Model Output Discussion:

[BristolBaggie]

So the snow is pretty much on its way for next week then if FAX charts hold true??? Tuesday/Wednesday at the latest but impossible to tell how much will fall and the exact locations this far out. We have the cold modelled to be locked in place and all thats left is to wait for the snow

The good thing for this setup - and indeed this winter overall is once a cold spell has settled on the models, They really have locked the idea in each month. December, January and now February.

I am curious how TEITS is managing to suggest snow showers though and what charts are being used to give this suggestion (not a rant or having a go, total interest in how its done. NAE timeline is about my scope lol)

That is simply not true. All models point to a mostly dry week with snow flurries in the East.

If the Met Office were expecting any disruptive snow next week they would have issued weather watches already.

Edited February 6, 2010 by BristolBaggie

[karyo]

The MJO continues it's progress towards phase 8 which is great news! http://cawcr.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/phase.Last40days.gif

I'd rather it stalls or slows down soon though, rather than continue to move as fast!

Karyo

[Guest North Sea Snow Convection]

I wanted to highlight the possibility of a sinker, although clearly the models are not showing this. What I would ask is if people looked at the 18z last night for Tuesday in isolation and particularly before this winter, then I believe most people would have called a sinker to be shown on subsequent charts.

The models have struggled woefully, perhaps because of no strong signal either way so perhaps for a time they defaulted to showing the more common pattern of Atlantic energy pushing NE. Trying to predict HP direct to the North of the UK is probably the most difficult of all.

As for severe, I don't think that is being shown, severe would be Jan 87 and whilst these synoptics look promising later in the week, nothing as cold/snowy as that is being progged.

The key to the question of the high pressure sinking though is to look at the relevant current background factors and take the situation on its own merits rather than based on assumptions about what has occured over recent decades influencing the outcome. From looking at those factors, there was and still is plenty of good evidence available to suggest that a sinking high was/is unlikely. We are in a sustained -AO pattern, not a +AO pattern.

Cycles move on, the weather patterns are dynamic and forwards moving, and just because they may have been stuck in one dominating phase for a relatively long period means nothing for what might happen tomorrow. This has always been the case and this winter, as well as last winter to a smaller degree, have borne that out very well. No surprise that the post 1987 theory has come unstuck, as was inevitable sooner or later

I think the models have always struggled with cold winter blocking patterns. It is nothing new. The old style forecasting found them just as difficult then as they are now. The difference was that they didn't go beyond 24 to 48 hrs. Wise people perhaps!

Edited February 6, 2010 by North Sea Snow Convection

[CroatianWeather]

Greetings to everyone,I am Karlo from Croatia,EX Yugoslavia......my English is not very good but I think you can understand me.....I am also on our Croatian Crometeo forum for 2 years,so I know something about models and meteorolgy!

I appreciate GFS and UKMO models,and looking at them today I can see that real cold spell will hit Britain and also Central Europe in nextcoming days.....

[Lewis]

This is what GFS says for Wednesday and Friday

Fridays chart shows temps only reaching 1 or 2C in the East and maybe up to 4C in the west

Im showing this as an example regarding how inaccurate the GFS is at the lower resolution.

The first chart shows 4c for me 12 noon on Wednesday, the following chart below is a custom skew-t chart from netweather extra, it's at a much higher resolution, and it makes a huge difference.

The skew-t chart shows a temp of 2.5c with a dew point of -3.5.

It's amazing the difference between the higher resolution and lower resolution.

[CroatianWeather]

February in wintry style....atlantic anticyclone blocking,and northerly cold air from scandinavia over all central and southern Europe!!!!!Really great snowfall is expected in next week over much of Europe!!!

Edited February 6, 2010 by CroatianWeather

[Snowyowl9]

I would say the cold spell that is showing up now as one or 2 have said well Tamara mainly about the very deep snow cover will be missing with no frontal heavy snow to begin with.

Slightly more thaw in the daytime but it`s still early/mid feb,look at last february first half,snow on the ground for 2weeks.

The sun maybe higher but the coldest spells usually come in as the days grow longer/cold gets stronger.

As what can happen in April.

February 1986 I rest my case -1.1 cet,except much much windier.

http://www.wetterzentrale.de/archive/ra/1986/Rrea00119860217.gif

http://www.wzkarten.de/pics/Recm2161.gif

http://91.121.93.17/pics/Rtavn601.png

[Snow Queen one]

Greetings to everyone,I am Karlo from Croatia,EX Yugoslavia......my English is not very good but I think you can understand me.....I am also on our Croatian Crometeo forum for 2 years,so I know something about models and meteorolgy!

