Model Output Discussion

[bluearmy]

Dave, yesterdays 12'z started to throw another factor into the mix which is ridges dropping out of the arctic. the longevity of the blocking over n scandi on the 12z ecm run is due to the arctic high ridging south and 'sucking' up the remainder of the siberian ridge which is, at that time, very much on the wain. the continuity of the extended ens to take the p/v out of the greenland area week 2 and replace it with blocking makes me wonder if we could end up with a straightforward slow retrogression from scandi across to greenland at a lattitude that may not be so beneficial to us in the short term whilst the trough heads east at our lattitude underneath the block. the 'fly in the ointment' on ecm latter stages is the AH although the appearance of the ridge off the eastern seaboard above a cut off low is never a bad sign. lots of mixed messages from ecm 12z.

[Frosty.]

I think the best that can be said for the general output this evening is that it's a mess into FI, even more so than normal. The ECM is contending with the block to the east, the AO going negative and also energy going into the southern arm of the jet so anyone calling a mild outlook obviously has a crystal ball at hand!

In terms of the possible snow event for Wednesday this is still a good possibility,the driest air and with the lowest dew points comes off a se flow in winter so this combined with heavy precip and uppers below freezing is perfectly capable of delivering snow. Snow off continental flows has different requirements than that for example off northerly flows.

Hi nick,

Looking at the 12z output, I would think any snow which falls next wednesday would revert back to rain as the fronts move through so any continental air ahead of the fronts would soon get mixed out as the fronts push northeast with places like northeast england and eastern/northern scotland being most favoured for any significant snow, with the strong SE'ly winds there will probably be drifting on northern hills as well, it's just a pity we only look like flirting with the cold air again as the block is just out of reach although it might yet end up a bit further west as we get nearer...hopefully.

[PB22]

I think the advisory is based on covering all bases at this stage, but will be removed nearer the time. The cold air is simply not in place to lead to a snow event apart from at the very highest levels.

Would have to agree at this moment in time Ian. I really cannot see much of a snow event for Wednesday on this evening's charts, except maybe for the hills of northern England northwards. We have the undercutting low:

http://www.wzkarten.de/pics/Rtavn961.html

But the cold air is mostly to the east:

http://www.wzkarten.de/pics/Rtavn962.html

Dewpoints aren't particularly favourable either, with only the highlands at or below 0C:

http://www.wzkarten.de/pics/Rtavn9610.html

Surface temperatures are a bit better for the hills of northern England and Scotland:

http://www.wzkarten.de/pics/Rtavn9617.html

This set-up looks pretty similar on the 12z UKMO and the 12z ECM:

http://www.wzkarten.de/pics/Rukm961.html

http://www.wzkarten.de/pics/Recm961.html

Again, looking at the ECM, the hills across the north are most favoured:

http://en.vedur.is/photos/atlant_evr_hitaspa/100116_1200_102.png

But there's not too much in the way of precipitation around:

http://en.vedur.is/photos/atlant_evr_urkomuspa/100116_1200_102.png

Its still worth watching over the next couple of days, but as it stands at the moment I really wouldn't raise your hopes unless you are up a Scottish hill.

Beyond this, there's reasonable agreement on an evolution back to milder conditions again:

http://www.wzkarten.de/pics/Rtavn1441.html

http://www.wzkarten.de/pics/Recm1441.html

http://www.wzkarten.de/pics/Rukm1441.html

[MR EXTREMES]

Lets hope the Meto have not been too Swift with there warnings or it might be hard too Swallow for some if it goes Tits Up, No doubt you will be chained to your Lamppost Puffin on those Ciggies, let's hope we dont all get Bittern again or some may have a funny Tern. If it comes off lots will be well Choughed!

Paul S

im sorry but that is just the post of the year absolutely funny brillant lmao.

back to models there is clearly confusion with model outputs but from what im seeing they have been pretty consistant and showing a slow gradual return to alantic domination.

im in the strong opion that the alantic will win im 80% certain of this anywhere in the south should be very carefull to get to excited with a snow event unless your on a hill or the futher east you are.

i agree with alot who also think longer term to look to the north and northwest i think the deep cold of recent weeks is past us now but cold snaps pretty likely.

with feb being milder than jan but not blowtorch dominated,

with sw flows still not being the dominating source,

most likely west northwest flow,

which to be honest is great news for those who missed out so far.

im happy as ive said with winter 2010 if we get anything more its a bonus i think it would be silly to ignore the trends that the models are producing for the last few days they say milder than recent days with some unsettled spells also could be pretty gray with drizzle but never blowtourch.

thats all im picking up on theres more outputs trending milder than colder.

Edited January 16, 2010 by badboy657

[Jason T]

So are we saying that netweathers, michael fish ,the M/O and the bbc are wrong from there models as they are all stating cold to return middle of next week,Surely they cant all be wrong ?.

I still think we will all no alot more from the models next tuesday or maybe alittle bit sooner.

