General Model Output Discussion

[Snowaddict]

Excellent 12Z GME to T+66..

GFS to T+30.. If you compare with T+36 and follow the isobars..

Everything is slightly further south.. By about 50 miles from what I can see at T+30..

[Matty M]

Another 50 mile push south by the GFS, we will probably see another 1 or 2 of these movements between now and the morning.

[rmc1987]

Ian Fergusson might be onto something in his last paragraph. Take a look at what Joe B from AccuWeather has just updated his European Blog........... (MODS hope this post is ok)

THREAT OF HEAVY SNOW SHIFTING SOUTH

Here is part of his blog...........Enjoy

The UKMET is considerably farther north than the European on this, which shifts to the main threat to southern England, including the threat of heavy, disruptive snow around London. It bothers me in looking at the map this morning, that sneaky chilly air has pushed into southeast England and an adjustment south in the storm track is needed. How much is still a question, but it does appear there is a threat for heavy snow before the core of cold presses south. The opening week of the New Year, and this is what this post and the one before are mere offshoots of, the idea over a week ago, is going to be very cold across much of Europe north of 40 north, probably harsher than a) the December outbreak and last year's cold outbreak.

Mmmm I'm not too sure what the models are showing but isn't this a warning to cover 'themselves' at UKMET?

[Snowaddict]

Another 50 mile push south by the GFS, we will probably see another 1 or 2 of these movements between now and the morning.

Yes Matty, absolutely definitely..

That's 100 - 125 miles in two runs..

If you compare the precip charts on Meteociel, now suggesting possible snow event a good 70% in line with the latest NAE model guidance.. Regardless of the rest of the run.. Up To T+36.. GFS is trending south, colder air south etc..

SA

[03jtrickey]

GFS is sneaking its way further southwards, at least in terms of the 0C line!

12Z http://charts.netweather.tv/gfsimages/gfs.20091228/12/30/h850t850eu.png

6Z http://charts.netweather.tv/gfsimages/gfs.20091228/06/36/h850t850eu.png

[Snowaddict]

I've seen enough in the early stages to sugges that GFS is definitely backtrack, but only slowly..

It seems to me that GFS has been underestimating the strength of the Greenland Block..

[nick sussex]

At T-60hrs the gfs 12hrs run is about 200 miles further south in terms of the zero upper air temps for the same time on the gfs 06hrs run! Looking very much like the ecm 00hrs run now.

Edited December 28, 2009 by nick sussex

[Eugene]

Pretty flabbergasted people are saying GFS 06Z is poor, within the high res it shows potential for the cold spell to last for another week after this week why do people concentrate so much on extreme FI esp on unreliable runs like GFS 06Z in low res.

A week ago or so ago we were supposed to be in a mild westerly cyclonic flow this week into next.

http://www.wetterzentrale.de/pics/Rtavn1801.png

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

It's easy to see the downward movement on the 0C isotherm charts:

6z:

12z:

[Snowaddict]

Id be happy were gfs have the precipitation all of ireland and n ireland get snow

12Z NAE to T+48 suggests that some snow is possible in Northern Ireland..

Meanwhile GFS @ T+66 suggesting a snow event for Ireland...

All extremely marginal but GFS has clearly trended further south, albeit slightly, when you compare it to the 06Z run and especially the 12Z run..

SA

[Matty M]

The models paint a potentially severe snow storm scenario for a large portion of Ireland and Wales.

The low stalls and bands of snow sweep west across Ireland for a very long period of time.

Huge quantities of snow are possible.

A severe weather alert should be issued, as this could be potentially the biggest fall of snow in some

areas in Ireland for a very very long time.

[TEITS]

Looking at +78 and there is a definate shift S compared to the 06Z and no this isn't my imagination!!

[nick sussex]

Game, set and match to the ecm! this is a major climbdown by the gfs and it also fills that nuisance feature near Norway quite quickly here also.

