Model Output Discussion 19th January 2014-18z onwards.

[fergieweather]

I think Gibby's post was balanced enough. By T+144 the latest UKMO assessment (just issued) has concerns re snow in NE/E Scotland but not elsewhere. Shannon Entropy highest d9 re timing of broadly zonal return (but confidence fairly high re latter eventually). Into 10-15d trend, broadly westerly mobility expected but ca 10% EC EPS & MOGREPS solutions showing periodic easterlies. Further trend update expected around 1130am.

[Severe Siberian icy blast]

Jet looks set to power up significantly on this run, so IF correct there looks a real danger that the Atlantic could come crashing on through later next week. Any sort of sustained cold looks very unlikely based on this.

 

Looking at that alone though how likely is it to be right at this time frame? The 06z is so progressive that's what it's famous for , so if it struggles with things inside the 100hr time frame how much more so is it likely to struggle after t144?

The models are slowly getting to grips with a pattern change and expect more flip flopping over the coming runs , the Russian high is an absolute beast , if the gfs was right a week ago we would have swept the Russian high aside as soon as it made its first appearance .

All in all a very big step this morning toward cold and snow , that's not dressing anything up , its how it is .

[Fozfoster]

http://cdn.nwstatic.co.uk/gfsimages/gfs.20140123/06/228/prectypeuktopo.png

Any one fancy this. ;-)

It is just for fun.:-)

Edited January 23, 2014 by Fozfoster

[shedhead]

I think Gibby's post was balanced enough. By T+144 the latest UKMO assessment (just issued) has concerns re snow in NE/E Scotland but not elsewhere. Shannon Entropy highest d9 re timing of broadly zonal return (but confidence fairly high re latter eventually). Into 10-15d trend, broadly westerly mobility expected but ca 10% EC EPS & MOGREPS solutions showing periodic easterlies. Further trend update expected around 1130am.

 Any more thoughs on Sunday's event Ian and do UKMO have concerns further down the line re rainfall, because regrettably it looks as though the Atlantic train is going to keep rolling.

Edited January 23, 2014 by Paul

[karlos1983]

1065mb Artic High 

 

[Southender]

Really think some are making the mistake of looking at the Isobars and not factoring in the airmass.

 

Take this chart for example.

 

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

 

Damn good snow event here.

 

DO NOT make the mistake of assuming mild just because LP systems are crossing the UK!!

 

Max temp 1C from a W,ly!!

 

http://www.wetterzentrale.de/pics/Rtavn2521.png

 

 

My thoughts as well TEITS.

 

There is some sub 510 Dam air wrapped up in these LP systems.

 

Couple that with 850's around -3/-4 and Dews 0c or below, then we could have a nice little snow event here. Even if it is temporary.

Edited January 23, 2014 by Shrimper

[Severe Siberian icy blast]

I think Gibby's post was balanced enough. By T+144 the latest UKMO assessment (just issued) has concerns re snow in NE/E Scotland but not elsewhere. Shannon Entropy highest d9 re timing of broadly zonal return (but confidence fairly high re latter eventually). Into 10-15d trend, broadly westerly mobility expected but ca 10% EC EPS & MOGREPS solutions showing periodic easterlies. Further trend update expected around 1130am.

Well I'm sure that's a very professional and balanced view at this moment in time , especially with the public in mind , however looking at the UKMO raw , the ECM postage stamps for Europe , and the JMA which has even excellent so far I for one is thinking their is a distinct possibility of a snow event next week for the uk, but I understand that you guys are the pro's and have insight to things we don't . Along with the fact been a model thread discussion we can talk more openly about what may happen as we have nothing to loose I suppose .

[Frosty.]

I don't think John Hammond will be saying mild to win like he did the other day as things now stand, this is a very fluid situation and things are changing quickly..building momentum from the runs yesterday and so far today on the 00z to the 06z. It could be a boomtastic 12z this pm.