[damianslaw]

Short term i.e. up to Wednesday all eyes on the high pressure advecting westwards out of Russia and into NE Europe, it looks like much of the country away from the far west will be pulling in some increasingly colder uppers and also surface cold by Tuesday evening courtesy of a SE flow off the continent and lower dewpoints, it is the depth of cold which will be the critical factor come Wednesday as to where and how heavy any snow develops. It looks like a slightly toned down version of what happened the Wednesday just gone, evaporative cooling aiding the development of heavy snow in the SW and Wales, this time the risk will be further north and east I feel with a stalling front and plenty of undercutting going on. The betting man would probably at this stage say only snow above about 250m, but every chance it will fall at lower levels, its a wait and see.

Beyond Wednesday it looks to me that we will be left in a bit of a no-mans state so to speak with the atlantic just that little bit too strong preventing those heights from advecting westwards, though Thursday could see much of northern and eastern Britain firmly under the influence of those heights to the east. I feel that by the end of next week another front will move in much like what we have seen today, however, at the same time heights will be building to the west and North West setting us up for a arctic blast in the last week courtesy of renewed northern blocking and negative AO. I'd trade in the potential for an easterly for a long lasting northerly any day! (NW bias talking here..).

[kev238]

Yawn- all this analysis for wednesday based on GFS. There was obviously a risk for a snowfall event when the Met Office were issuing an advisory this morning- I doubt they were using the GFS for guidance on this.

The weather in the medium term never looks mild, merely average, and there are hints from ECM that the continental influence may last up to 144 hours.

[MR EXTREMES]

i the jet is going to play a big part in future developments.

we can sit all night trying to get our point of view across which this thread is for,

but in honesty i think people that think cold is just going to digg in and stay here i think will be dissapointed.

alot of people are saying about the gfs its not just this model that is trending towards alantic domination every model including some of the smaller models are all trending this in one way or another.

although this dont mean we can have a arctic blast but looking east or northeast is very much pointless.

also se flow thats predicted for wed looks rather tame to me infact id go as far as to say none event tame.

Edited January 16, 2010 by badboy657

[Ben_Cambs]

The models suggest average, not mild. Regarding Wednesday, theres plenty of factors which will determine the outcome of the event. Im not going to make a judgement atm, as there is plenty of time for the models to change on what they think will happen. But I agree the place now where we are going to get colder weather from is from a Northerly. The Polar vortex really doesnt look like its going to budge atm. Hopefully some displacement will occur sometime soon so we will just see what happens. Though there are signs that we may have a cold spell from the NE towards the end of the month.....

Edited January 16, 2010 by Snowman0697

[Shiny_Bottom_1]

P.S Looks like the Seagulls were right based on the Met O warnings!

Come on Dave Thats a slight stretch to what you said yesterday:

during the winter if you see a mass of Seagulls this is a sign of the weather coming from Siberia

[MP-R]

Sorry to be a pain but does anyone know how to get hold of the archive charts between now and Jan 1st this year. All the ones up to Dec 31st 2009 are available but none after that. Cheers.

[Cloud 10]

Sorry to be a pain but does anyone know how to get hold of the archive charts between now and Jan 1st this year. All the ones up to Dec 31st 2009 are available but none after that. Cheers.

Meteociel - Cartes du modèle numérique GFS pour l'Europe

Not as good as the wetterzentrale ones but better than nothing.

[Thundery wintry showers]

The archives come from Wetterzentrale and are usually updated well into the following month- so once we're a week into February we may see the archives for January 2010.

[MP-R]

Thanks Cloud 10 and TWS!

[Stephen_Mcr]

GFS 18z rolling out.... interesting to see of the end of Jan pattern continues along with some advances on the wed/thu disupute thats been ongoing

[Ben_Cambs]

Yes it is deep in FI in what Im about to post, but this is the model discussion. There has been agreement over the past few GFS runs of a colder spell as we go into the last week of January.

ECM:

Intresting that SST's temps have dropped in the Baltic region, with the Northern Baltic sea starting to freeze over. It will be interesting to see how it will affect our weather and the chances of a North Easterly/Easterly

So Unlikely to be a cold spell until around the 25th of Jan at the earliest

Edited January 16, 2010 by Snowman0697

[phil nw.]

Good model consistency now for next week.

Temps. returniing to near normal with Weds. looking the coldest day as some surface cold is drawn off the near continent as the next frontal system moves across from the West.

http://www.wetterzentrale.de/pics/Rtavn9617.png

http://www.wetterzentrale.de/pics/Rtavn962.png

Maybe a short spell of wet snow for higher ground further North but dewpoints rising as the perc.moves in.

http://www.wetterzentrale.de/pics/Rtavn9610.png

Further out the trend of disrupting the Atlantic trough Eastwards towards the North of Scotland as the Eastern block eases away continues to be modelled.

http://www.wetterzentrale.de/pics/Rtavn2401.png

http://www.wetterzentrale.de/pics/Recm2401.gif

Looks like now we are into a about a week or 10 days of Atlantic driven weather now with temps near average and a quite a few rainy days.

