General Model Output Discussion

[TEITS]

ill say it before and ill say it again, it isnt worth worrying about specifics until 48 hours at the earliest. these projections will most likely change.

Don't worry HD is looking at yesterdays.

Amazingly the updated fax charts dismiss the UKMO and go with the ECM!!

http://www.wetterzentrale.de/pics/brack4.gif

Edited December 25, 2009 by THE EYE IN THE SKY

[LomondSnowstorm]

Even here the easterly is marginal with the 18Z! I suspect it will be a bit of a mild outlier, but even so it is a pretty good run overall. At least across central and northern Scotland, the mild spell looks like being pretty much non-existent, with the models having switched to a much colder outlook a few days ago.

[Barb]

Looking through ensembles the 18z is a pretty big mild outlier for the southern half of Britain, if not the very mildest run. A lot of runs still bring the snow over the South, a few barely bring precip to the S coast. So who knows.

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

Looks like a more southerly track, and slightly delayed.

[Cecil Hogmanay Melchett]

SO SORRY Everyone the updated fax charts are a million miles better i was looking at yesterdays.Tonights are MUCH BETTER!

[Barb]

Yes TEITS the latest faxes bear little resemblance to the UKMO output or GFS op. Much better for the south.

As you can see OP is a big mild outlier.

[TEITS]

SO SORRY Everyone the updated fax charts are a million miles better i was looking at yesterdays.Tonights are MUCH BETTER!

No probs mate as i've done that many times.

What I said earlier about the fax charts still stands but blimey that is a stunning fax chart for +120. The 3-5 day Met O forecast should be interesting tomorrow morning. Such a damn shame they release this at 3-4am!

[Cecil Hogmanay Melchett]

No probs mate as i've done that many times.

What I said earlier about the fax charts still stands but blimey that is a stunning fax chart for +120. The 3-5 day Met O forecast should be interesting tomorrow morning. Such a damn shame they release this at 3-4am!

HEHE thankd Dave,

That fax chart is brill,great big high stretching from the mid Atlantic to GReenland and LP moving SE.

I hope ukmo looks like that in the morning!

[phil nw.]

fax charts go with ukmo unfortunately.the angle of attack looks poor,little snow for Eng and wales going by the 528 dam line which is being pushed well into Scotland at 120h

Looks like a Rain to Snow event for many in England and Wales

http://www.meteociel.fr/modeles/ukmo2.php?ech=96&carte=2000

http://www.meteociel.fr/modeles/ukmo2.php?ech=120&carte=2000

Cold air much further South than 18z GFS at same time.

We wont be sure for a couple of days anyway,i shouldn`t think.

Overall a great cold setup going forward whatever the timing of the low midweek,it`s only detail.

[Geordiesnow]

Interesting FAX and should cheer some people up a little bit until tomorrow morning at least.

I too feel the low will be further south than the current GFS and UKMO runs show, although my prediction is really just based on previous runs and the amount of data that actually show the low to be further South.

[TEITS]

The Iceland SLP mean is rising. I checked this yesterday and the mean was 1022mb. Now as you can see this is 1030mb.

http://charts.netweather.tv/ensimages/ens.20091225/18/prmslReyjavic.png

Im probably around 2-3 days away before I properly start getting excited. The only reason im cautious is due to the track of the LP system but I also want to see a decent shaped Greenland HP of 1070mb. Actually around 1050mb will do. :lol:

Night all im off early as I have terrible indigestion due to those horrible sprouts. I can't stand the bloody things!

[kold weather]

The fax charts are great however we see both the UKMo and the GFS op go for a less snowy evolution on both runs, granted the UKMO is far more extreme...but where have we seen the op runs agree whilst the ECm and the ensembles not before recently...yes....with the very cold spell itself.

Saying that they probably are a good bit too far north on todays runs, expect the 00z run to send them back south again, closer to the 12z ECM then the thier own most recent runs.

Anyway a rather great FI tonight though once again we could very well loose it all as the Greenland block isn't too large in coverage...but as long as the jet is surpressed enough then we will avoid another milder interlude like the one we are having now...the Greenland high however is stronger in terms of peak strength which is always a good thing if any attack was to be attempted from the SW...

[rmc1987]

Slough is too far inland from many points - North/South/East/West for showers to be a consistent snow giver.

That's like my region - it's too far south for Northerly and North Easterly showers which burn out over Suffolk and North Essex. Obviously too far East for Westerlies. You don't really get southerly showers. My region is only favourable for ESE showers and when that happens it needs to be cold enough for the snow to settle, which often it is not. Being inland you have the advantage over where I live in colder temps but disadvantage of less showery PPN.

We both need to look out for frontal PPN that sweeps across the country, and we need it cold enough so that PPN falls as snow. You can't miss frontal snow except by bad luck which could affect any region. Frontal snow could come from the North or from the South - the latter in battleground scenarios where maritime low pressure crashes into embedded continental cold spilling over NW Europe.

