Model Output Discussion

[yamkin]

Always the risk because at the moment I would put the N limit around Lincs. However if the LP exits around Essex rather than Norfolk our locations would miss out.

I don't agree about light precip. Look at the +48 accumlations and you will see between 10-15mm. I have taken tomorrow into account I hasten to add.

http://expert.weatheronline.co.uk/daten/proficharts/en/nae/2010/02/20/basis12/ukuk/rsum/10022212_2012.gif

Latest +48 fax chart.

http://www.meteociel.fr/ukmo/fax/fax48s.gif

The latest fax illustrates why the MetO have issued their latest Advisory Warning http://www.metoffice.gov.uk/weather/uk/uk_forecast_warnings.html

[MKN]

I wouldnt be suprised to see large snowfall totals back by the 18z as it does seem that the gfs is more likely to produce similar synoptics to its most recent run of the same time, rather than the most recent run.

[Harsh Climate]

I wouldnt be suprised to see large snowfall totals back by the 18z as it does seem that the gfs is more likely to produce similar synoptics to its most recent run of the same time, rather than the most recent run.

I agree, I expect the 18z to show some big snowfalls for midlands/northern england. Best place for the gfs 12z is the bin

[kold weather]

Well like yesterdays 12z the GFS is well north, the ECM is something of a synoptic fusion yet again, a stronger low however means more milder air into the circulation of Wednesday's system, BUT the ECM is quite keen to give the Midlands northwards some decent falls...

Also looking at the 12z GFS, I'd be shocked if that came off, no doubt IMO that won't be happening, if anything the trend hasa been to the south recently...so much so Monday is now really in doubt.

[Geordiesnow]

I agree, I expect the 18z to show some big snowfalls for midlands/northern england. Best place for the gfs 12z is the bin

I'm not quite sure why people are so dismissive of the GFS 12Z output for? It probably is being over progressive as TWS says but it could be onto something?

Not to sure what to make of the ECM 12Z in all honesty, it could deliver s snow event to central parts of Northern England and Scotland but it looks marginal for those in the East due to the wind off the North Sea.

[Thundery wintry showers]

Looking at the ECM it has the negative NAO fading out as the main block retrogresses westwards from Greenland into Canada, leaving Britain exposed to the full force of the Atlantic with pressure rising over Europe. The ECM is a more plausible evolution to milder conditions IMO, slowly warming up with the main track of frontal systems heading northwards, as opposed to the sudden switch on the GFS.

[kold weather]

I wouldn't discount it either but with these lows the models tend to over do them and they have to trend the whole lot further south with time, just like we are seeing with Monday. The ECM once again is a middle ground between the models. Probably wrong side of marginal for a good part of Midlands, lots of snow for those in the north though on this run thats for sure.

For now people its best we don't look beyond 48hrs with any confidence at all, because even small changes like a tiny secondary depression will make a huge difference!

[johnholmes]

-ve NAO is simply that pressure is higher over Iceland than it is over the Azores-at T+240 its higher by about 5-10mb so technically at that time its still a -ve NAO!

[bluearmy]

i find much of the 12z output unconvincing. dont know what it is but the runs appear to chop and change in their direction of evolution. i think i'll hang on for another couple of runs before firming up on my thoughts from this morning. there may be changes afoot from a less cold outlook which seemed on the cards earlier. the upstream pattern is set to move east and nick s was rather confused as to why it wasnt showing downstream. it looks as though it might be beginning to.

[Thundery wintry showers]

-ve NAO is simply that pressure is higher over Iceland than it is over the Azores-at T+240 its higher by about 5-10mb so technically at that time its still a -ve NAO!

True, so the bit about "the negative NAO fading out" isn't wholly accurate- though the block certainly shows strong signs of retreating westwards (in stark contrast to the suggestions of the whole pattern shifting east!).

ECMWF doesn't look particularly warm to me in its later stages- just close to the long-term average although even that will be a shock to many of us after the persistent below-average temperatures of recent times. Probably dull and wet with plenty of frontal depressions about.

[kold weather]

Just seen the 12z NAE, suggesting snowfall for Monday, I'd imagine evap cooling during the morning hours plus the slight slant of the low which helps to drag colder air on the western edge because the low keeps its identity for long enough, thats going to make such a big difference to be honest!

