Some noteworthy weather coming up, in particular the violent conditions predicted for next week.

Plenty of interest for everyone then, even the possibility of a bit of the white stuff for the snow starved south.

As normal keep it on topic whatever you wish for..........

http://modeles.meteociel.fr/modeles/gfs/runs/2015011012/gfsnh-0-102.png?12

http://modeles.meteociel.fr/modeles/gfs/runs/2015011012/gfsnh-0-114.png?12

Blizzards for the North is verified

To be fair, I suspect that a) there was still enough uncertainty (ie average or mild cluster members in MOGREPS) to not warrant mentioning a colder outlook as being the most likely and b) the last couple of days' storminess would - rightly - have taken priority in the Met Office's attention.

That said, to see GFS showing snow crossing the UK in around 4 days' time is very interesting to me, as mentioned in the last thread snow on a westerly is literally a once in a generation thing down in this corner of the UK. Of course, it's far from gauranteed to happen but there's enough of a signal there for it to remain on my "things to look out for" list.

The other thing to look out for, as you allude to, is the chance of secondary lows / waves whizzing around the parent low once we have cold air in place. That's the pefect recipe for nothern-flank snow, as winds will be lighter there (a mini col is created, effectively), meaning evaporative cooling can have more impact. Added to which, again as mentioned in the last thread, low pressure close by means the 850 layer is that much closer to the ground and thus, for example, instead of looking for -7s and -8s, -4 or -5 may just be enough.

In a situation as chaotic and knife-edge as this there's simply no way of pinpointing specifics until just a few hours out. And that means we're in for a fun week of model-watching, regardless of whether it snows or not!

Remarkable consistency from the GEFS and also the 15 day EPS with regard to next weekends cold spell.

For once this 'feels' like things are finally going in the right direction with deeper cold progged as we move into high resolution territory.

From the previous thread

http://expert-images.weatheronline.co.uk/daten/proficharts/en/2015/01/10/basis12/ukuk/rart/15011318_2_1012.gif

http://expert-images.weatheronline.co.uk/daten/proficharts/en/2015/01/10/basis12/ukuk/rart/15011400_2_1012.gif

Possible area of snow cross England , one to watch

The trend to slow the low down continues in earnest on the 12z GFSP run... not far off what GEM produced this morning.

Worth keeping an eye on the potential for the ridge to hold on to our NE for a time IMO, but we could do with a better dig of low heights into Europe than shown on the above chart.

As it is, by day 9, this run has brought the pace of events back in line with the 06z and looks set up to follow that run quite closely, though perhaps slightly improved in terms of cold conditions, as there is more in the way of low heights hanging around just to our east and the Atlantic jet is bucked more sharply (trough less 'wide').

12z GFS still rather broad with the trough - the loop south in the jet is too gentle. Often underestimated by the model. the day 10 chart looks quite unusual really - a huge, stalled out trough centred just NE of Iceland.

Not nearly good enough and again the model starts levelling off the jet. Not cool! 

GFSP keeping the amplification more out to day 10, Azores High about to be eroded away by a shortwave... way better than GFS' offering but the progression sure is a lot slower than was seen on yesterday's GFSP runs or this morning's ECM.

Thanks for pointing that one out Gooner - it slipped right under my nose! Looks really quite good on the GFSP version! 

It was just the wrong side of marginal for the south on the 06z so not worth getting hopes up just yet.

Marcus we have a dedicated thread for the mid-week storm.

As for the outlook after the 'storm', there does appear to be some consolidation of a colder pM theme and although I am still not convinced, should I see lying snow from it I'll have my chequebook ready

Some proper icelandic charts suggested tonight. By icelandic I mean westerly based, but very cold. I think a reasonable prognosis is that it is just going to get colder and colder with the moderate periods becoming briefer and less significant. 

Somewhere is going to get very significant snow in the next two weeks. 

"Just cut and pasted today's new MJO observation dot on top of yesterday's model outlooks, notable that the MJO has continued to amplify at a time when all but GEFS had it going the other way!

The amplification is in the upper end of the spread of GEFS predictions that there were on the 9th.

Meanwhile the progression is a bit further east. So stronger and further east... "

This is something I just messaged to a friend of mine who follows the MJO closely like I do.

