Model Output Discussion

[johnholmes]

When was the last time we had such a major retrogression event like this.

I don't know Julian-its all adding up to a really interesting weekend watching just what does happen. I'm really pleased I'm going to be around to be able to follow it.

[Bolton67]

I don't know Julian-its all adding up to a really interesting weekend watching just what does happen. I'm really pleased I'm going to be around to be able to follow it.

Seems the jet stream being further south over north africa is going to be a pain next week How typical

http://news.bbc.co.u...10&region=world

[Duane S.]

Polar lows can be extremely snowy and aggressive however their size is anything between 100 to 500 miles and are usually short lived affairs from 12 to 36 hours but id like one over the south coast to dwarf the measly 1cm so far this year.

I stand to be corrected but I'm not sure if the South Coast has ever been hit by one? Maybe Kent or East Sussex could in theory but we are in the worst place possible in the UK to get affected by one of these I would imagine. To get to us in the mid South coast (I think you live in Poole?), it would need to travel over a fair bit of land, thus draining it of all its energy very quickly and rendering it null and void in term of it being a Polar Low.

But they are indeed beautiful and rare (in terms of impacting the UK) creatures that can be incredibly intense.

There's always talk of such features appearing whenever there is so much of a sniff of a Northerly during the winter. Much excitement when sombody spots anything resembling a comma shape in the satelite imagery but in the same way as 'seeing' funnel shapes appearing left right and centre in clouds during high cape periods, they usually come to nothing.

I may be wrong but I suspect this setup is pretty good to spawn one above Scotland later on though.

[Severe Blizzard]

I stand to be corrected but I'm not sure if the South Coast has ever been hit by one? Maybe Kent or East Sussex could in theory but we are in the worst place possible in the UK to get affected by one of these I would imagine. To get to us in the mid South coast (I think you live in Poole?), it would need to travel over a fair bit of land, thus draining it of all its energy very quickly and rendering it null and void in term of it being a Polar Low.

But they are indeed beautiful and rare (in terms of impacting the UK) creatures that can be incredibly intense.

There's always talk of such features appearing whenever there is so much of a sniff of a Northerly during the winter. Much excitement when sombody spots anything resembling a comma shape in the satelite imagery but in the same way as 'seeing' funnel shapes appearing left right and centre in clouds during high cape periods, they usually come to nothing.

I may be wrong but I suspect this setup is pretty good to spawn one above Scotland later on though.

There have been several - but not recently.

December 7th 1937 - heavy snowfalls in New Forest.

December 15th 1950 - Very heavy snow on I.O.W. where depths reached 15 inches!

December 8th 1967 - Heavy snow along south Coast with 11 inches of snow at Brighton. This fell in 8 hours and was accompanied by thunderstorms (due to convection over the relatively warm English Channel).

Parts of Wales and the north coast of N. Ireland saw 17 inches and 14 inches respectively - so northern areas do well in this set up - but the south coast is favoured if the circulation is overhead and convection plays a role and maintains the intensity of snow in the cold and unstable air mass.

March 27th 1975? - Mostly a frontal event.

March 19th 1987 - Heavy snow along S. Coast with depths of 20 cm. 5 cm reported in 10 minutes. There was no closed circulation with this event and tended to move along the trough line with north to south then N.W. to S.E. movement.

The snow storms of late April 1981, which affected Salisbury Plain severely, originated on a large depression which slowly moved S.E. with waves forming on the occluded front. This was not a classic 'Polar Low' - i.e. small depression developing in a baroclinic zone near Iceland and moving rapidly S.E. or S.S.E.

Hope this info is useful.

[TEITS]

I think a lot of people are underestimating the models and what they show and the 18z is a good example. Very unstable yes, but very significant amounts of snow for large parts of the country in a near time frame and beyond!

It could get very dangerous out there!

Im afraid Robert nobody can make any assumptions about next week. If the current trend continues then its going to be a case of taking each day as it comes. Even then it might be that marginal that we have to rely on the lamp post.

Remember this isn't your typical -10C upper temp cold spell with snow showers moving from the N Sea. What we have is a block over Greenland with a jetstream much further S than normal. Now what is uncertain is not just the track of the LP but how far S this will go.

Looking at the overall trend and I can see why the ECM mean is colder in the longer range than it was a few days ago. I feel the models have backed away from a return to milder SW,lys and in my opinion the outlook remains cold. What could happen is the intial LP eventually moves E and we pull in a colder N,ly flow. The next possibility is the LP pushes that far S we end up with a cold NE,ly.

