Model Output Discussion - 23rd Jan - 12z onwards

[nick sussex]

Ian Fs latest tweet says by Thurs nearly all showers will be of snow - that doesn't scream marginal...Be nice to hear what the METO are thinking for the next weekend. Temps /precip especially.

Nearly being the give away.Lol! Everyone knows I haven't just turned to the dark side but simply urging some caution because the set up is messy and not a clean Arctic blast. I don't doubt there will be some snow but just trying to lower expectations to what is possible within the initial set up.

[Optimus Prime]

Absolutely. The 850mb temp profile is only one aspect. Here's a chart I wheel out every year to show it is not the be all end all.

I'm not trying to draw any similarities to the upcoming cold spell, just pointing out not to simply look at the upper temps and assume yay or boo to whether it will snow in your garden. They are a good guide, probably the best single guide but too simplistic to rely on solely

 

I like to think of the 850's as a beginners trap. If you only hit on one variable and draw a quick conclusion you'll never get it right. 850's are good when it comes to determining mild sectors at short range.

 

[stratty]

For those who are looking at the 850hPa temperature profile and determining that it won't be cold enough for widespread low lying snow;

 

 

London was hit by heavy snowfall that day and record low temperatures followed over the coming days.

The winter you mention above is the reason I love snow so much! For the sort of temperatures recorded around my area then (just outside of Gloucester), worth a quick read here:

 

http://www.gloucestercitizen.co.uk/Look-frozen-winter-1981-2/story-14267881-detail/story.html

 

Will be interesting to see if the GFS 'cleans up' it's northerly track today, or that the messy track is going to be the way forward...........

[IDO]

Ian Fs latest tweet says by Thurs nearly all showers will be of snow - that doesn't scream marginal...Be nice to hear what the METO are thinking for the next weekend. Temps /precip especially.

If you read the rest of the tweet it highlights what today's postings have suggested. https://twitter.com/fergieweather/status/559269963958345728

[Ali1977]

A nice run of tweets from Ian now if people want an idea of the METOs thought...sounds colder than some predicting here. Slightly les cold fri pm, then much colder weekend. Aimed for the West Country but still good indication. I Personnally expect a GFS upgrade this next run back towards the ECM output.

[stratty]

If you read the rest of the tweet it highlights what today's postings have suggested. https://twitter.com/fergieweather/status/559269963958345728

........and also shows his fine taste of suits!

[nick sussex]

BA do you have news yet on the control run? the ne flow caught my eye , does it build the ridge ne before toppling this?

[Frosty.]

Nearly being the give away.Lol! Everyone knows I haven't just turned to the dark side but simply urging some caution because the set up is messy and not a clean Arctic blast. I don't doubt there will be some snow but just trying to lower expectations to what is possible within the initial set up.

After the cr*p winter we have had so far, these models look great, like a breath of fresh arctic air really.

[nick sussex]

If you read the rest of the tweet it highlights what today's postings have suggested. https://twitter.com/fergieweather/status/559269963958345728

I'm quite happy with his tweet especially the bit about markedly colder again after some less cold conditions. As I've been saying the deep cold is more likely after the initial messy Euro trough scenario. The Euro troughing I'm hoping will just be a starter!

[Snow Grain]

The winter you mention above is the reason I love snow so much! For the sort of temperatures recorded around my area then (just outside of Gloucester), worth a quick read here:

 

http://www.gloucestercitizen.co.uk/Look-frozen-winter-1981-2/story-14267881-detail/story.html

 

Will be interesting to see if the GFS 'cleans up' it's northerly track today, or that the messy track is going to be the way forward...........

I remember December 1981. The weather then was progressively coming from the east, so unless that happens next week, it won't be anywhere near as cold or as snowy. Northerlies never live up to their name!

[Frosty.]

I remember December 1981. The weather then was progressively coming from the east, so unless that happens next week, it won't be anywhere near as cold or as snowy. Northerlies never live up to their name!

You can get polar lows and a number of organised snowy troughs swinging south if the northerly is sustained, and according to the Ecm in particular, this one is still going strong at day 10!

[doctor32]

just going by my amateur knowledge of model/chart watching, its seems like most runs the past fair few days are prolonging this cold spell and with more in the know coming on board... ie: the expert forecasters and meto, this may turn out to be the best cold spell for the last couple of years for most people.

 

already this year I have seen more snow and lying snow than the past two years with 850 uppers not to different from what is forecast this coming week and beyond, As for snow in any one location, it is pointless commenting on this as it will be a case of now casting on the day... I do believe that some areas will see some troublesome snow though.

