General Model Output Discussion

[FENDER.]

Very Cold NE'ly from the ECM with plenty of Snow about . The high starts to topple around +216 but then it looks like we will need to look towards Scandi. Very impressive yet again .

Very cold without doubt. But I fail to see where the snow is coming from. A very dry outlook I would have thought.

[snowmadchrisuk]

Very cold without doubt. But I fail to see where the snow is coming from. A very dry outlook I would have thought.

I can not see Showers escaping central and SE on this chart. We also have -10 850's embedded by this time.

[Frosty.]

Very Cold NE'ly from the ECM with plenty of Snow about . The high starts to topple around +216 but then it looks like we will need to look towards Scandi. Very impressive yet again .

The UKMO 00z out to T+144 is also very impressive with a NE'ly feeding snow showers into the north & east, especially counties bordering the north sea. The GFS 00z is my least favourite run this morning but it's an improvement on the 18z. It's probably inevitable that high pressure will set up across the uk not long after T+200 hours, let's hope the orientation of the hp will be favourable for future wintry reloads.

[West is Best]

Such cold ensembles! Snow risk in any number of directions from these runs, including the south-west peninsular Sunday-Monday.

GFS has FI getting milder, but I'm not too worried about that evolution at the moment.

Brrrrr .... like old times.

[Iceberg]

I very very good ECM IMO, the chart below shows where considerable precip for the south is progged and with -5C or below it will certainty be snow, due to the digging of the unstable cold air, a low rapidly forms of the SW approaches moving moving away, a classic setup and believeable if it gets some support from subsequent runs.

I don't rate a scandy tbh, the movement of the split PV into scandy is too strong and there is no way a surface high can either form or survive there.

The 240Z from ECM shows IMO a high that is ready to retrogress NW again, the lows and strong Jet traveling underneath the high, the split PV mentioned above coming down east side and the natural migration of the high to the existing N.American high would be favourite, providing another reload. As long as the upstream patterns continue as they are I don't see a massive pattern change.

Worth mentioning that a fair few Ensembles (GFS and ECM) are still going for the snow in the south on Sun/Mon/Tues, maybe Wed.

[FENDER.]

Is the low thats coming up from the SW, still going to slip into France. Could that track further North, leading to widespread snow for South, midlands and wales

[KTtom]

Certainly a cold week comming up, but It does look as though 90% of the country will be dry with just the far north of Scotland and eastern counties looking like getting any snow showers.

GFS and GEM let the GH topple over us with GEM bringing in SW'lies in FI without the widespread snow most are looking for.

The latest Fax looks good although the weekend low looks to miss to the south it actually acts as a spoiler in stopping the northerly make it through the country which would be a far better scinerio for westerners. North easterlies will certainly be cold but ppn looks to be extremely limited.

[Shiny_Bottom_1]

I have to admit that the models have, and are still, showing what, in terms of temperature, really is quite an amazing spell.

For example, I don't think I have seen greater than 5oC at home for around 10 days, and the model projections are further extending this spell, currently, to approximately 10th-12th of Jan for Central England. This is, at a guess, possibly one of (if not, the) coldest spell for quite some time for many areas if the models come off.

In terms of snow, comments regarding the eastern side of the UK, are in general, spot on. However, the snowfall the week before Christmas was not projected at such a range out. But whilst the dry theme is one that is perhaps favoured at the moment for the bulk of the country, movements of pressure centres, shape etc can change all that. Throw in some troughs, and it really is a 'stick your finger in the air' situation again.

One word of warning, especially when viewing the GFS, is before jumping for joy on the Op run charts, wait for the verification of the ensembles. Even at a very short range (<T+36), the GFS Op run has been out compared to other members. Worth bearing in mind.

[Geordiesnow]

Outlook seems quite dissapointing then?

Nope, outlook still looks good if you like the cold and snowy weather.

I must say, the ecm is an upgrade because it tightens the isobars slightly thus showers tend to penetrate more inland than they would of done on last nights ecm.

Not too concerned about the GFS lowering heights in Greenland, would like to think, we saw quite a bit of snow before then!

[winterof79]

I can not see Showers escaping central and SE on this chart. We also have -10 850's embedded by this time.

A sensible post.The 120 fax would bring disruption for definate,to say that there will be no snow is quite niave frankly.The charts on this mornings models and the one shown will spawn plenty of embedded troughs etc.A little patience is required,the frigid air is not yet upon us. The media will only forecast 24 hours out, i would have thought, in these cases and their updates will change quite quickly to reflect the developing cold.Enjoy weather lovers

Edited December 31, 2009 by winterof79

[snowmadchrisuk]

Outlook seems quite dissapointing then?

