General Model Output Discussion

[yamkin]

Confidence now increasing on a cold but very dry spell of weather for the UK. Largely unremarkable really with no ice days likely in the south for the next 5 days at least. Possibly some low minima for central and northern areas but again nothing too remarkable here.

Overall the phrase "at least it won't be mild!" come to mind, but I'm finding it increasingly difficult to find anything worth getting excited about in the model output at the moment.

Cheers & all the best for New Year.

Could you explain why it will be very dry. The reason I ask is because NOGAPS 06Z is showing ppn at times http://www.meteociel.fr/modeles/nogapse_cartes.php?ech=6&code=0&mode=2&carte=0

[I remember '63]

Confidence now increasing on a cold but very dry spell of weather for the UK. Largely unremarkable really with no ice days likely in the south for the next 5 days at least. Possibly some low minima for central and northern areas but again nothing too remarkable here.

Overall the phrase "at least it won't be mild!" come to mind, but I'm finding it increasingly difficult to find anything worth getting excited about in the model output at the moment.

Cheers & all the best for New Year.

Having looked at the models I can only say I'm in complete agreement. This rather unremarkable winter continues. As someone with experience of almost 60 winters, so far I'd put this within the bottom dozen for excitement. Of course things can change but I can see nothing on the horizon yet.

[Frosty.]

Reading through the posts, it seems apparant that the 6z run has been trashed again, much as yesterday. It's a pretty wintry run out to next wed/thurs but we then seem to lose the coldest air. The 6z run bears no relation to today's meto update as their update prolongs the very wintry spell, especially in the north & east until towards mid January.

[Matt12]

Having looked at the models I can only say I'm in complete agreement. This rather unremarkable winter continues. As someone with experience of almost 60 winters, so far I'd put this within the bottom dozen for excitement. Of course things can change but I can see nothing on the horizon yet.

Within the bottom dozen? Not sure where you've been for the last 20 years, but this is definitely one of the coldest/snowiest starts to winter I can remember (i.e. since the late 80s/early 90s)!

Also, it's worth bearing in mind that charts do change with regards to precipitation. The current charts CANNOT accurately predict snowfall in 3 or 4 days' time, let alone in a week! If the cold stays with us for another 2/3 weeks, it will almost definitely snow everywhere at some point!

[Bolton67]

Could you explain why it will be very dry. The reason I ask is because NOGAPS 06Z is showing ppn at times http://www.meteociel...&mode=2&carte=0

The GFS 6z is also showing ppn at times but different amounts to those shown in the NOGAPS 6Z

http://www.meteociel...6&code=0&mode=2

[johnholmes]

it could be that the poster was trying a wind up-I suppose if its snow excitement then we really have no idea beyond 2-3 days.

Regarding the mean temperature then as to the start to winter-December began with the first 5 days at a mean of 5.4C-its looking like ending with a mean of about 3.4-3.5C, the lowest since I started taking my own readings in January 1997.

Not sure about the stats for Finningley over their 50 year period but, hang on gets large file out,

1992=3.3

1981=-0.5

1978=3.2

1976=1.9

1969=3.3

1968=3.2

1964=3.5

1963=3.3

1962=1.5

1961=2.1

1950=1.3

1946=3.1

1944=3.4

so its not that bad for the, no I won't say that term about the winter!

so about the 13/14th coldest December in nearly 70 years for this area.

Edited December 31, 2009 by johnholmes

[I remember '63]

i think the post was a joke!

No, not a joke - I've seen no snow so far (apart from a small dusting) and temperatures are what I would expect around this time of the year. I know some have had a brief spell of spell of heavy snow but I'm afraid I don't really understand all the excitement.

For me an unremarkable run-of-the-mill winter so far but things may change. I apologise if some feel this is a wind-up, it wasn't meant to be.

Edited December 31, 2009 by I remember '63

[Paul]

Thanks for the reply.

I suppose the best way of using the NMM isn't to take it literally but more as a guide to where convection is likely to occur.

Yep, most definitely no mesoscale model is fool proof on this front as convection can be so localised (with some cells well below 1km in size). Currently the resolution of the model is at 8km, we will (most probably) be bringing that down to 4km in 2010 which will obviously improve accuracy another notch, with the eventual aim to run it at 2km.

[Cecil Hogmanay Melchett]

The way im reading the situation is this.

Its going to get colder,probably very cold.

This cold spell looks the best since 1996,some really low minma look likely if the flow becomes slack as we head through next week.I wouldn't be at all suprised to hear of reports of freezing ponds/canal's.

Now,snow,and its important we dont get obsessed with it and let it ruin the discussions.

Some will get,some won't,thats the way of life.Nobody really knows whats going to happen in the next 24 to 48 hours so let things take care of themselves after that.

