Model Output Discussion - 28th November - 4th December

[phil nw.]

I dont have access to NW extra data anymore

Can someone post the 500 MB temps at T84 on the GFS For Greenland- in the zone i highlighted- Really needs to be sub -40C for a polar low

S

This may be usefull Steve.

http://expertcharts.weatheronline.co.uk/daten/proficharts/en/2011/11/29/basis12/euro/z500/11120300_2912.gif

There is some -40c at 500hpa around that circulation so i would say it has the look of a Polar low--at that point--good for Iceland.

Does show how cold the vortex is so early in the season.

Edited November 29, 2011 by phil n.warks.

[SMU]

This may be usefull Steve.

http://expertcharts....120300_2912.gif

There is some -40c at 500hpa around that circulation so i would say it has the look of a Polar low--at that point--good for Iceland.

Does show how cold the vortex is so early in the season.

Cheers

Exactly as cold as I thought it would be- but as an overall not a good signal for winter as a whole

S

[Cheviot]

Steve - what inferences are you making? I can't connect..

[SMU]

steve as it stands all things considered do you have any thoughts on locations for snow and altitude required?

I havent got a lot of time to look at the thicknesses & gradients, I dont really look any more-

I would say because of the track of teh cold is longish + early season- it will be somewhat moderated when it arrives- so I guess 2/300 M

I am going to Glencoe Saturday & Sunday-- so looking forward to it.....

S

Steve - what inferences are you making? I can't connect..

colder stronger vortex= tighter vortex around the pole & a faster jet = less northerly blocking-

S

[Cheese Rice]

Well I guess with a faster jet you can see more polar influences.

[SMU]

YES you were correct

The ECM 192 chart is the best chart ive seen today for 'hopeful' developments down the line

S

[Snowmad79]

YES you were correct

The ECM 192 chart is the best chart ive seen today for 'hopeful' developments down the line

S

216 looks even better to me lol... Azores trying to bash its way into Greenland ... really is laughable

Edited November 29, 2011 by Snowmad79

[karyo]

A slightly more amplified ECM 12z which makes a notable difference on our chances for cold, even if it is bried.

After a cold start to next week another chance for a northwesterly comes towards the end: http://www.meteociel.fr/modeles/ecmwf.php?ech=192&mode=1&map=1&archive=0

Karyo

[Gibby]

Good evening. With a bit more time on my hands this evening here's a summarisation of the 12z output of GFS, UKMO and ECM.

GFS shows very unsettled weather in the short to medium term with active Low pressures to the North with a strong West and at times NW flow over the UK. This would drive active fronts East over the UK with periods of heavy rain mixed with squally showers. With the air cold at times some snowfall could occur over all upland areas North of the Midlands. Then as we move through FI the GFS operational shows a displaced Azores High pressure move in towards SW Britain cutting off the strong and cool NW flow and replacing it with much less windy and eventually calm conditions with attendant frost and fog problems widely as the High pressure centres over the UK for a while.

The GFS Ensembles tonight show the operational being an increasingly mild outlier in its latter stages with most members preferring something rather colder aloft in the latter stages of the run. Consequently, the average for the run for London averages somewhat below the long term mean. Changeable condittions are shown throughout the run further North in Aberdeen.

UKMO tonight also shows a windy period to come with spells of rain and showers mixed with shorter brighter spells. Some of the rain will be heavy and squally and fall as snow on hills at times especially early next week.

ECM also shows a very windy week to 10 days to come with marked troughs linked to depressions sweeping East over the UK. As we move towards the end of the run a mid Atlantic High starts to ridge North to Greenland giving us just the chance for a time of a Northerly blast late next week. More runs needed.

In Summary its a very disturbed picture tonight with temperatures a little on the low side at times, accentuated by the strength of the wind. Some snowfall will occur at times on high ground in the North with ECM hinting at something a little more wintry as we reach the end of next week.

[phil nw.]

Yes an amplified jet makes a big difference to the outlook when we have a strong vortex like we have now.

Although we have a strong +Ao and +NAO the ECM12z shows that with the vortex trough ejecting into Scandi and E.Europe it keeps any approach of an Azores High at bay and it builds a ridge in the Atlantic instead,keeping the UK on the colder side of the flow.

