GFS 06z charts discussion

[nick sussex]

Have to agree with you there John. It is early days but the best set up we've seen in the reliable timeframe for many a long year. There is huge potential especially if the low progged to be out near Rockall on thurs decides to slide SE wards down the edge of the block as in days of old.

A nightmare to call knowing the how ignorant the media reaction that will follow if the forecasters go small and it comes big and conversely if they go big and it doesnt go big in the south east.

I do hope whatever happens that theres not too much criticism of the ukmo as this really is one of the hardest set ups to forecast, if it was summer no one in here would care less where the rain is but as its snow its liable to cause much hysteria! Can I also just ask that even those who dont believe in prayer to start praying that the ecm was just a rogue run and had been infiltrated overnight by some mild rampers! and to return to the fold and be a little less miserable regarding the weeks snow prospects.

Edited February 4, 2007 by nick sussex

[SP1986]

For the higher ground in the west maybe...but as it crosses eastwards over the pennines it is progged to either stall or become much lighter and patchier.

I'm not excited yet at all.

I dont know, I seem to recall on these events with rain where it stalls for more than 24 hours there can be some orographic lifting even over some moderately elevated eastern areas. Lets face it though, even light snow and a light covering would be welcomed by the majority, so what the models are showing now is positive for many. Like you hint though, we shouldn't get excited yet. If its being showed similarly on the charts at 24 hours, and also being shown as something at least showing settling snow I may sneak in a ramp. Still this far west I expect quite a bit of rain from the front here (preceded by sleet/snow of course) Hanging in the balance with regard to the intensity/type of any PPN yep.

[Duane S.]

Very fascinating Ian. This scenario has Feb 1978 written all over it to me. I personally feel that even the meto and( apologies for mentioning it) countryfile forecast have been to progressive in the north-east movement of the precipitation. The last chart on the CF forecast was a dead ringer for Feb 18/19 1978.

On that occassion here in Dorset we got 18 inches of level snow blwon into 25 foot drifts !!

Ive only waited 29 years to see another chart with that sort of potential.

I remember that like it was yesterday. Awesome doesn't even begin to describe it!

The thing with being stuck where we are MC is that, compared with virtually every other part of the UK, we don't get snowed on a lot or with as much frequency. But - with the right conditions, cold to our east cming up against an LP moving up from the moist SW, we will get far more than most others wil ever see in one dumping. Problem is, it is soooo rare.

These charts do however show some promise, much more than any I can remember over recent years. Only around a 15% chance of something a bit special but I'll take that right now.

[mcweather]

I remember that like it was yesterday. Awesome doesn't even begin to describe it!

The thing with being stuck where we are MC is that, compared with virtually every other part of the UK, we don't get snowed on a lot or with as much frequency. But - with the right conditions, cold to our east cming up against an LP moving up from the moist SW, we will get far more than most others wil ever see in one dumping. Problem is, it is soooo rare.

These charts do however show some promise, much more than any I can remember over recent years. Only around a 15% chance of something a bit special but I'll take that right now.

You've got it in a nutshell there S4. Feb 1978 was the most disruptive weather event here of the last 40years. Not even the storms of 1987 and 1990 casued as many problems.

[andy_leics22]

I dont know, I seem to recall on these events with rain where it stalls for more than 24 hours there can be some orographic lifting even over some moderately elevated eastern areas. Lets face it though, even light snow and a light covering would be welcomed by the majority, so what the models are showing now is positive for many. Like you hint though, we shouldn't get excited yet. If its being showed similarly on the charts at 24 hours, and also being shown as something at least showing settling snow I may sneak in a ramp. Still this far west I expect quite a bit of rain from the front here (preceded by sleet/snow of course) Hanging in the balance with regard to the intensity/type of any PPN yep.

I agree Stephen, I mean all I want from this is a dusting, if I get more then fantastic! But I am always cautious about things that look good 4 days away, only will I get excited when the snow is falling and the radar looks good, thats the only time I get truly excited about how much snow will fall and the fact that it is actually snowing I mean this potential battle ground scenario was showing up on the GFS 3-4 days ago so it's not like it's only just picking up the potential for it to happen, it seems to me the closer we are getting to it, the more it upgrades which can only be a good thing of course!

