the south.

 

24 hours later, the differences at the surface from the slight modelling difference above become clear.

 

Once again, first the GFS (T120)

GFS T120 (12Z)

 

A long swath of low pressure (and low heights) can be seen stretching all the way from Newfoundland toward Scandinavia. This essentially blocks the opportunity for high pressure to set up over Scandinavia itself.

 

Next the ECMWF (T120):

 

ECMWF T120 (12Z)

 

The Polar high has now got the opportunity to build in between the lows near Iceland and the Baltic States, providing more of a blocking scenario (Scandinavian high). 

 

As can be seen above, a very slight difference in modelling of the low heights near Greenland can make a huge difference in the eventual outcome of the weather in NW Europa. (westerly or easterly, zonal or meridional etc). It shows that this could be a very hard time for the models to give the right idea of what the weather will be in 5 days. In other words, uncertanity is very high beyond the 5 day mark.

 

This is also shown in the temperature distribution forecast of The Bilt (credits to Nick Sussex for finding those):

KNMI statistical maximum temperature forecast distribution (50 members)

 

It shows that after 6 days, every maximum temperature category is possible, with equal likehood of occuring. Such spread indicates that no definitive things can be said about the exact weather in 6 days.

 

Moreover, the wind direction forecast (new layout) also shows a large degree of uncertanity:

KNMI wind forecast distribution (50 members)

 

What can be seen is, for example, the main wind direction for the first 5 days will be from the southwest. At T196 most members (including Oper and Control) are keying on an easterly to develop. Thereafter, the spread is about 60% (South)westerly, 30% easterly. 

 

Concluding, wheather an easterly will develop in about 5 days is far from certain. A slight change can have a major impact even at just 5 days. It will be interesting to see what the final outcome of this situation will be.

 

EDIT: the wind distribution and the temperature diagram forecast are outdated (run of yesterday), and therefore, check the link below for the actual wind and temperature forecasts.

 

EDIT2: The temperature graph has been updated to the last output. The wind graphs haven't been updated yet.

 

EDIT3: The critisism on Steve Murr's post has been removed as it wasn't valid (check reasoning below).

 

http://www.weerplaza.nl/15daagseverwachting/?type=eps_pluim

 

Sources:

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

http://www.knmi.nl/exp/pluim/

Edited January 5, 2014 by Vorticity0123

[SMU]

Vorticity you miss the point completely-

 

The reason I chose 138 is because thats the time that GFS closes the circulation off-

 

some 18 hours to late & over 1000 miles to far east- ( A product of the GFS progessive pattern)

 

As the GFS corrects west & amplifies so the GFS will approach a time nearer the ECM....

 

so look at 120 or 126 on the 18z & see if the circulation has closed off earlier-

 

S

[Snowman.]

GFS has better heights so far still not as strong as the ECM but its getting there.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014010518/gfsnh-0-96.png?18

 

ECM for comparison.

 

http://www.meteociel.fr/modeles/ecmwf/runs/2014010512/ECH1-96.GIF?05-0

 

 

Lets hope by the morning the would have inched closer together, lets hope the GFS takes the bigger step in order for some cold or dryer weather.

 

Just another thing to add the 12z does nothing but delays the cold things are looking interesting above the troposphere so we have that going as well.

 

One thing that everyone can agree on is that a end to this terrible spell of wet and windy weather to come to an end before the end of the month would be most welcome.

Edited January 5, 2014 by SN0WM4N

[Ali1977]

Already looking better at T90, much weaker vortex south of Iceland

[SMU]

http://modeles.meteociel.fr/modeles/gfs/runs/2014010518/gfsnh-0-120.png?18

 

Here we go then all aboard the failboat. Can it get the trough to dig enough to bring the high up through Ireland.

 

I bet the 18z will ...

 

S

[Snowman.]

Comparison at T126

 

18z12z

 

 

Clear steps towards the euros.

Edited January 5, 2014 by SN0WM4N

[Gaz1985]

Compare 850's shall we? 

 

ECM @ 144hrs (138 hrs now)

 

 

GFS @138 hrs - both quite similar just a couple of subtle differences 

 

Edited January 5, 2014 by Gaz1985

[Ice Day]

It's trying really really hard!!!!!!!!!!!!

 

[Mucka]

http://modeles.meteociel.fr/modeles/gfs/runs/2014010518/gfsnh-0-120.png?18

 

Here we go then all aboard the failboat. Can it get the trough to dig enough to bring the high up through Ireland.

 

I bet the 18z will ...

 

S

 

It had already failed for me at 120 Steve.

 

Look West and you can see how far back the low that rebuilds heights comes from with ECM/JMA and GEM then check the fail UKMO/GFS below.

 

 

Edited January 5, 2014 by Mucka

[garbagebags]

So. Many. Lows... 

Wouldn't be surprised if these merge to make yet another monster storm.

[Purga]

The failboat GFS 18z is living up to it's name

High res does nothing to indicate any reasonable amplification

 

Then we're into low re FI so may as well stop viewing.

 

Best check what UKMO / ECM shows in the morning & not get hung up on the non-stella tonight.

[Mucka]

GFS going for a 3rd bite?

 

[garbagebags]

Then we're into low re FI so may as well stop viewing.

 

 

Don't agree. FI is particularly useful at these times when looking for an overall pattern shift. 

[R.P. McMurphy]

Mmmm, ice day.

 

[garbagebags]

Mmmm, ice day.

 

 

On high ground. First thing in the morning. Yes.

[Mucka]

Why is this winter so rubbish?

 

Because it's mild wet and windy?

 

 

De ja vu?