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

[MR EXTREMES]

t132 gfs this low pressure system pretty much stays out west of the uk only slowly approaching this means that any cold air in england and wales gets mixed out this is a no event for england and wales.

ecm at t144 this does make it into the uk its a no event apart from some areas on the ne side of england and scotland would do well out of this.

ukmo t120 would be good event for most of england and wales but will soon be mixed out over most of southern england up to around the midlands by t144.

[kold weather]

Ecm is exceptional for snow Midlands north.. Remember we already have strong surface cold in place at that point. Ecm at 144 is more or less a US type winter storm.

Mr, Gfs is not great, Ecm is superb away from southern counties

Edited January 15, 2013 by kold weather

[nick sussex]

Morning all

Alot of people on here given you're an hour behind me!

Just a word about the models this morning I think people might be falling into the trap of taking the output at face value without seeing whats happened over recent days, corrections south and west.

There are differences with the handling of the trough to the west, I think for the best snow event this is the UKMO especially as 120hrs with that low in the Channel but both the GFS and ECM also have snow.

Again though will these outputs look the same at 144hrs come the day, its noticeable how the GFS which once had a huge deep low which too an age to fill now has a weaker feature.

With high pressure still evident to the ne then theres always a chance the models will edge the pattern south and west.

Still alot of uncertainty going forward.

[TobyT]

The GFS has edged further again towards colder regime. The posters above are NOT picking up on the fact [MAYBE ON PURPOSE OR NOT] that the GFS further holds the Atlantic back and we see a further shift south overall of the jetstream again. Another small step by the GFS towards a colder outlook. ECM is similar to yesterdays but overall I'd say a further improvement. UKMO again is a stormer.

Re snow, I remember the great Jan 1985, I was still in Swansea back then, we had attacks from the SW. I can't post charts as at work BUT the first assault remained as rain below 300 meters but the second brought the goods big style. It may be the samne this time but overall IMO the outlook improvement continues.

BFTP

That was the point I was trying to put across and totally agree GFS is moving closer to the UKMO and I would not rule out cold holding the Atlantic further back further west/south in the coming runs.

Edited January 15, 2013 by TobyT

[MR EXTREMES]

good post.id have to concede that the 850s arnt great and maybe the surface cold is slightly mixed out but the set up synoptics wise is very knife edge and always capable of great snowfall

there is always a chance and there absolutely every chance this could all slip a little futher south which would be a little more of a safer route for good cold snow event this is possible and yes there is every possibility it was one of my concerns yesterday when looking at the runs and this morning the odd one out is the ukmo, i hope im wrong and the ukmo is right and i wont disscount anything right now just commenting on the models.

[Hammer]

Model rollercoaster be interested to know your thoughts from yesterday, you haven't mentioned them much this morning.

I don't think I have ever seen a low from Atlantic that hasn't been corrected a little in its position at day 0 from its prediction days before.

All to play for.

Edited January 15, 2013 by Hammer

[MR EXTREMES]

there is always a chance and there absolutely every chance this could all slip a little futher south which would be a little more of a safer route for good cold snow event this is possible and yes there is every possibility it was one of my concerns yesterday when looking at the runs and this morning the odd one out is the ukmo, i hope im wrong and the ukmo is right and i wont disscount anything right now just commenting on the models.

when i say the ukmo is the odd one out i just ment by its more southerly extent.

[BLAST FROM THE PAST]

there is always a chance and there absolutely every chance this could all slip a little futher south which would be a little more of a safer route for good cold snow event this is possible and yes there is every possibility it was one of my concerns yesterday when looking at the runs and this morning the odd one out is the ukmo, i hope im wrong and the ukmo is right and i wont disscount anything right now just commenting on the models.

MRC

The GFS has edged further S and W on each run over the last day or so, if it was edging away from an incredible outlook your point would have more body to it BUT the fact is the GFS continues to improve towards cold and the UKMO. There's always ifs anf buts re UK admittedly but its vastly better than 2-3 days ago.

BFTP

Edited January 15, 2013 by BLAST FROM THE PAST

[MR EXTREMES]

Model rollercoaster be interested to know your thoughts from yesterday, you haven't mentioned them much this morning.

i explained in my post a few minutes ago the worry was that we would become the parking zone for low heights.

more runs are needed to see if im right but as i said the models dont seem to push the low heights any futher than the uk which tells us that to our east cold is holding firm.

but in later fi they do all seem to be hinting at a renewed push of cold from the northeast which GP said about yesterday with a slight warm up for a few days or so.

when i say warm up i mean warmer than current conditions.

but cool cold zonal wet windy.

[TobyT]

when i say the ukmo is the odd one out i just ment by its more southerly extent.

