Model Output Discussion

[Bobby]

This is very much following my script with +192/+216 showing stage 3 that I mentioned.

Clearly see this cold spell isn't going to arrive with a bang. This could well differ to the last cold spells as this has more potential for being even more prolonged. I feel Steve M summed it up perfectly by saying slow to start slow to end.

True, it's reminding me of the first cold spell in December where we had a few days with high pressure nearby keeping things chilly but quiet before it headed to greenland and opened the flood gates for the real cold and snow.

13th December: http://91.121.94.83/modeles/gfs/archives/gfs-2009121312-0-6.png?12

17th December: http://91.121.94.83/modeles/gfs/archives/gfs-2009121712-0-6.png?12

[Cheshire Freeze]

Yes the 216 and 240 charts are STUNNERS but they are 9-10 days away.....let's not forget, this last week the models have struggled to nail 9-10 HOURS let alone days

[I remember Atlantic 252]

deep deep FI, last 2 charts, thinking about the Cheshire Gap again, what a northerly, gfs almost attempts it as well

nogaps though the best model after 12Z's in reliable, ECM best in FI

[Guest North Sea Snow Convection]

It has been the story of the winter so far. As I have said before any easterlies have either been short-lived or delivered next to nothing. It has been to look north for the real snowy episodes and to me it looks as though it is following that pattern.

Thats a good observation and quite true. Clearly we will have to see if the GFS and UKMO move towards the ECM here, but it wouldn't be surprising to see that happen and the easterly for this week get squeezed out further.

[Ben_Cambs]

ECM 12z shows -12C 850 Uppers clipping Eastern fringes of the UK at T+168

Edited February 6, 2010 by Snowman0697

[TEITS]

Well after viewing all of the models today here are my feelings.

Looking at the end of the week into next Saturday and I do feel the HP might be slightly further N than currently progged.

http://www.wetterzentrale.de/pics/Recm1681.gif

At +192 I do feel the 12Z is progressive and the likely pattern is we continue with the E,lys for another 24/36hrs before the HP backs NW.

Do I need to say anything about +240!

http://www.wetterzentrale.de/pics/Recm2401.gif

So a summary of next week is. Cold during Sun-Wed with scattered snow showers, Thurs-Sun snow showers being more frequent especially in E Anglia/SE where these could merge into a spell of more prolonged snow. Moving into the following week and a strong indication we could be looking to our N!

I will also add that for some areas especially W/NW much of next week could be just cold, dry, frosty. However don't be disappointed because precip is a nightmare to forecast and im often wrong with my precip predictions!

[Cheshire Freeze]

March? I don't understand you ? Next week looking very cold and no sign of mild that i can see?

You misunderstand me. Both UKMO and GFS show more snow potential and a greater depth of cold THIS WEEK, in a more relaible time frame. The ECM, not including la la land, shows HP much more prevalent and to extrapolate from those charts, 80% of the country will see no snow, slack winds and will feel rather pleasant in the sunshine. Albeit with some hard night frosts. The northerly at 216 and 240 is pure fantasy and if that evolution fell apart the majority of the public would not even call it a cold spell as it would feel nice in the sun. Hence the UKMO and GFS, to me, are preferred solutions.

[LomondSnowstorm]

Thats a good observation and quite true. Clearly we will have to see if the GFS and UKMO move towards the ECM here, but it wouldn't be surprising to see that happen and the easterly for this week get squeezed out further.

It is beginning to look a lot like the December spell actually - initial easterly is beginning to look (on the ECM at least) a short-lived affair before a trough moves south towards us. Not sure though because I feel a middle ground solution between the three models is still probable at this stage as TEITS says.

LS

edit: Still very happy with the long term outlook though, which is the main thing - get the cold in for long enough and it's bound to snow!

Edited February 6, 2010 by LomondSnowstorm

[Yeti]

This is very much following my script with +192/+216 showing stage 3 that I mentioned.

Clearly see this cold spell isn't going to arrive with a bang. This could well differ to the last cold spells as this has more potential for being even more prolonged. I feel Steve M summed it up perfectly by saying slow to start slow to end.