[Snowaddict]

The models paint a potentially severe snow storm scenario for a large portion of Ireland and Wales.

The low stalls and bands of snow sweep west across Ireland for a very long period of time.

Huge quantities of snow are possible.

A severe weather alert should be issued, as this could be potentially the biggest fall of snow in some

areas in Ireland for a very very long time.

I agree that it's a possibility Matty, although I would like to see another 100 mile shift southwards on GFS to be more confident.

12 NAE has widespread snow over Ireland at times over the next 48 hours. It would seem that significant accumulations are possible on high ground.

I agree though, the potential is there for a snow event.

[Rollo]

Game, set and match to the ecm! this is a major climbdown by the gfs and it also fills that nuisance feature near Norway quite quickly here also.

Surely the question has to be asked--why oh why has it taken this length of time.

[on the coast]

Game, set and match to the ecm! this is a major climbdown by the gfs and it also fills that nuisance feature near Norway quite quickly here also.

Yep stubborn to the end wasnt it, expect another small change to the ECM when the 18z comes out too.

[Bolton67]

Game, set and match to the ecm! this is a major climbdown by the gfs and it also fills that nuisance feature near Norway quite quickly here also.

Overall in your opinion the ECM the better model?

[SteveB]

Yep stubborn to the end wasnt it, expect another small change to the ECM when the 18z comes out too.

That's if the ECM doesn't change, model of the moment seems to be GEM.

[West is Best]

Big backtrack by the GFS with the centre of the low now no longer making landfall. Precisely what GEM progged overnight. Well done to ECM and GEM by the looks of it ...

We're in for a heck of a cold reload here folks. Somewhere, perhaps several places, is/are going to cop a significant snowfall.

We await ECM/GEM/UKMO with great interest.

[casparjack]

Game, set and match to the ecm! this is a major climbdown by the gfs and it also fills that nuisance feature near Norway quite quickly here also.

I think it's facinating how the GFS has slowly retreated back to the default setting as shown by the Euro models...

[johnholmes]

I'll do an update on the blog about the next 48 hours with a look into the start of the New Year early this evening.

Just as a comment about those not accepting what the northern hemisphere markings show.

You are of course entitled to your opinion but do take my word for it-ECMWF on 80% if not more of occasions is superior to GFS and the other models.

It not only does better in this area, as it should, talk to the people on the forum who Storm chase in the US, and ask them which model they have most faith in and also the US forecast centres say in the summer, let alone now if you read the NOAA daily 6-14 day outputs.

Of course it will be wrong at times, but its less wrong and far less often than GFS is.

Don't misunderstand me, GFS at times can be stunningly accurate from a long way out but overall ECMWF is the better of the two.

As to EC and UK Met, well they are only comparable from T+72 as the EC model was specifically set up to try and improve forecasting from T+72 out to T+240. UK Met only goes, that we see, to T+144.

Comparing GFS and UK Met models in the T+00 to T+72 time frame then its about 80% again in favour of UK Met v GFS.

Not on memory but on hard fact over the past 5 years with data stored to show it.

Also always look at the UK Met Fax charts. Believe me, from many years experience, the man/model mix is almost always superior to the model on its own.

[Richard Lake]

Well now that Models are depicting snow/rain for the SW and SE within the next few days and there are separate threads for this purpose. Does anyone have an idea what will follow this?

[SMU]

http://91.121.94.83/modeles/gfs/run/gfsnh-0-126.png?12

Finally a chart & a run I am happy with from the GFS- a long time coming-

12z Shift in the mid term around 75 miles south- this is imperitive to get the cold air in the south earlier on..

S

Edited December 28, 2009 by Steve Murr

[izi]

the gfs still shows the precip moving much further north than ukmo does tho, doesnt it? (yes novice looking)

[johnholmes]

Overall in your opinion the ECM the better model?

see my later post and yes, usually by quite a margin-BUT the trick is knowing WHEN GFS is more right!