Spring Model Discussion 18Z 9/3/13 onwards....

[Snowman.]

Disagree with the above posts about spring like temperatures. We have been spoilt over the last 3 years. I would not call 8 degrees springlike sorry but to me springlike is 14-15 mild sunny days.

8 Degrees is around average.

[chris55]

sorry but 'normal' seasonal, it might not be interesting but imho true weather fans like ALL types. normal for march isnt the same for normal in may (spring months) ... imho the coming days will see 'normal' (but on the cool side of normal) for what we expect in mid march. if that is so, wouldnt that be 'spring weather'?

To be honest, we can see cold wet and miserable in the middle of July, or warm and sunny in January!! With us living next to a massive ocean and not having the luxury of a continental climate, I'd grab those extremes of weather at any time of year with open arms.

[nick sussex]

Significant snow possible at 120 and 144hrs on the ECM with a slow moving front likely to be straddling central areas.

The boundary though is likely to change between runs and still complications with phasing of energies. At 168hrs deep low approaching trying to remove the cold. If theres some trough disruption at 192hrs could be interesting for northern areas,bitter cold pool to the east, will it make it?

[cooling climate]

After coming within a couple of hundred miles of perfect winter synoptics

for perhaps a one in fifty year snow storm event. With the bitter uppers

in place and a southerly tracking low that was so close to taking the

perfect track. I wonder how long before we see a similar scenario, another

50years.

It is very hard to get excited again at a possible wintry outbreak when we

were so near to perfection but if the GFS op and some of its ens members are

correct then it may be worth the ride one more time. Although it still looks

as though the GFS is on its own out to t144.

PS The video in the previous southeast and east Anglia thread of northern france

(where some areas recieved two feet of level snowfall and massive drifts)is well

worth the look and is exciting and scary at the same time to think that could have

been us,we were that close.

[Paul]

Can we keep to discussing the model output please, anyone who wants to discuss personal weather preferences they're welcome to start a thread about it elsewhere.

[Cheshire Freeze]

Significant snow possible at 120 and 144hrs on the ECM with a slow moving front likely to be straddling central areas.

The boundary though is likely to change between runs and still complications with phasing of energies. At 168hrs deep low approaching trying to remove the cold. If theres some trough disruption at 192hrs could be interesting for northern areas,bitter cold pool to the east, will it make it?

The trough is already disrupting at 168....notice that little low over Poland (ish), that should help to entice disruption along with heights to the N

[Cheshire Freeze]

LP begins to negatively tilt, cold pooling over Norway now

Could be a similar 216 and 240 to the GFS

Nope not this time!

[nick sussex]

After coming within a couple of hundred miles of perfect winter synoptics

for perhaps a one in fifty year snow storm event. With the bitter uppers

in place and a southerly tracking low that was so close to taking the

perfect track. I wonder how long before we see a similar scenario, another

50years.

It is very hard to get excited again at a possible wintry outbreak when we

were so near to perfection but if the GFS op and some of its ens members are

correct then it may be worth the ride one more time. Although it still looks

as though the GFS is on its own out to t144.

PS The video in the previous southeast and east Anglia thread of northern france

(where some areas recieved two feet of level snowfall and massive drifts)is well

worth the look and is exciting and scary at the same time to think that could have

been us,we were that close.

To be honest CC if I was still living in Sussex I would be glad the snow storm missed, no power, trees blown down, I understand people would like to experience an unusual and rare set up but even though I love snow I'd be saying no thanks.

The ECM at 192hrs no trough disruption and the block is poorly orientated so that would be the end of the road in terms of the operational run.

It does tie in with the UKMO update, we'll have to see what the ECM postage stamps look like later,models as we know aren't great with energy distribution with blocking to the ne.

[nick sussex]

I think overall theres too much uncertainty to have much faith in any of the models in terms of detail. On the face of it the ECM/UKMO deliver some snow especially for central and northern areas, the GFS is cool and wet and then has an easterly tease later.

You can make a case for a significant snow event for those on the northern flank of the front that's likely to be running through the UK, the problem is at this range that front can be shifted around north/south.

There are also complications because upstream energy is likely to phase with troughing near the UK, if you live in the south you want that phasing taking place later because this stops the southwards push on the pattern, if you live in the north you should be pretty happy with both the ECM/UKMO at least for some snow. For central areas this is the high risk/high reward area at the moment in terms of snow.

For the timebeing many options open and that still includes the GFS with its cool wet view upto 168hrs, lots of uncertainty and I think we need to see cross model agreement before raising expectations too much.

[cooling climate]

I wonder if we could amalgamate the ECM up to t144 then the GFS

later output t168 to t300 would the weather oblige.