Still the NAE is suggestive of two events in the next 48hrs and if that happens if the worst does happen on Wednesday, so be it!

[BornFromTheVoid]

By T72 the big three are all quite similar for the British Isles, though even by this stage, the GFS has much higher pressure over Greenland

By T120 while there is some differences between the UKMO and the ECM, the GFS is clearly out on its own. The small differences in the positioning of the low between the UKMO and the ECM still means all the difference with whether you get snow or rain.

Basically, no point in looking beyond T72 for now.

[phil nw.]

Just to confuse you even more here is the GEM.

Monday LP is much further S.

http://91.121.94.83/...un/gem-0-48.png

Next LP tracks further S than the other models suggest.

http://91.121.94.83/...n/gem-0-102.png

Next LP is even further S!

http://91.121.94.83/...n/gem-0-144.png

Conclusion is its a waste of time sitting here looking at these models.

You`re doing some sterling work viewing all these models Dave.I must admit i have tended to skip through them lately.

I am finding all these inter run short term changes exhausting to keep up with.

Having said that i can see signs of the status quo starting to breakdown next week as we can`t keep this cold indefinately without re-enforcing of the cold uppers and there`s no sign of that now.

My general overview is 12z output wants to shift the Cold Upper Trough gradually further North and West and mixing out the colder air as the week goes on,especially in the South East quadrant..

http://www.wetterzentrale.de/pics/Rukm1201.gif

http://www.wetterzentrale.de/pics/Recm1201.gif

http://www.wetterzentrale.de/pics/Rtavn1201.png

The latest fax for T72hrs. shows well the push from the South behind the occlusion ,with that Low to the South West modelled to move towards us during the week.

http://www.meteociel.fr/ukmo/fax/fax72s.gif

With no re-enforcing of cold from the North East modelled, inevitably daytime temps. will creep up as the cold upper pool gets more and more modified by the continual cyclonic activity.

I get the feeling that Sundays and Mondays Snow events currently modelled for my area could be the last ones this far South, in this current pattern.

I am not saying that Winters over but i believe this current cold setup is running low on fuel now.

[kold weather]

Ensembles are coming into better agreement about the pattern ,the 12z GFS is more or less an outlier...

They do have a big difference with regards to the northern extent of the front, some take it towards Scotland, whilst a couple don't even get Mondays front into the south yet alone into the Midlands.

Still as I've said, best not take anything outside 48hrs too seriously to be honest!

[Frosty.]

A wintry ECM 12z for northern britain for the whole run but becoming somewhat less cold across the southern half of the uk with time. I really have no idea which model currently has the best grasp of the situation but I would still expect the change to less cold to be a slow one with scotland remaining locked in cold and wintry conditions at least until the beginning of march.

[Tim Bland]

I think giving the volatile behaviour of he lows the met office are currently covering all bases. Look at today for instance, the front was forecast yesterday (by GFS and NAE etc)to head across to the wash with SE being too far south to see any percipitation. The outcome was that it went along the chanel with a few convective showers across the region.

Going by this the low on monday could push up to yorkshire or stay in the extreme south. The warnings now extend right down to Southampton! Even the NAE has the snow only as far south as Northamptonshire!

[TEITS]

You`re doing some sterling work viewing all these models Dave.I must admit i have tended to skip through them lately.

I am finding all these inter run short term changes exhausting to keep up with.

I get the feeling that Sundays and Mondays Snow events currently modelled for my area could be the last ones this far South, in this current pattern.

I am not saying that Winters over but i believe this current cold setup is running low on fuel now.

Cheers for your comments mate.

I agree beyond midweek I feel the risk is going to move N. However in saying this why do I have this nagging doubt that the LP on Monday will be further S than the NAE suggests. I also feel the LP on Wed will also be slightly further S. However like I say after this I feel this risk will move further N.

Some will be surprised in what im about to say but in some respects I would welcome a spell of very mild SW,lys in the model output.

[Cheese Rice]

I agree beyond midweek I feel the risk is going to move N. However in saying this why do I have this nagging doubt that the LP on Monday will be further S than the NAE suggests. I also feel the LP on Wed will also be slightly further S. However like I say after this I feel this risk will move further N.