I dont have a problem with posters referring to their regions when discussing the models,but lets bare in mind we have regional sub forums for specific regions,lets concentrate to some degree on the global or european synoptics as much as posible in here,that way people dont get peeved off with posts about other maybe more snowy regions.

Just a thought.

[03jtrickey]

Yep, most definitely no mesoscale model is fool proof on this front as convection can be so localised. Currently the resolution of the model is at 8km, we will (most probably) be bringing that down to 4km in 2010 which will obviously improve accuracy another notch, with the eventual aim to run it at 2km.

Regarding the NMM, do you actually run the model on the NetWeather servers, or is it retrieved from a central location? If you run it on your servers, does this mean that the Meteociel version of NMM could in fact yield different results to the NetWeather version?

Also, I've noticed there has been some discussion in the short term on TWO and uk.sci.weather about a feature off the coast of Norway which could bring heavier ppt towards the UK. The 0Z NAE showed it moving quite far south, reaching the SW http://expert.weatheronline.co.uk/daten/proficharts/en/nae/2009/12/31/basis00/ukuk/prty/10010200_3100.gif , but the 06Z seems to have backed away from keeping its intensity as it moves southwards http://expert.weatheronline.co.uk/daten/proficharts/en/nae/2009/12/31/basis06/ukuk/prty/10010200_3106.gif . Does anyone know what is likely to happen with this feature?

[nick sussex]

After the gfs 06hrs run i think we can see a trend developing, the mistake the gfs makes though is to be too progressive, the general guidance is likely IMO to play out like this, the low coming in from the sw heads east linking up with the Scandi trough, several days of ne winds, eventually the Greenland high will edge east but the central core will be further south, depending on the PV it's likely to be a high centred from Iceland to western Norway in that vicinity. It's clear from the ensembles the further north you are the less of an outlier the operational run is, the further south into europe the opposite.

Theres very good support for a warm up in Iceland but not the major warming we see with a Scandi high centred in the heart of this region. So the area of high pressure is more likely in the area i previously mentioned. Where the pattern goes after this who knows but its unlikely the high will sink as there should be decent energy going into the southern arm of the jet to prop the high up, in many previous winters it would be a case of the whole pattern eventually sinking however the PV remains disorganised because of this it might just be a little lull in proceedings, it's funny the Greenland high has been such a rare visitor in recent winters but it might be like waiting for a bus, you wait for ages and then a whole load turn up at once!

[kold weather]

temperatures are what I would expect around this time of the year.

Temps have been WAY below normal in the last 15 days on average, we've seen a slightly milder spell in the last few days but even then its still fairly below average, with maxes expected to reach about 5-6C at this time of year roughly...

As HD says as well as GP on the other thread mins could be a big part of the story, expect some very cold mins, esp as the high topples over the UK with still low thicknesses and cold uppers...

[nick sussex]

Temps have been WAY below normal in the last 15 days on average, we've seen a slightly milder spell in the last few days but even then its still fairly below average, with maxes expected to reach about 5-6C at this time of year roughly...

As HD says as well as GP on the other thread mins could be a big part of the story, expect some very cold mins, esp as the high topples over the UK with still low thicknesses and cold uppers...

I think whats really exciting about the projected synoptics is that for the first time in many years they're arriving in proper mid winter not at the middle to end of February.

[weather eater]

Does the fact that we could finally be within grasp of a severe winter month (sub 1.5C) help bring out the excitment a little more, given we've not had one now since Feb 91?

Also whilst we may not get no ice days at first, I'm willing to bet by the 5-7th we will see ice days, indeed the 0z ECM is rather suggestive of many ice days at Reading, some occuring in the next 5 days as well...

Looking at recent model output there’s plenty of signs for a cold start to the month followed by a warm up, other output suggests a protracted spell. Personally I think the models will back off the idea of an earlier warm up. I can’t blame people from certain areas of the country being shall we say, less excited than some others, It’s not ice days that people want, its snow and snow cover. However I would remind folk that the further outlook will most likely evolve differently from what the models are now showing and who knows what that will bring. The classic snowy spells of the past mostly started with embedded cold, the snow came after. Plenty to look forward to with gripping model watching to enjoy, but as I said earlier we don’t need hyperbole posts, they are as irritating as the constant moaning ones.

[rbw]

The way im reading the situation is this.

Its going to get colder,probably very cold.

This cold spell looks the best since 1996,some really low minma look likely if the flow becomes slack as we head through next week.I wouldn't be at all suprised to hear of reports of freezing ponds/canal's.

Now,snow,and its important we dont get obsessed with it and let it ruin the discussions.

Some will get,some won't,thats the way of life.Nobody really knows whats going to happen in the next 24 to 48 hours so let things take care of themselves after that.