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

The favourite solution by the GFS12z in the medium term is still the High building NE towards the UK but the ECM op and some of the GFS ens runs show that it`s not the only way forward at this stage.

http://www.wetterzentrale.de/pics/Rtavn2161.png

Meanwhile we have plenty of interesting weather in the next 7 days with deep low pressure never very far away from N.Scotland with frontal rain strong winds and hill snow for the north at times.

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

Steve`s Polar Low does appear around Iceland for 24hrs. or so but appears to start to warm out as it stalls insitu.

http://www.wetterzen...ics/Recm961.gif

Edited November 29, 2011 by phil n.warks.

[nick sussex]

Can I order the ECM please!

Most likely the 264hrs would show the high toppling and an east/ne flow here in sw France.

If you could squeeze a bit more amplification then the high could retrogress a bit further north and west, then as it topples towards Europe you could have a cut back of colder air into the UK from the east.

Its a longshot though to even get to the 240hrs output and I shouldn't even be suggesting such a thing! there is a certain sense of irony here as the best chance for eastern and se areas to see some snow would probably be as the ridge toppled but you'd have to have the high sufficiently north to begin with.

More than likely the latter stages of the ECM output won't even be close to verifying and the jet will be too strong without enough amplification but nice to see the output all the same.

[Snowmadsam]

I'm abit confused about next monday, local forecaster said about snow for north and west wales, whats going on? (sorry if this is in the wrong section)

Looked at GFS 12z 528 line just missing me....

[phil nw.]

Can I order the ECM please!

Most likely the 264hrs would show the high toppling and an east/ne flow here in sw France.

If you could squeeze a bit more amplification then the high could retrogress a bit further north and west, then as it topples towards Europe you could have a cut back of colder air into the UK from the east.

Its a longshot though to even get to the 240hrs output and I shouldn't even be suggesting such a thing! there is a certain sense of irony here as the best chance for eastern and se areas to see some snow would probably be as the ridge toppled but you'd have to have the high sufficiently north to begin with.

More than likely the latter stages of the ECM output won't even be close to verifying and the jet will be too strong without enough amplification but nice to see the output all the same.

Yes that Atlantic High was a bit of a suprise Nick but with the troughing deep into Scandinavia and E.Europe it`s shaping into a tilted block --if pressure could fall a bit more to the South to hold it up.However as you say there`s alot of energy to the North and you have to favour the High giving way further on.

GEFs average for London is below 0C for much of the period now.

http://176.31.229.22...ndres&runpara=0

the OP run milder towards the latter stages.

Gradually the mean is getting lower so are we slowly moving towards a colder solution than we dared hope for only a couple of days ago?

Edited November 29, 2011 by phil n.warks.

[Snowmadsam]

Yes that Atlantic High was a bit of a suprise Nick but with the troughing deep into Scandinavia and E.Europe it`s shaping into a tilted block --if pressure could fall a bit more to the South to hold it up.However as you say there`s alot of energy to the North and you have to favour the High giving way further on.

GEFs average for London is below 0C for much of the period now.

http://176.31.229.22...ndres&runpara=0

the OP run milder towards the latter stages.

Gradually the mean is getting lower so are we slowly moving towards a colder solution than we dared hope for only a couple of days ago?

In english please, sorry...

[nick sussex]

Yes that Atlantic High was a bit of a suprise Nick but with the troughing deep into Scandinavia and E.Europe it`s shaping into a tilted block --if pressure could fall a bit more to the South to hold it up.However as you say there`s alot of energy to the North and you have to favour the High giving way further on.

GEFs average for London is below 0C for much of the period now.

http://176.31.229.22...ndres&runpara=0

the OP run milder towards the latter stages.

Gradually the mean is getting lower so are we slowly moving towards a colder solution than we dared hope for only a couple of days ago?

Not a surprise if you still believe in Santa Claus! :smiliz19:

Yes folks its that time of year when I become a Santa emoticon junkie!!!

In terms of the ECM it of course doesn't have alot of support in the GEFS ensembles, but there are a few members that look similar in trend.

Will be interesting to see what the ECM ensembles make of that operational run later.

I think with the vortex well set the High is going no more further North than the ECM shows.

Disappointing to note once again Nick that whilst we are currently looking at a situation that could deliver a fair bit of snow for Scotland and perhaps other high up areas in the North, your focus is on some unlkely evolution to benefit the E/SE of England

Oh no you're not bringing this out again, actually it would benefit me here in sw France with the high further north but if you looked back I did highlight snow chances in Scotland!

Why is it that i'm not allowed to highlight any synoptics that might occur in case they favour the se, anyone would think you didn't like anyone south of Watford!