Edited January 23, 2014 by Frosty.

[shedhead]

Looking at that alone though how likely is it to be right at this time frame? The 06z is so progressive that's what it's famous for , so if it struggles with things inside the 100hr time frame how much more so is it likely to struggle after t144?

The models are slowly getting to grips with a pattern change and expect more flip flopping over the coming runs , the Russian high is an absolute beast , if the gfs was right a week ago we would have swept the Russian high aside as soon as it made its first appearance .

All in all a very big step this morning toward cold and snow , that's not dressing anything up , its how it is .

Well the ECM also has another system bowling towards UK at the same time, on what looks to be a flattening and increasingly powerful Jet, so for now it looks rather more likely than not to me I'm afraid.  Until I see something sustained that suggests the contrary I'm going to stick with it.

 

Edited January 23, 2014 by shedhead

[stratty]

1065mb Artic High 

 

........and still raining! We continue to chase a cold wintry spell and still always a week away and shown differently in each model 

[nick sussex]

I think Gibby's post was balanced enough. By T+144 the latest UKMO assessment (just issued) has concerns re snow in NE/E Scotland but not elsewhere. Shannon Entropy highest d9 re timing of broadly zonal return (but confidence fairly high re latter eventually). Into 10-15d trend, broadly westerly mobility expected but ca 10% EC EPS & MOGREPS solutions showing periodic easterlies. Further trend update expected around 1130am.

The problem with those ensembles is that in the last two weeks they have constantly signalled a return to a Westerly mobile pattern which hasn't materialized.

 

Just looking at the operationals shows the same bias when indeed the block has proved more resilient, we'll see but I'm not convinced that they are correct, broadly mobile upto the UK then hitting a brick wall seems more likely.

[stratty]

My thoughts as well TEITS.

 

There is some 510 Dam air wrapped up in these LP systems.

 

.....do they ever come to fuition though really, especially for more southern areas........they always seem to get watered down nearer the time!

[MPG]

Any more thoughs on Sunday's event Ian and do UKMO have concerns further down the line re rainfall, because regrettably it looks as though the Atlantic train is going to keep rolling.

Wow Shedhead, you may be correct. But your broad brush predictions of what weather we get (ie no cold) are incredible. I do not have the knowledge to come out with such predictions as you do, but I can see a battle between west and east, and at the moment the winner is not known.

[karlos1983]

........and still raining! We continue to chase a cold wintry spell and still always a week away and shown differently in each model 

 

Agreed, but I was more speaking in terms of "that's impressive" 

[nick sussex]

Just to illustrate my point, this the ECM prediction from Sunday for the 29th January:

 

 

And todays T144hrs to the same time:

 

 

How far out was that in terms of pattern progression:

 

The ensembles generally will be even worse because of their lower resolution, simply looking at the outputs in isolation of recent trends misses a big chunk of the background signal.

 

 

 

 

 

[fergieweather]

The problem with those ensembles is that in the last two weeks they have constantly signalled a return to a Westerly mobile pattern which hasn't materialized. Just looking at the operationals shows the same bias when indeed the block has proved more resilient, we'll see but I'm not convinced that they are correct, broadly mobile upto the UK then hitting a brick wall seems more likely.

....hence the high entropy marking the uncertainty of how the change will be manifested and when. Moreover detailed assessment is only out to Tues currently. What happens Weds onwards is an open book re wintriness etc.

[LomondSnowstorm]

It does look as though any return to the 'Atlantic train' will be heavily influenced by the blocking to our north/northeast, which opens up the possibility of some major snowfalls, either through February '96 style trough disruption or through Arctic sourced northwesterlies. Either way, I don't see an easy route to anything especially 'mild' in the medium term even if we can't quite manage a full blown easterly. This is obviously more promising the further north you are (although far from exclusively so and the outlook could shift the pattern further south), and isn't good news for those affected by flooding as any big marginal snowfall events are likely to only make matters worse for low lying areas.