[Gibby]

Good evening. Here is the evening look at the 12z output from the big three models of GFS, UKMO and ECM with a look at the GFS Ensemble data and Jet stream forecast for the next 7 days, rounding off with my own viewpoint on what the models indicate means for us soon the surface over the coming two weeks.

All models show a deepening Low pressure area moving steadily SE towards NW Scotland and then areas further South over the weekend where it is shown to become slow moving near Southern England for several days with a large quantity of heavy and thundery showers with hail, sleet and snow all in the mix almost anywhere in the UK.

GFS then shows little change in the overall pressure pattern through next week with Low pressure close by with further cold weather with rain and snowfall for many before a trend to rather less cold weather pulls up from the South late next week. By the weekend though winds on the operational are shown to back SE and East with cold weather returning from the East with a strong breeze making it feel very cold with rain and sleet likely from troughs to the South and wintry showers blown in off the North Sea towards Eastern coasts. the cold weather then hangs on out to the last days of the run with complex Low pressure North and South of the UK giving the risk of further wintry showers or more general precipitation in places.

The GFS Ensembles show the operational was a cold outlier in the second half of the run with the vast majority of members keeping things rather less cold or near the seasonal average for mid to late March. The North does show a chance of rather colder conditions hanging on for rather longer than areas further South. There is quite a lot of scatter later in the run though with rainfall spikes indication a continuation of Low pressure based weather with rain at times for most areas.

The Jet Stream shows a split flow developing in the coming days with the UK the target of the Northern arm as it flows SE over the UK towards Southern Europe. The Southern main arm of the flow continues to flow East at far Southerly latitudes than is normal but does at last show signs of inching slowly North as we move through the second half of next week.

UKMO for midweek shows a Low pressure belt stretching from Western Russia across to Germany and West across Southern England and further West to the North of the Azores. High pressure lies across the Arctic with a strong ridge to Eastern Greenland. The weather would remain unsettled and cold with showers or longer periods of rain, sleet and snow, the snow chiefly over hills in the South and more generally at times in the North as an Easterly cold wind sets up.

ECM tonight shows a similar evolution to UKMO with Low pressure in a belt West to east across Southern Britain in the middle of next week. Late in the week it, like GFS shows a deep Low developing to the West of the UK with the net result being rather milder air moves steadily North over the UK with rain and strong winds still a large feature of the weather. Towards the end of the run the driving Low develops a new centre even further west with it's troughs moving more slowly NE across the UK maintaining the less cold air down here but with cold air remaining very close or over NE Britain which could still give rise to sleet and snow over the higher ground of Northern and Eastern Scotland.

In Summary the weather looks like turning very unsettled over the coming 24 hours. With the low dragging cold air down from Northern latitudes into it's circulation it looks like being rather cold for most of the time with the chance of some wintry precipitation at times almost anywhere but probably more so in the North. Later next week as Low pressure develops to the West it pumps milder Southerly winds up across the UK at the same time as producing rain and strong winds too, especially in the North and West. Cold air looks like only being pushed back to a position just to the NE of Britain still threatening the far North and NE at times with rather cold conditions right out to the end of the output. Despite the possibility of milder air coming into the mix later next week it still looks like we are a long way from anything dry and springlike anytime soon.

[winterof79]

I remember yesterday certain posters / rampers saying if ever in doubt stick with the MO update. That was yesterday's very cold and wintry one.

Funny how todays update is totally different and has not been mentioned and we are back to the usual overhyped ramps based on own preferences and assumptions..

I am one who quoted the METO update and am still with them.Easterly feed next week.Advance from the s/w is what they predicted.

http://www.meteociel...M1-120.GIF?14-0

http://www.meteociel...M1-192.GIF?14-0

http://www.meteociel...20-21.GIF?14-18

Never said anything different mate.No assumptions just what the output is showing...rest is FI as per usual

Read the update and then look at the charts to see why they issue it.

UK Outlook for Tuesday 19 Mar 2013 to Thursday 28 Mar 2013:

Remaining unsettled and cold at first with further outbreaks of rain, sleet and snow but with some bright spells. The snow is most likely in the north and east, with the risk of some accumulations here. Widespread overnight frosts are also likely. Later next week, milder conditions will probably spread northwards across most parts bringing some wet and possibly very windy conditions at times. However the milder weather will be slow to reach northern parts with the northeast likely to remain cold with a continuing risk of snow. The rest of the period is then likely to remain unsettled but with temperatures probably recovering to near normal for the end of March and any snow risk becoming confined to the far northeast.

