General Model Output Discussion

[snowmadchrisuk]

The trend I have noticed over the last few runs is for pressure to rise from the South and head towards Scandi. From Experience this nearly always ends up in an eventual cold spell/snap . Simplistic view I know but the ECM , UKMO and GFS all show this at points in there output. It usually takes about 2 weeks from the onset of pressure starting to rise . I think we are in for a very interesting period of Model watching.

[PB22]

Well, looking at the models this morning there can be no denying that the trend to milder conditions taking over later this week is very much evident, and this coming weekend looks set to feel very different to last weekend. Of course, when I say milder, I do mean temperatures returning to nearer normal values rather than the very cold values we have seen recently - temperatures of 5-8C will feel postively balmy though compared to recently!

It appears that the trend was picked up last night, although it was dismissed as being over progressive by some quarters. This may still turn out to be the case as there is scope for change, but given the set of charts at T+96 and T+120, it would take a brave person to go against the obvious trend.

http://www.wzkarten.de/pics/Rtavn1201.html

http://www.wzkarten.de/pics/Recm1201.html

http://www.wzkarten.de/pics/Rukm1201.html

Of those charts, the UKMO is the coldest for eastern Britain, whilst the 06Z GFS brings 12C for Cornwall by the weekend:

http://www.wzkarten.de/pics/Rtavn13217.html

Longer term remains very much open to question, but I wouldn't be surprised if we end up stuck in no-man's land with that huge high to the east blocking Atlantic weather systems taking over, with mildish southerlies the outcome.

[Weather-history]

The Manchester 2m temps show a definite warming trend but seems to dip again after the 18th and note how few ensembles dip below 1000mb, doesn't suggest raging zonality.

http://www.wzkarten3.de/pics/MT2_Manchester_ens.png

Edited January 11, 2010 by Mr_Data

[Guest North Sea Snow Convection]

Well, looking at the models this morning there can be no denying that the trend to milder conditions taking over later this week is very much evident, and this coming weekend looks set to feel very different to last weekend. Of course, when I say milder, I do mean temperatures returning to nearer normal values rather than the very cold values we have seen recently - temperatures of 5-8C will feel postively balmy though compared to recently!

It appears that the trend was picked up last night, although it was dismissed as being over progressive by some quarters. This may still turn out to be the case as there is scope for change, but given the set of charts at T+96 and T+120, it would take a brave person to go against the obvious trend.

http://www.wzkarten..../Rtavn1201.html

http://www.wzkarten....s/Recm1201.html

http://www.wzkarten....s/Rukm1201.html

Of those charts, the UKMO is the coldest for eastern Britain, whilst the 06Z GFS brings 12C for Cornwall by the weekend:

http://www.wzkarten....Rtavn13217.html

Longer term remains very much open to question, but I wouldn't be surprised if we end up stuck in no-man's land with that huge high to the east blocking Atlantic weather systems taking over, with mildish southerlies the outcome.

Not quite correct there Paul.

What was suggested to be over progressive was the potential extent of atlantic based weather, and the fact that any SSE airstream would still be relatively cold and not as mild as some members were believing.

There is a less cold trend, at least for a while, but temps in the east especially could conceivably stay somewhat below average and although I would be slightly less optimistic about a resurgence from the north east than yesterday - the possibility is very much there and it won't take much for that to come back on the agenda once again

Edited January 11, 2010 by North Sea Snow Convection

[Snowyowl9]

In the mean time, a few days' less severity might be rather a good thing?

Yes especially with what we have to come for the next 3 days which looks a bit like february 2007.

Another foot of snow from this then,I will welcome a thaw to be honest now after a good blizzard first.

http://www2.wetter3.de/Animation_06_UTC/60_30.gif

At least temps will get lower tonight,not as they were high last night lol.

http://91.121.93.17/pics/Rtavn2417.png

http://91.121.93.17/pics/Rtavn3617.png

Strong winds tomorrow before the heavy snow comes later.

http://www.wzkarten.de/pics/brack0a.gif

Edited January 11, 2010 by Snowyowl9

[Craigers]

Not quite correct there Paul.

What was suggested to be over progressive was the potential extent of atlantic based weather, and the fact that any SSE airstream would still be relatively cold and not as mild as some members were believing.

There is a less cold trend, at least for a while, but temps in the east especially could conceivably stay somewhat below average and although I would be slightly less optimistic about a resurgence from the north east than yesterday - the possibility is very much there and it won't take much for that to come back on the agenda once again

that's the most realistic post ive seen today! certainly wont be mild and with all the jigsaw pieces in place then there's always something round the corner and the models have been hinting this

[Guest North Sea Snow Convection]

that's the most realistic post ive seen today! certainly wont be mild and with all the jigsaw pieces in place then there's always something round the corner and the models have been hinting this

Yes, after the midweek low there is every chance that we will see high pressure build over us and link up with the high to the east. As I mentioned earlier, any potential reload if it is to come, may not happen in the shorter term but from a position of high pressure in charge then it will be a lot easier to get back to a very cold pattern than if we had the jetstream roaring just to our north. The polar vortex is going to regroup but I think that it could well be rather like Jan 1991, it might be far enough west the 'right' side of Greenland to allow pressure to stay high near or over us. And we know what happened late in that month. That sort of scenario for months end is quite possible - especially if the current signals of a possible MMW increase further. We could see another polar ridge appear with yet another vortex split courtesy of MMW displacement and the ridging over us and to the east get pulled northwards once again.