The implications are that IF the models continue to underestimate the intensity and progression east, then the corrections each day will translate to increased amplification in the pattern. Just how large those corrections would be, I cannot say.

A few days ago, the Met Office were really behind the idea that GEFS were overcooking the MJO, so we are witnessing a rare example of them having got it wrong with respect to a fairly important driving force.

To be fair, it could still rapidly subside - faster than any model currently shows - and leave the GEFS red-faced, but so far, it's all been heading in favour of that model's raw output (but not so much the bias corrected version used by the op runs.)

Another notable change today is that the bias corrected GEFS stop just short of reaching phase 7 before decaying, which is likely reducing the signal for high latitude blocking that the op runs have to work with (not removing it - the phase 6/7 barrier is only imaginary after all). If the MJO continues to progress faster than anticipated over the coming few days, this adjustment could be undone. Otherwise, we may have to make do with less dramatic high latitude blocking than some recent runs have teased us with.

All of this means that output beyond the next week or so needs to be viewed very skeptically, because you have this potential MJO error on top of the usual overcooking of the jet and so on.

The 12z GFS and GFSP runs give me cause to quote an old favourite from the better winters of past,

"at least all the colder charts are in the higher-res!"

I rarely say this, but I actually think amplification might be a bad thing at this stage. As it is we have a pattern that is westerly, but the jet is trending to the south, the result; Pm rather than rPm, and even the rPms are unusually cold. At this stage the low heights to the NW want to keep pushing us into colder and colder air until eventually we might get a northerly or even easterly. 

The last thing I want now, is for mid-atlantic amplification to give a toppler followed by a Euro high. 

I've not integrated into the TWO chart viewer yet, but the GEFS snow stamps should be updating. At the time of posting these are for 18GMT on Tuesday 13th Jan generated from the GEF6z. 

Edited to suit this thread Neil

Now that today's warmth is out of the way, it's no surprise to see the UK turn blue on the anomaly charts!

http://wxmaps.org/pix/temp4.png

One colder-than-average week on the way, at least if that chart is to be believed...

Looks like being the coldest week IMBY for some time

It depends... I was thinking of amplification making the loop south in the jet and hence the associated trough sharper, with a more direct feed from the high latitudes days 9-10.

There also remains the outside chance that the high doesn't fully topple and sits to our N/NE for a time, which is achievable if the trend seen between the 06z GFSP and the 12z GFSP continued just that little bit further. With the MJO corrections happening in the +24 hour range, the effects could feasibly be seen soon enough. I think the ECM might go some way to helping us decide whether this is really an option or not.

The 12z GEM is rather unhelpful because it stalls the initial trough SW of Greenland and only ejects a small low SE to the UK. Such behaviour has not featured on any other recent run so a bit of a wild card. Good for a snow event but, compared with GFSP, it leaves us with a slightly longer road back to cold once the ridge has collapsed through. Having said that, the way GEM has things set up for day 8, height rises ought to have been stronger to our NE... bit of a dodgy looking outcome to be honest.

Overall... no real reason to expect a Scandi High I suppose. A sharper dig south of the jet seems the more likely benefit from amplification.

Anything more than a transient Euro High would be unlikely from further amplification because such jet behaviour always allows ridges to build north sooner or later. A UK high, maybe.

What we don't want to see is a broad loop south in the jet that results in cold having a longer maritime track to reach the UK while also increasing the risk of unfavourable shortwave behaviour - the 12z GFSP shows what that could lead to - the return of HP from the Azores, though it does start to build toward the higher latitudes right at the end of the run.

Man, I need to sit back and chill for a bit 

Interesting how much warmer than usual Eastern Europe is. That looks to be addressed in the second week though. Could do with an Easterly then!

Some unusual snow bands on tuesday, as we get a SW based lake effect! 

Looking at the (old) 120hr fax - not often you see the 528dam line approaching the south of France on a straight westerly!

http://www.wetterzentrale.de/pics/brack4.gif

The snow stamps for 18GMT on Tuesday based on the GEFS12z:

Very true! Well spotted Rob

Getting a bit like January 1984.

Need to watch that low on thursday, if it takes a slightly different track things could be very different. 

You can't say this isn't interesting MO times!