It looks like the BBC Met are going with the cold..the local forecast is giving max -1c sat with snow so not set in stone but at this point they seem to be backing their own model.

Whatever the outcome very good model viewing to come

Edited January 15, 2013 by TobyT

[Ian Brown]

Model Rollercoaster, you are misreading the charts. The cold air cannot get mixed out easily from this angle of attack until the frontal boundary has crossed. There would be snow for England and Wales, in varying degrees from both the ECM and GFS this morning.

Clearly a lot of uncertainty, but we have low pressure over Europe and heights trying to build to the NE, there can be no return to conventional zonality whilst these aforementioned factors remain in place. The situation is a nightmare for forecasters as it was back in the eighties when these set-ups were more commonplace.

[Captain Shortwave]

High risk stuff this. GFS, the -5 isotherm sticks to the far north East of Scotland throughout, many places in the UK would have a snow to rain event and would be cold but not very cold. At the end of high resolution, the low clears with a north Easterly pulled in as heights rebuild over scandinavia (ignore low res as the low in the Atlantic reverses and ploughs right into us instead of retreating further)

ECM - -5 Isomer stays from a line Birmingham northwards, lots of potential major snow events though the far South would probably have rain.

UKMO, even further South with probably only the south coast and devon and Cornwall will have rain, whilst a snowfest begins for many South of the border with scotland perhaps keeping a showery east/south east feed.

This is a forecasters nightmare whilst there is some sort of agreement on the breakdown, times are rather different and the line between snow and rain varies. UKMO still holds firm with the other two models slowly progressing towards that solution. Who will get snow? TBH no one will know until about 12 hours out at the earliest.

Also breakdown here I mean as in the loss of high pressure over the uk, not necessarily cold.

Edited January 15, 2013 by Captain shortwave

[NorthernRab]

i explained in my post a few minutes ago the worry was that we would become the parking zone for low heights.

more runs are needed to see if im right but as i said the models dont seem to push the low heights any futher than the uk which tells us that to our east cold is holding firm.

but in later fi they do all seem to be hinting at a renewed push of cold from the northeast which GP said about yesterday with a slight warm up for a few days or so.

when i say warm up i mean warmer than current conditions.

but cool cold zonal wet windy.

There is always the possibiity that the heights are "parked" favourably with most of the UK, most especially the north, receiving easterly winds crashing against the heavy percipitation.

Fairly huge potential in this respect.

[MR EXTREMES]

It looks like the BBC Met are going with the cold..the local forecast is giving max -1c sat with snow so not set in stone but at this point they seem to be backing their own model.

Whatever the outcome very good model viewing to come

and to be honest at this moment in time i would to as this model must be the best to use for uk as it is a short term model.

but as it stands plenty more changes to come as this weekend went from strong ne flow on the fax to a more weaker easterly flow although over all still going to be a cold week.

[bluearmy]

If you thought this had been tough for forecasters, it seems its about to get a whole lot more difficult!!

[Iceberg]

Model Rollercoaster, you are misreading the charts. The cold air cannot get mixed out easily from this angle of attack until the frontal boundary has crossed. There would be snow for England and Wales, in varying degrees from both the ECM and GFS this morning.

Clearly a lot of uncertainty, but we have low pressure over Europe and heights trying to build to the NE, there can be no return to conventional zonality whilst these aforementioned factors remain in place. The situation is a nightmare for forecasters as it was back in the eighties when these set-ups were more commonplace.

Totally agree ian maybe more of a nightmare as the forecasters have very very little experience forecasting these situations as they just aren't old enough. Just posted in my regional thread but the models are showing the first attempted breakdown as snow the second as marginal sleet, snow, but there just isn't any real mild air in the breakdowns as we never tap into the sw contingent of the feature. It wouldn't surprise me if the second attempt stays as snow and is repelled and a third and forth attempt comes about, or the ener is lost and a high builds.

[IDO]

GFS continues with its relentless pursuit of the UK (as per Dec) at the end of the Atlantic train. All in FI of course so if it is wrong at least it has been consistently wrong. A very north south split for this type of pattern. The south may get transitional snow events, the north and higher ground should have snow fields. Late in FI we try to get another cold incursion from the NE, till another cyclonic westerly shifts the cold back NE.

UKMO still showing a better undercut but again that looks likely to be relatively poor for the south, for laying snow. The track may change so hypothetical, but any snow to a relatively quick thaw for south.

ECM is also suggesting that north/south split for snow this weekend and also follows the Atlantic train route. The north should have plenty of laying snow; again the south more transitional.

All marginal at the moment so possible changes likely either way. Much like this snow event just gone.

