Winter Model Discussion 18Z 13/1/13 onwards.

[nick sussex]

I'm afraid some of you cant read charts. The 00z output is stunning if you want deep snow in the uk. Clearly it cant snow everywhere. Judging by the latitude of the jet, there could be some dodgy periods in this thread over the next few days.

Yes it won't be pleasant!If the trend of the ECM and UKMO is to be believed then someone is going to get alot of snow, some are going to stay dry and some will get rain!

Really all to do with how strong the block is, so I certainly would say to those celebrating snow at this range, don't, for those thinking damn sodden rain, wait a while longer and for those thinking I might end up dry, you might still get something.

However we often have this discussion every winter, the further north and east any snow gets the more likely it is to be a signal that the Atlantic will overpower the block.

Historically if the block is underplayed the snow remains in the south, west and sw and then slides away into the continent.

The models have to perform a juggling act and perhaps the most complex thing they have to model, each run will likely push the snow belt north then south and then a clearer trend will develop after this thread has seen IMBY carnage on an epic scale!

[BLAST FROM THE PAST]

and some charts explaining what is good really would improve your post and make for a fuller understanding of charts for newcomers Fred-so PLEASE can we have charts when you comment-thanks?

At work John....so in a word no can do computer settings won't support it so let's accept why I or anyone doesn't post a charts on occasions and IMO its very clear what I'm saying anyway? If previous post I wrote was also read it would make it clearer. There's help and there's no need for help when trolling occurs.

And those liking JH post, give it a rest and think about the 'ability' to post charts. Ridiculous thread this morning.

BFTP

Edited January 14, 2013 by BLAST FROM THE PAST

[Froze were the Days]

UKMO and ECM (showing some undercutting) - so good but GFS stuck in the same pattern with the strong northern jet arm powering through, who will be correct? or will it be a half way situation. Even if we do get some undercutting the Atlantic at this point still looks to strong.

[phil nw.]

Another day on and again the Atlantic knocks on the door and again the majority of models show the block saying not today thankyou.!

http://www.wetterzen...cs/Rukm1201.gif

http://www.wetterzen...cs/Recm1202.gif

http://www.wetterzen...cs/Rgem1202.gif

GFS the only doubter this morning but looks on the mild side of it`s ens from day 6.Some very low mean temps showing.

http://www.wetterzentrale.de/pics/Rtavn1202.png

http://nwstatic.co.u...0be08d5f285da5c

This cold block just keeps hanging on and the UK and ECM runs in particular look very snowy towards the weekend.

Edited January 14, 2013 by phil n.warks.

[Timmytour]

Are all the models now starting to fall in line with the CMA?

[bobbydog]

i wonder if the Meto's new strat computer is getting a grip on the SSW effects, with the UKMO modelling the strongest scandi block and not really backing away from it

[Methuselah]

When considering some of the recent way-off-the-mark prognostications from those who claim that they can read the charts, let's have a wee bit of patience towards, and give a little more leeway to, those who are new to the forum and only want to learn??

None of us was born an 'expert'?

Thank you!

[TEITS]

Are all the models now starting to fall in line with the CMA?

Well the latest CMA is very much like the UKMO at +96.

[nick sussex]

Are all the models now starting to fall in line with the CMA?

Lol! The CMA has just arrived on the scene and I can't find any verification stats for it, in terms of falling in line all the models have been poor in terms of continuity apart from the UKMO which in terms of trend has at least had the block holding on.

Whilst it still dishes out cold runs it will be much lauded, at such point that it dares to deliver something milder it will fall out of the net weather popularity charts !

[Snow and storms]

So if this undercut was to come off, surely the blizzard it would produce would be something to go in the history books? thats a low of 968 pressure with nice tight isobars.

[Timmytour]

Lol! The CMA has just arrived on the scene and I can't find any verification stats for it, in terms of falling in line all the models have been poor in terms of continuity apart from the UKMO which in terms of trend has at least had the block holding on.

Whilst it still dishes out cold runs it will be much lauded, at such point that it dares to deliver something milder it will fall out of the net weather popularity charts !

Very true Nick. So little experience of it but I must say, Chart Viewer at the moment looks to have found a jewel. if this cold spell verifies to the degree it seems to have consistently, more than any other model, shown, then it puts itself in the firing line for further scrutiny. As you say...when the mildness comes might be the test. At the moment, it may be like Nick Clegg before the election...most popular leader. We saw how that changed when he was put in a position of attracting more scrutiny!

