General Model Output Discussion

[kold weather]

Well so far the 18z GFS is a shocker thats no doubt...

However that shows perfectly what I was saying earlier...we NEED the LP to take the more southerly track, otherwise the cold air wil lstruggle to get far enough south, the south has a total screw job if this run is correct!

Everything is worse about this run thus far...I can't actually find one thing thats an upgrade on the 12z, not even one, thats quite impressive.

EDIT---finally!!!

144hrs shows a better orientation to the upper high over Greenland than the 12z run!

Edited December 27, 2009 by kold weather

[cyclonic happiness]

The GFS has its wobbles as well. Remember the way it backed off the E,ly showing a very slack, non descript E,ly. This upgraded as the event came closer.

Having said this I would prefer to see model agreement. I wonder if the new GFS model is being run by a ZX Spectrum.

Excuse me TEITS but my turbo zx spectrum can run Halo 3 with no lag!!! DON'T DIS DA SPECKY!

I'm gonna ignor this run as it's going all weird even in the mid range, but at least it's being consistantly weird.

I think the midlands is reasonably safe for the snow looking at all other charts and forecasts.

I just hope they are right and the GFS is wobbling again.

[Supercell]

EVerything thus far in the run is a downgrade for cold, the low is further north earlier on, it takes longer to get out of the way of the UK and the upper high over Greenland is not quite so favorable in terms of its slant, I think its 50-50 as to whether the GFS shows anything decent in Fi, may show us just on the wrong side of any cold boundary in Europe...

Also add the LP in the Atlantic isn't as good either...I think this is going to be a rather poor run...we shall see though, the upper high over Greenland could save it.

It really is all going to hinge on this one low. I didn't even bother looking further on in the run because it wasn't going to show what I wanted it to. The eventual positioning is key to unlocking this cold spell or unravelling all the positive signals.

The nowcast is looking inevitable. It's always the way. I'd much prefer to be put out of my misery sooner rather than later, otherwise this forum is going to head in to a mass depression ! It'll be especially frustrating for those that have seen it come closer each year, only for it to go wrong as we are within touching distance of an event or cold spell.

[swfc]

Shocking run and the atlantic is ready to make a move at 130 hrs.

[nick sussex]

So this low forms off the Brest Peninsula at 78hrs ambles its way up the Channel heads into the North Sea and at 132hrs decides its bored everyone to death and fills! and then looks like its going to become absorbed by the next Atlantic low! but then decides it wants to keep going all by itself, i mean who writes this rubbish?

Who cares what the rest of run shows its a pile of tosh!

[Optimus Prime]

Looks as if SW winds may start to take over.

Still very cold for Scotland but fairly near average temperatures for the south on this run. Certainly wouldn't disregard it.

[casparjack]

The GFS has its wobbles as well. Remember the way it backed off the E,ly showing a very slack, non descript E,ly. This upgraded as the event came closer.

Having said this I would prefer to see model agreement. I wonder if the new GFS model is being run by a ZX Spectrum.

Could be a ZX80!!

...but seriously, I think there is such a tight margin between rain/snow in the initial event that we might not even know in any real detail until it actually starts to happen on the day!!

[snowmadchrisuk]

Excuse me TEITS but my turbo zx spectrum can run Halo 3 with no lag!!! DON'T DIS DA SPECKY!

I'm gonna ignor this run as it's going all weird even in the mid range, but at least it's being consistantly weird.

I think the midlands is reasonably safe for the snow looking at all other charts and forecasts.

I just hope they are right and the GFS is wobbling again.

Well as all the Internet sites use GFS data for there forecasts , at least if it does rain it will make there forecasts look better IMO If the GFS us wrong at +24 by such a large margin then there is no point even looking at the rest of the run.

[Spurry]

Can't believe how much the GFS has backtracked in the last 2-3 days, at one point we were looking at a serious cold blast from the north, now the northerly has all but vanishesd and we are offered a bit of an Easterley but thats so far out it's hardly worth considering

[kold weather]

Another rain/seet/snow mess on this run at 144hrs, slightly more southerly focus on this run though for the places south of the M4, yet another screw job sadly if this run is correct.

Anyway the whole run is WAY too progressive IMO with what it brings in...in every respect from the Atlantic low between 96-120hrs to sinking of the Greenland high towards a more favourable position.

Anyway going to be VERY tight between us getting a cold easterly and a mild/very mild southerly on this run.