Thank you for your reply. I've heard reference to N/NE'lys and them not being ideal for my area etc. It would appear I'd require a lot more to happen for snow than other parts of the UK say, is that right?

Although, in summer we get some of the highest temperatures and best of storms from the continent.

Edited December 25, 2009 by rmc1987

[snowmadchrisuk]

No probs mate as i've done that many times.

What I said earlier about the fax charts still stands but blimey that is a stunning fax chart for +120. The 3-5 day Met O forecast should be interesting tomorrow morning. Such a damn shame they release this at 3-4am!

This Chart shows the outlier nicely for the 29th - 1st .

[nick sussex]

Nice to see the fax charts dismissing the ukmo raw output however something caused the model to come out with that run. To be honest though I can only remember one previous time that the ecm has been way out at T-96hrs, in terms of the ukmo here we're not just talking about the northern track of the low but also the trajectory, it just looks all wrong, anyway we'll know which way the trend is going tomorrow with the 00hrs run.

We don't want delays here,the longer the low takes to clear se the more chance another variable might pop up.

[Paul_1978]

fax charts go with ukmo unfortunately.the angle of attack looks poor,little snow for Eng and wales going by the 528 dam line which is being pushed well into Scotland at 120h

Not on the 120 FAX I'm looking at. The 528 DAM line goes right across the south cost of England:

[kold weather]

Of course the issue with the fax charts is there actually isn't all that much precip about, I'd imagine light sleet/snow in the far south from that the main action is if anything shunted a little too far south.

Quite interesting to see the GFS is an outlier in terms of temps, though looking at the ensembles run by run there is a little support for taking the LP further north, just with less mild uppers compared to the 18z...of course quite a few still bring in much colder air quicker.

Anyway in the longer term the ensembles are still a mess, most are cold but with varying styles and quite a few come close to having the whole thing implode on the 2nd/3rd as the upper high drifts too far west and a deep low pressure forms in the Atlantic, very similar to how the devolved into this north-south split this cold spell...

However I really think you can throw those members into the bin that destroy the -ve nAO that quickly, with the global teleconnections as they are, there is no reason why the -ve signal won't last a good solid 10-14 days....saying that with a strong jet stream its quite probable we will see an attack from the SW, but I feel quite confident with a -ve NAO and probably a strong PV lobe over Scandinavia, we should cash in with that sort of solution.

Edited December 25, 2009 by kold weather

[Barb]

Personally I'm backing the WMC:

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

Personally I'm backing the WMC:

Looks good.

I would like to the trough positioned a little further west to allow the really cold uppers to reach us.

[cold snap]

The ukmo fax is much better or is it?

Some people would by the sound of it prefer that lower further north and some further south.

Plain and Simple

UKMO fax would bring less ppn but colder weather

GFS is a marginal situtation which could go either way regarding that low and may bring heavy rain or snow.depending on location.

What would you prefer?

Actually dont answer that as it will go off topic.

But you get the point.

[Geordiesnow]

The ukmo fax is much better or is it?

Some people would by the sound of it prefer that lower further north and some further south.

Plain and Simple

UKMO fax would bring less ppn but colder weather

GFS is a marginal situtation which could go either way regarding that low and may bring heavy rain or snow.depending on location.

What would you prefer?

Actually dont answer that as it will go off topic.

But you get the point.

I'll answer, and i would say i would prefer the FAX chart by miles, if the low is further South, less mild air comes up and 2 more chance of getting a good old North-easterly on this.

Apart from Scotland(which incidentally is quite a snowfeast on the 18Z), for the first part of the run, GFS is the wrong side of marginal. Yes, it improves later on but you don't want delays don't you? You want the cold air over you ASAP. Also, if the low is over the UK and it starts to fill then the north easterlies are less likely too happen.

I would not worry about PPN on the fax chart(not sure how you can tell how much PPN are on FAX charts) because as the ECM and GFS shows, there should be PPN around.

[Barb]

Bit too early to to start talking about exact precip amounts, need to figure out where this LP is going first.

[Guest]

Sorry that this is not a fully model related post, but there was supposed to be a warmer/mild day up into Scotland for Boxing Day with rain and 4C. This has now passed through as a dissolving band of snow which has hit the cold air and given up the ghost. The cold air is deeply entrenched across Scotland and will return south very soon. Every model has consistently kept us Scots in cold air for almost the entire +168 of any run. Tomorrow's "mild" spell has gone away along with any chance of heavy snow for SW Scotland tonight.

Every indication from the models is that while England, and especially the far south, may be milder at times, Scotland is set to bask in temps no higher than 2C for a while to come.

[SnowBallz]

Personally I'm backing the WMC:

looks like mild outlier to me! :lol:

[rich1]

Personally I'm backing the WMC:

Maybe during the ice age you could have seen something like that... could you imagine Gibraltar and Sicily buried under snow...would be unheard of

I sense a slight computer error there