I dont have a problem with posters referring to their regions when discussing the models,but lets bare in mind we have regional sub forums for specific regions,lets concentrate to some degree on the global or european synoptics as much as posible in here,that way people dont get peeved off with posts about other maybe more snowy regions.

Just a thought.

I largely agree - I think the special thing about the forthcoming cold spell is that it is going to be prolonged. I am sure we will see freezing canals as the winds and clouds drop away and we need to watch for the possibility of snow developing. Apart from the possible long duration of the cold spell, I however see nothing particularly unusual. Lows of -9C are not that rare when we get these conditions but I don't think we will see a repeat of 1981 when we had ice floes on some of the major rivers, despite looking like that might happen a few days ago.

A question - does the GFS always try to turn anything into a south westerly flow eventually? I wonder if it is biased to do ?

R

[bluearmy]

i cant quite understand some of the comments re the upcoming cold spell. the sypnotic patterns and solution churned out by the nwp over the past month has been some of the best ever seen on the web, given the time of year from a coldie perspective. as this thread is for discussing the model output, i suggest those who feel they want to comment on this winter being unremarkable do it in another thread. the comments are way off the mark from a statistical pov and certainly from the perspective of model discussion.

regarding the current nwp output, the way the models are dealing with the likely drift se of the greeny blocking is fascinating. GFS has persistantly modelled a euro rise in pressure connected to the west asian high which brings a southerly drift. over the past few runs, i detect the nuance to turn this se as the southerly jet persists into iberia. if it weren't for the strength of the scandi trough, i'm sure this pressure rise would find its home in scandi. what seems pretty likely is that this will occur in around 8 to 12 days time as opposed to the op GFS which wants to bring it in a couple of days earlier, due to its determination to collapse the greeny block sooner than the other models. remember last time the models were about 4 days too keen to drop the heights in this area. ECM out to T240 doesnt show a sustained trend yet re where this height rise is headed. by the end of the weekend, we will have seen enough GEM and ECM T240 output to have a handle on what they propose to do with this height rise.

absolutely superb and thats without considering all the tooing and froing we have in the meantime with sypnotics under mean uppers around -8c. i think a few posters will be surprised whats possible when temps are as low as they are likely to be with low dp's and an island surrounded by warm seas.

[NorthantsSnow]

Does the fact that we could finally be within grasp of a severe winter month (sub 1.5C) help bring out the excitment a little more, given we've not had one now since Feb 91?Also whilst we may not get no ice days at first, I'm willing to bet by the 5-7th we will see ice days, indeed the 0z ECM is rather suggestive of many ice days at Reading, some occuring in the next 5 days as well...

Indeed. Sustained cold if it occurs would be interesting, but we can't say with any certainty that that is how January is going to pan out. I'm just concentrating on what's being shown for the next 5 days or so and I can't see anything particularly wintry just yet.

Could you explain why it will be very dry. The reason I ask is because NOGAPS 06Z is showing ppn at times http://www.meteociel.fr/modeles/nogapse_cartes.php?ech=6&code=0&mode=2&carte=0

I was using the GEFS ppn ensembles for my location and indeed key UK cities. Not much joy on those up until the 8th at the very earliest. For Aberdeenshire they look a bit more promising mind. The ECM is very dry as well- and NOGAPS to me is not very reliable so I don't pay too much attention to it.

it could be that the poster was trying a wind up-I suppose if its snow excitement then we really have no idea beyond 2-3 days

Not at all. I think we can build up a pretty good idea by following the models on a run to run basis and looking at the ensembles for specific towns/cities. Away from the extreme NE, I'm not seeing much in the way of snow potential. If you can prove me wrong then please do so, that would certainly be a preferable response to baseless accusations. Cheers.

Edited December 31, 2009 by NorthantsSnow

[Paul]

Regarding the NMM, do you actually run the model on the NetWeather servers, or is it retrieved from a central location? If you run it on your servers, does this mean that the Meteociel version of NMM could in fact yield different results to the NetWeather version?

Also, I've noticed there has been some discussion in the short term on TWO and uk.sci.weather about a feature off the coast of Norway which could bring heavier ppt towards the UK. The 0Z NAE showed it moving quite far south, reaching the SW http://expert.weathe...010200_3100.gif , but the 06Z seems to have backed away from keeping its intensity as it moves southwards http://expert.weathe...010200_3106.gif . Does anyone know what is likely to happen with this feature?

Yep it's run on our own servers and is definitely different to the meteociel version - the resolution is different and as the NMM has a variety of options within it then they're likely to be running using different physics too.