[bluearmy]

http://www.meteociel.fr/modeles/naefs_cartes.php?ech=192&code=0&mode=0&map=1

the 12z NAEFS continue the cold outlook for the end of the month. the various high anomolies in our vicinty all end up in a cross polar block stretching from southern greenland to siberia.

there is an ineteresting feature on the mean uppers whereby a warm sector actually seems defined around the 25/26th to pass nw/se across the western side of the country. at such a long range on a spread of 50 ens runs, thats a pretty strong indicator of something potent closeby. could the cold spell start with a snow event somewhere in the ne quadrant of the UK coupled with a storm affecting the southern half ??

i watch each run and expect a downgrade, but all i seem to see is a steady upgrade.

[kev238]

Well the NAE only goes out to 48 hours from what I can see although i maybe incorrect in this?

However, I am fairly convinced that the Met Office have more access to data than we can cobble together online!

What I am fairly sure of, is that the Met Office dont have an agenda behind their short term forecasts, unlike so many online forecasters who let their preference for a certain weather type cloud their forecasts in the short and medium term.

[weather eater]

Must say I'm rather surprised at the amount of posts in regards a marginal snow event this evening, but hey ho.

For myself, I'm really looking beyond the mid-range to see if we can continue what has been, so far, a fantastic winter. The ECM looks rather random this evening, almost as if each chart has been plucked from past runs in a pick and mix fashion. The GFS is doing what it often does and that's being very consistent up to a point and then being clueless and as each run passes the clueless stage gets closer and closer, a shrinking FI if you like.

The general picture at the moment it seems to me, is that although we will see some interference from the Atlantic it is a far from a foregone conclusion that it will dominate the rest of the month or indeed winter.

Edited January 16, 2010 by weather eater

[The PIT]

Nothing to do with wishing it. Maybe you could elaborate why you think the warning will be gone tomorrow.

What a majority have been missing is between +72/+96 we pick up a colder SE,ly flow.

Now you have to remember you don't need bitterly cold upper temps with a SE,ly. The surface cold and the low dewpoints is the reason why the Met O have put out a warning.

What I find interesting is these past few days much reference has been made to mild and yet here we are with warnings for snow. Also last night a weatherview forecast I watched with RM referred to how uncertain next week is. So some members reading this thread must be confused why there is this discrepancy between the posts on here and the BBC/Met O forecasts. Well I shall answer why this is.

I have maintained all along that when it comes to forecasting using the models you also need to use instinct. Now the reason RM said next week is uncertain is because they also realise that the models might be underestimating the block to our NE and are also using forecasting instinct. Now members such as Nick Sussex correctly mentioned the chance of a snow event on Wed but sadly this has been missed by many because they have been too focussed on the Atlantic returning.

Even I confess the chance of an E,ly is pretty much gone. However the chance of snow events occuring this week remains a possibility. Also how influencial the block to our NE becomes is still uncertain.

The warning will have gone because the met office will have a re-think. If it not it will go either Monday or Tuesday bet you ten virtual pints.

[snowmadchrisuk]

IMO the models look very marginal for Snow on Wednesday at the moment , infact they seem to be getting even more marginal with every run that goes by . I personally think the Met office have put a warning out to early after there mistakes of last week. (Infact it is probably the fact they were grilled for missing the snow event last week that they have issued this warning so early) Currently I do not believe they have more than 50% confidence cause I certainly don't ... As for the models I see it out to +144 as wet and windy with an increasing chance of drier spells in the South and East but still with the chance in the East of overnight Frost and Fog at times.

[J10]

Interesting comment about all of the analysis about the potential snow event with warnings from the Met Office and the fact that most of the analysis been done on here via the GFS.

If we stretch our minds back to the potential Snow event for South Western parts last Tuesday, GFS was having none of it at this range, but there was a Met Office advisory out. In that event it turned out the UKMO was the closest to the mark and indeed the NAE was closer still.

Saying that does the GFS 18Hz give a potential snow event, well IMO a resounding no.

Both thicknesses are not really conducive for snow (sub 528 and 129), are never really over the UK, and these charts for chosen for giving the best thickness levels for us, earlier charts when there was precipitation had higher thicknesses.

However, even though GFS says no, doesn't mean that snow can be ruled out, for the reasons above, although IMO a snow event is not looking that likely and certainly not likely at all for western areas.

[Cloud 10]

Is that a 935mb low i see before me from the 18z?:o

edit. down to 930 in the next frame.

edit. 925mb at +174

Edited January 16, 2010 by Cloud 10

[bluearmy]

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

this T96 FAX screams possible snow to me but i fear that temps on the near continent aren't quite low enough. could be a close run thing though and too many are dismissing it on here this evening too simplistically.