 

Look forward to next weeks model watching

[Paul_1978]

If you read the rest of the tweet it highlights what today's postings have suggested. https://twitter.com/fergieweather/status/559269963958345728

And both of you haven't mentioned that these tweets are all preceded by the word W COUNTRY, so only applicable for that region!

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY SUNDAY JANUARY 25TH 2015.

NEXT UPDATE MONDAY JANUARY 26TH 2015 08:00

THE CURRENT GENERAL SITUATION A milder SW flow will extend across all areas today followed by a cold front moving SE across the UK tonight and leading to a ridge of High pressure moving into the UK from the West later tomorrow.

MODELS-2 WEEK HEADLINE Changeable with rain at times but some drier spells too. Less cold. Turning more generally unsettled and very cold again later with snow in places, especially over the North and East.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Forecast shows the flow driving sharply South over Europe later next week and ridging North across mid Atlantic keeping the UK on the cold side of a Southeast moving flow to the SW of the UK by next weekend. thereafter following the model members data the pattern flattens to a West to East flow over the UK in Week 2.

GFS OPERATIONAL The GFS operational today shows the benign Westerly flow across the UK early this week strengthening and slowly veering from Wednesday as cold and blustery weather with wintry showers extend South midweek. Deep Low pressure in association with this pattern slips SE into Europe with winds veering further to Northerly at times through next weekend and the following week with disturbances running SE into the cold air enhancing the risk of more prolonged snowfall in places before things gradually turn quieter under a strong ridge of High pressure from off the Atlantic late in the run.

THE GFS CONTROL The GFS control run follows in similar vein through the first week to 10 days before setting up a more coherent High pressure belt first across the UK and then to the North later with cold weather continuing if largely dry and frosty by then until a cold Northeast flow introduces snow showers to the East at the final frames of the run.

THE GFS CLUSTERS The GFS Clusters today don't support the evolutions of the operational or control much with a 50% group showing a less cold WNW flow around Low pressure to the North and High pressure to the Southwest. Of the rest only 10% show any extension of an Azores High towards Scandinavia and that too far South.

UKMO UKMO this morning continues to illustrate a dip into cold and wintry conditions later in the week as from Wednesday the currently benign weather pattern turns into strong NW then North winds with snow showers peppering all exposed locations facing North and giving rise to frosts by night and the risk of more sustained snowfall as disturbances will no doubt pop up at short notice and move South within the flow.

THE FAX CHARTS The Fax Charts follow the tracks of the raw data well with most of the UK falling under sub 528 dam air from Wednesday with increasingly wintry showers affecting many following a cold front SE midweek Winds will be from the NW as Low pressure deepens to the NE and slips SE over Europe later in the week.

GEM GEM today also shows a 4-5 day spell of cold and windy weather with wintry conditions under NW or north winds and snow showers in exposure. Later in the run the inevitable cut off ridge of High pressure crosses the UK and brings back cold zonality type conditions late in the run from the NW.

NAVGEM NAVGEM today shows the shift to cold and windy conditions too after Wednesday with Low pressure close by over the North Sea bringing showers or longer spells of wintry precipiation in places especially thise with exposure to the North and NW. The end runs with cold North winds still blowing across the Uk at the start of next week with the Atlantic ridge weak and still some way to the West of the UK.

ECM ECM this morning continues to look the best in terms of extended cold as it holds the ridge out across the Atlantic maintaining a cold feed of varying degrees of strength right out to the end of the run. This means that from Wednesday onward and well into next week the UK will see North winds and snow showers and some longer spells of wintry precipitaion almost anywhere at times as small Lows disrupt and move SE into the cold air across the UK.

ECM 10 DAY MEAN The 10 Day Mean this morning supports the evolution that Low pressure will lie to the NE and East of the UK over Scandinavia and Europe as well as Greenland. Contrastingly High pressure is shown to most likely to be ridged between the Azores and Iceland keeping the UK under a cold feed from the North.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend remains for much colder and windy weather later next week and through next weekend. The longevity of the spell is still unclear with various options both for a longer spells and not are shown this morning.

