General Model Output Discussion

[kold weather]

Whats really interesting is that the fact the GFS/ECM show vastly different FI solutions we still remain in a cold set-up. If anything the 12z GFS is a more sustainable set-up, the ECM one whilst colder and probably more interesting is far more prone to breaking down as the upper high looks like its further west and weakening.

Still 18z GFs will be interesting, as long as the first low doesn't end up too far north and the upper high stays solid for long enough to last the next attack, then it should be a good run...

BTW, the 12z is a very cold run indeed it should be said!

[Rollo]

How do i view the ECM?

Go to metiociel and scroll down.

[SMU]

Evening-

just for the people struggling to make head nor tail of the outputs I broadbrushed three images to give a quick overview of whats happening-

Each chart has the -5c lin & the 0c line on it- the most snow will be along the front close to either side of the -5c line-

The 3 charts are for 12pm Tues weds & thurs...

12pm Tues- Central & Northern Wales the sweet spot it appears-

12pm Weds- The snow zone moves south but also WEST as its getting shunted out of the way- being replaced by the colder air-

I suspect by this time 12pm Tues > 12pm Weds the BULK of any snow will have fallen over Wales- ( elevation especially)

12pm Thurs- Central & western areas drying out- possibly the time for the South & South East ( Poss SW as well)

by then the cold getting well entrenched everywhere - dewpoints dropping right out as well-

remember this is based on the ECM- no other model-

Cheers

Steve

[nick sussex]

Just a quick note here before tonights gfs 18hrs run, this will be followed a little later by the ukmo 48hrs model which should give the latest trend for the lows track.

In terms of tonights model output we've seen the superb ecm 12hrs run but looking through the ensembles of the gefs a more southerly track of the low does correlate with a better longer term prognosis, its sometimes important to remember here that in this type of set up a hundred miles can make a huge difference locally but also early changes can manifest themselves later in terms of how far south the jet runs. In this instance the further south the better chance of the next low undercutting the block.

[phil nw.]

Whats really interesting is that the fact the GFS/ECM show vastly different FI solutions we still remain in a cold set-up. If anything the 12z GFS is a more sustainable set-up, the ECM one whilst colder and probably more interesting is far more prone to breaking down as the upper high looks like its further west and weakening.

Still 18z GFs will be interesting, as long as the first low doesn't end up too far north and the upper high stays solid for long enough to last the next attack, then it should be a good run...

BTW, the 12z is a very cold run indeed it should be said!

Yes Kold still some early differences re,the path of the low but overall the NH pattern showing the omega block for this week has been agreed across all the models,yes even the GFS.

The only thing with some of the recent GFS runs is that they have overcomplicated the flow with those s/waves and excessive trough disruption at times thus placing the low differently to the others.

The general overview of the upper features have generally been along similar lines but because of the importance of the battleground event coming up there`s been a lot of focus on the placement of the surface features.

I said yesterday that inspite of the worries,mainly over the GFS,a cold pattern was still in place going forward and that definately looks the case now.

[Archie_Lewis]

Evening-

just for the people struggling to make head nor tail of the outputs I broadbrushed three images to give a quick overview of whats happening-

Each chart has the -5c lin & the 0c line on it- the most snow will be along the front close to either side of the -5c line-

The 3 charts are for 12pm Tues weds & thurs...

12pm Tues- Central & Northern Wales the sweet spot it appears-

12pm Weds- The snow zone moves south but also WEST as its getting shunted out of the way- being replaced by the colder air-

I suspect by this time 12pm Tues > 12pm Weds the BULK of any snow will have fallen over Wales- ( elevation especially)

12pm Thurs- Central & western areas drying out- possibly the time for the South & South East ( Poss SW as well)

No snow for the home counties then based on ECM?

by then the cold getting well entrenched everywhere - dewpoints dropping right out as well-

remember this is based on the ECM- no other model-

Cheers

Steve

Steve,

No snow for the home counties then based on ECM?

[SMU]

Steve,

No snow for the home counties then based on ECM?

Not according to the ECM - ( although the PPN distribution is generally frontal- not convective- )

EPIC ECM ENSEMBLES-

S

[john mac]

Yep looks like a big rain fest for us in the south east, if the low gets 100-150miles furthur south then bingo

[kold weather]

Yes Kold still some early differences re,the path of the low but overall the NH pattern showing the omega block for this week has been agreed across all the models,yes even the GFS.

The only thing with some of the recent GFS runs is that they have overcomplicated the flow with those s/waves and excessive trough disruption at times thus placing the low differently to the others.

The general overview of the upper features have generally been along similar lines but because of the importance of the battleground event coming up there`s been a lot of focus on the placement of the surface features.

I said yesterday that inspite of the worries,mainly over the GFS,a cold pattern was still in place going forward and that definately looks the case now.

Yep and its that placing of the low that is very key, as I said earlier I don't think its by chance that pretty much all the milder runs on the ensembles also have the low further north...the colder ones tended to be the runs that kept the low further south...I think its quite obvious why that would be the case, because the further north the orginal low goes, the more and longer of a drag we need to get the cold air in place before we get an attack from the SW low pressure system, if the ridge isn't in place on that 12z run we'd have ended up with a mild SSE/S flow...

Anyway none of that would matter if the 12z ECM came off as that has a different kind of set-up...still anyway there is more scope for cold then for mild at the moment lets put it that way.

By the Steve, I totally agree with you, thats what I'd call as well now, starting to become a little interested in the amount of rain thats possible down here, esp on the 12z ECM...

