Model Output Discussion 17th Dec.2013-12z onwards.

[pip22]

Its not all bad. it is showing North-westerly winds on the 28th:

 

It may bring wintry showers on that day, especially northwestern areas. Widespread gales too.

Edited December 21, 2013 by pip22

[Snowman.]

Remember the current warming predicted by the GFS is no SSW as of yet if we're to see one it would most likely be some time in January 2nd or 3rd week, this then has to move through the different layers of the Start which is where we see the disruption of the vortex taking place during Feb, and even then an SSW is no guarantee of cold conditions effecting the UK just a highly increased chance.

 

Until we see the transition of the p.v away from Canada it could take some time but will end up happening sooner or later.

[Jason M]

The best thing that can be said about the 06z is that it only goes out to 384 thereby not inflicting any further misery.

The detail changes run to run but the overall pattern is rock solid. Maybe one tiny chink of light is that heights seem to be lower to our SE in recent runs and if that trend continues something might pop up at the 10 day range. Unlikely though.

[Frosty.]

I think some of us have a good chance of a technical white christmas with the air being cold enough for snow in the heavier showers and more generally across hills, especially in the north. The Ecm 00z op run shows plenty of cold air over the uk at times during the christmas period with 528 dam, even 522 dam is shown so some low thicknesses at times and as for mild weather, there really isn't much mild weather at all, just the occasional milder day but soon blown away by colder air rushing in from the west. There is also a risk of snow just after christmas on the ecm as a low tracks east across the south and hits the cold air, to the north of the low centre the ppn could be of snow, again especially with some elevation. So, I would say, looking at the overall picture from the 00z, the christmas / new year period has more of a wintry flavour with the risk of snow in places from time to time but the main theme is of rainfall totals well above average with an ongoing risk of flooding and with severe gales / storm force gusts at times but with temperatures generally close to average and occasionally slightly below with just brief milder incursions, most of any significant snow across northern hills & mountains but with icy patches and slight frosts during the xmas period. The bottom line is, it's not mild zonality, there will be cold incursions.

[Stuie]

Serious straw clutching but you can only hope for a flicker in the Costa del Anglia.

[MP-R]

All I will say is that the difference between the GFS and ECM at the moment is pretty striking - the difference between Atlantic bombs on the former and sinking lows into Europe on the latter. Post-Christmas is anyone's guess. Both are in agreement though of a continuation of the increasingly cool but very unsettled and windy weather, perhaps climaxing on Tuesday before a calmer day on Christmas Day itself. The variation comes after that with the GFS still gung ho for another considerable storm, on a slightly southerly track compared to the Christmas Eve one. The ECM on the other hand shows a much less active but still cyclonic setup which would promote colder surface conditions as winds fall lighter. One thing is for sure though, mild is going to be at a premium over the next week.

[damianslaw]

Struggling to keep up with this fast moving situation - really a case of sticking to the reliable timeframe i.e. 96 hrs. Subtle shifts in the position of the low pressure will make all the difference. After a year of very benign weather at times - we are certainly ending it on a very stormy volatile note - quite exciting for weather enthusiasts who like quickly changing situations and a far cry from a stagnant pattern where high pressure sits over the country bringing non-descript weather.

 

I do think for the NW quarter of the country a few wintry surprises will occur over the christmas period. I said yesterday the outlook is far from mild - indeed very seasonal weather for the time of year, and much better than the mild dross of last christmas and the year before, which may seem to have forgotton about. We could do with a bit of brightness though - this is turning into a very dull dark December.

[Mucka]

Except the extended ECM ens continue to show weakly positive high euro anomolys and naefs similar. infant the 00z has built a reasonable one over the Low Countries/w Germany. I'd like to be positive about the first half of jan from a cold perspective but nothing to support that currently. Only caveat is that we see a fair amount of high latt high anomolys and our build of heights near us could easily be sucked up to our ne or retrogress west if the pattern dictates.

Hi Blue,

 

Granted there is no deep cold spell looming but on the one hand you say nothing to support cold for Jan and no reason to be positive but then on the other you outline what we should be positive about as a caveat.

I quoted you not because I disagree with what you are saying, there is nothing to disagree with, but because for me it is indicative of the mood of the forum, it seems to be more concentrated on the negative aspects of the output rather than the positive.

 

Speaking to the forum now.

Taken at face value there is no deep cold programmed but the situation is far more nuanced than that and there is tons of interesting weather around and yes wintry potential even for the big day itself.

 

I'm not sure what burden of evidence is required before people recognise the potential of a Southerly tracking jet but maybe that is part of the North/South divide in that such a set up offers much better prospects up North for wintriness. Regardless, not so many years ago the forum would of been buzzing with excitement over the current charts. (Yes they were dark days but it seems expectations are set way too high since the dramatic cold and rare winter spells we have seen in recent winters)

 

If you are in the North of England or have some elevation then there will be ample opportunity to see snow falling at some stage over the coming week or two but I think even the South may see some snow falling at some stage between Xmas eve and New Year - granted it is hit and miss and only transient but it is not so long ago people would of bitten your hand off to see the current output being modelled.