[SP1986]

I agree Stephen, I mean all I want from this is a dusting, if I get more then fantastic! But I am always cautious about things that look good 4 days away, only will I get excited when the snow is falling and the radar looks good, thats the only time I get truly excited about how much snow will fall and the fact that it is actually snowing I mean this potential battle ground scenario was showing up on the GFS 3-4 days ago so it's not like it's only just picking up the potential for it to happen, it seems to me the closer we are getting to it, the more it upgrades which can only be a good thing of course!

Absolutely, In my own experience 60% or so of patterns picked up on the charts tend to come off and give what they showed in more or less the same style etc, that's why I'm positive because at 96 hours (4 days away) it's not bad - I know it can change as SF reminded us before in the 48 hours before but that was one of the 40% that didnt occur. A lot to look forward to though, and if there's one thing that the charts are good for it's showing us that these type of situations are still possible

[SP1986]

It is fun to speculate but regarding snowfall - it will be the last detail to fall into place IMO.

Tbh, I'm much more interested in any prospects of the high pressure to the north east bringing about a possible pattern change in the weather through this month - and resultant potential longer lasting snowfall that way. Brilliant if the systems stall and the cold air wins out producing snowfall that is going to have some mileage to it - but on the other end of the scale an hour or two of snow (maybe more) and accumulations followed by rain and rising temps is no excitement to me at all.

Yes, any snow is of course better than nothing, but if it marks the end of a cold spell then I would much rather it stayed dry and cold with much better and less marginal opportunties for snow down the line.

Anyhow, there is much to be decided yet in the models and I won't be 'will it won't it' regarding snowfall for a while longer yet.

Tamara

I've seen 'I'm getting bored' when there has been weeks of dry, cold weather from people who like cold weather on here, so without doubt some don't share your enthusiasm I think the major attraction to this pattern is the heavy snow rather than the cold itself. You're right in the sense that height rises would rbing some very cold temperatures, a record breaker would be interesting although on a personal note not so handy (alot of destruction in the garden)

[Cymru]

It is fun to speculate but regarding snowfall - it will be the last detail to fall into place IMO.

Tbh, I'm much more interested in any prospects of the high pressure to the north east bringing about a possible pattern change in the weather through this month - and resultant potential longer lasting snowfall that way. Brilliant if the systems stall and the cold air wins out producing snowfall that is going to have some mileage to it - but on the other end of the scale an hour or two of snow (maybe more) and accumulations followed by rain and rising temps is no excitement to me at all.

Yes, any snow is of course better than nothing, but if it marks the end of a cold spell then I would much rather it stayed dry and cold with much better and less marginal opportunties for snow down the line.

Anyhow, there is much to be decided yet in the models and I won't be 'will it won't it' regarding snowfall for a while longer yet.

Tamara

Couldn't agree with you more, Tamara. Snowfall that turns to rain is useless as far as I am concerned. What's the point? I would much rather have cold, frosty days and nights with plenty of sun than an hour of snow followed by drizzle and mild temperatures.

[mcweather]

It is fun to speculate but regarding snowfall - it will be the last detail to fall into place IMO.

Tbh, I'm much more interested in any prospects of the high pressure to the north east bringing about a possible pattern change in the weather through this month - and resultant potential longer lasting snowfall that way. Brilliant if the systems stall and the cold air wins out producing snowfall that is going to have some mileage to it - but on the other end of the scale an hour or two of snow (maybe more) and accumulations followed by rain and rising temps is no excitement to me at all.

Yes, any snow is of course better than nothing, but if it marks the end of a cold spell then I would much rather it stayed dry and cold with much better and less marginal opportunties for snow down the line.

Anyhow, there is much to be decided yet in the models and I won't be 'will it won't it' regarding snowfall for a while longer yet

Tamara

We could of course get both scenarios Tamara. Fronts coming giving some of us a real dumping then retreating as the high takes real control leading the way for further temporary frontal incursions etc etc. Now that would be a classic, a record feb to end the record mild. Wow.