UKMo High res (NAE) model is showing Snow moving so far inland tomorrow it reaches Cornwall

[TEITS]

Another set of stunning runs this morning with very little sign of the cold spell coming to an end. However rather than looking at +144 im concentrating more onto tonight.

The GFS indicates a band of snow showers moving in E Anglia/E Midlands. However the Met O are having none of it.

http://www.wetterzentrale.de/pics/Rmgfs273.gif

I feel from now on its very much keeping an eye on the radar plus the fax charts if your looking for snowfall. As for next week and to be honest it still uncertain where that LP will track and what type of flow we shall have. At the moment a NE,ly seems the most likely but the strength of the flow is uncertain. Still I can't be bothered to worry about +144 when we could have exciting weather over the next 48hrs, especially in N/E areas.

Just checked the NMM model and this agrees with the GFS. A band of snow showers pushing in through the wash and then spreading all the way to SW England.

I will finally add that I resubscribed to NW Extra last night. I strongly urge members to join to get the best out of this cold spell. I find other radars unreliable not to mention the extra data you have from the models.

Edited December 31, 2009 by THE EYE IN THE SKY

[Lewis]

Another set of stunning runs this morning with very little sign of the cold spell coming to an end. However rather than looking at +144 im concentrating more onto tonight.

The GFS indicates a band of snow showers moving in E Anglia/E Midlands. However the Met O are having none of it.

http://www.wetterzentrale.de/pics/Rmgfs273.gif

I feel from now on its very much keeping an eye on the radar plus the fax charts if your looking for snowfall. As for next week and to be honest it still uncertain where that LP will track and what type of flow we shall have. At the moment a NE,ly seems the most likely but the strength of the flow is uncertain. Still I can't be bothered to worry about +144 when we could have exciting weather over the next 48hrs, especially in N/E areas.

I think that precip chart is just like the feature/trough developing during Saturday, the metoffice are playing it down, because they are very uncertain on the track of it, and where it makes land fall.

But i would expect them to update closer to the time frame.

I also agree about +144, way far out, it's only now we are starting to see agreements between the GFS and EUROS regarding the LP.

Although saturdays LP that will bring a trough down the eastern coast pushing south looked marginal on the 18z, it's looking much better, as the 00z upgrades dew points.

All in all looking very promising indeed,

Lewis

Edited December 31, 2009 by Storm Force Lewis

[Lewis]

Sorry guys OT I know, but can someone tell me what IMBY is please I see it a lot and have no idea what it means.

Thanks and please feel free to delete.

I think it stands for "In my back yard"

lewis

[phantom]

I think it stands for "In my back yard"

lewis

That explains a lot.

Many thanks

[Shiny_Bottom_1]

Anyway....as Dave says, the potential for snow extends tomorrow to Cornwall (not really s/e biased).

However, for Dave, as i've said a few times, it will be interesting to see if this snow verifies for tomorrow.

Looking at the ensembles, the ppn ensembles show this a possibility, with the further East you are, the better - by going on the Op run.

I remain cautious however, as the support from other members is not so great, although again, the further East you go, there are one or two members showing something similar.

The reason for the cautiousness, is that during the 29th, the GFS Op run went for -5oC 850's for Derbyshire, whilst the other members had agreement on a warmer value.

As we had no snow here, and whilst I still try and verify the value from somewhere, I would say it was wrong.

However, and interestingly, it seemed to have got spot on for the northerly movement of the ppn.

The former point was also <T+12!

Lets see, as i'm not sure we have done as much model verification since the GFS moved to a higher res.

[bluearmy]

http://www.ecmwf.int/samples/d/banner/page.html

almost a week of ice days in central southern england.

[TEITS]

Anyway....as Dave says, the potential for snow extends tomorrow to Cornwall (not really s/e biased).

I must admit I would prefer to concentrate on the whole of the UK when I refer to the models but there are a few reasons why I don't.

This morning I have prefered to concentrate on the next 48hrs. Now the reason I have focussed on my region is because of my local knowledge of this area. The models disagree with the precip tonight but this is where local knowledge comes in. Im pretty sure a NE,ly with upper temps of -8C will bring the snow showers that the GFS/NMM indicates.

Looking at the UK over the next 48 hrs and the general trend is clear. During the day we're going to see the front finally clear to the S. The NE of Scotland which is experiencing heavy snow showers as a type will extend S into NE England later on today. This risk then pushes further S during the evening/night. Into tomorrow and there is a chance of more organised bands of snow showers pushing S during the day into parts of the E Midlands. However I wouldn't rule out snow anywhere from tomorrow into Saturday.