Edited March 14, 2013 by winterof79

[mcweather]

It is worth noting from the ecm and and UKMO that the real milder push suggested for next week is beyond 144 at present and is therefore in FI by no means set in stone. Even the meto in their further outlook only say that milder weather will probably push northwards. A little trough disruption and we could be looking at a very different scenario especially with so much bitterly cold air not far from our shores.

To my mind the outlook is from done and dusted.

Edited March 14, 2013 by mcweather

[mushymanrob]

Disagree with the above posts about spring like temperatures. We have been spoilt over the last 3 years. I would not call 8 degrees springlike sorry but to me springlike is 14-15 mild sunny days.

spring is a season not a weathertype so whatever is around average for the time of year march to may inclusive is normal spring weather.

tonights ecm is the best run yet for average march weather. after a few cool wet days followed by a cold two, things are suggested to improve later next week. both the gfs and e!m have picked up on this today. given the time of year they must be regarded as being strong possibilities. but nothing is certain, and with that strong northerly block the cold is far from over.

[Cheese Rice]

spring is a season not a weathertype so whatever is around average for the time of year march to may inclusive is normal spring weather.

tonights ecm is the best run yet for average march weather. after a few cool wet days followed by a cold two, things are suggested to improve later next week. both the gfs and e!m have picked up on this today. given the time of year they must be regarded as being strong possibilities. but nothing is certain, and with that strong northerly block the cold is far from over.

I'd say that a milder southerly is unlikely to pan out, all models have a tendency to underestimate high pressure to our NE. We've seen time and time again nearer the time frame the output becomes increasingly erratic for the UK in regards to whether we can tap into the cold air to the NE or not.

Edited March 14, 2013 by Cheese Rice

[Sky Full]

I have been encouraged to join this forum for the first time having followed the comments and opinions of all the contributors with avid interest for months. I thought I knew a thing or two about the weather (as an amateur enthusiast, not a professional) but have come to realise that I still have much to learn. On behalf of all the other silent 'students' of our weather on this excellent site I want to take this chance to thank all the regular posters on this forum who go to such lengths to try and understand and explain the infinite variations of the models we love to watch.

My hopefully relevant question about the models is this: we clearly still have a long way to go before any of the models can be relied upon much beyond 96 to perhaps 120 - sometimes they are near enough but more often than not, much rapid correction is necessary between 48 and 96. Can anyone say what would be needed to improve this reliability? Do we need even more powerful computers, or do we need more historical and current data to feed into them, or both. In the opinion of those with the longest experience of watching the output, have the models generally improved their reliability over the last ten years, say?

I apologise if this is considered way off topic but it seems to me that this forum is where a beginner can get the best information....

[Mair Snaw]

I have been encouraged to join this forum for the first time having followed the comments and opinions of all the contributors with avid interest for months. I thought I knew a thing or two about the weather (as an amateur enthusiast, not a professional) but have come to realise that I still have much to learn. On behalf of all the other silent 'students' of our weather on this excellent site I want to take this chance to thank all the regular posters on this forum who go to such lengths to try and understand and explain the infinite variations of the models we love to watch.

My hopefully relevant question about the models is this: we clearly still have a long way to go before any of the models can be relied upon much beyond 96 to perhaps 120 - sometimes they are near enough but more often than not, much rapid correction is necessary between 48 and 96. Can anyone say what would be needed to improve this reliability? Do we need even more powerful computers, or do we need more historical and current data to feed into them, or both. In the opinion of those with the longest experience of watching the output, have the models generally improved their reliability over the last ten years, say?

I apologise if this is considered way off topic but it seems to me that this forum is where a beginner can get the best information....

Welcome to the mad house Sky Full.

[snowking]

I have been encouraged to join this forum for the first time having followed the comments and opinions of all the contributors with avid interest for months. I thought I knew a thing or two about the weather (as an amateur enthusiast, not a professional) but have come to realise that I still have much to learn. On behalf of all the other silent 'students' of our weather on this excellent site I want to take this chance to thank all the regular posters on this forum who go to such lengths to try and understand and explain the infinite variations of the models we love to watch.

My hopefully relevant question about the models is this: we clearly still have a long way to go before any of the models can be relied upon much beyond 96 to perhaps 120 - sometimes they are near enough but more often than not, much rapid correction is necessary between 48 and 96. Can anyone say what would be needed to improve this reliability? Do we need even more powerful computers, or do we need more historical and current data to feed into them, or both. In the opinion of those with the longest experience of watching the output, have the models generally improved their reliability over the last ten years, say?

I apologise if this is considered way off topic but it seems to me that this forum is where a beginner can get the best information....

