General Model Output Discussion Thursday December 24Th:

[rich1]

Not a big fan of battleground setups per se, usually rubbish down here, always seem to be just a bit too far north and have me pounding the walls with frustration at snow reports 20 miles north whilst we get stuck with the pishing rain. Yuk

but can see the bigger picture and the set up is very good on the whole, and to some degree the cold weather will probably win out. Would rather not see any mild weather, maybe a couple of days here, just hope it doesnt drag on though...kind of like the ice and zero degrees weather, hate heavy rain

lots of potential there though and the mountains of scotland could end up having a bumper snow season 06z better than the 00z and the ECM looks very good indeed for many including here

wasnt around back then but guess there is a 78-79 look to the charts right now looking at the archives...occasional thaws in the south, Scotland an icebox and plunges of cold air down the country with heavy snowfalls

Edited December 24, 2009 by rich1

[Cecil Hogmanay Melchett]

Fascinating battleground situation, my call at this point is heavy snow for Mid/South Wales, SW Midlands and Central Southern England.

Its very tricky to call but its looking like it might well get much colder as head through next week.

I can't get ecm out of my head i pray its right because that run brings some bitter cold in towards the end.

Hopefully the meto update will be more positive this morning,if they go off the ecm/ens then there has to be

a mention of severe cold towards the end of the period.

All eyes on the update coming out in the next hour!

[snowhope]

Do not tease! Have had the max of about 5mm of snow here.

Similar here Bish, Todays output is looking so much more promising. I would be cautious though, although the trend is there, the finer details are yet to be pinned down, a bit like playing pin the tail on the mosquito at the moment!

[rich1]

Its very tricky to call but its looking like it might well get much colder as head through next week.

I can't get ecm out of my head i pray its right because that run brings some bitter cold in towards the end.

Hopefully the meto update will be more positive this morning,if they go off the ecm/ens then there has to be

a mention of severe cold towards the end of the period.

All eyes on the update coming out in the next hour!

tend to find these updates follow the outputs more or less rather than the outputs following them. If we see more cold runs which i think is likely then there will be a slightly toned down 'Its 2009, we cant quite believe the outputs and we love mild but we cant ignore the trend' type of updates, promising shall we say 'below average temperatures' and 'increasing risk of snow especially in higher northern parts'. I would never expect them to go all Joe bstardi on us but suspect the met office will be going for progressively colder weather as we approach the new year

[Nick L]

Met Office update seems very underwhelming considering the likes of the ECM!

[snowlover2009]

Way too early to tell.

At the moment if the model output continues with the same trend then it could be anything between the N or S Midlands/S Yorks/N Yorks. Even this would change until +24hrs. In these situations its quiet possible that only 30miles is the difference between heavy rain or a blizzard.

I will add though that if the battleground is further S then parts of E Anglia/SE would probably see rain whereas inland locations would see snow. The reason for this is due to the NE,lys spreading across the warmer sea. Something worth considering whilst we ponder on where this battleground will be.

yes your right. it would be astonishing if this was nailed on now. i have seen forecasts where they predicts snow the day before and it usually changes. looks brilliant. New years eve looking very cold and overnight very cold, which could lead to a similar scenario to last year, when it was bitterly cold. What a way to see out the new year! If this cold spell lasts till mid jan, then the winter for me would be better than last years.

besides thats its a ral white out here, so it looks like we will have a white christmas here which is just brilliant

Met Office update seems very underwhelming considering the likes of the ECM!

probably because if they predict another week of bitter and wintry weather, then there winter forecast would not be anything like what some parts of the country are having atm. when will they do an update on the winter forecast?

[Optimus Prime]

Remember though...all it takes is for the winter average temperature for the UK to rise 0.1c above normal to make their season forecast a success.

[Frosty.]

They haven't updated yet?

They have and it's almost a carbon copy of yesterday's update except the final sentence actually makes sense this time.

The ecm output seems to have been ignored, in fact, it's hard to tell which output they have gone with to be honest.

underwhelming sums it up nicely.