[Fred Sykes]

I think Gibby's post was balanced enough. By T+144 the latest UKMO assessment (just issued) has concerns re snow in NE/E Scotland but not elsewhere. Shannon Entropy highest d9 re timing of broadly zonal return (but confidence fairly high re latter eventually). Into 10-15d trend, broadly westerly mobility expected but ca 10% EC EPS & MOGREPS solutions showing periodic easterlies. Further trend update expected around 1130am.

Luckily for us coldies, nothing is set in stone! Looking at a 10 - 15 day trend counts for nothing at the moment IMO. In the mean time we have a lot of rain to get through before a shot at some colder weather at last!

[bluearmy]

 

....hence the high entropy marking the uncertainty of how the change will be manifested and when. Moreover detailed assessment is only out to Tues currently. What happens Weds onwards is an open book re wintriness etc.

 t120 - that makes more sense ian. any chance of an insight into dp's associated with the day 5/6 raw output ??

[TEITS]

Gibby summary of the 0Z GFS for example was wrong. He states "average temps" and yet for much of the run the temps were actually below normal and on occasion max temps were only a few degrees above freezing. This was due to upper temps around -5C combined with heavy precip which would also drop the max temp.

 

Like I keep saying you have to look in detail at the model output because what may appear a mild chart isn't always the case.

 

Finally even yourself stated the models appear to be colder than yesterday which contradicts Gibbys post!

[Frosty.]

Luckily for us coldies, nothing is set in stone! Looking at a 10 - 15 day trend counts for nothing at the moment IMO. In the mean time we have a lot of rain to get through before a shot at some colder weather at last!

Indeed, the track of sunday's stormy low is crucial, if it plays ball and slides southeast to the southwest of the uk early next week it's hello winter.

[shedhead]

It does look as though any return to the 'Atlantic train' will be heavily influenced by the blocking to our north/northeast, which opens up the possibility of some major snowfalls, either through February '96 style trough disruption or through Arctic sourced northwesterlies. Either way, I don't see an easy route to anything especially 'mild' in the medium term even if we can't quite manage a full blown easterly. This is obviously more promising the further north you are (although far from exclusively so and the outlook could shift the pattern further south), and isn't good news for those affected by flooding as any big marginal snowfall events are likely to only make matters worse for low lying areas.

Exactly LS...most of us realise that the return of the Atlantic or the dominance of the Atlantic does not mean there will be no wintry weather, in fact all the heaviest snowfalls in the UK occur when the Atlantic tries to make inroads into a cold block.  That to me looks the most likely set up now going forward, it's all about where that boundry lies as regards to who gets snow and who gets rain. However as far as sustained cold is concerned. i.e the kind of cold provided by a long drawn E'erly, I think that remains the rank outsider.

[tight isobar]

I think on whats on offer anything past midnight Sunday is a shot in the dark forecast.but with tending to a colder based scenario, with currently modeling. As on the same token as some see the Atlantic bulldoze, I can clearly see as other s at this stage, growing hints for eastern influence, with perhaps the much talked battleground scenario.

[liam79]

Jet looks set to power up significantly on this run, so IF correct there looks a real danger that the Atlantic could come crashing on through later next week. Any sort of sustained cold looks very unlikely based on this.

 

Hi Im not a regular poster, but as the jet dives south right over the U.K, wouldn't that aid in the diversion of low pressure south under any block to the east? Thanks in advance

[nick sussex]

The issue IMO going forward is will we see the same trend of recent weeks repeated? its obvious from across the model suites that they have had the pattern too far east in their FI's. I'm sure the UKMO would have noted this and even though their ensembles and other products might be saying one thing I would be surprised if their forecast did not have a caveat included for that eventuality.

 

I don't expect them to produce a more wintry update today but would expect the wording re a chance of more snow or colder weather to be included, we'll see when it comes out.