Yes, I seem to remember that during previous cold spells this winter the models were already showing breakdowns which kept being put back over and over again. However this time the ops just keep it cold all the way through, even to T384. This can only be a good sign - and we should bear in mind also that although good synoptics are difficult to get, they are also very difficult to get rid of, rather like mild patterns. With the SSW kicking in later, we could be in for a very cold February overall.

[TEITS]

Thats a good observation and quite true. Clearly we will have to see if the GFS and UKMO move towards the ECM here, but it wouldn't be surprising to see that happen and the easterly for this week get squeezed out further.

Depends on your location.

The cold spell of Dec 17/18th gave me the heaviest snowfall when the flow was from the E. When the flow has been from the N I have seen very little. Infact snowfall wise the cold spell of Feb 09 remains better for my location!

Edited February 6, 2010 by THE EYE IN THE SKY

[Snowyowl9]

We do have an easterly which does last longer this time,ECM does cut it off short like the last 2 cold spells but we are starting from this.

http://wzkarten.de/pics/brack0.gif

http://wzkarten.de/pics/brack1.gif

http://www2.wetter3.de/Animation_12_UTC/48_30.gif

[Buzzit]

Hello All

I note the NMM is showing a bit of snow about on Sunday night.. What is the % accuracy of the NMM or should it only be considered +12 / +24 ?

Thanks

[LomondSnowstorm]

Hello All

I note the NMM is showing a bit of snow about on Sunday night.. What is the % accuracy of the NMM or should it only be considered +12 / +24 ?

Thanks

Pretty accurate to be honest, but look at the dewpoints - see if they are below freezing. If so, you might be in luck!

LS

[TEITS]

Hello All

I note the NMM is showing a bit of snow about on Sunday night.. What is the % accuracy of the NMM or should it only be considered +12 / +24 ?

Thanks

Very accurate. Infact I even rate it above the NAE model.

This is purely based on our cold spells during Dec, Jan.

[Geordiesnow]

Can't say i'm fully impressed with the ECM, snow will be quite limited and until later on in the run, we don't reach the cold uppers.

This easterly is turning quickly into an equivalent of a Northerly toppler, few locations get snowfall and most places will stay cold, sunny and frosty.

[Cheshire Freeze]

It must also be noted that GFS 12z ensembles rise towards the end and have shown this trend for quite a few runs now. Now considering the GFS is supposedly good at picking up trends, it puts it into perspective how vulnerable that retrogression outcome shown on the ECM is. Considering that the ECM is probably the best model in the close-medium range and the GFS is good at longer term trends, it is perfectly reasonable to believe that we may end up with a non descript anticyclonic easterly followed by a return to the Atlantic. Hence my fears.

[Polar Continental]

All models varying slightly projecting this up and coming cold spell. What’s clear is a cold north to north easterly gets going about now, all be it slack at first.

So gradually getting colder as the new week progresses. Initially the block sits close to the north east of the UK, though later in the week around T144 the block is shown to regress further northeast towards Greenland, so further interesting developments from that point.

Precipitation wise, the GFS is better as the high is set a little further north east and allows low pressure to sit closer to eastern areas tightening up the isobars, which would be good for advecting the more unstable cold easterlies.

A good deal to be sorted out in the week ahead I think.

Cold easterly

very cold 850's

[Cheshire Freeze]

lol well it was looking like wind rain and very mild temps when we looked at the models last week.

some people are never happy.whats wrong with cold dry frosty weather in Feb?we live in the uk not siberia.

A bit of measurable snow would be nice. Here for example, in the Jan cold spell whilst Manchester was being hit hard along with many parts of the country, we missed 90% of the action which passed just to the north of us. Some of us had to endure picture after picture of 10 inch+ snowfalls whilst enduring a few small flurries. A country wide unstable cold spell gives us all the chance to see more snow and gives the opportunity for those who have seen no where near the copious amounts that others have already received this winter, a second bite of the cherry

[LomondSnowstorm]

It must also be noted that GFS 12z ensembles rise towards the end and have shown this trend for quite a few runs now. Now considering the GFS is supposedly good at picking up trends, it puts it into perspective how vulnerable that retrogression outcome shown on the ECM is. Considering that the ECM is probably the best model in the close-medium range and the GFS is good at longer term trends, it is perfectly reasonable to believe that we may end up with a non descript anticyclonic easterly followed by a return to the Atlantic. Hence my fears.