Edited January 11, 2010 by North Sea Snow Convection

[bluearmy]

cant dissagree with much that has been posted this morning. i am seeing signs on NAEFS fi over the past few runs of a cold easterly/ north easterly arriving in a couple of weeks time. the blocking to our north east is anolomolous just to the north of norway which will no doubt allow more of an atlantic influence, certainly the further south and west you are.

the small rise in heights to our south is also evident in the medium term although one would hope this will end up to our north.

[PB22]

The next few days look to be Atlantic based weather for many areas to me but I guess we'll have to agree to disagree:

http://www.wzkarten.de/pics/brack1.html

http://www.wzkarten.de/pics/brack2.html

If it wasn't Atlantic based, then we'd have no Atlantic weather fronts affecting us!

Sure, the S/SE'lies will be chilly, but not as cold as they would be if they had a true continental origin rather than an Atlantic one. Even tomorrow we can trace the origin back to the Atlantic for many parts:

http://www.wzkarten.de/pics/brack0.html

If the origin was eastern Europe, it would be cold.

Highs of 4 to 6C in the south by the end of the week won't be far from the norm, and by the weekend, we could see double figures in the south!

http://www.wzkarten.de/pics/Rtavn15617.html

Still, I suppose the Scottish Highlands and Germany hang onto the cold!

[nick sussex]

Looking at the models it's hard to see how on earth the UKMO came out with their further outlook, it doesn't resemble any operational model output.

It seems to suggest that the high to the east will extend a ridge westwards and then a low come in from the Atlantic towards the SW. With the block holding to the ne.

[qseghj6]

May be of use for those that want to see what is going on upstream.

http://weather.unisys.com/gfsx/index.html

[Candice]

Looking at the models it's hard to see how on earth the UKMO came out with their further outlook, it doesn't resemble any operational model output.

It seems to suggest that the high to the east will extend a ridge westwards and then a low come in from the Atlantic towards the SW. With the block holding to the ne.

Although the time and date on the UKMO further changes about 12ish each day, I've noticed that the text does not change until about an hour or so later - this may be because the time/date stamp is automated in some way and then they change the text according to the 06z. Slightly OT I know but it is model related - honestly!

[Paul]

Bit of an excuse to show off some new charts we've made for the NMM today (both nw extra lite and full subscribers can access these on the nmm chart viewer), but all the talk of where the next cold shot may or may not come from is perhaps jumping the gun a bit - the cold air is still very much entrenched across the UK and tuesday's front could potentially bring some quite significant snow:

[nick sussex]

Although the time and date on the UKMO further changes about 12ish each day, I've noticed that the text does not change until about an hour or so later - this may be because the time/date stamp is automated in some way and then they change the text according to the 06z. Slightly OT I know but it is model related - honestly!

It's definitely changed from yesterday as i read yesterdays update. They of course do have access to much more data than us, perhaps they've gone with one of the ecm ensemble members.

[winterof79]

Looks like they are going with their own models output.the 120 fax shows the528 dam not too far off the east coast.As mr corbett alluded to yesterday,the concrete block says NO.

[Glacier Point]

Bit of an excuse to show off some new charts we've made for the NMM today (both nw extra lite and full subscribers can access these on the nmm chart viewer), but all the talk of where the next cold shot may or may not come from is perhaps jumping the gun a bit - the cold air is still very much entrenched across the UK and tuesday's front could potentially bring some quite significant snow:

Indeed Paul, the 06z NAE and NNM have trended towards a solution where the low approaching from the SW develops a short wave which cuts SE and becomes quite slow moving acoss the Channel. There is potential for sustained moderate intensity precipitation over 12-15 hours from SW england, much of Wales and central southern England (NMM slightly further north). The circulation developing around the low has 850 and 1000 hP winds from the South-east and east, becoming northerly as it pulls away eastwards. This drags down some of the colder air to the north and 850 values are no higher than -2 C with dew points below freezing throughout. That looks like a substantial fall of snow for large parts of the SW.

A transitory ridge topples in on Thursday which should enable the snow to persist for another 24 hours before the next trough drops in from the Atlantic bringing snow on the leading edge before turning to rain.

The ECM is less convincing about the short wave sending it quickly SE and much less precipitation whilst the GEM has everything a lot further south which would take the snow threat further south.

Longer term, both GEM and GFS ensemble mean guidance suggests a significant block to develop over Northern Scandinavia days 11-15 resulting in something of a standoff situation with the UK stuck in a transition between mild air to the west and colder air to the east.