Ian please get into the festive spirit and stop this nonsense of me being obsessed with the se, I don't even live in the UK anymore!

[A Winter's Tale]

I do apologize to Steve Murr about my sarcastic comments and I think really no one really does have a clue to whether a Polar Low will or will not happen but knowing our luck it may not. But the models do look better for cold and snow who knows what will happen and perhaps a polar low will happen and I would love it if it did.

Tonight is also pretty cold with some showers with hail mixed in but I think Friday onwards is pretty interesting.

[Geordiesnow]

Disappointing to note once again Nick that whilst we are currently looking at a situation that could deliver a fair bit of snow for Scotland and perhaps other high up areas in the North, your focus is on some unlkely evolution to benefit the E/SE of England

You say that but even in Scotland the current set up will struggle too see snow at lower levels until later on in the run and we know its fairly unrealiable at this stage. That said, higher parts of Scotland and in particular the highlands look likely to get quite a bit of welcomed snowfall so some good news on that front.

I guess also with these cooler/colder shots, we should start seeing the SST falling a little bit more as they are above average by the looks of things for the time of year.

[ANYWEATHER]

To Be Honest, the charts and the weather now and the likely predictions in the days ahead are very realistic for this time of year. Snow will often plaster the Scottish Mountains, Normal in December, periods of wind and Rain, Normal for December and even some Wintry stuff on the Hills further South such as the Cotswolds, Malverns and Chilterns, Normal for this time of year. For those looking for real cold have some patience, it will come! Charts out to t+120 from Ecm And Gfs show some good shots of rPm air and that is likely to continue in the forseeable future! Anyway some charts to back up what Ive been saying and anyone interested "My Winter Forecast will be OnLine Tomorrow".

[Gavin Hannah]

Ok, So it's at the end of the run on the ECM, but the fact that one of the models has thrown this possibility up is a good sign surely? I know it will likely change but anything's possible right?

[Grimsby Snow Lover]

A possible straw to clutch at yes and something that is worth looking out for over the next few days. What we will need to see though is a continuation of similar themes been brought up by the ECM/GFS over the next few days. Expect things to change and don't be suprises if the ECM looks different in the morning, however if it is a new trend then similar charts could also be thrown up. I have read many long range forecasts that have suggested a pattern change mid month onwards so you never know.

[Gavin Hannah]

I've a draw full of straws lol. There was a chart a day or two ago on the GFS showing the high nudging up north towards greenland. It never made is as far north before making it's way SE. A similar idea on the above chart but with the high making progress further north.

[Robbie Garrett]

What would the azores high have to do within the next week or so, to give us a cold plunge as shown by the GFS mid-next week for Europe. As follows.

Ok, So it's at the end of the run on the ECM, but the fact that one of the models has thrown this possibility up is a good sign surely? I know it will likely change but anything's possible right?

MadSnowboarder, looks very similar to the GFS - but the GFS wants that ridge further East than the ECM.

[Upgrade]

Looks like the high in the atlantic may link to Greenland, and with low pressure to the north east, we'll be in a screaming northerly with tons of snow for everyone before Christmas !

[A Winter's Tale]

Ok, So it's at the end of the run on the ECM, but the fact that one of the models has thrown this possibility up is a good sign surely? I know it will likely change but anything's possible right?

The likes of Mark Vogan, Weather Logistics [and Piers Corbyn] would be hoping for more charts like that!

But in the meantime there are polar maritime airmasses heading our way in the coming day with snow for the hills = yes, but also there is the possibility of lower areas getting some snow (and I hoe so too). Even 24-48 hrs before the event you can't say that "oh it will just be the Scottish Hills" because things could change and some wet snow might find it's way into Greater Manchester!

But at the moment what a contrast to a few weeks ago when people were already writing December off and now December looks like starting off on a chilly note. My chilly start to winter in my forecast is looking good and I'm hoping for more charts like the one above to coincide with my severe cold spell in the 2nd half.

[Duane S.]

I would have thought today's 12zs warranted a bit more hype! Seems to me, certainly the ECM, is about as good a scenario, country-wide, as we could hope for from this point and time!

Whilst it's very encouraging I fear though that EVEN if we do get a mid Atlantic ridge situation we could then be looking at a couple of days of decent snow showers for favoured spots at least before it sinks and we end up with, yikes, another Euro high in situ. BUT... at least it's something of interest for the medium term