Model Output Discussion

[kold weather]

Very mixed ensembles, esp further south where some runs have much milder conditions in by the end of the weekend whilst some runs have colder air coming back in with LP attack from the SW, once again the key in pretty much every evolution is the low/upper low that forms just to the west of the UK, where that tracks will make a massive difference...

As per before, Scotland has the greatest risk and the risk for N.England looks decent, hopefully if it all isn't good enough for the south, at least lets get a LP across the UK so places further north can have some fun.

[Guest North Sea Snow Convection]

I think we are in a similar situation to a couple of weeks ago, in at least some ways, in that the real outcome is still not showing. I said then that the ensembles were a very poor guide to what was going to happen and I would say the same now. Nick S has outlined some of those reasons - once again I think that people should not read too much into the GFS because i think it is wrong for the medium and longer term.

And I am not saying that because it is less favourable for the south, purely because I think the GFS has picked the wrong signals, which will have repercussions for the whole of the Uk and could in the long term make the north even colder than it is suggested to be, as well changing things in the south!

[kold weather]

Models looks decent for the north of the UK, at least with the set-up that the models are prediciting there will be plenty of disturbances about, its just a matter of how far south the cold air gets before each disturbance/low pressure system comes in...

Quite a few poor runs from the GFS ensembles for the south it has to be said, some real amazing ones for the north, some would give Scotland a very noteable snow period...

[Nick L]

Models looks decent for the north of the UK, at least with the set-up that the models are prediciting there will be plenty of disturbances about, its just a matter of how far south the cold air gets before each disturbance/low pressure system comes in...

Quite a few poor runs from the GFS ensembles for the south it has to be said, some real amazing ones for the north, some would give Scotland a very noteable snow period...

KW - I tried contacting you via PM but your inbox is full, to put it short somebody has posted a comment on my profile I am not happy with, sorry about this but you are the only mod online!

[Frosty.]

yes its also on the ukmo it is shifting west looks very cold aswell.

could someone deal with the troll.

I sometimes wish the ukmo went further than just six days but then we have the meto updates and I agree the ukmo 12z run has more promise so hopefully the ecm won't disappoint later. A wintry week ahead, especially further north.

[LomondSnowstorm]

Anyway, the 12Z looks slightly less good than the 6Z for snowfall in Scotland, but these things keep changing on every run and the main thing is that uppers are cold and low pressure is in charge.

[cooling climate]

I think we are in a similar situation to a couple of weeks ago, in at least some ways, in that the real outcome is still not showing. I said then that the ensembles were a very poor guide to what was going to happen and I would say the same now. Nick S has outlined some of those reasons - once again I think that people should not read too much into the GFS because i think it is wrong for the medium and longer term.

And I am not saying that because it is less favourable for the south, purely because I think the GFS has picked the wrong signals, which will have repercussions for the whole of the Uk and could in the long term make the north even colder than it is suggested to be, as well changing things in the south!

The signal for blocking to the northeast and over Svalbard is one to do with the MMW which

perhaps the models are not picking up correctly perhaps.

This blocking should allow even stronger blocking over Greenland especially if NOAA are correct

with trough amplification over the eastern US.

The models are really making a meal I think out of the lows over the UK this week and by the

time we get to Wednesday the models will be looking very different to what they do now.

I am very hopeful the ECM tonight will develop this blocking that we (several posters) have

been discussing.

[J10]

Quite a number of off topic posts have been deleted, please try to stay on topic.

[cheeky_monkey]

To me the GFS has been very consistent in what it has been showing for days now..if anything it wants to keep pushing the cold further north and west slightly on each run..the high over the svalbard region never really moves south from there and hasnt looked like doing so either.

I dont see how the cold pinned to the north is going to come south esp with the pressure building over north east canada and western greenland?

[remymartin]

The gem model has the low a bit more south.

but then creates a low to the west of ireland.

[TEITS]

Well if we are going to pull in a colder NE/E,ly flow we're going to have to rely on the LP to our SW tracking to the S.

However I do fear the possibility of mild SW,lys!

[Cecil Hogmanay Melchett]

Well if we are going to pull in a colder NE/E,ly flow we're going to have to rely on the LP to our SW tracking to the S.

However I do fear the possibility of mild SW,lys!

Im not at all keen on tonights ecms dave.doesnt look overly cold to my eyes!

[Tom D]

This set up reminds me of the one the models struggled with before the northerly last weekend and the subsequent easterly.

Due to a trough over Scandinavia all the lows and shortwaves coming across the Atlantic were being taken northeast across the UK into northwestern Europe. It turned out the GFS in particular (but also the ECM/UKMO at times) overdid the southwest to northeast track of the systems, and I remember TEITS pointing out shortly before it all fell into place that the shortwaves could also slide southeast over Spain and the Med.

It's a messy set up and it may be that for the south in particular it could turn milder before another cold spell from somewhere comes along again.

[Snowyowl9]

Well if we are going to pull in a colder NE/E,ly flow we're going to have to rely on the LP to our SW tracking to the S.

