Winter Model Discussion - Cold Hunting - 20th Dec

[Gavin Hannah]

You get 10/10 for being so optimistic, and we need more of that in these testing times but there are some hints here and there for a colder pattern or at least a cold snap or two in the near future.

Cheers Frosty. I haven't been on much recently thanks to all the mild mush that's been around. So my main focus is on FI and what we could be heading towards come Xmas through to early jan. And I've decided to be only positive at this most festive time of year.

[nick sussex]

I know after the easterly let down its easy for people to assume that any colder looking potential will just implode but we are talking about chalk and cheese in terms of how the models handle those as compared to northerlies.

The aspects to be more wary of at this stage are longevity of any northerly/n'werly and the cold uppers associated with it. Less so whether it will verify.

Its not like an easterly which can easily implode within 144hrs, to get a northerly in the UK generally you need two things a positive PNA pattern in the USA and eastern USA troughing. Both of these are likely to occur, the degree of amplification however is still open to some uncertainty.

So a more amplified eastern USA trough will lead to better WAA into Greenland and a stronger push south of colder air into the UK.

[bradymk]

I know after the easterly let down its easy for people to assume that any colder looking potential will just implode but we are talking about chalk and cheese in terms of how the models handle those as compared to northerlies.

The aspects to be more wary of at this stage are longevity of any northerly/n'werly and the cold uppers associated with it. Less so whether it will verify.

Its not like an easterly which can easily implode within 144hrs, to get a northerly in the UK generally you need two things a positive PNA pattern in the USA and eastern USA troughing. Both of these are likely to occur, the degree of amplification however is still open to some uncertainty.

So a more amplified eastern USA trough will lead to better WAA into Greenland and a stronger push south of colder air into the UK.

Yes as good as some easterlies have been for Southern UK in the past, Northerly's are better for personal health due to the lower stress levels when watching them get modelled. Like you say, some newer members may think its in FI and it will never happen which is understandable after the last few weeks but the models are generally far better when modelling northerlys as there is so much more to go wrong with easterly's. I wont be getting excited yet but it wont take as many runs to persuade me that a northerly is likely compared to an easterly so if this is still showing tomorrow evening, it will be an extra christmas present Also, from past experience, i have always found GFS better at northerly's. Don't ask me why but in the past, they have picked up and modelled them better than ECM, generally.

[nick sussex]

Yes as good as some easterlies have been for Southern UK in the past, Northerly's are better for personal health due to the lower stress levels when watching them get modelled. Like you say, some newer members may think its in FI and it will never happen which is understandable after the last few weeks but the models are generally far better when modelling northerlys as there is so much more to go wrong with easterly's. I wont be getting excited yet but it wont take as many runs to persuade me that a northerly is likely compared to an easterly so if this is still showing tomorrow evening, it will be an extra christmas present Also, from past experience, i have always found GFS better at northerly's. Don't ask me why but in the past, they have picked up and modelled them better than ECM, generally.

Yes the GFS for all its faults will often pick out especially northerlies around the 240hrs mark and run with them.

The one thing though with the GFS is that it will tend to overdo the cold and longevity of these without a proper Greenland high, so its good at picking them out but best to fall back on the Euros once these enter the 168/144hrs timeframe.

You're right though theres less to go wrong with a northerly and hence it does have a better chance of verifying.

We'll see though over the coming days, the UKMO further outlook doesn't mention even the chance today which I find strange, if those upstream changes verify then that would certainly lead to an increased chance of some colder shots from the north or north west, even the De Bilt ensembles show that trend with a good cluster supporting a cool down over there, the wind directions of those colder members suggest directions between west and north.

[Dee-Dee]

As I am Still learning I don't post very Often I enjoy everyone's comments and views and I would just like to say I wish everyone on here a very Merry Christmas and let's hope are very Snowy New Year

[Candice]

Just out of interest, does anyone know how to bank this run? Synoptically I like the way it develops and progresses and see it as a 'potential' player. Would like to see how it pans out as a general theme.

BFTP

Screen grab each frame

[SnowObsessor90]

We'll see though over the coming days, the UKMO further outlook doesn't mention even the chance today which I find strange, if those upstream changes verify then that would certainly lead to an increased chance of some colder shots from the north or north west, even the De Bilt ensembles show that trend with a good cluster supporting a cool down over there, the wind directions of those colder members suggest directions between west and north.

Perhaps the MOGREPS suite didn't look all that enthusiastic and backed a similar scenario to the one the 00z OP runs were showing? as that's the only possible reasoning I can think of.

Edited December 22, 2012 by Anonymous21

[Gael_Force]

Frosty, I didn't ask that mate, I know and have read all the views from members etc, just want to know how to save it please

BFTP

All the GFS runs are archived on Meteociel so you can just check back as long as you remember which run it was.

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=6&code=0&carte=0&mode=0&archive=1

Alternatively, you can save an individual frame by clicking on the floppy disc symbol above the chart.

[tinybill]

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=204

hi just looked into fantasy world wished i had not its looking pretty nasty with more heavy rain heading to the u.k. , mind you shopping all done and rapped up result !!