I appreciate GFS and UKMO models,and looking at them today I can see that real cold spell will hit Britain and also Central Europe in nextcoming days.....

Welcome to our forum Thank you for your input it is nice to see people from other countries giving us their views. I hope you are right and i am in the right place to make the most of the cold weather with a bit of snow thrown into the mix.

I wish you well and lookforward to seeing more of your post.

[Eugene]

It seems some people moaning are making the same mistake i did just before the early to mid January cold spell and calling it cold and dry, well we know what happened then don't we, snow can pop up in short notice, anyway i'm not sure why some are banging heads agianst the wall for dry and cold weather, surely thats the next best thing to cold/snow and miles better than mild wet and windy rubbish.

Fantastic output btw across the board, lots to keep people interested in the next 7 to 10 days.

Edited February 6, 2010 by Eugene

[Cecil Hogmanay Melchett]

February in wintry style....atlantic anticyclone blocking,and northerly cold air from scandinavia over all central and southern Europe!!!!!Really great snowfall is expected in next week over much of Europe!!!

Welcome brother,, forza croatia!!!

[Eugene]

Not sure if anybody has mentioned GEM 00Z but what an incredible run, this last chart would cause lots of excitement thats for sure.

http://www.wetterzen...cs/Rgem2401.gif

Not sure i agree with those saying cold can't be as cold in early to mid February as early to mid January, some of our coldest cold spells have been early to mid February, if i recall correctly February 14 is on average the coldest day of the year in the UK or somewhere around that day, solar input isn't as great as say early to mid march, cold arctic airmasses are at their coldest and the seas surrounding us are approaching their coldest.

Edited February 6, 2010 by Eugene

[CroatianWeather]

Thanks everyone for great welcome.....

I still go to school so i have lot to learn but I will try to be as more I can active on this huge and really nice forum.....

Edited February 6, 2010 by CroatianWeather

[West Sussex Kate]

Welcome brother,, forza croatia!!!

Do Croatia know something about the models that we don't!!

[weather eater]

It seems some people moaning are making the same mistake i did just before the early to mid January cold spell and calling it cold and dry, well we know what happened then don't we, snow can pop up in short notice, anyway i'm not sure why some are banging heads agianst the wall for dry and cold weather, surely thats the next best thing to cold/snow and miles better than mild wet and windy rubbish.

Fantastic output btw across the board, lots to keep people interested in the next 7 to 10 days.

I don’t see anybody moaning, they are drawing conclusions from the model output, I don’t think we have a rule on the model thread that says you cannot post unless you suggest there will be loads of snow, and I have to say it’s this sort of post which puts people off posting. Yes of course with snow its often a now cast situation and we will have to wait and see how things develop, however a cold easterly is not a guarantee of snowfall and the models do not look promising in a reliable time frame for widespread heavy snowfall, that’s called being observational, not being a moaner.

[TEITS]

It seems some people moaning are making the same mistake i did just before the early to mid January cold spell and calling it cold and dry, well we know what happened then don't we, snow can pop up in short notice, anyway i'm not sure why some are banging heads agianst the wall for dry and cold weather, surely thats the next best thing to cold/snow and miles better than mild wet and windy rubbish.

Fantastic output btw across the board, lots to keep people interested in the next 7 to 10 days.

I remember back in January, myself and Nick S recieving some stick from members because whilst we were talking about snowfall they were suggesting cold and dry. I seem to remember being accused of being misleading. You just never know what will develop because even now the pattern towards the end of the week isn't certain yet wrt detail.

Also I see some are suggesting this cold spell won't be as cold as the one in January. Well for starters we may now have longer days but the SSTS are very cold especially around E Anglia. Now synoptically based on the model output this could be better. During our last cold spell the intial flow was a very slack NE,ly. When this did veer E,ly the cold pool only lasted around 24/36hrs!

As I said earlier what the models are suggesting is the HP backing W towards Greenland. As this occurs we continue with the E,lys and although the cold pool warms from -12C to -8C this is still cold enough. If the HP does manage to move into Greenland then the chance remains of pulling another pool of cold air S.

So in summary synoptically this cold spell could be better. Now weatherwise this could be the case for the reasons I say above. Remember a cold E,ly blowing across a snow covered continent combined with below average SSTs could bring even colder temps than we witnessed back in Jan.