It pretty much always rises when we're looking at a cold spell or falls when mild is on the cards in the short-term. Because the models go out to +384 which is super deep FI the models are always going to diverge and end up with a less cold/less mild mean than shown in the short-term.

LS

[Cecil Hogmanay Melchett]

It must also be noted that GFS 12z ensembles rise towards the end and have shown this trend for quite a few runs now. Now considering the GFS is supposedly good at picking up trends, it puts it into perspective how vulnerable that retrogression outcome shown on the ECM is. Considering that the ECM is probably the best model in the close-medium range and the GFS is good at longer term trends, it is perfectly reasonable to believe that we may end up with a non descript anticyclonic easterly followed by a return to the Atlantic. Hence my fears.

you are contradicting yourself.You said earlier the models cant get it right at 10 hours letalone 10days and then in the next post you are talking about a warming trend in FI.lol.

[Cheshire Freeze]

you are contradicting yourself.You said earlier the models cant get it right at 10 hours letalone 10days and then in the next post you are talking about a warming trend in FI.lol.

With regard to specifics, it is daft to look past 144 hours. GFS ensembles are a different story and although they can be just as unrelaible, they can often pick trends out. The ECM 12z is just one run and that is what I was referring to. so no, no contradiction.

[Geordiesnow]

lol well it was looking like wind rain and very mild temps when we looked at the models last week.

some people are never happy.whats wrong with cold dry frosty weather in Feb?we live in the uk not siberia.

Nothing wrong with cold frosty weather at all HD, infact it would be nice too see some sunshine! However, when you have fairly decent charts in the last few days then its sickening to see this current ECM run as snow risk is very limited. It increases later on in the run and has a decent FI but for 90% of the UK, it will be dry and that what most people in here don't want.

Still, it is cold weather and what the charts had to offer before this new trend came in was rather poor to say the least, so the output can and will change. I still think we will see some changes but it is looking less and less likely to cold snap will produce anything significant in terms of snow amounts. I also don't mean localised snow amounts, i mean more nationally.

[Cecil Hogmanay Melchett]

Nothing wrong with cold frosty weather at all HD, infact it would be nice too see some sunshine! However, when you have fairly decent charts in the last few days then its sickening to see this current ECM run as snow risk is very limited. It increases later on in the run and has a decent FI but for 90% of the UK, it will be dry and that what most people in here don't want.

Still, it is cold weather and what the charts had to offer before this new trend came in was rather poor to say the least, so the output can and will change. I still think we will see some changes but it is looking less and less likely to cold snap will produce anything significant in terms of snow amounts. I also don't mean localised snow amounts, i mean more nationally.

ok mate i understand you better now.

[kev238]

I expect snow to be quite limited in the next five days- no model really shows anything severe in that period. I think it is all about getting the cold established next week- and then seeing what opportunities present themselves from next Friday onwards.

As TEITS says Feb 09 was far better for my location (nottingham) than anything this year so I am remaining cautious regarding prospects as the coldest Jan in 25 years didnt really produce the goods IMBY!! I really hope the hints in the output of Easterly winds come into fruition; however I do feel the best charts are remaining at t144 on the UKMO!

[LomondSnowstorm]

With regard to specifics, it is daft to look past 144 hours. GFS ensembles are a different story and although they can be just as unrelaible, they can often pick trends out. The ECM 12z is just one run and that is what I was referring to. so no, no contradiction.

I've lost a lot of faith in the ensembles in the last week and a half, as I'm sure many on here have, as they've flipped just as much as the operationals! But what does this tell you? http://cirrus.netweather.tv/ensimages/ens.20100206/12/t850Fife.png Cold for the foreseeable, uncertainty after this but still generally cold. Similar to the set before the December spell really, in terms of the length the mean is below -5.

Very nice IMO

LS