[winterof79]

I highly doubt we will be starting the New Year in the freezer, in fact the first week of January is a case of more of the same at this moment in time, Then we are at the mercy of the weather gods in any SSW having an effect on this tiny island.

Do i take it you are not using the 06z GFS output to back up your early January forecast

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=240&mode=2

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=240&mode=1

[Panayiotis]

The changes from the 06z to the 12z are vast at 102hrs, on the 06z we have a nice northerly, on the 12z we have a WSW. It seems that the models are struggling with the low around Christmas.

Edited December 22, 2012 by Panayiotis

[Weathizard]

I'm sensing Zonal here, what is with the lows barrelling off the Eastern seaboard? Relentless.

[Ian Brown]

The changes from the 06z to the 12z are vast at 102hrs, on the 06z we have a nice northerly, on the 12z we have a WSW. It seems that the models are struggling with the low around Christmas.

Yes, this often happens when this comes within T96, you see the jet quite a bit further North than was anticipated.

[bobbydog]

I'm sensing Zonal here, what is with the lows barrelling off the Eastern seaboard? Relentless.

i was just going to say the opposite- there looks to be less energy coming across the atlantic as per the 06z and apparently even less than the 06z. look how that turns out! i'm sensing the atlantic running out of steam and a colder (or at least different) pattern emerging. a few more runs required but i think the new year could be the turning point of this winter....

[Winter Monsoon]

i was just going to say the opposite- there looks to be less energy coming across the atlantic as per the 06z and apparently even less than the 06z. look how that turns out! i'm sensing the atlantic running out of steam and a colder (or at least different) pattern emerging. a few more runs required but i think the new year could be the turning point of this winter....

I doesnt appear to be as many lows in 12z over 6z.

[swilliam]

I doesnt appear to be as many lows in 12z over 6z.

Look like the Northerly has gone though

[Grimsby Snow Lover]

As soon as we enter the low res section of the run the Atlantic kicks in again and we loose the build of high pressure towards Greenland replacing it with something not far from a barlett. Oh the joys of FI on the GFS.

[-uksnow-]

Look like the Northerly has gone though

Is that not down to the fact that the lows are weaker and more spaced out, less energy allowing the troughs to dig not as far south therefore the northerly is 'off'. ?

[IDO]

I had thought GFS had plumbed the depths for poor op runs, but the 12z is as bad as it gets. The Iberian High stars in early Jan: http://cdn.nwstatic....300/h500slp.png

http://cdn.nwstatic....372/h500slp.png

Temps probably +5c above average in the south.

Zero chance of snow for 80% of the Country on that run.

It can only get better from here!

Edited December 22, 2012 by i'm dreaming of...

[Methuselah]

Not good. Not good at all! Is that a faux displaced Bartlett I see?

[bobbydog]

early promise but inconclusive really.

now, what is really catching my interest is this-

[LomondSnowstorm]

I had thought GFS had plumbed the depths for poor op runs, but the 12z is as bad as it gets. The Azores High stars in early Jan: http://cdn.nwstatic.co.uk/gfsimages/gfs.20121222/12/300/h500slp.png

http://cdn.nwstatic.co.uk/gfsimages/gfs.20121222/12/372/h500slp.png

Temps probably +5c above average in the south.

Zero chance of snow for 80% of the Country on that run.

It can only get better from here!

Agreed, fortunately NAEFS is starting to build a positive heigh anomaly over south Greenland and the pole and negative anomalies to the south east...

[AGAL]

Blimey the GFS is so wet and mild we should rename the thread 'The Hunt for Mold'. What lousy charts. As usual you can rely on the GFS nearly all of the time with SW Atlantic weather but never from the other direction. I'm afraid it's a miserable wet mild outlook for sometime. The only consolation is we didn't get that ghastly sw on the edge of that southerly high that was programmed last week on several occassions, which ilicited that stupid term 'scorchio'. No ,no one will be on the porchio but the lack of real cold will be torchio..

[Zakos]

Significant downgrades today, though there is still ample opportunity for change, and either way Northern Scotland looks in a prime position for some decent snowfalls.

The bigger picture of a relatively mobile theme remains, how cold it will be depends entirely on the track of the Jet stream.

Meanwhile, some very encouraging stratospheric forecasts being shown, even if the PV reforms as the GFS FI shows, it doesn't look like it will last very long, Janurary 10th onwards looking increasingly like a significant cold spell.

[PubliusEnigma]

I had thought GFS had plumbed the depths for poor op runs, but the 12z is as bad as it gets. The Iberian High stars in early Jan: http://cdn.nwstatic....300/h500slp.png

http://cdn.nwstatic....372/h500slp.png

Temps probably +5c above average in the south.

Zero chance of snow for 80% of the Country on that run.

It can only get better from here!

Temps of up to 16oC would be possible with the aid of the fÅhn effect.

Usually as we come to the end of December and into the new year, the atmosphere tends to settle into its winter

pattern lets hope the new year doesnt show the trend for the remainder of winter. For a lot of the 12z run, the theme is

very much of high pressure over the continent, or Iberia, the PV close to western Greenland, and endless lows rattling in

from the south west at times, bringing potentially way above average rainfall looking likely for the coming two and half weeks.

Edited December 22, 2012 by PubliusEnigma