[SMU]

The GFS has been renamed F.F.S

Totally at odds with every other model-!!! oh well waiting for the 00z to put us out our misery-

S

Edited December 27, 2009 by Steve Murr

[davehsug]

So this low forms off the Brest Peninsula at 78hrs ambles its way up the Channel heads into the North Sea and at 132hrs decides its bored everyone to death and fills! and then looks like its going to become absorbed by the next Atlantic low! but then decides it wants to keep going all by itself, i mean who writes this rubbish?

Who cares what the rest of run shows its a pile of tosh!

Hi Nick. Have you been checking on NOAAs thoughts today? Which model/ensembles have they been going with?

Thanks

[bluearmy]

any chance of an update re the UKMO 18z run when its out re placement of the trough ?

[cyclonic happiness]

Well as all the Internet sites use GFS data for there forecasts , at least if it does rain it will make there forecasts look better IMO If the GFS us wrong at +24 by such a large margin then there is no point even looking at the rest of the run.

No i meant the ecm/gem/gme....etc, and the metos own, as they never cry snow unless they are almost certain because of all the costs to the country of them getting it wrong.

[NorthNorfolkWeather]

As to that T+60 Fax chart-I would back that rather than GFS and don't worry overmuch about where the so called magic 528DM thickness line is.

That is far less important in frontal situations such as this than the 1000-850mb thickness line. Unfortunately the only real clue we have to that is within Extra and that is from the GFS output.

and PLEASE don;t restart the red herring about lack of data.

Neither NOAA nor UK Met nor ECMWF, if you exchange e mails with them, subscribe to that idea.

John, taking you up on the thickness for the 1000-850mb, what would you expect it to be for snow? I've just looked at the chart on Extra, and it seems somewhere between 1290 and 1320. Can I have a professional's opinion please?

[rich1]

Can't believe how much the GFS has backtracked in the last 2-3 days, at one point we were looking at a serious cold blast from the north, now the northerly has all but vanishesd and we are offered a bit of an Easterley but thats so far out it's hardly worth considering

Looks a somewhat strange pattern and at odds with all the other output so hopefully its wrong

bizarre really but there is a first time for everything that there is so much disagreement here between one and the rest

hopefully its just one of these mad 18z it chucks out from time to time

[kold weather]

Looks as if SW winds may start to take over.

Still very cold for Scotland but fairly near average temperatures for the south on this run. Certainly wouldn't disregard it.

The upper Greenland high is coming SE around 144hrs so that will probably keep a easterly kink to the wind.

However as we can now as see, its utterly vital that we keep the low as far south as possible...its not without support either from the 12z GFs ensembles, the milder runs all had a similar low set-up to the GFS 18z op run.

[johnholmes]

sure

UK Met take 1290 as the 70% prob line for snow to low levels

1281DM is 90%

1293 is 50%

hope that helps

[on the coast]

The GFS has been renamed F.F.S

Totally at odds with every other model-!!! oh well waiting for the 00z to put us out our misery-

S

Yep. Make or break i reckon. Fingers crossed for the ECM.

[BARRY]

So this low forms off the Brest Peninsula at 78hrs ambles its way up the Channel heads into the North Sea and at 132hrs decides its bored everyone to death and fills! and then looks like its going to become absorbed by the next Atlantic low! but then decides it wants to keep going all by itself, i mean who writes this rubbish?

Who cares what the rest of run shows its a pile of tosh!

Well summed up.There is just to much chopping and changing on the Gfs.

[cyclonic happiness]

It's a different evolution at 172hrs from the 12z so how can we take it too seriously, things ony really start to diverge between gfs runs in FI, but this goes awry at 96+ or even before, I really do think this run is a "wobble" run.

Now I'm gonna go back to looking at the ECM because it's showing me what I want to see

[NorthNorfolkWeather]

sure

UK Met take 1290 as the 70% prob line for snow to low levels

1281DM is 90%

1293 is 50%

hope that helps

Yes thanks, all we have to do now is find somewhere on the web that publishes that data ( for free) that isn't the GFS, as the GFS runs were shocking

[Optimus Prime]

It's very strange to see such a huge change from one model to another and from one run to another. But it has happened before and has come to be the trend setter!

We could well have a trend setting in here.

[Geordiesnow]

even at SIX hours, the GFS/UKMO are not in agreement regarding the strength of the low, differences are small but they could be significant.

Says it all really...

By the way, i would watch the 23:57 BBC forecast with interest, as that is the only time you will see the 18Z UKMO being used and it will be interesting to see where they do place that PPN band.

[rich1]

well, its not mild next weekend on this run and its not 'that' far away from a push from the east, cold air massing over there...