 

Of course everyone is entitled to feel the way they wish about the output and I'm not trying to dictate reality here, it is just that I am of the opinion that the output is actually quite good considering where we were a few days ago and the signal for potential blocking to form as we head into January has actually strengthened with time not weakened. 

Overall prospects look much better than they did a few days ago but with my (negative) caveat being that any blocking attempt will struggle to establish itself while the PV is programmed to hang around Greenland. However, even if we don't get lucky with the Polar high that is programmed to develop, with a Southerly tracking jet we can get undercut of even transient ridges and disrupting lows bringing the prospect of some heavy snowfalls.

 

The only time I will feel negative about January's prospects of delivering anything wintry is if I see a signal for the Azores high to ridge back in and the jet return North (It will always be modelled to ridge back in temporarily between depressions) - that is possible but just as there is no strong signal for a block to establish itself there is no strong signal for a typical zonal flow to return either as yet- it hangs in the balance IMO.

 

Don't read too much into 10 day ensemble mean pressure charts at the moment or even ensemble temp charts. Look for how many individual ensemble members are pushing the jet back North and looking to return a flatter pattern and how many are maintaining a more amplified pattern and throwing up ridges or MLB or HLB that can impact upon our weather.

 

All I have ever said is that conditions for potential blocking will be better back end of December, first week of January and I believe we are seeing that reflected in the output overall even though this mornings Op's certainly don't scream "potential". 

If we do get lucky and blocking can have more influence on our weather then we will still likely not see any prospect of a cold spell until the second week of January so this is definitely a long game but we will know our likely fate the other side of Xmas.

 

Yes an optimistic look at the output but why not? It's Christmas. 

Edited December 21, 2013 by Mucka

[Snowman.]

Takes 384 hours to move the PV away from Canada.

 

 

Warming reaches its strongest.

 

 

Begins to cool again but shifting heat towards Canada.

 

Edited December 21, 2013 by SN0WM4N

[mcweather]

Hi Blue,

 

Granted there is no deep cold spell looming but on the one hand you say nothing to support cold for Jan and no reason to be positive but then on the other you outline what we should be positive about as a caveat.

I quoted you not because I disagree with what you are saying, there is nothing to disagree with, but because for me it is indicative of the mood of the forum, it seems to be more concentrated on the negative aspects of the output rather than the positive.

 

Speaking to the forum now.

Taken at face value there is no deep cold programmed but the situation is far more nuanced than that and there is tons of interesting weather around and yes wintry potential even for the big day itself.

 

I'm not sure what burden of evidence is required before people recognise the potential of a Southerly tracking jet but maybe that is part of the North/South divide in that such a set up offers much better prospects up North for wintriness. Regardless, not so many years ago the forum would of been buzzing with excitement over the current charts. (Yes they were dark days but it seems expectations are set way too high since the dramatic cold and rare winter spells we have seen in recent winters)

 

If you are in the North of England or have some elevation then there will be ample opportunity to see snow falling at some stage over the coming week or two but I think even the South may see some snow falling at some stage between Xmas eve and New Year - granted it is hit and miss and only transient but it is not so long ago people would of bitten your hand off to see the current output being modelled.

 

Of course everyone is entitled to feel the way they wish about the output and I'm not trying to dictate reality here, it is just that I am of the opinion that the output is actually quite good considering where we were a few days ago and the signal for potential blocking to form as we head into January has actually strengthened with time not weakened. 

Overall prospects look much better than they did a few days ago but with my (negative) caveat being that any blocking attempt will struggle to establish itself while the PV is programmed to hang around Greenland. However, even if we don't get lucky with the Polar high that is programmed to develop, with a Southerly tracking jet we can get undercut of even transient ridges and disrupting lows bringing the prospect of some heavy snowfalls.

 

The only time I will feel negative about January's prospects of delivering anything wintry is if I see a signal for the Azores high to ridge back in and the jet return North (It will always be modelled to ridge back in temporarily between depressions) - that is possible but just as there is no strong signal for a block to establish itself there is no strong signal for a typical zonal flow to return either as yet- it hangs in the balance IMO.

 

Don't read too much into 10 day ensemble mean pressure charts at the moment or even ensemble temp charts. Look for how many individual ensemble members are pushing the jet back North and looking to return a flatter pattern and how many are maintaining a more amplified pattern and throwing up ridges or MLB or HLB that can impact upon our weather.

 

All I have ever said is that conditions for potential blocking will be better back end of December, first week of January and I believe we are seeing that reflected in the output overall even though this mornings Op's certainly don't scream "potential". 

If we do get lucky and blocking can have more influence on our weather then we will still likely not see any prospect of a cold spell until the second week of January so this is definitely a long game but we will know our likely fate the other side of Xmas.

 

Yes an optimistic look at the output but why not? It's Christmas. 

 

Good measured post Mucka.

 

Its is definitely looking like a waiting game this winter.