[Bolton67]

absolutely superb and thats without considering all the tooing and froing we have in the meantime with sypnotics under mean uppers around -8c. i think a few posters will be surprised whats possible when temps are as low as they are likely to be with low dp's and an island surrounded by warm seas.

Nail on head.

[snowray]

My apologies for the rather brief any misleading post earlier, I have been somewhat busy and finding it hard to keep up with events and all the posts on here. Also half the post never came out for some reason.

My point was that upto a couple of days ago it looked as though the oclusion which is clearing South as I write, was due to produce a fair bit of snow in the Midlands and Wales, it turned out as rain away from the highest ground. Thursday, IE today, and new years day was looking like a day of sunshine and hefty snow showers and streamers moving well inland from East Anglia and the South East, yes? In fact the snow line remains in the North East of England and once temperatures get to the right side of marginal there will be hardly any PPN left, it would seem, away from the East coast.

I wasn't looking out at T144 or some other way out chart in FI, just what I can see going on now and in the next 24-72 hour period. After that, yes a prolonged period of cold or very cold looks on the cards, but I think most on here also want to see a bit of the white stuff, and the PNN charts for snow are not looking all that right now for many inland areas.

[johnholmes]

A question - does the GFS always try to turn anything into a south westerly flow eventually? I wonder if it is biased to do ?

R

no model has any bias in spite of a number on here maintaining they do.

All base their output on the laws of thermodynamics-all have slightly different soft ware packages (not a really apt name for the complexity of these) which is likely to give differing results even using the same basic data input. But none have preprogamming in to make for a default set up at any stage.

They have differing numbers of levels through the atmosphere, differing methods of doing the mathematics, differing time scales, differing length grid points and some differing length grid points at different time intervals.

Some times I am quite surprised with all these differences at just how close the results are for them. Just goes to show that the basic laws they all follow do work IF we had an absolutely accurate set of data which can never ever happen. Nor can the human made rules for the computers ever be as perfect as they would have to be to get perfect answers to the weather, be it 1 hour ahead or 1 month or 1 year-fortunately in my view.

this is the link into UK Met web site about their models so may be of interest to you and others; I would imagine that you can log on to both GFS (NOAA) and ECMWF, and get a similar amount of information about how they programmes their models.

hope it helps anyway

http://www.metoffice.gov.uk/science/creating/first_steps/

Edited December 31, 2009 by johnholmes

[Iceberg]

Cheers John, it's worth saying as well (re the models producing similar output), that when a particularly successful bit of modelling (maths/algorithms) takes place they do share this amongst the models, I remember a case maybe 5 years ago when something started in ECM model, then got used in the METO Global Model, then finally got incorporated in GFS (although the whole process I was told took 3 years ! ).

But I think this is mainly due to the fact the the software release schedule is planned 18 months in advance, with bug fix drops a quarterly intervals.

[johnholmes]

The classic snowy spells of the past mostly started with embedded cold, the snow came after. Plenty to look forward to with gripping model watching to enjoy, but as I said earlier we don't need hyperbole posts, they are as irritating as the constant moaning ones.

very true in most winters that have featured cold and snow-only very occasionally does the snow arrive at the start-one in the mid 50's I remember but the date/month I cannot

We had a very mild fairly windy and wet spell-several days. I went to bed with a moist wet very mild sw flow and woke up next morning to a white world. It had happened according to my father-out dog walking around 11pm- almost instantly,one minute pouring rain the next huge snowflakes and the thermometer in our back garden had gone from 10C to zero C in a very short time.

I;; see if my garage will reveal the very old weather diary with this event in.

[West is Best]

Some posters on here are even more fickle than the crowd which allegedly welcomed Jesus with palm fronds one Sunday, only to crucify him five days later. It really is absolutely ridiculous to have to trawl through the whining whingeing drivel on here day after day that has little or nothing to do with model outputs. Sorry but this has to be said.

The synoptics are probably the best we've seen in this country since the 1980's. It is December 31st, not March 31st and the two pricipal winter months lie in front of us, off a very cold start. Now for goodness sake: grow up some of you.

Edited December 31, 2009 by West is Best

[Stoxs]

very true in most winters that have featured cold and snow-only very occasionally does the snow arrive at the start-one in the mid 50's I remember but the date/month I cannot

We had a very mild fairly windy and wet spell-several days. I went to bed with a moist wet very mild sw flow and woke up next morning to a white world. It had happened according to my father-out dog walking around 11pm- almost instantly,one minute pouring rain the next huge snowflakes and the thermometer in our back garden had gone from 10C to zero C in a very short time.

I;; see if my garage will reveal the very old weather diary with this event in.

Sorry but i can`t resist

excellent wording again John.

I do apologise

A real good patern forming for the next week as always lets get it cold the the white stuff will appear.

Slush isn`t very exciting to me