[LomondSnowstorm]

Having had a closer look at the precipitation charts the idea of it being mainly dry is perhaps not entirely true - http://cirrus.netwea...6/51/ukprec.png The suggestion also that Scotland will see much less precipitation than eastern England seems to be a fairly sensible one on the face of the charts, but again charts like these make me think that perhaps this may not be the case http://cirrus.netwea...20/ukprec.pngOf course convective showers from the North Sea are hard for the models to pick up, not least in intensity, but these charts are by no means disheartening in the slightest, especially given how weak the flow is at this point http://cirrus.netwea...h500slp.pngAlso, the dewpoints for Monday morning http://expert.weathe..._0606.gifAround or below freezing for much of northern and inland Britain. http://expert.weathe...020806_0606.gif Not warm either.You can also see 1290 850-1000hpa thicknesses across much of the UK, another promising indicator when looking for snow. Also note that the higher resolution NAE shows pressure a few millibars lower than the UKMO http://expert.weathe...020806_0606.gif http://expert.weathe...20800_0600.gifI expect these charts to be very useful in the coming days when looking at precipitation amounts (though these again tend to be slightly less than what materialises) and more especially how conduicive conditions are to snowfall. LS

edit: late December was exceptional as 2 of the heaviest snowfalls came when uppers were just -3 or -4, presumably due to the frozen ground meaning the surface stayed very cold. When the flow was directly from the east, with no hint of north in it, even with colder uppers than those it was very marginal, so perhaps a north of east flow is preferable to a straight easterly.

Edited February 6, 2010 by LomondSnowstorm

[weather eater]

I remember back in January, myself and Nick S recieving some stick from members because whilst we were talking about snowfall they were suggesting cold and dry. I seem to remember being accused of being misleading. You just never know what will develop because even now the pattern towards the end of the week isn't certain yet wrt detail.

Also I see some are suggesting this cold spell won't be as cold as the one in January. Well for starters we may now have longer days but the SSTS are very cold especially around E Anglia. Now synoptically based on the model output this could be better. During our last cold spell the intial flow was a very slack NE,ly. When this did veer E,ly the cold pool only lasted around 24/36hrs!

As I said earlier what the models are suggesting is the HP backing W towards Greenland. As this occurs we continue with the E,lys and although the cold pool warms from -12C to -8C this is still cold enough. If the HP does manage to move into Greenland then the chance remains of pulling another pool of cold air S.

So in summary synoptically this cold spell could be better. Now weatherwise this could be the case for the reasons I say above. Remember a cold E,ly blowing across a snow covered continent combined with below average SSTs could bring even colder temps than we witnessed back in Jan.

Truth is Dave nobody is being misleading in regards snowfall, as we just don’t know yet, but as this is a thread for discussing the models then it is not unreasonable to say that the models neither show heavy snowfall or temperatures down to the levels we saw in January. It’s also reasonable to suggest that changes in the evolution of this cold spell could well develop into a situation where temperatures did fall to those levels and snowfall could become heavier and more widespread. There is nothing wrong with members having different ideas as to how this cold spell will affect the UK and it’s a shame that some members seem to want to bully others towards their point of view, it’s not nice and it’s not necessary.

[Jason M]

I remember back in January, myself and Nick S recieving some stick from members because whilst we were talking about snowfall they were suggesting cold and dry. I seem to remember being accused of being misleading. You just never know what will develop because even now the pattern towards the end of the week isn't certain yet wrt detail.

Also I see some are suggesting this cold spell won't be as cold as the one in January. Well for starters we may now have longer days but the SSTS are very cold especially around E Anglia. Now synoptically based on the model output this could be better. During our last cold spell the intial flow was a very slack NE,ly. When this did veer E,ly the cold pool only lasted around 24/36hrs!

As I said earlier what the models are suggesting is the HP backing W towards Greenland. As this occurs we continue with the E,lys and although the cold pool warms from -12C to -8C this is still cold enough. If the HP does manage to move into Greenland then the chance remains of pulling another pool of cold air S.

So in summary synoptically this cold spell could be better. Now weatherwise this could be the case for the reasons I say above. Remember a cold E,ly blowing across a snow covered continent combined with below average SSTs could bring even colder temps than we witnessed back in Jan.

Hi TEITS

Another point that some are forgetting is that the slightly increased solar input will probably result in showers forming inland. later in the week I wouldn't be suprised to see some Thunder Snow in some places in central southern england.

Jason

[ribster]

I don’t see anybody moaning, they are drawing conclusions from the model output, I don’t think we have a rule on the model thread that says you cannot post unless you suggest there will be loads of snow, and I have to say it’s this sort of post which puts people off posting. Yes of course with snow its often a now cast situation and we will have to wait and see how things develop, however a cold easterly is not a guarantee of snowfall and the models do not look promising in a reliable time frame for widespread heavy snowfall, that’s called being observational, not being a moaner.