 

We have been spoilt at times over the last five or six years with December being on the cold and wintry side on a number of occasions, especially the amazing Dec 2010.

In reality December is far more often than not likely to be an extension of Autumn  rather than a deep winter month.

 

I think we will see some widespread wintry weather this year but probably not until around or just after mid January, So we might just start to some hints of this from the models during the weekend after Christmas.  If I had to plump for a year that the second half of winter might follow I would probably go for something like 1977/78, not because the pattern up to date has been a copy ( it hasn't) but just in terms of the timing of a quite deep wintry spell.

 

The strat guys are talking about it taking a while for the vortex to be affected by any attacks and that is why I feel any deep cold and snowy conditions will happen very much in the second half of winter.

Edited December 21, 2013 by mcweather

[nick sussex]

Xmas shopping done! just perusing all the outputs and the ECM raised an eyebrow with it departing from consensus at the T144hrs timeframe with that low moving rapidly eastwards, looking at the thicknesses and 850's certainly a chance of some snow on its northern flank, indeed the ECM is the best in terms of keeping some colder air over the UK at 168hrs with that slack flow.

 

It has to be viewed at the moment as an outlier solution because of the lack of support, we'll see this evening whether theres a shift by the other models, after that the ECM looks best in terms of potential.

 

The high pressure in the Arctic does look like verifying and whilst that remains there always a chance something more wintry might pop up.

[Captain Shortwave]

Well I'm certainly in the Christmas mood, I hope the models are too  , hopefully the models will follow the ECMs mid-range trend of shoving the low after Boxing day East through southern England or even push it further south. I think out of the first wave of model output today the UKMO will be important as it's probably the most likely to cotton on to a change in trend if there is indeed going to be one.

Edited December 21, 2013 by Captain shortwave

[winterof79]

I do not think it would take much adjustment from the GFS 12Z to get to the ECM outcome at 144

http://modeles.meteociel.fr/modeles/gfs/runs/2013122106/gfsnh-0-144.png?6

http://www.meteociel.fr/modeles/ecmwf/runs/2013122100/ECH1-144.GIF?21-12

Same could be said the other way though.Totally agree with Mucka,many on here looking for the negatives.The output is seasonal at present.

 

Nice to se the Arctic high building and the russian high also in place at 144z

Edited December 21, 2013 by winterof79

[terrier]

Looking at the models and the set up been shown I can't but help think we are heading towards a 2005 winter. With the wet and unsettled weather until mid jan before a colder feb march. But to the here and now apart from some snow for highest parts of Scotland and Northern England. It's pretty grim viewing. Unless high winds and rain float your boat.

[Continental Climate]

looking at the northern hemisphere profiles I seem to think we are not in to bad shape really http://www.wetterzentrale.de/pics/Rhavn1441.gif!! Whilst this isn't perfect and we could do with that big lobe over Baffin to bugger off it isn't too bad and it looks to me with a few tweaks we could be seeing things improve a lot in the new year.

At the same timeframe the ECM also backs a height rise in the arctic as well http://www.wetterzentrale.de/pics/Recmnh1441.gif!! I think combined these charts show us some good news and we should maybe be a little more upbeat.

 

Now I am no expert in the strat and haven't a clue whether my optimism will pay off but I think we are in a lot better shape than we were a week ago.

[snowice]

Snow showers in the west on xmass eve from 12zgfs

Edited December 21, 2013 by snowice

[Mucka]

UKMO with a step toward this mornings ECM?

It is certainly developing that secondary low less than previous efforts and the GFS with it likely to track further South.

 

 

See how fast it deepens on the 120h chart when it is out.

Edited December 21, 2013 by Mucka

[ANYWEATHER]

Looks like the storm  for Monday/Tuesday has the low deeper still at 932mbs, theres certainly going to be some very nasty weather with this one...  

[Mucka]

Some nice WAA up through Scandinavia with the Arctic high waiting 

 

[Skullzrulerz]

Looks like the storm  for Monday/Tuesday has the low deeper still at 932mbs, theres certainly going to be some very nasty weather with this one...  

From what i can see its around 928mb.

[Captain Shortwave]

Some nice WAA up through Scandinavia with the Arctic high waiting 

 

Just a shame it's too far east really, but at least some sign of some action which is within 4 hours flight of here 

[nodrog]

From what i can see its around 928mb.

 

This chart has it at 924 mid day Christmas Eve. Has pressure ever dropped below 900 for the UK?

[Skullzrulerz]

 

This chart has it at 924 mid day Christmas Eve. Has pressure ever dropped below 900 for the UK?

Pressure has not dropped below 900 in the uk since records began. 

[Summer Sun]

 

This chart has it at 924 mid day Christmas Eve. Has pressure ever dropped below 900 for the UK?

 

925.6mb at Ochertyre, near Crieff, Perthshire on the 26th January 1884 is the current record

[Mucka]

Just a shame it's too far east really, but at least some sign of some action which is within 4 hours flight of here  

 

So we want a nice flat pattern with no height rises toward the pole to aid future blocking prospects?

Edited December 21, 2013 by Mucka