Hi SF, and a very warm welcome!

I think you've opened a huge can of worms potentialy here.

To try and keep things short and sweet, the current limitations of numeric weather prediction (NWP) is our understanding of the physics of the atmosphere. The way I can see it, either we are missing something crucial in our current understanding of Physics (which, to a certain extent, if the Higgs Boson has truly been found at CERN, ratifying the Theory of Everything, is a rather small possibility), or our current knowledge of Physics of the atmosphere has taken us as far as we can possibly go with NWP, and we have to seek a new 'signal' for forecasting further afield than T+72 (or wherever we feel NWP currently becomes unreliable). This may be solar, lunar, seaweed, literally anything, but it may be that we need a new way of determining medium range weather patterns. Powerful computers and higher resolution will only take you so far if the physics you are using to run NWP has a limitation in its usefulness beyond a certain period owing to chaos theory.

There is a third, and perhaps unacceptable possibility for weather enthusiasts, and that is that no matter how hard we try, there is no way of predicting the weather further ahead than a few days, try as we might, and that the weather is truly chaotic with no defining factor. It is unlikely that you will ever see that accepted as reality on a weather forum!

Overall, though, there is no definitive answer to this question, only theories

Kind Regards

SK

Edited March 14, 2013 by snowking

[Methuselah]

Welcome to the forum, Sky Full...

[Snowman.]

Just seen the GFS run.

[Yarmy]

Hi SF, and a very warm welcome!

I think you've opened a huge can of worms potentialy here.

To try and keep things short and sweet, the current limitations of numeric weather prediction (NWP) is our understanding of the physics of the atmosphere. The way I can see it, either we are missing something crucial in our current understanding of Physics (which, to a certain extent, if the Higgs Boson has truly been found at CERN, ratifying the Theory of Everything, is a rather small possibility), or our current knowledge of Physics of the atmosphere has taken us as far as we can possibly go with NWP, and we have to seek a new 'signal' for forecasting further afield than T+72 (or wherever we feel NWP currently becomes unreliable). This may be solar, lunar, seaweed, literally anything, but it may be that we need a new way of determining medium range weather patterns. Powerful computers and higher resolution will only take you so far if the physics you are using to run NWP has a limitation in its usefulness beyond a certain period owing to chaos theory.

There is a third, and perhaps unacceptable possibility for weather enthusiasts, and that is that no matter how hard we try, there is no way of predicting the weather further ahead than a few days, try as we might, and that the weather is truly chaotic with no defining factor. It is unlikely that you will ever see that accepted as reality on a weather forum!

Overall, though, there is no definitive answer to this question, only theories

Kind Regards

SK

The physics of the atmosphere *are* understood and have been for over a 100 years (Navier-Stokes etc). That isn't the issue. The big problem is the data assimilation process, i.e. working out the initial values for wind, pressure, humidity, temperature, etc at every box in your grid. You obviously can't measure it everywhere so you have to take the millions of data points you receive and somehow extrapolate it from that. In fact what actually happens is that the previous run's output is taken (for T6 or T12 or whatever) and the real physical data is used to amend it to get the starting point for the new run.

Edited March 14, 2013 by Yarmy

[Summer Sun]

ECM short ensemble is showing an upward trend to positive territory

Most of the members on the full ensemble go above the 0c line

[CardiffStorm]

I agree with Yarmy that the Physics is understood but getting the initial values is the problem.

Take a look at CFD (Computational Fluid Dynamics), it's used to model how aircraft and other vehicles move through the air and the physics there is very well understood. The air movements over aircraft can be perfectly modelled and that's because they input good quality data.

[rory o gorman]

finally a bit of hope of spring starting on the ECM tonight , heights to the north getting eroded slowly hopefully the GFS will start to pick up the trend.

[Frank Trough]

I'd say that a milder southerly is unlikely to pan out, all models have a tendency to underestimate high pressure to our NE. We've seen time and time again nearer the time frame the output becomes increasingly erratic for the UK in regards to whether we can tap into the cold air to the NE or not.

where is the evidence that, in this type of set up, at this time of the year that "all the models underestimate high pressure to our NE"? It's a genuine question, because we hear that phrase fairly often on here. I presume it's actually just a gut feeling people have? Certainly we do sometimes see high pressure being slightly more stubborn and break downs a little quick but generally it's just a timing issue.

I haven't seen the models for a couple of days and i'm surprised at the change in outlook, especially as the METO outlook seems to have changed substantially as well.

at face value, i'd say a switch to something milder looks a really decent bet. i like the potential in this chart:

shame it won't verify!

Edited March 14, 2013 by Pharaoh Clutchstraw