MY THOUGHTS Most cold lovers should be quite pleased with this morning's output as one day on and the models still suggest a cold period commencing from wednesday across the UK. There is total cross model support that this evolution to cold NW then North winds will take place and it's only the longevity of the spell once in that is very fluid within the output at the moment. This is quite normal for models to play around with various evolutions to get us back into the defaurlt Westerly mode we in the UK are so used too. GFS is resolute in this resolve this morning which after 7-10 days bring back milder westerly winds under a flattening pattern, highlighted within it's clusters and mean pressure charts for that time. GEM is also looking like going a similar way while the highlights of the morning is once more the ECM model and the GFS control run. The former brings a couple of reloads as the ridge over the Atlantic is still shown to slowly builds towards Iceland and the NW locking the UK in cold weather out to Day 10 while GFS jostles around High pressure over the Atlantic and eventually delivers a cold NE flow to the UK at the end as pressure rises to the NE too. There is still a lot of 'if's' and 'buts' surrounding the longer term evolutions of week 2 but none surrounding the onset of the cold which is a given now for Wednesday and Thursday of this week. So sit back and enjoy the ride as the models continue to throw out differing evolutions on how long and how wintry the spell or snap will evolve but I wouldn't mind betting the newsprint will be latching onto this soon and for once there will be some locations in the North especially where this may for once be justified come next weekend.

[Snow Grain]

You can get polar lows and a number of organised snowy troughs swinging south if the northerly is sustained, and according to the Ecm in particular, this one is still going strong at day 10!

like I said, if it is more North easterly, sustained and a slacker flow, then it could be fun and games. Time will tell.

[Wynn D Woo]

like I said, if it is more North easterly, sustained and a slacker flow, then it could be fun and games. Time will tell.

IMBY Poster alert!

Troughs and little surprises frequently spring up at short notice in Northerly air flows so I wouldn't worry too much about precipitation distribution just yet.

[Iceberg]

this was always going to be the fun and games between T72 and T120, as its when the models start playing and then dropping various low energy features which causes the messy charts.

EC ENS shows that the OP was milder at T120 and T144 than it's mean (by a far margin in places), purely because of this early playing.

For Friday, I have no doubt that Ian is talking about the small milder section that comes into the SW for around 12 hrs, it obviously has precip associated with it, but its position and depth of less milder air is impossible to predict. Not least because widespread showers of snow that have settled on the Thursday could easily depress DP's by 1 or 2C.

I tend to find that in these situations the UK T96 and T120, with ENS at this time from the other models gives a better idea of how the pesty low energy features will behaviour, you then need to blend the uk T144 with the GFS and EC T144 to get a better picture.

Any strong support for low energy features will show on the ENS..

[ANYWEATHER]

If people care to look at the dewpoints from Wednesday onwards you will a see an almost continuous envelope of negative dewpoints right across the nation for a long time span from there on. A good signal for snow ,given any precip    

[bluearmy]

BA do you have news yet on the control run? the ne flow caught my eye , does it build the ridge ne before toppling this?

Yes nick, the control has the mid Atlantic ridge more amplified mid run and it slowly slowly sinks across the uk by day 15. Sub zero uppers last over the southern half uk throughout.

The lower anomalies remain over Europe and I suspect if any ridge does extend across us, it would be a cold one for a fair while.

[Gibby]

Can't understand some of the negativity on here through the run up to the expected cold spell. I'll again say we have the best cross model support for a strong northerly that we have seen for several years in the UK. Perhaps some people would rather see a straight westerly feed with uppers in the + category. People need to chill out and not worry about uppers too high or marginal. The Northern hemisphere is at it's coldest point in the season right now and I will guarantee with the exception of any small frontal features injecting warm sectors within the flow precipitation will be of snow all the way to ground level from Thursday, certainly to the North and for much of the time in the South too especially from next weekend on. I concede a lot of inland Central UK will stay largely dry but coastal West, North and East could do very well for snow and that includes Cornwall. I honestly feel that people tend to spend too much time analysing the charts in too much depth that they often miss the cold spell and snow evolving around them because their heads are stuck in the computer looking for the inevitable end. I sometimes wonder whether folks are obsessed by Model watching rather than the weather itself.

 

My advice is take a break and just view the models twice a day 00zs and possibly the 12zs and reserve judgement to once a day' It has really helped me as like many on here and the other side I once became obsessed by every model run to the point where it distorted my mind and thoughts. Using the above tact I now see things in a comparable day to day environment rather than run to run

[bluearmy]

Can't understand some of the negativity on here through the run up to the expected cold spell. I'll again say we have the best cross model support for a strong northerly that we have seen for several years in the UK. Perhaps some people would rather see a straight westerly feed with uppers in the + category. People need to chill out and not worry about uppers too high or marginal. The Northern hemisphere is at it's coldest point in the season right now and I will guarantee with the exception of any small frontal features injecting warm sectors within the flow precipitation will be of snow all the way to ground level from Thursday, certainly to the North and for much of the time in the South too especially from next weekend on. I concede a lot of inland Central UK will stay largely dry but coastal West, North and East could do very well for snow and that includes Cornwall. I honestly feel that people tend to spend too much time analysing the charts in too much depth that they often miss the cold spell and snow evolving around them because their heads are stuck in the computer looking for the inevitable end. I sometimes wonder whether folks are obsessed by Model watching rather than the weather itself.