[nick sussex]

Given this mornings model output I'm happy to stick to my thoughts of yesterday evening shown below:

An interesting trend developing in the ensembles which i've been keeping an eye on, a few days back many more southern european locations had a switch to milder conditions as the models were keeping the southerly tracking lows further north with of course these areas more often on the warmer side of these. For a few runs now more colder options appearing, for London some colder members down to around -12, now interestingly for Paris some down to -15 aswell as Toulouse. Now looking at Iceland a warm up going on up there later next week this seems now to suggest that possible high pressure closer to the north and possibly ne.

Also looking at the ecm ensembles the operational run is one of the warmer options for days 8-10 this probably because of the switch round to a more onshore flow for the Netherlands, I suspect the colder options are keeping the flow more from the east. So just a little uncertainty here as to where we go next with the pattern, a possible toppling of the ridge ne 'wards towards Scandi with another shot of colder upper air being pulled westwards on its southern flank this would go some way to explaining the increased colder ensemble members across central and southern europe.

The models may of course go off into a different pattern but just another possible option to think about.

Just one thing to add here from yesterday evening are this mornings NOAA discussions:

A CLOSED HIGH /POSITIVE ANOMALY/ OVER GREENLAND IS EXPECTED TO

PROGRESS THIS PERIOD AS AN INCREASINGLY AMPLIFIED WESTERN RIDGE

DEVELOPS WHICH FORCES TROUGHING DOWNSTREAM IN CENTRAL NORTH

AMERICA WHICH KICKS THE VORTEX NEAR THE NORTHEAST/ATLANTIC CANADA

NORTH AND NORTHEASTWARD.

If the high can stay far enough north as it moves eastwards then a chance of a Scandi high or high pressure centred to the north around the Iceland area with some reinforcing colder upper air backing westwards especially for more se areas.

Edited December 31, 2009 by nick sussex

[Duane S.]

Just finished perusing the 00z output and everything seems to be steamrollering forwards towards a classic cold spell for the whole of the UK.

GFS looked at one point as as though it was going to be a party pooper but ended up demonstrating, quite graphically, why once in place this cold spell is not going to go away any time soon. ECM is just excellent as indeed is the METO.

I still see our GL high being, IMO, dis-assembled far too readily in some of the charts though.

Speaking from MBY, I will be looking down to the SW over the coming few days. There is a fair bit of model divergence over the impact of that system for the South. If it does come closer than the METO would have it, which is probably unlikely but nevertheless not completely implausable, then I can already forsee some worrying about the marginal situation that will, quite naturally, arise. Unfortunately it has always been this way. When a LP system attacks from the SW it will pretty much always bring embedded warm(er) air, the good news is though that we should be entrenched in cold enough air initially to make things very interesting although the SST's may still make it too marginal right here on the coast.

It's not the first time (nor probably the last) but I will post these two charts for anybody so concerned about about advancing warmer 850's. Here's what can happen, even on the coast where Weymouth was cut off for days, when cold air is in place FIRST. Anybody living in the SW should be very excited about the prospect of a repeat sometime in the next few weeks, as the setup is nearing perfection for it to potentially occur again.

http://www.bbc.co.uk/devon/content/articles/2008/02/21/blizzards_1978_archive_video_feature.shtml

Edited December 31, 2009 by s4lancia

[TEITS]

Very exciting ECM ensembles.

http://www.knmi.nl/exp/pluim/vijftiendaagse/Data/15DAAGSE_06260_NWT.png

Remember a few days ago the mean at +240 was around 0C and I said watch how the mean will drop for this period. Now I said this because its inevitable the mean will rise because its so low!

If you check now the mean at +192 is well below 0C and if anything the mean at +240 is just as cold.

[Snow storm]

Snow in N Africa?

Lol.

[snowray]

Out to T+48, wheres all the PPN in Central/Eastern areas gone? UKMO were right after all, cold and dry apart from near North Sea coasts.

Where did the heavy snow for Wales, West Midlands, etc etc go btw?

[Lewis]

Out to T+48, wheres all the PPN in Central/Eastern areas gone? UKMO were right after all, cold and dry apart from near North Sea coasts.

Where did the heavy snow for Wales, West Midlands, etc etc go btw?

This is what i love about models, nothing is certain even in reliable time frame, don't worry about precipitation amounts. The last cold spell, the GFS had none of it, and look what happened...

Lewis

[TEITS]

Out to T+48, wheres all the PPN in Central/Eastern areas gone? UKMO were right after all, cold and dry apart from near North Sea coasts.

Where did the heavy snow for Wales, West Midlands, etc etc go btw?

I must be missing something here.

All the model runs I have seen suggest possible snow showers into NE England/E Scotland/E England. Now the GFS 0Z indicated snow showers moving into the wash and then moving SW tonight. However the UKMO doesn't sugggest much snow for E Anglia tonight but they do suggest snow showers moving S tomorrow.

SO I have to ask where in the model runs was heavy snow suggested for W Midlands/Wales?