[MKN]

I've seen 'I'm getting bored' when there has been weeks of dry, cold weather from people who like cold weather on here, so without doubt some don't share your enthusiasm I think the major attraction to this pattern is the heavy snow rather than the cold itself. You're right in the sense that height rises would rbing some very cold temperatures, a record breaker would be interesting although on a personal note not so handy (alot of destruction in the garden)

I think the heavy snowfall is more interesting as far as im concerned last year was cold and frosty for a fair while with no snow, so its nothing new if that were the outcome, heavy snowfall on the other hand is something i can hardly remember.

[SP1986]

Hello Stephen

That is not quite what I said - I did say a cold pattern with some longevity that offers the potential of longer lasting snow.

Cymru - good to see some support for this view!

It will be more interesting than ever to watch the output over the next day or so. The UKMO model is on the right lines - the more those lows can undercut the better.

The northerm arm of the jet has been overestimated by the models (and still is IMO). I'm still not sure that they have a good grasp of the dveloping high pressure to the north east.

We will see

Tamara

ok peace - true what you say although its the gambling theory with allowing to go on for longer - having said that it's all gambling from our point of view

[Paul]

This thread will be locked in around 20 mins to make way for the 12z discussions

[PersianPaladin]

That ECM run is really annoying me and I'm dreading a 12z downgrade.

[johnholmes]

Afternoon John do I detect even a little ramp from yourself! I don't envy the ukmo at all this week as it looks a real nightmare to forecast. I must say though that the ukmo 120hrs raw data is a great chart its a shame that the ukmo have edged away from that in their fax charts. Lots of fun model watching though even though its a real thriller.

me! ramp, heaven forbid, although I'm as much a snow and frost fan as the most ardent on here. This makes it doubly difficult at times to give as unbiased and as non judgemental view as I wish to give.

I think the best idea for much of the hour is to go and have a cup of tea and a piece of cake and watch the back garden, just to let the GFS have time to spurt its latest ideas out, IF this and other weather web sites don't cause a total melt down!

[Harsh Climate]

That ECM run is really annoying me and I'm dreading a 12z downgrade.

Same ere fella, theres no way things will go smoothly from now untill thursday, just cant see it...

Its just about getting through each day without any major downgrades and getting the ECMWF on board now...

[Mondy]

. There is huge potential especially if the low progged to be out near Rockall on thurs decides to slide SE wards down the edge of the block as in days of old.

Don't you worry about that low. I'll give it a little nudge nearer the time..

[johnholmes]

By the way, the famous blizzard of February 1978 (seldom mentioned on here) which cut off the south-west peninsular was from memory largely unforecast: it took all by surprise. 25 foot drifts on the M5 and 30cm of level snow in Exeter, with 100cm of level snow on Dartmoor. Now that's the real deal! I fear very much for disappointment this time, especially with the rampometre now broken through the roof!

not sure about our operational colleagues but I was doing my AFC(Advanced Forecast Course) at Shinfield Park, the Met O college just down the road, in those days, from Reading Uni. I do recall 2 members from the south west, one of whom had done the 'practice' forecast that previous Friday, not being able to get back due to that snow. His embarrassment, and also that of the tutor, was that there had been no forecast of such conditions, snow yes, but not that far south west or in that quantity!

Edited February 4, 2007 by johnholmes

[wellington boot]

We could of course get both scenarios Tamara. Fronts coming giving some of us a real dumping then retreating as the high takes real control leading the way for further temporary frontal incursions etc etc. Now that would be a classic, a record feb to end the record mild. Wow.

Yes i agree with tamara about heavy snow followed immediately by rain and mild having no interest for me, but as you say, we could get both. If the front stalls, theres every chance the high pressure to our east with push the LP back eventually, but the front would have to stall in exactly the right place. It certainly wouldnt happen for all of us anyway.

Way too many ifs and buts right now though. Its so uncertain whats going to happen. Except i think the ukmo, gfs, nogaps, and jma all have it about right with the low breaking off the atlantic mass across our south. the specifics will be crucial though. and beyond that its all up in the air. as it always is these days it seems...

[PersianPaladin]

A rare incursion by me into this thread, but wanted to respond to your very sensible post Stu. It's nice to see that sort of post amidst talk of shovels and record snow depths - do some people never learn?!