[grab my graupel]

Just thought I should mention:

The GFS 18z run can be viewed here on Netweather.

http://www.netweather.tv/index.cgi?action=nwdc;sess=

The Netweather charts are in a Higher resolution than those on Wetterzentrale, and they have the added bonus of being in English :lol:

[kold weather]

Not according to the ECM - ( although the PPN distribution is generally frontal- not convective- )

EPIC ECM ENSEMBLES-

S

I think thats just about the coldest ECM ensembles I've ever seen, the mean stays below 0C there all the way through 15 days!

The control run gets upto 1-2C in FI and thats one of the mildest runs!

Pretty mental, lets see what the 18z GFS brings.

[Cloud 10]

Not according to the ECM - ( although the PPN distribution is generally frontal- not convective- )

EPIC ECM ENSEMBLES-

S

[yamkin]

Yep looks like a big rain fest for us in the south east, if the low gets 100-150miles furthur south then bingo

Rain feast to start with, but ECM 12Z 72h onwards shows the potential for snow in the SE :lol:

[snowray]

A bit off topic I know, but that is very true.

1900's: Average, snowier start + end with a mild middle.

1910's: Average, a variety of winters with 16/17 a severe winter.

1920's: Average, mild winters with a few snowy ones mixed in.

1930's: Average, but a run of snowy winters towards the end.

1940's: Average-mild, lots of rubbish winters, except of course 46/47.

1950's: Snowy, but not very snowy.

1960's: Snowy.

1970's: Mild, except towards the end.

1980's: Snowy, lots of cold winters but a mild end.

1990's: Mild, 1991 and 1996 the exception.

2000's: Mild.

Is someone after Mr Data's job here? Times must be hard! :lol:

Great looking runs this evening, particularly ECM, will the 18z fall into line I wonder? :lol:

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

GFS 18z rolling out.

If it continues showing what it has shown the past few runs, low moving further north, let the wrist slashing commence. If it joins every other model with the low further south and cold conditions after, let the over excited cold ramping posts commence!

[swilliam]

For those who were hoping next weeks event was going to be like Dec 31 1978 if you look further down the evolution of the GFS it is clearly illustrated how if we get the cold air in place then it is very likley to happen. Looking at the T162 chart we can see a small channel trough.

But this produces plenty of precipitation

And nearly of this will be fine powdery drifting snow if you look at the 850s of -5 (with a huge gradient), temps and dewpoints widely below zero and a NE wind of >15kts.

This event lasts for the best part of 24 hours so you could expect large snow totals. On this run this is followed by the very cold Easterly blast so lying snow for days.

So the point is that all models are showing the protracted cold spell and once this is well established there would almost certianly be snow for everyone. This would include those in the South who are fretting about next weeks event. I would say have patience and something interesting is almost certain to come at some time during the spell.

[Geordiesnow]

Lol, even at 24 hours, the GFS has the low a good 5-7MB deeper than the UKMO, i know its not much but at 24 hours, surely it would of been near enough accurate.

At least so far, GFS has the low further westwards which is kind of trending towards the euros as they don't bring in the low as quick as the 12Z, whether it will mean anything or not we shall see.

edit: I feel whilst there might be a slight trend southwards, i don't think it will be that much different. I think of the reasons why the GFS has the low further North is because it is predicting a deeper low than the UKMO for example. UKMO has a 985 MB low at 42 hours whilst the 18Z at 36 hours has a 975MB low!!

Edited December 27, 2009 by Geordiesnow

[conor123]

The GFS 18z is identical to the 12z at 60 hours, its still got it about 100-150 miles further north than the UKMO...

[john mac]

Lol, even at 24 hours, the GFS has the low a good 5-7MB deeper than the UKMO, i know its not much but at 24 hours, surely it would of been near enough accurate.

At least so far, GFS has the low further westwards which is kind of trending towards the euros as they don't bring in the low as quick as the 12Z, whether it will mean anything or not we shall see.

edit: I feel whilst there might be a slight trend southwards, i don't think it will be that much different. I think of the reasons why the GFS has the low further North is because it is predicting a deeper low than the UKMO for example. UKMO has a 985 MB low at 42 hours whilst the 18Z at 36 hours has a 975MB low!!

No way i dont think the low is going to be that deep. The GFS is over doing the low definately

[phil nw.]

In the early stages it looks like a repeat of the 12z

http://www.wetterzentrale.de/pics/Rtavn541.png

[Supercell]

The GFS is again at odds with the other models, at least in the short term.

[snowmadchrisuk]

Lol, even at 24 hours, the GFS has the low a good 5-7MB deeper than the UKMO, i know its not much but at 24 hours, surely it would of been near enough accurate.

At least so far, GFS has the low further westwards which is kind of trending towards the euros as they don't bring in the low as quick as the 12Z, whether it will mean anything or not we shall see.

edit: I feel whilst there might be a slight trend southwards, i don't think it will be that much different. I think of the reasons why the GFS has the low further North is because it is predicting a deeper low than the UKMO for example. UKMO has a 985 MB low at 42 hours whilst the 18Z at 36 hours has a 975MB low!!

850 wise the 18z is even worse than the 12z for Tues/Wed . If GFS is correct the only place that would see any frontal Snow would be the Mountains in Wales.

[kold weather]

Well the 18z is even milder then the 12z for most!

Most of the changes in the GFS will come for tomorrows 0z, I'd be rather shocked if the GFS is correct as to it going quite that far north...

Also will be interesting to see if this causes a downgrade in FI as per the 12z ensembles would suggest given the more northerly low...

[on the coast]

The GFS is again at odds with the other models, at least in the short term.

Write the GFS of at your peril?

[nick sussex]

Quite an amazing difference here between the gfs and every other model at such a short timeframe, not just the track but the orientation of the low, so will this be it's sudden clawing back of it's credibility or a further descent into model obscurity!