Whatever synoptically we get it looks like remaining colder than average for some time. GFS at T384:

In the short/medium term all models appear to be in agreement that an easterly is doubtful due to the PV lobe migrating from the US to the Atlantic and PM shots are are main source of cold via cyclonic westerly's. For this to also favour the south we would need the UK trough to continue to shift south and all models are hinting at this. Then possibly a good pattern for the full effects of the SSW, to give the UK a memorable Feb.

[swfc]

It looks like the BBC Met are going with the cold..the local forecast is giving max -1c sat with snow so not set in stone but at this point they seem to be backing their own model.

Whatever the outcome very good model viewing to come

good call and it may preserve sanity in doing so

[MR EXTREMES]

Model Rollercoaster, you are misreading the charts. The cold air cannot get mixed out easily from this angle of attack until the frontal boundary has crossed. There would be snow for England and Wales, in varying degrees from both the ECM and GFS this morning.

Clearly a lot of uncertainty, but we have low pressure over Europe and heights trying to build to the NE, there can be no return to conventional zonality whilst these aforementioned factors remain in place. The situation is a nightmare for forecasters as it was back in the eighties when these set-ups were more commonplace.

so before this front hits the united kingdom on this chart the flow is from west then up from the south before going onto a southeasterly but surely that would mixout surface cold.

but i do agree with the rest of your post im just looking at things from all perspectives.

Edited January 15, 2013 by model rollercoaster

[NorthernRab]

Whatever synoptically we get it looks like remaining colder than average for some time. GFS at T384:

A chart from 31st of Jan...honestly?

[swfc]

The bottom line i guess in this set up is that the snow if it transfers north or east is bound to leave parts of the uk in lesser 850s and slightly milder air,its the uk afterall not the interior of russia!The trade off is staying very cold with coastal snow showers or fronts trying to push in with the chance of heavy snow ete,make your choice i guess!!!!

[Jason M]

The GFS has edged further again towards colder regime. The posters above are NOT picking up on the fact [MAYBE ON PURPOSE OR NOT] that the GFS further holds the Atlantic back and we see a further shift south overall of the jetstream again. Another small step by the GFS towards a colder outlook. ECM is similar to yesterdays but overall I'd say a further improvement. UKMO again is a stormer.

Re snow, I remember the great Jan 1985, I was still in Swansea back then, we had attacks from the SW. I can't post charts as at work BUT the first assault remained as rain below 300 meters but the second brought the goods big style. It may be the samne this time but overall IMO the outlook improvement continues.

BFTP

On purpose or not? Sorry I take a degree of exception to that comment! Personally I think the many messages in here promising blizzards are far more misleading.

ECM would deliver transitory snow for much of England and Wales and nothing more. METO is much better although without more info its hard to tell as these charts can be deceiving as the air ahead is cold but nothing special.

I'm fully aware that the models may shift everyone south and indeed I made the point that a couple of hundred miles would do the job. Actually there is a good chance that things will shift south agin as I alluded to re the trends. I wouldn't actually be surprised if the whole lot drops into France.

Ian makes the point this morning about angle of attack and he's spot on, but the charts here and now this morning largely suggest rainfest or England and Wales after a period of snow. Midlands northwards, would likely do better. Anyway, hopefully a further shift south or sharpening of the angle of attack will occur later on today.

Jason

[IDO]

A chart from 31st of Jan...honestly?

If we continue to get cold charts at the end of FI that to me suggests a locked in cold pattern. This is starting to occur. Obviously the synoptics and fine details will change but that chart shows a meridional synoptic and we want these to show up rather than hints at returning to a milder setup.

[Iceberg]

When people say poor for the south, can we clarify please that they are talking about the weekend....and not about the front that stalls over the west Friday giving the sw 12-24hrs of snow first....

[Mr Sleet]

Morning all

Alot of people on here given you're an hour behind me!

Just a word about the models this morning I think people might be falling into the trap of taking the output at face value without seeing whats happened over recent days, corrections south and west.

There are differences with the handling of the trough to the west, I think for the best snow event this is the UKMO especially as 120hrs with that low in the Channel but both the GFS and ECM also have snow.

Again though will these outputs look the same at 144hrs come the day, its noticeable how the GFS which once had a huge deep low which too an age to fill now has a weaker feature.

With high pressure still evident to the ne then theres always a chance the models will edge the pattern south and west.

Still alot of uncertainty going forward.

Indeed,there will still be a lot of uncertainty even on the day of the event in this situation.Going back to the seventies and eighties when this type of event was more common, a straight on south west attack was often repelled if the block was strong enough, what eventually broke it down was an undercut slowing down over France and sucking up some milder air from southern europe, this was mixed in as a south easterly, cutting off the supply of cold air from the east and opening the way for a conventional Atlantic push.

Whether that will happen here is anyone's guess!

I think your comment yesterday about some people getting a snowy plastering, some getting rain,and some getting nothing, is spot on.