Although synoptically there may appear a similarity with '47, 79 and the 80's I really think the comparisons are fraught with danger. Those winters had deep, deep, cold pooling ahead of advancing fronts. I know this from memory (except '47) as well as factually by the CET. Even the much-trumpeted mild start to '47 was anything but (why does this error continually get repeated?) compared to this year's near record warmth in the UK and in much of western and northern Europe.

Secondly, the orientation is very important. When fronts stalled in those classic set ups they sometimes did so with front edge easterlies - pulling really cold air in from an already cold continent. This time, at the moment, the orientation looks much more south-easterly and perhaps southerly, and without such a cold pool draw.

As it happens, these events were frequently over-ramped by forecasters in the 80's, normally by the low pressure centres tracking slightly further north at the last minute. They were usually marginal set-ups even then, with all the cold and synoptic conditions I have just mentioned. This time looks precarious in the extreme to me, and unless things change I'm not mindful to think anywhere south of, say, Northamptonshire is likely to get more than the briefiest of initial flurries before the rain kicks in. On the high ground to the north it may be a different story, but I'm really saying that just so as not to appear a party-pooper (which I'm not).

By the way, the famous blizzard of February 1978 (seldom mentioned on here) which cut off the south-west peninsular was from memory largely unforecast: it took all by surprise. 25 foot drifts on the M5 and 30cm of level snow in Exeter, with 100cm of level snow on Dartmoor. Now that's the real deal! I fear very much for disappointment this time, especially with the rampometre now broken through the roof!

By the way, not all stalling is good. You need an undercut. I can recall several instances of stalling fronts simply fizzling out with generally rising temps. When the ppn eventually did arrive it was in the form of rain. OK, I'll bugger off back to the in-depth thread!

Have to agree with you there, WIB. Although its still in F.I. I think not enough cold air actually gets into the UK for a significant snowy scenario.

The jet is looking dangerously close to re-flattening as well.

[johnholmes]

almost time for the 12z, only 123 on so far, I'm sure that will go up shortly, and no doubt our mods will start another thread anyway.

Off for tea and cake for a while.

[mcweather]

By the way, the famous blizzard of February 1978 (seldom mentioned on here) which cut off the south-west peninsular was from memory largely unforecast: it took all by surprise. 25 foot drifts on the M5 and 30cm of level snow in Exeter, with 100cm of level snow on Dartmoor. Now that's the real deal! I fear very much for disappointment this time, especially with the rampometre now broken through the roof!

not sure about our operational colleagues but I was doing my AFC(Advanced Forecast Course) at Shinfield Park, the Met O college just down the road, in those days, from Reading Uni. I do recall 2 members from the south west, one of whom had done the 'practice' forecast that previous Friday, not being able to get back due to that snow. His embarrassment, and also that of the tutor, was that there had been no forecast of such conditions, snow yes, but not that far south west or in that quantity!

I think me and S4 LANCIA are the only guys that mention it John. but along with the Jan 82 in wales and the JAN 78 FALL in it was by far an away the biggest snow event in Britain of the last 30 years

[Stratos Ferric]

Feb 2005, Clerkenwell

850s -11C

Thickness c. 519dam

Rain!

Although it did produce about 3cm of lying snow in the Regents Park area less then 3km away.

Has to be a classic example of the UHI impacting the lowest km or so of the atmosphere. It's likely that even the 850s might have appeared to "fib" on that occasion; the reality is that plotted charts are low resolution and predictive; reality is high resolution and in the moment. When it's a tight call (and it often is nowadays, in fact it virtually always is here in the UK) that's why it's hard to forecast accurately everywhere.

[wellington boot]

Same ere fella, theres no way things will go smoothly from now untill thursday, just cant see it...

Its just about getting through each day without any major downgrades and getting the ECMWF on board now...

remember though with the ecm, that it has consistently progged a raging atlantic recently. Its been generally poor for a good portion of the last month. Remember, when other models were at least progging this brief northerly were going to have, and they showed a bit of delay with the atlantic and some cold air coming in, the ecm consistently had the atlantic coming straight in, pretty much by today. Its not on form at the moment

[Paul]

Locking this one now - 12z discussion is available here:

http://www.netweather.tv/forum/index.php?showtopic=36161