[phil nw.]

Good Day and a Merry Christmas everyone,

No doubt now that we are entrenched in a Cold pattern going forward into the New Year.

Previous posters have given excellent summaries and links to all the model outputs so i will not post them again.

However it`s always usefull to view the 00z GFS/ECM Mean ht. 500hpa comparisons.

http://www.meteo.psu...0z/hgtcomp.html

This confirms the hemispheric overview of cross polar heights and the Scandi.troughing,couldn`t be better for cold.

The probable battleground setup for next week that is being modelled is something that we havent seen for many years and reminds me of Winter weather from the 60`s-80`s.

This would be a classic scenario for somewhere to see heavy and prolonged snowfall as the fronts between the contasting airmasses stall,before the cold air undercuts and pushes South.

This chart gives an idea of the differences in the upper air temps. between north and south.

http://charts.netwea.../h850t850eu.png

So a little easing of the cold for the next few days and then it looks like a return to some real Wintry weather next week.

Edited December 24, 2009 by phil n.warks.

[swilliam]

Fascinating battleground situation, my call at this point is heavy snow for Mid/South Wales, SW Midlands and Central Southern England.

My only concern about this battleground situation next week is that most of it might actually be more cold rain if the orientation is not favourable. The cold air is not well established initially with highish uppers (-3/4) and not much surface cold in England and Wales). This is highligted by the forcasted temperatures and dewpoints at the peak of the event as forecast by the last run.

If the trough does not align correctly then we could have a lot of rain in England and Wales with only a brief transition to snow as the final low scoots through. We have all been fondly remembering 78/79 New Year when the cold air became established and then the battleground developed as the wave depsression passed along the English channel. The alternative though is what happened in Jan 1982. We had a similar situation to then as is projectd now

The siutaion remained static like this for a while until the low finally shot through

The result of this was copious amounts of rain in England and Wales with realtively mild temperatures. There was only a brief changeover as the low passed rapidly through. In this case though this is forgotten as there was follwoing low and new battleground became established with massice snowfalls across the whole of England and Wales.

In our case we do not have a low following so we would not get this situation. What we do have is much better establishment of the block and the potential for a longer lasting cold spell with snow.

So I think we need to watch the developments early next week and not get too excited yet by the potential synoptic situation. Although we are better placed than Jan 82 it still looks bit marginal for a major event There are several things needed to go in our favour to get a large snowfall from this situation.

Edit: Meto update shows same concerns

Edited December 24, 2009 by swilliam

[nick sussex]

Met Office update seems very underwhelming considering the likes of the ECM!

The ukmo has exactly the same forecast as yesterday even though it says Thursday, to be honest it's really only us model anoraks that ever look at it, i suspect most of the general public wouldn't really be that interested. They won't call definite cold on that until they're absolutely sure and to be honest just look at how the forecasts have changed in just one day, more snow possible for southern Scotland and a small chance of a little snow in the far se as low pressure heads ne from France and collides with a weak front over the east,at the same time some colder upper air heads se from the north, could be a surprise coming for these areas! again the track of the French low might change, preferably if you're in the se you want this to head slightly further west.

[Cecil Hogmanay Melchett]

The ukmo has exactly the same forecast as yesterday even though it says Thursday, to be honest it's really only us model anoraks that ever look at it, i suspect most of the general public wouldn't really be that interested. They won't call definite cold on that until they're absolutely sure and to be honest just look at how the forecasts have changed in just one day, more snow possible for southern Scotland and a small chance of a little snow in the far se as low pressure heads ne from France and collides with a weak front over the east,at the same time some colder upper air heads se from the north, could be a surprise coming for these areas! again the track of the French low might change, preferably if you're in the se you want this to head slightly further west.

To be honest nick it looks to me like they are going with the UKMO run and you'd have to say its the less wintry of the model output,if you compare ecm and ukmo at 144h there is quite a massive difference between them

on events to the SWest and how the low behaves.

[TEITS]

Met Office update seems very underwhelming considering the likes of the ECM!