I do get fed up with the assumption that everyone wants snow though, I realise it's down to personal preference, but for me I like winter to be winter. If we get any snow, then that's a bonus!

[Yeti]

There is lots of talk about longer days and a stronger sun which is certainly true, but we ought to remember that this also increases convection potential. A stronger sun than in Jan, shining over a comparatively cold N Sea should result in a lot of beefy snow showers - the question is will these make it far inland. The flow isn't great if we're honest, but it's better than a lot we've had where snow showers have formed in many areas, so I think it would be fair to say that some places could see a good amount of snow even this week - particularly parts of East Anglia and the SE from Wednesday onwards - the risk zone being a bit further N prior to this.

[Eugene]

I now have very high confidence that bitter east winds will return by the end of this weekend bringing a return to hard frozen ground and severe frosts. This cold weather will last into the following week. So be prepared, we are in the coldest part of winter now on Dartmoor and once cold establishes itself up here at this time of year it can be very stubborn.

Will hand mentions that Dartmoor in Devon is at it's coldest part of the winter now and cold patterns can be very stubborn once these cold blocking patterns get established, could last all month with LP systems trying to move north later in February but getting pushed back south.

Edited February 6, 2010 by Eugene

[Jason M]

There is lots of talk about longer days and a stronger sun which is certainly true, but we ought to remember that this also increases convection potential. A stronger sun than in Jan, shining over a comparatively cold N Sea should result in a lot of beefy snow showers - the question is will these make it far inland. The flow isn't great if we're honest, but it's better than a lot we've had where snow showers have formed in many areas, so I think it would be fair to say that some places could see a good amount of snow even this week - particularly parts of East Anglia and the SE from Wednesday onwards - the risk zone being a bit further N prior to this.

The extra solar input won't make the showers off the sea any heavier but it will allow us to 'grow our own' over land during the day to a limited extent. Best example is during the summer months where the showers fall inland whilst coastal areas can stay sunny all day.

Being early Feb the sun won't have a lot of strengh, but i suspect it will be just enough to cause some activity inland (as long as there isn't a sheet a grey low cloud).

[Methuselah]

Greetings to everyone,I am Karlo from Croatia,EX Yugoslavia......my English is not very good but I think you can understand me.....I am also on our Croatian Crometeo forum for 2 years,so I know something about models and meteorolgy!

I appreciate GFS and UKMO models,and looking at them today I can see that real cold spell will hit Britain and also Central Europe in nextcoming days.....

Welcome to netweather Karlo...I used to be a member on Crometeo - but I lost everything when my PC went funny...

[cheeky_monkey]

There is lots of talk about longer days and a stronger sun which is certainly true, but we ought to remember that this also increases convection potential. A stronger sun than in Jan, shining over a comparatively cold N Sea should result in a lot of beefy snow showers - the question is will these make it far inland. The flow isn't great if we're honest, but it's better than a lot we've had where snow showers have formed in many areas, so I think it would be fair to say that some places could see a good amount of snow even this week - particularly parts of East Anglia and the SE from Wednesday onwards - the risk zone being a bit further N prior to this.

im not sure this is the case..the sun does not have huge strength in Feb..plus the colder the airmass the less moisture..plus as the sea is colder the less convective showers will be produced than if the sea was warmer..surely the models would pick up on this potential if it were the case??..i always thought these sun driven shower activities occurred in march and april usually with unstable north westly airflows?..maybe im completely wrong?

[len]

There is lots of talk about longer days and a stronger sun which is certainly true, but we ought to remember that this also increases convection potential. A stronger sun than in Jan, shining over a comparatively cold N Sea should result in a lot of beefy snow showers - the question is will these make it far inland. The flow isn't great if we're honest, but it's better than a lot we've had where snow showers have formed in many areas, so I think it would be fair to say that some places could see a good amount of snow even this week - particularly parts of East Anglia and the SE from Wednesday onwards - the risk zone being a bit further N prior to this.

Several have commented on the now very cold North Sea helping to reduce warming modification.

But it also reduces the convective potential by reducing moisture & energy transfer into the air mass.

But convection is also driven by cold uppers of course which don't look too terrible although not Snowmaggedon.

But as several have pointed out, my own experience is that a lot of snowfalls come from minor developments that occur at short notice, whereas many potential blizzards disappear after agonising waits.