Overall though this isn't the time to be looking into detail or making statements such as "it could get dangerous out there". If the current model output continues then next week could be one of the biggest challenges the Met O have seen for many years. I certainly don't envy them because it could prove to be a nightmare. I will add this also isn't the time to be looking at the BBC 5 day forecasts!

[LomondSnowstorm]

Im afraid Robert nobody can make any assumptions about next week. If the current trend continues then its going to be a case of taking each day as it comes. Even then it might be that marginal that we have to rely on the lamp post.

Remember this isn't your typical -10C upper temp cold spell with snow showers moving from the N Sea. What we have is a block over Greenland with a jetstream much further S than normal. Now what is uncertain is not just the track of the LP but how far S this will go.

Looking at the overall trend and I can see why the ECM mean is colder in the longer range than it was a few days ago. I feel the models have backed away from a return to milder SW,lys and in my opinion the outlook remains cold. What could happen is the intial LP eventually moves E and we pull in a colder N,ly flow. The next possibility is the LP pushes that far S we end up with a cold NE,ly.

Overall though this isn't the time to be looking into detail or making statements such as "it could get dangerous out there". If the current model output continues then next week could be one of the biggest challenges the Met O have seen for many years. I certainly don't envy them because it could prove to be a nightmare. I will add this also isn't the time to be looking at the BBC 5 day forecasts!

Absolutely. My feeling is that A lot of Scotland will be a slushy icy mess, with a few inches of snow a few miles away from slightly slushy ground. I even doubt the NMM/NAE will be able to clarify the situation that much with dewpoints around freezing or slightly and uppers around -4/-5 - take it as it comes really. Some will be lucky, some less so, most will probably see falling snow at some point. At least it's not mild for the foreseeable future : http://charts.netweather.tv/ensimages/ens.20100211/18/t850Fife.png

http://charts.netweather.tv/ensimages/ens.20100211/18/t850Norfolk.png

[robert]

Do you work for the Daily Express! you were already told off some more experienced members that your earlier statement regarding the 18z was way off the mark! So what do you do, come out with the same nonsense after the 00z

I am just going by what I see and the models are indicating exactly the kind of weather I predicted.

Only time will tell if I was right or wrong. I am sticking to my guns on this because it's clear to see what they show.

[johnholmes]

Robert;

I have no idea why you say much of the UK will be lying under deep snow because the models do not show anything of the kind. They show more like I suggest in the blog in the forecast area. Much uncertainty about even IF there will be snow on low ground, in the south it seems rather unlikely and for the north more a case of in places.

Much better to be realistic than make the comments you have in my view.

[John London]

Looking at that 00z I would say without fear of contradiction that the whole country will be snowed in for over a week.

[johnholmes]

Obviously Friday morning is bringing the comics out!

[MR EXTREMES]

I am just going by what I see and the models are indicating exactly the kind of weather I predicted.

Only time will tell if I was right or wrong. I am sticking to my guns on this because it's clear to see what they show.

OMG I thought I was bad,only thing predicted is snow for some in the north rain for the south but feeling cold.

it's pretty maginal way to optimistic Robert.

But there after rarely cool but quiet with a chance of colder conditions than this weekend.

[cyclonic happiness]

Morning all, Morning John

Well it all looks very messy to me. There's so much mixing of layers that I think most of us will probably see sleet/rain/snow within the same day over the next few days.

Certainly very hard to call and we may yet end up in a southerly, so still a definate 'nowcast' situation again I'm not saying any more

[Frosty.]

Looking at the 00z I would say many parts of scotland could get a lot of snow next week, heavy falls and SE'ly to E'ly winds with temps close to freezing by day and just below overnight, the hills of northern britain will have deep snow if the low follows the latest track. For central and southern britain it looks less cold but still cold enough for snow on the pennines and maybe higher parts of the midlands and wales but unfortunately it just looks wet in most of southern britain with sleet mixed in the heavier bursts of rain and temps between 4-6c. I think carol kirkwood will swap her woolly hat for an umbrella next week

[cooling climate]

Blocking to the north showing up even more this morning.

I would not be surprised on future runs to see the low clear the UK and

then run east perhaps along the channel.

The lows movement southwest is due perhaps to the retrogression and

and reverse zonal wind anomalies then as it clears south of the UK it

picks up the west to east jet and moves in a easterly direction.

[John London]

Blocking to the north showing up even more this morning.

I would not be surprised on future runs to see the low clear the UK and

then run east perhaps along the channel.

