General Model Output Discussion

[Harsh Climate]

Latest gfs looks like a huge upgrade for the east midlands towards london and a huge downgrade for the likes os south east wales/west midlands...

http://www.wetterzen...cs/Rtavn184.png

http://charts.netweather.tv/gfsimages/gfs.20100105/06/18/ukprec.png

looks like the heaviest preciptation/developing low may be further east now

Edited January 5, 2010 by Jed Bickerdike

[swilliam]

Latest gfs looks like a huge upgrade for the east midlands towards london and a huge downgrade for the likes os south east wales/west midlands...

http://www.wetterzen...cs/Rtavn184.png

http://charts.netwea...6/18/ukprec.png

looks like the heaviest preciptation/developing low may be further east now

I would not bother with the GFS for this short timescale and detailed ppn. The latest (06Z) NAE is just out and is still showing the ppn intensifying over CS England and the West country

Still over 20cms snow predicted

[TEITS]

I would not bother with the GFS for this short timescale and detailed ppn. The latest (06Z) NAE is just out and is still showing the ppn intensifying over CS England and the West country

Still over 20cms snow predicted

I disagree.

During the cold spell last Feb I found on a few occasions the Met O disagreed with the GFS charts and the GFS was proved correct. I would never go against the GFS precip charts from 0+ to +48.

As i've said in the regional thread this will come down to nowcasting.

[Frosty.]

Awful isnt it?

Compared to how the ecm currently evolves through next week...yes it is although it would still be a cold outlook relative to the typical british winter which this most certainly isn't.

[mcboz]

GFS has the attached percipitation chart for around now, but it's currently just started to snow in Reading. Tempreature is - 1.1.

Looking at the latest GFS run looks as though could be a fair amount of snow this evening / night.

The trend for the next few days and into next week is looking amazing, be interesting to see how it evolves!

[Eugene]

Latest gfs looks like a huge upgrade for the east midlands towards london and a huge downgrade for the likes os south east wales/west midlands...

http://www.wetterzen...cs/Rtavn184.png

http://charts.netwea...6/18/ukprec.png

looks like the heaviest preciptation/developing low may be further east now

Wow as i was not expecting much snow today into tomorrow if any at all i am still amazed how much its changed since yesterday, no warnings yesterday for the west midlands but now plenty of them out, massive upgrade to me.

Will the cold ever end ECM 00Z and the ensembles suggest NO

Edited January 5, 2010 by Eugene

[Cheshire Freeze]

Just checked the ensembles on meteociel.....they are a downgrade with the ensemble mean regarding 850 temps at 180 hrs much higher than the previous run. Doesn't really fit with the ECM and UKMO, someone has got it badly wrong

FWIW i don't rate the GFS at all since its switch to the old parallel run, seems even less accurate than the old GFS, if it flips in this scenario I really don't think I will be using it again. Fairplay if it has the evoloution correct though

Aaron

Edited January 5, 2010 by CreweCold

[Nick B]

Just checked the ensembles on meteociel.....they are a downgrade with the ensemble mean regarding 850 temps at 180 hrs much higher than the previous run. Doesn't really fit with the ECM and UKMO, someone has got it badly wrong

FWIW i don't rate the GFS at all since its switch to the old parallel run, seems even less accurate than the old GFS, if it flips in this scenario I really don't think I will be using it again. Fairplay if it has the evoloution correct though

Aaron

At that distance better to look at overall 500 hPA trends. 850's best within 120 hrs if you want to be discussing anything reasonably reliable...

[Shiny_Bottom_1]

I disagree.

During the cold spell last Feb I found on a few occasions the Met O disagreed with the GFS charts and the GFS was proved correct. I would never go against the GFS precip charts from 0+ to +48.

As i've said in the regional thread this will come down to nowcasting.

At the moment though Dave, I would go against the GFS. The Op run appears to always be at the higher end of the ppn quantities, and for today (based yesterday) it was an outlier for some areas further east.

I agree about not discounting it, as your last reason is the exact way forecasting needs to be at the moment.

[Frosty.]

Quite a progressive GFS 06z with the very cold block being pushed away eastwards and the more typical atlantic weather moving in, hopefully the 12z will be different.

[Cheshire Freeze]

At that distance better to look at overall 500 hPA trends. 850's best within 120 hrs if you want to be discussing anything reasonably reliable...

It's the evolution of the GFS and its member that is concerning me. Going by the GFS we will be over the worst of this spell by the end of the weekend. The ECM is a stunner and its ensembles are consistent, we just need to see this consistency keep going. I am leaning towards the ECM......just. It could all implode on its next run though. I'm looking for the 12z to give some general signs that it is moving towards the UKMO and the ECM thoughts

Aaron

[sandstorm2]

I'm a bit of a novice at reading the charts but it looks like out of the GFS ECMF and UKMO that the GFS is the odd one out wanting to bring the atlantic back in very quickly.

SS2

[wysiwyg]

I think it's fair to say that we have seen these over-progressive 06z runs on a fair few occasions. I read somewhere that it has issues with data collection particularly N of say 60N and as that is the general direction the weather is coming from then I guess this may just be one of those runs. Given the wider teleconnections I would say that the current latest ECM medium range is just about favourite for me in extending the cold spell out past the weekend. I think it's reasonable to expect some milder incursions from the west at times but I suspect that out past 100 hours all the models will be struggling to pinpoint the relative position of any northern blocking and this will ultimately be the key as to just how cold the UK remains in general.