Why seems fantastic to me and perfectly goes with what I said earlier. Note they say a risk of snow for Wales, Midlands, well this is due to what I was saying earlier about E Anglia/SE probably being too marginal due to the warming effects of the N Sea, although I expect the W parts of E Anglia would be at risk. Beyond and like I said to you in the Midlands thread, if you have a cold NE,ly bringing snow showers then central parts of the Midlands would escape the worst due to being inland. The ideal situation for the Midlands is a series of LP systems taking a trip along the Channel.

At the moment the general trend from the models is staying cold in the N. The risk of snow from midweek next week anywhere N of the M4 and then becoming colder with snow showers especially in N/E areas.

[Solar Cycles]

Fascinating viewing, and if I was to guess where the battle lines were to be drawn, I would say the North Midlands up to Southern parts of Cumbria. If my memory serves me well, I seem to remember several big snow events during 78/79, where this happened with similar synoptics!

[Rollo]

Morning TEITS, What has been obvious in this spell so far(and indeed in previous notable wintry spells) is the tendency for areas not expecting heavy snow to apparently get tham so to speak out of the blue. As things are looking good at this stage for next week I have no doubt the same will occur again,Roger does not seem quite as upbeat as you do but there again he will not be here to enjoy the fun. Have a good Xmas,Mike.

[Southender]

Why seems fantastic to me and perfectly goes with what I said earlier. Note they say a risk of snow for Wales, Midlands, well this is due to what I was saying earlier about E Anglia/SE probably being too marginal due to the warming effects of the N Sea, although I expect the W parts of E Anglia would be at risk. Beyond and like I said to you in the Midlands thread, if you have a cold NE,ly bringing snow showers then central parts of the Midlands would escape the worst due to being inland. The ideal situation for the Midlands is a series of LP systems taking a trip along the Channel.

At the moment the general trend from the models is staying cold in the N. The risk of snow from midweek next week anywhere N of the M4 and then becoming colder with snow showers especially in N/E areas.

TEITS. Can I ask. Why is the M4 always used as the Snow/Rain border?

It's about time we had an event where anywhere South of the M4 can get in on the action as well. What do we need to make this happen?

[TEITS]

To be honest nick it looks to me like they are going with the UKMO run and you'd have to say its the less wintry of the model output,if you compare ecm and ukmo at 144h there is quite a massive difference between them

on events to the SWest and how the low behaves.

No the Met O is definately going with the ECM. The UKMO at +144 wouldn't bring a risk of snow for the Midlands/Wales but the ECM would.

If some members are getting confused by this let me explain.

The track of the LP system next week is all important as to whether you see frontal snowfall or rain. However once the LP system moves E everyone would be experiencing colder weather. If you want to know whether it will rain or snow then the first thing you need to look for is are you on the N side of the LP. Look at the chart below from the ECM.

Now if that verified what would happen is N of the M4 rain would turn to snow in Wales, Midlands and W parts of E Anglia. As the LP moves E the risk of snow would move S & E so other areas would see rain turning to snow.

Use that above link as a guide for future models runs and you won't go wrong.

[azores92]

clearly it didnt update at half past ten, and the much better update from the MO has just been released.

for those who havent seen it, here it is:

UK Outlook for Tuesday 29 Dec 2009 to Thursday 7 Jan 2010:

Scotland and Northern England should have sunny spells on Tuesday and Wednesday with occasional showers. These should be most frequent in the Northeast and could also fall as sleet or snow. Frost and freezing fog is possible overnight. Further south it is likely to be wet and windy with a risk of snow for Wales and the Midlands. This clearing to wintry showers during Wednesday. Temperatures are expected to be briefly mild in the far south but cold elsewhere. The rest of the period will have sunny spells but also wintry showers. Some longer spells of rain, sleet of snow are possible, although inland Central parts should see some good dry and sunny interludes. It will be cold or very cold with hard overnight frosts.

Updated: 1212 on Thu 24 Dec 2009

highlights the potential for snow next week, and clearly turning much colder, though staying drier for inland parts, i.e the midlands.