The lows movement southwest is due perhaps to the retrogression and

and reverse zonal wind anomalies then as it clears south of the UK it

picks up the west to east jet and moves in a easterly direction.

I wonder if it would be possible for the model watching experts on here to add some information at the end of technical posts like this stating what type of weather would be likely to occur if the scenario they have just outlined comes to fruition? On a seperate point, the organisors of the Winter Olympics are having to truck snow to the venues as they haven't got any.

Edited February 12, 2010 by John London

[Frosty.]

The GEM 00z also looks very wintry for the northern half of scotland in particular thanks to the angle of the complex troughing further south but again it just looks wet and chilly in southern britain, there is no mild weather on the horizon though with the jet way south.

[karyo]

The more we approach the event, the more it becomes clear that the snowfest that the models were showing only a couple of days ago, will not happen! Instead, bands of rain and showers with some hill snow. The problems also is that the low is quite deep likely to cause air mixing, if it was a shallower feature with lighter winds, there would be a better chance for snow in the heavier bursts.

The bbc northwest forecast, just like yesterday, showed rain for next week and not a mention of the 's' word!

Karyo

Edited February 12, 2010 by karyo

[Frosty.]

The more we approach the event, the more it becomes clear that the snowfest that the models were showing only a couple of days ago, will not happen! Instead, bands of rain and showers with some hill snow. The problems also is that the low is quite deep likely to cause air mixing, if it was a shallower feature with lighter winds, there would be a better chance for snow in the heavier bursts.

The bbc northwest forecast, just like yesterday, showed rain for next week and not a mention of the 's' word!

Karyo

At least it won't be mild and I still think it looks all white for northern hills and maybe some lower ground ooop north.

[karyo]

At least it won't be mild and I still think it looks all white for northern hills and maybe some lower ground ooop north.

Yes, thankfully! But quite a downgrade from what was shown before! Even the 6z yesterday was a snowfest, only for this to go downhill in subsequent runs.

Karyo

[Weather-history]

The bbc northwest forecast, just like yesterday, showed rain for next week and not a mention of the 's' word!

Karyo

As I said yesterday, take those local forecasts with a huge pinch of salt. Its a type of scenario that gives unexpected snowfalls and rainfall when one expects snowfalls.

[MisfitDog3]

is this the sort of set up we could risk getting 'freezing rain' out of, or is it all just too mobile and mixed up for that?

[snowmadchrisuk]

is this the sort of set up we could risk getting 'freezing rain' out of, or is it all just too mobile and mixed up for that?

I think Freezing rain is unlikely , Doesn't seem to quite get cold enough for that with temps staying around 0-1 degs . Snow is a different kettle of fish altogether though . The 00z would likely fall as snow next week from Tuesday at least over the Midlands as we get into some heavy ppn , the 528 dam is over us and temps 0-1 deg . We are talking about a low pressure system which in effect is bigger than the whole country and nailing it's track over tiny Britain is going to be a now casting event IMO . Some Cold uppers are bound to get dragged back into the mix somewhere though due to the direction it is coming from .

[TEITS]

Looking at this mornings output and I have to refer to what I said yesterday again. With the exception of Scotland and higher ground of N England if your looking for a widespread snow event then either two things need to happen.

The LP needs to move E which brings a N,ly flow and colder temps. At the same time a disturbance moves N and brings snow to S areas i.e what the 0Z shows. The other scenario is the LP moves far enough S to allow a colder E/NE,ly flow.

So in summary it isn't the intial LP that could bring a snow event for many low lying areas. What happens after is where a snow event could occur and this is more likely towards the end of next week into next weekend. Having said this at the moment there is a risk of rain turning to snow on Tues as the front moves E.

[MisfitDog3]

"this is more likely towards the end of next week into next weekend."

That seems to have been a reoccurring theme for those waiting for a snow event from this particular cold spell (and away from Kent of course!). Always just over the metaphorical horizon!

[Wilks]

"this is more likely towards the end of next week into next weekend."

That seems to have been a reoccurring theme for those waiting for a snow event from this particular cold spell (and away from Kent of course!). Always just over the metaphorical horizon!

I completely agree with that, this time last week the models were shwoing us in a cold spell, harsh frosts, possible snow yesterday/today not just in Kent. It's a bit chilly, but cold, no not really. Hopefully we'll start to see some decent cold appear in FI - that way we can be sure that as it gets nearer the time it would have flipped completely and we'll be having some nice spring warmth!