 

My advice is take a break and just view the models twice a day 00zs and possibly the 12zs and reserve judgement to once a day' It has really helped me as like many on here and the other side I once became obsessed by every model run to the point where it distorted my mind and thoughts. Using the above tact I now see things in a comparable day to day environment rather than run to run

Indeed Martin, it's best to try to step back from the posts which seem to refer to what doesn't exist in the NWP.

if fi is unclear then why bother over analysing it or even picking a random chart from it unless there is some supporting evidence which can be posted with it. of course, that's true for both mild and cold charts.

[chionomaniac]

Technically we could say that the forecast northerly is a toppler because of the lack of any heights to our NW. But it is the trough to the NE that is sustaining the northerly - and this is being determined by stratospheric vortex positioning. Another forecast warming will help keep the displacement of the strat vortex towards the Eurasian sector, and therefore help to prolong the tropospheric pattern. 

 

So we could have the most sustained toppler in the history of topplers, and who knows, if the MJO and GWO align favourably during this time then we could actually see heights build to our north and then the toppler is no longer and we have true northern blocking.......

[BLAST FROM THE PAST]

Agree re I F tweet, 'markedly colder' that is quite standout. For me this upcoming cold spell is a 'spell' as it isn't going anywhere fast. Snow WILL become a real problem for many and I sit and await the impending weather warnings. The models remain superb in cold outlook.

 

 

 

BFTP

[snowblizzard]

Can't understand some of the negativity on here through the run up to the expected cold spell. I'll again say we have the best cross model support for a strong northerly that we have seen for several years in the UK. Perhaps some people would rather see a straight westerly feed with uppers in the + category. People need to chill out and not worry about uppers too high or marginal. The Northern hemisphere is at it's coldest point in the season right now and I will guarantee with the exception of any small frontal features injecting warm sectors within the flow precipitation will be of snow all the way to ground level from Thursday, certainly to the North and for much of the time in the South too especially from next weekend on. I concede a lot of inland Central UK will stay largely dry but coastal West, North and East could do very well for snow and that includes Cornwall. I honestly feel that people tend to spend too much time analysing the charts in too much depth that they often miss the cold spell and snow evolving around them because their heads are stuck in the computer looking for the inevitable end. I sometimes wonder whether folks are obsessed by Model watching rather than the weather itself.

 

My advice is take a break and just view the models twice a day 00zs and possibly the 12zs and reserve judgement to once a day' It has really helped me as like many on here and the other side I once became obsessed by every model run to the point where it distorted my mind and thoughts. Using the above tact I now see things in a comparable day to day environment rather than run to run

Wow! really positive post from Gibby!

Some fantastic model watching coming-up in the next few days.

Edited January 25, 2015 by snowblizzard

[Mark Parsons]

Can't understand some of the negativity on here through the run up to the expected cold spell. I'll again say we have the best cross model support for a strong northerly that we have seen for several years in the UK. Perhaps some people would rather see a straight westerly feed with uppers in the + category. People need to chill out and not worry about uppers too high or marginal. The Northern hemisphere is at it's coldest point in the season right now and I will guarantee with the exception of any small frontal features injecting warm sectors within the flow precipitation will be of snow all the way to ground level from Thursday, certainly to the North and for much of the time in the South too especially from next weekend on. I concede a lot of inland Central UK will stay largely dry but coastal West, North and East could do very well for snow and that includes Cornwall. I honestly feel that people tend to spend too much time analysing the charts in too much depth that they often miss the cold spell and snow evolving around them because their heads are stuck in the computer looking for the inevitable end. I sometimes wonder whether folks are obsessed by Model watching rather than the weather itself.

 

My advice is take a break and just view the models twice a day 00zs and possibly the 12zs and reserve judgement to once a day' It has really helped me as like many on here and the other side I once became obsessed by every model run to the point where it distorted my mind and thoughts. Using the above tact I now see things in a comparable day to day environment rather than run to run

Well said Gibby, maybe we need a mature model thread!!!!