[Guest North Sea Snow Convection]

The next few days look to be Atlantic based weather for many areas to me but I guess we'll have to agree to disagree:

http://www.wzkarten....ics/brack1.html

http://www.wzkarten....ics/brack2.html

If it wasn't Atlantic based, then we'd have no Atlantic weather fronts affecting us!

Sure, the S/SE'lies will be chilly, but not as cold as they would be if they had a true continental origin rather than an Atlantic one. Even tomorrow we can trace the origin back to the Atlantic for many parts:

http://www.wzkarten....ics/brack0.html

If the origin was eastern Europe, it would be cold.

Highs of 4 to 6C in the south by the end of the week won't be far from the norm, and by the weekend, we could see double figures in the south!

http://www.wzkarten....Rtavn15617.html

Still, I suppose the Scottish Highlands and Germany hang onto the cold!

With respect, I think you are rather deliberately splitting hairs and misrepresenting what i am saying. Extent of atlantic based weather clearly intended to mean (as most other people will have appreciated) a suggestion of a more progressive return of tropical maritime influence with low pressure getting further east of the meridian to push mild air through the greater part of the UK. There is no indication that this is going to happen at the present time

The airstream between the high pressure to the east and the lower pressure to the west doesn't have 100% influence over the UK from the atlantic. Eastern most parts, especially, look to be never very far away from something of a continental feed from France throughout virtually all of the upcoming period. As suggested by the de bilt ensembles there is a high likelihood that Amsterdam for eg will stay decidedly cold over the next ten days, and this will apply to much of the low countries and parts of France as well - so any air imported from there is going to keep eastern areas very much on the chilly side.

However, if you want to believe the GFS 06z at face value, without taking into account any other data or model output, then temps might indeed exceed 10C by the weekend in some parts of the south ....

Edited January 11, 2010 by North Sea Snow Convection

[Thundery wintry showers]

The UKMO further outlook seems to support the longer-range outlook from the ECMWF which as previously mentioned brings in another easterly in a week's time, but I still feel it's a bit out on its own on that one. It will be interesting to see if the three main models prog that easterly outbreak again but I have a feeling that the ECM will back away from it and leave Britain in a dull damp no-man's land.

[Methuselah]

It's a very finely-balanced (as were many 1960s winters) situation, IMO...Whilst, I cannot envision a Modern Winter 'paint-stripper' of a SWerly arriving any time soon, the same can (I think?) be said of any immediate return of the last few weeks' deep cold?? That said, the GFS's idea of an ever-growing pool of cold over NW Russia later in the run could be a warning of things to come...Who knows? :lol:

[cooling climate]

If I'm reading things correctly, current model indications for a spell of milder weather have backing from both teleconnections and stratospheric-temperature signals? Maybe, I'm wrong; but, I'd expect to wait a while before we see much in the way of deep cold returning...

In the mean time, a few days' less severity might be rather a good thing?

I would agree, cold perhaps at times but very cold (big freeze) not until post 23rd time frame I think.

I am also surprised at the lack of optimism for a significant snow threat later Tuesday into Wednesday

for Wales, Central Southern and East Anglia, Southeast England.

[nick sussex]

I would agree, cold perhaps at times but very cold (big freeze) not until post 23rd time frame I think.

I am also surprised at the lack of optimism for a significant snow threat later Tuesday into Wednesday

for Wales, Central Southern and East Anglia, Southeast England.

Theres alot of uncertainty as to how far ne the precip will get. The highest risk for the moment remains for the sw, south Wales and western areas of southern England, in effect the high to the east will weaken the precip as it moves ne. The models still suggest a shortwave to run east along the Channel, the models may develop this further, anyway not long now till the next model runs come out.

[snowingtequila]

The UKMO further outlook seems to support the longer-range outlook from the ECMWF which as previously mentioned brings in another easterly in a week's time, but I still feel it's a bit out on its own on that one. It will be interesting to see if the three main models prog that easterly outbreak again but I have a feeling that the ECM will back away from it and leave Britain in a dull damp no-man's land.

Later in the period, cold and more settled weather probably becoming confined to the far northeast, with less cold and unsettled conditions spreading across more of the UK. suggests to me they are following their own model

[Eugene]

Don't think its going to be as clean cut as people think, the models are struggling with blocking to our northeast, i fully espect the blocking to win as per most of this winter, i think people take the models too literally at times.

[Osbourne One-Nil]

I suppose in the model discussion thread, at least, they're going to? It's also what I look for in the model discussion thread; model-based discussion!

[Rollo]

Don't think its going to be as clean cut as people think, the models are struggling with blocking to our northeast, i fully espect the blocking to win as per most of this winter, i think people take the models too literally at times.

II have to say that I am almost in total agreement there,certainly going by similar situations in the past the war of attrition is eventually won by the persistant high pressure to our east,only proviso is it is a long time since we have been in such a synoptic situation and we have GW and if you believe it AGW,all in all the model viewing over the next week should be worthwhile.