I think the general trend is to push the lows further south, that is usually the case with these lows. Going by past experience even if the models predict further north they usually don't track any further north that the midlands/Yorkshire,

[MR EXTREMES]

I think the general trend is to push the lows further south, that is usually the case with these lows. Going by past experience even if the models predict further north they usually don't track any further north that the midlands/Yorkshire,

as ive been saying for the last few days the trend was pointing towards low pressure system one after another shifting futher north as each depression passes through i fear monday maybe tuesday will be the last really snow event for sometime.

i think every models knows it wants to bring thease in but on what track?

i think the portsmouth advisory by the met o is somewhat very confusing indeed,

i cant see that advisory being there tomorrow night.

i think for some reason the ecm is safe bet because its in the middle ground,

but there is certainly some wet windy and milder weather on the way mid week onwards i dont buy into the models are wrong theory.

theres no hope casting from me just what im seeing from the model perspective and slow evolution is certainly the way its heading.

so perhapes someone could answer is the east based nao now a no go?

[MR EXTREMES]

if you take all 3 of the main models theres no getting away from the fact that they have there own idears cold air is not deep around the uk and the cold air that was to our very north and into scandi has slowly been retreating,which is ofcaorse normal for this time of year,

but my thinking has not changed for sometime now im not saying it will be blowtourch but it is already feeling milder here at times i expect this to extend futher north over time more so mid week onwards.

the 3 models have low pressures moving in on the model 1 its near the south coast.

on model 2 midlands,

and then model 3 southern scotland/northern england then take the lesser models along with the ens and you do see where its all heading.

as for what type of weather i like well its extremes so heat cold thunder gales the works.

Edited February 20, 2010 by grab my graupel

[bluearmy]

as ive been saying for the last few days the trend was pointing towards low pressure system one after another shifting futher north as each depression passes through i fear monday maybe tuesday will be the last really snow event for sometime.

i think every models knows it wants to bring thease in but on what track?

i think the portsmouth advisory by the met o is somewhat very confusing indeed,

i cant see that advisory being there tomorrow night.

i think for some reason the ecm is safe bet because its in the middle ground,

but there is certainly some wet windy and milder weather on the way mid week onwards i dont buy into the models are wrong theory.

http://en.vedur.is/weather/forecasts/atlantic/#type=prec

ecm 12z op is about as supressed as any model.

[conor123]

Will the 18z make it 3 evening's in a row of showing Snowmadgeddon? were find out shortly.

[thegreat316]

as ive been saying for the last few days the trend was pointing towards low pressure system one after another shifting futher north as each depression passes through i fear monday maybe tuesday will be the last really snow event for sometime.

i think every models knows it wants to bring thease in but on what track?

i think the portsmouth advisory by the met o is somewhat very confusing indeed,

i cant see that advisory being there tomorrow night.

i think for some reason the ecm is safe bet because its in the middle ground,

but there is certainly some wet windy and milder weather on the way mid week onwards i dont buy into the models are wrong theory.

theres no hope casting from me just what im seeing from the model perspective and slow evolution is certainly the way its heading.

so perhapes someone could answer is the east based nao now a no go?

Indeed as we head towards spring it will get warmer. As we head towards summer it will get even warmer, and by next winter it will get cooler, thats the way i see it, no hopecasting from me...... eventually your call for it to get warmer will be right i have no doubt.

It does seem as though each succesive lp system could attack further and further north introducing the long term trend for a milder uppers. Even when we eventually fall into a system of average temps, there still could be nice blast of easterlies in early spring. A few GFS FI evoloutions show how this could progress.

18Z soon to roll out, hopefully these LP systems are further south like the UKMO 12Z and the colder uppers stay further south.

[bluearmy]

latest NAEFS develops an marked omega block to our west first week march. blocking anomoly becomes strong in the iceland area and the jet retreats back down to iberia, having made it as far north as central france. a cool northeasterly mean flow is the result by the end of the run (T384). i guess this need to be looked for on the GFS fi - currently seems keen on a scandi high but this may well trend further west, given this latest run.

[MR EXTREMES]

ok heres some charts to futher explain what i mean there all around 96h to 120h and im not suggesting that futher out cold might no return because i dont want to make this thread explode with rage lol.

anyway thease are all the model outputs and i do tend to look for the 0 line.

gfs 96h

gem 96h

nogaps 96h

jma 144h

ukmo 72h

ecm 144h

they all look like there trending towards different weather type rather than cold snowy.