However I do fear the possibility of mild SW,lys!

Agreed this run gives a ridge of HP over Spain the same as UKMO and so the low ends up further north.

Different to last nights ECM.

I think everyone waiting for the T192 chart to come out to confirm that.

[TEITS]

Im not at all keen on tonights ecms dave.doesnt look overly cold to my eyes!

Such a tricky call because we could have either cold NE,lys or mild SW,lys. All depends on that LP.

If you took the model output as gospel you would have to favour the mild SW,lys. However as we have seen the models sometimes track these LPs NE when infact the reality is a spitting of the LP tracking SE!

As the cold air is to the N of the LP then I would say Scotland is most at risk of remaining cold followed by N England.

I will add the GEFS ensembles suggested this a few days ago. Amazing to think the ECM has backtracked towards some of the GEFS members. Funny old game this model watching is.

[Guest]

I can't work out why some members keep saying "the models are struggling" - they've been showing almost exactly the same weather for this week coming for about 5 days now, so how can they be struggling?! i.e. a mixture of rain, sleet and snow.

[Guest North Sea Snow Convection]

The ECM is suggesting exactly the same as the models did two weeks ago with large low pressure area in the mid western atlantic and trying to throw energy way way too far north east.

The whole low pressure complex is being overcooked - just like before

I would ignore the FI part of this particular output especially. One for the proverbial wheelie bin

[Cecil Hogmanay Melchett]

Such a tricky call because we could have either cold NE,lys or mild SW,lys. All depends on that LP.

If you took the model output as gospel you would have to favour the mild SW,lys. However as we have seen the models sometimes track these LPs NE when infact the reality is a spitting of the LP tracking SE!

As the cold air is to the N of the LP then I would say Scotland is most at risk of remaining cold followed by N England.

Looks like the ecm has the 850's low enough esp the further North you go.Further south and east it looks far more

marginal.

So maybe the ecm isnt to bad for the north especially up to 120hrs.

[TEITS]

Awful +216 chart.

http://www.wetterzentrale.de/pics/Recm2161.gif

This is why I referred this morning to the ECM mean.

However like I just said and Tamara, are the models making the same mistake yet again?

I have absolutely no idea.

I don't think so CC, the pattern is all wrong to get the cold air here - that's not to say we can't get snow events over the next week, but we already have HP over Greenland with reverse zonal winds to the South, from such a set-up we are not going to get HP to the North or North East.

Odd statement.

We don't need HP to our NE to bring very cold air across the UK. All we need is the LP system to track E/SE rather than NE to back the cold SW. Rather surprised im having to say this!

[Guest North Sea Snow Convection]

Awful +216 chart.

http://www.wetterzen...cs/Recm2161.gif

This is why I referred this morning to the ECM mean.

However like I just said and Tamara, are the models making the same mistake yet again?

I have absolutely no idea.

Like two weeks ago the ensembles will no use at all atm. I know that no outcome a second time around is always the same, but I do think that history in the making may be trying to repeat itself here.

[Matty M]

I quite like the ECM this evening.

Looks quiteeeee interesting in the shorter term for here and many places!

Potential for alot of snow perhaps.

[TEITS]

Like two weeks ago the ensembles will no use at all atm. I know that no outcome a second time around is always the same, but I do think that history in the making may be trying to repeat itself here.

I quiet agree about the ensembles.

When the models were progging mild SW/S,ly for last week and virtually everyone dismissed a cold spell the ECM mean rose from -4C to +7C. At the time I even thought the ECM mean would rise to 10C if the operationals continued. However it only took a few ECM cold operationals to bring that mean down again.

The ensembles are nothing more than a herd of sheep!

Im going to sit on the fence with this one because I can see how a cold NE,ly could develop but I can also see how mild SW,lys could occur.

[Cecil Hogmanay Melchett]

I quiet agree about the ensembles.

When the models were progging mild SW/S,ly for last week and virtually everyone dismissed a cold spell the ECM mean rose from -4C to +7C. At the time I even thought the ECM mean would rise to 10C if the operationals continued. However it only took a few ECM cold operationals to bring that mean down again.

The ensembles are nothing more than a herd of sheep!

Im going to sit on the fence with this one because I can see how a cold NE,ly could develop but I can also see how mild SW,lys could occur.

herd of sheep. i like it!!!!!!

Anyway ,ecm looks very interesting for those up north esp with 200m altitude and above.Could be some wintry

scenes on northern hills next week.

[The PIT]

Well it we could get someone to sit on the Low and push it SE we'd get a good north easterly. ECM is interesting when you take the 850's into account.

[Duane S.]

The difference between last time the models started toying with SW'erlies and this time, is that last time it made no sense. This time, IMO, it does. However, if that trough plays ball we could drag in v. cold air and end up with blizzards!

Still to see a trend from the models to give us the latter though. I thought we may get it from the ECM after the +144 but to no avail.

I am talking with a southerly bias here, I think the Northern half of the UK are still pretty looking good. Although with this setup it won't be that prolonged.