[Paul_1978]

When considering some of the recent way-off-the-mark prognostications from those who claim that they can read the charts, let's have a wee bit of patience towards, and give a little more leeway to, those who are new to the forum and only want to learn??

None of us was born an 'expert'?

Thank you!

I think most of us can tell the difference between a keen learner and a troll. ;-)

[Methuselah]

I think most of us can tell the difference between a keen learner and a troll. ;-)

And we will deal with any trolls, believe me. But there's no need to feed them!

[Carlrg]

I know it's in FI but 120 to 144 the low stalls to the West of Ireland and hardly moves, can anybody give me an insight as to the reason? Is it the higher pressure sitting in the heart of Europe? Thanks, Carl.

http://www.meteociel...=120&carte=1021

Edited January 14, 2013 by Carlrg

[TEITS]

So if this undercut was to come off, surely the blizzard it would produce would be something to go in the history books? thats a low of 968 pressure with nice tight isobars.

Potentially yes. However for me personally I would prefer to see any frontal snow stay away from me and only affect the far SW/S. The reason I say this is if it managed to get this far N then potentially it would turn milder beyond.

Still way too early to discuss this and don't forget Saturdays band of precip ended up being much further S than initially progged. This often happens in these situations.

[rory o gorman]

I know it's in FI but 120 to 144 the low stalls to the east of Ireland and hardly moves, can anybody give me an insight as to the reason? Is it the higher pressure sitting in the heart of Europe? Thanks, Carl.

http://www.meteociel...=120&carte=1021

It is due to the cold pool of air to the East which is very dense its hard for the Atlantic to push through it hence it stalls . hope that helps

[latitude]

Potentially yes. However for me personally I would prefer to see any frontal snow stay away from me and only affect the far SW/S. The reason I say this is if it managed to get this far N then potentially it would turn milder beyond.

Still way too early to discuss this and don't forget Saturdays band of precip ended up being much further S than initially progged. This often happens in these situations.

Good call TEITS. That potential snowy end of the week could be the begining of the end for the cold spell.

Ive only looked at the GFS but I noticed the -5 850's are pushed back east as the front arrives at the end of the week with a quick thaw? (might have that wrong)

[Coventry Lee]

Can I ask why some are labelling the latest model runs 'fantastic'? The nw ten day forecast suggests that, in my area at least, temperatures will climb to 5-6c for the weekend. What am I not understanding?

[Frosty.]

The Ecm 00z at T+120 is jaw droppingly good with a super undercut from that slider, it also looks like the slider solution is gaining support and if we get one, there will be widespread severe blizzards, even beyond that, the ecm keeps it cold with trough disruption over the uk and despite losing the coldest uppers from most areas, we keep surface cold and I reckon the ecm would continue cold and unsettled with an ongoing snow risk after the initial weekend carnage. In the meantime, a very cold week with sunny spells for most and severe frosts, snow showers for the eastern side of the uk but the bulk of the snow showers towards the southeast, then a risk of snow into the west by friday with strengthening SSEly winds, then saturday could be a white out.

[Great Plum]

Can I ask why some are labelling the latest model runs 'fantastic'? The nw ten day forecast suggests that, in my area at least, temperatures will climb to 5-6c for the weekend. What am I not understanding?

The n/w 10 day uses the latest gfs output and that is currently the only model (I think) showing a return to westerlies...

[Coventry Lee]

The n/w 10 day uses the latest gfs output and that is currently the only model (I think) showing a return to westerlies...

Ah, that explains it. Thanks.

[stodge]

Can I ask why some are labelling the latest model runs 'fantastic'? The nw ten day forecast suggests that, in my area at least, temperatures will climb to 5-6c for the weekend. What am I not understanding?

Put simply, if we knew, without a doubt, what the weather was going to be in ten days, this forum wouldn't exist. The point is that this forum functions on the glorious uncertainty of our weather. It MAY get milder next weekend but it may not. Those who analyse the model output in depth rather than commenting on every frame of the Operational output, will tell you that currently trying to predict what will happen tomorrow is a challenge.