[swilliam]

I disagree.

During the cold spell last Feb I found on a few occasions the Met O disagreed with the GFS charts and the GFS was proved correct. I would never go against the GFS precip charts from 0+ to +48.

As i've said in the regional thread this will come down to nowcasting.

I hope you are right - it would be much better for me. It will be an interesting comparison after the event.

[johnholmes]

For what it is worth to anyone-in my view there is no chance that the weather will remain anything other than very cold over the weekend.

As to snow-then look no further than what is happening this morning.

We are all trying to play catch up-in fact the 06z/Extra may well have the first 12-18 hours better sorted than any of UK Met outputs. Or that is the way it seems at the moment.

The developed low, which seemed to give birth over Lancs is tracking SSE BUT the radar clearly shows that the precip is winding itself around the northern flank and not seeming to want to move very far very quickly.

I would imagine that UK Met should be issuing amends/updates as their forecast for this area for this morning was fairly wide of the mark.

I've just commented into the mod thread that their mainly light snow has accumulated a slight covering of 8cm here. Probably the most for Doncaster areas in well over 20 years.

Edited January 5, 2010 by johnholmes

[TEITS]

I hope you are right - it would be much better for me. It will be an interesting comparison after the event.

Certainly fasinating to watch it develop later on.

Looking at the updated +24 fax chart and we can see another band of snow moving into E Midlands/Norfolk tomorrow morning which moves S during the day.

http://www.meteociel.fr/ukmo/fax/fax24s.gif

The GFS supports this at the moment.

Edited January 5, 2010 by THE EYE IN THE SKY

[Optimus Prime]

We need to make sure we're nopt looking too much into individual runs. Every run will change and lets be honest the chance of things warming up next week stand fairly small to me.

GFS has done really poor this winter so far. ECM is the one to watch but I certainly feel the GFS may eventually get it right. I guess the main problem with the GFS is that it has too many runs in comparison to ECM and UKMET.

[NorthNorfolkWeather]

Looking at the FAX charts I keep feeling that everything is progged slightly too far East. Gut feel as much as anything makes me think that London will get between 2 and 5 cm of snow, while Reading, Swindon possibly as far West as Bristol may get up to 20-25cm. The Valleys of South Wales also look as though they could get a pasting as the front develops.

Tomorrow will be rather more interesting for the East, although probably will be better In South Suffolk/Essex and all points south rather than Norfolk.

Scotland in the Meantime is in a very slack NE flow, so snow on Eastern coasts today, a minor front coming in to the far north tomorrow, and some very cold temperatures

Edited January 5, 2010 by NorthNorfolkWeather

[mountain shadow]

GFS has been particularly useless in the >T+72 with the upper pattern, and can be ignored, particularly the 6z and 18z. ECM consistently delivering and is the one to watch in the medium term.

[BLAST FROM THE PAST]

I spoke the other day and many have too, that in situations like this expect upgrading. The SE is likely to miss the worst of this weather but areas SW of London should join in the snowfest...this time round [i've got to explain to my 4 year old who is expecting snow!!!]. As the easterly develops then troughs will b ring bands of organised and heavy showers to the SE. Those concerning themselves with the GFS....too soon and ECM is my preferred option...however, less cold is likely at some stage prior to a reload of bitter cold...but we are still talking 10days to 2 weeks of very cold weather yet!!!!

BFTP

[Timmytour]

Taking the situation as it is right now, which of the model runs from this time last week came closest in its +160 forecasts?

[Michael Fishermans Friend]

Quite a progressive GFS 06z with the very cold block being pushed away eastwards and the more typical atlantic weather moving in, hopefully the 12z will be different.

I thought the 6z GFS was a slight upgrade on previous runs to mid-range, the block continues with a slight easterly by this time next week there after we see more of a push from the Atlantic, will be interesting to see if the GFS gently heads in the direction of the ECM.

[Eugene]

The facts are GFS 06Z is a very cold run mostly becoming less cold towards the end but still cold, can't believe people actually believe a strong high to our NE is going to just get blown away so easily not in this winter anyway its different.

[kold weather]

If anything the models have moved towards GFS again at 96hrs, with the idea of a flabby easterly rather then the potent one suggested by UKMO/ECM yesterday, still will drag in very cold air though below 700mbs but not going to have any real depth to it...

The longer term evolution however is still at odds. The GFS still wants to blow up the Atlantic low upto 960mbs whilst all the other models are weaker with this feature. The other models split some of the energy off into a cut-off low. Given the current set-up I'd be surprised if the GFS soikution is right simply because it does what it always does and goes a little OTT with the low.

Even on the more progressive GFS run we still have severe cold until the 15th.

[swilliam]

Certainly fasinating to watch it develop later on.

Looking at the updated +24 fax chart and we can see another band of snow moving into E Midlands/Norfolk tomorrow morning which moves S during the day.

http://www.meteociel.../fax/fax24s.gif

The GFS supports this at the moment.

Maybe the MetO are supporting the GFS as well - they have just issued a warning for Northamptonshire (and other areas - including Peterborough) possibly more the 20cm of snow this evening.