Edited December 24, 2009 by azores92

[Guest North Sea Snow Convection]

Met Office update seems very underwhelming considering the likes of the ECM!

The update is an improvement in the longer term and does suggest support for the ECM imo . They are not going to predict huge snow storms at this range. Yesterday it mentioned the possibility of less cold settled weather (ie a high close by). Today suggests that the cold NE'erly with pressure higher and further away to the NW will occur. I think that reflects the ECM well. They aren't going to ramp it up totally yet - but that is about as good as it could be expected to get at this stage. Although some of us south of the M4 might have to endure some rain and higher temps first.

[Southender]

No the Met O is definately going with the ECM. The UKMO at +144 wouldn't bring a risk of snow for the Midlands/Wales but the ECM would.

If some members are getting confused by this let me explain.

The track of the LP system next week is all important as to whether you see frontal snowfall or rain. However once the LP system moves E everyone would be experiencing colder weather. If you want to know whether it will rain or snow then the first thing you need to look for is are you on the N side of the LP. Look at the chart below from the ECM.

Now if that verified what would happen is N of the M4 rain would turn to snow in Wales, Midlands and W parts of E Anglia. As the LP moves E the risk of snow would move S & E so other areas would see rain turning to snow.

Use that above link as a guide for future models runs and you won't go wrong.

Thanks TEITS.

Can't quite work out whether I'm N or S of the M4!

But either way it's going to be marginal for my location at first. From an IMBY point of view, I'd like the LP to be slightly further South.

Nice to see the METO update starting to turn the right way for next week....

Edited December 24, 2009 by LeighShrimper

[NorthantsSnow]

Fantastic model output all around from a cold perspective with things getting interesting again as early as Monday for some areas. I cannot believe this thread is so quiet considering the quality of the charts!

[Wales123098]

TEITS. Can I ask. Why is the M4 always used as the Snow/Rain border?

It's about time we had an event where anywhere South of the M4 can get in on the action as well. What do we need to make this happen?

Lol, I live just north of the M4 in Cardiff and on many occasions you would drive up the A470 from Cardiff go under the M4 and soon as you go under the M4 bridge it would be snow and on the other side rain so in personal expierence its a good boundary.

[TEITS]

Last post as I need to prepare for tomorrow.

The ensembles say it all really. Note the rise in pressure over Iceland and the drop in pressure over Madrid/Paris.

http://charts.netweather.tv/ensimages/ens.20091224/06/prmslMadrid.png

http://charts.netweather.tv/ensimages/ens.20091224/06/prmslParis.png

http://charts.netweather.tv/ensimages/ens.20091224/06/prmslReyjavic.png

Im fairly confident of this S,ly tracking LP although still uncertain about the track. Beyond and to be honest I would prefer to concentrate on this LP.

[kold weather]

Still some big differences between the GFs/ECM in the long term, though they are both now in decent agreement about a Iceland block rather then a Greenland block, at least at first. However given how the set-up evolved last time and how favourable conditions are, I'd imagine it would eventually evolve just like the ECM suggests.

The GFS still powers up the Candian vortex which makes things that little bit more prone to failing to link up, whilsat the ECM goes for the Scandi vortex, which of course is going to be a very good set-up for the UK.

Anyway we have good agreement indeed for a cold NE general flow and a -ve NAO to develop again...then to what extent this all happens is whats somewhat up in the air.

As for the battleground, I wouldn't get too excited about it, I think swilliam makes a very good point and I suspect whislst there will be some large northern edge snowfall its not going to be clearcut, esp where the milder air is present from now on....whilst that does leave us somewhat on the 28-29th we still don't really have quite cold enough conditions...its all far too marginal to call, though no doubt it could give someone snow but far to early yet...

It does have somewhat a classic look saying all that...

Edited December 24, 2009 by kold weather

[mushymanrob]

..id just like to say... congratulations to all the people here who have longed for a decent cold spell over recent years. this year it is delivering what youve yearned for for so long. :lol:

i just hope for a nice mild february now!