The forecast you have picked up uses an extrapolation of data to produce an outcome but the chaos that is the atmosphere defeats most if not all attempts to understand and predict it. Looking back to New Years Day, how many of the models forecast the current scenario? Very few. If you are going to use a single temperature forecast as your basis for predicting the weather, fine. You'll be no more wrong than most other people.

All we have to go on is a combination of past evidence and regular updates. Past experience tells us cold blocking systems CAN be very difficult to shift.

[Gibby]

Good morning everyone. Here is the start of a new week and the first working week report on the 00z output from the big four, namely GFS, UKMO, GEM and ECM for today Monday January 14th 2013.

GFS shows a cold week to come with the current weak Low pressures trundling away SE to Europe over the next 48 hours taking their rain and snow with them The cold intensifies somewhat midweek as the High pressure over Scandinavia throws a ridge SW over Britain with very frosty nights and dry weather the form horse before the Atlantic pushes into the block at the weekend. Thereafter, after a period of snow turning to rain the weather becomes Atlantic based through FI as deep Low pressures to the North steer wet and windy weather across Britain in a rather chilly cold zonal pattern. Some snowfall would occur at times over the hills as cold fronts pass and showery interludes intervene.

The GFS Ensembles show a trend towards less cold conditions from the end of the week and with the increase in precipitation spikes the influence of the Atlantic is likely to win through with rain or showers likely next week, though still with a snow risk at times over the hills.

The Jet Stream shows the disrupted flow currently gradually giving way to a stronger feed across the Atlantic towards the British isles by the end of the week and the weekend as the High to the NE gives way.

UKMO today shows a depression moving SE over Eastern Britain over the coming 24 hours with a band of rain, sleet and snow currently moving SE over the UK gradually clearing away in a day or so with winds changing to a raw and cold Easterly for a time with some snow showers in the East. With a blocking High over Scandinavia Low pressures from the Atlantic take their energy SE, one on Thursday to the SW with a sleet or snow risk there before stronger versions move up against the cold air over the UK late in the week and weekend giving some heavy snowfall for Southern areas with a trend for this to revert to rainfall in the far SW and South Coast with time in strong winds by then.

GEM shows Low pressure too sliding SSE across the UK today and tonight with some rain or snow, chiefly across the East. High pressure then pushes a ridge SW from Scandinavia with a cold few days of dry and frosty weather away from the East Coast where some snow showers could occur. Late in the week and weekend it too shows sliding Low pressure into the SW of the UK with snow turning to rain with time as somewhat milder and wetter conditions win through from off the Atlantic next week.

ECM finally also shows Low pressure clearing away SSE over the next 24 hours as well as another wave to the SW taking attendant rain and snow with them. A few cold days under the Scandinavian ridge then ensues over the middle of the week before it too brings disrupting Low pressure SE again late in the week. With the cold air in place over Britain some snow would develop again towards the weekend, turning to rain as the cold air is diluted and pulled slowly away NE leaving a snow risk just for NE areas with time with some copious rain events likely for the South and west at times.

In Summary this week is going to be cold with a snow risk at times, chiefly in the East and later in the West and SW. Thereafter the cold weather looks like being slowly displaced by milder air moving in slowly behind successive frontal troughs giving snow back to rain scenarios with snow restricted to the higher ground of the North and NE as we move deeper into next week. Some heavy rain is likely though again, especially in the SW should some of the output of this morning verify. It should be noted that the models only bring a tentative return to milder air and changes on the output over the next few days back towards cold or more decisively mild options are likely to be shown.

[johnholmes]

Some of you may not like it but the upper pattern being predicted for 10 days time, this is the ECMWF_GFS output this morning does suggest especially on the ECMWF version pushing deepish cold strong westerlies way into the continent with ridging over the north of Scandinavia back towards Greenland; GFS is less keen on pushing the westerlies as far east.

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

NOAA last evening in its 6-10 and 8-14 day upper air outlook was fairly similar but with the flow not as strong. Again indicating that the blocking is well north of this country.

Not mild by any means on any of them but not blocked either

[johnholmes]

.

Looking back to New Years Day, how many of the models forecast the current scenario? Very few.

all 3 of the anomaly charts were starting to show this weather pattern and are usually more correct than the synoptic models at ranges beyond 6 days, or that is how I judge both outputs?