Model Output Discussion 13/11/13 >

[Man With Beard]

GEFS Ensemble mean shows no change from the overall theme of the last few runs - high to the NE of Scotland + low pressure in S Europe = a keen cold easterly wind into most of the UK. 

[Summer Sun]

Latest from Gibby

 

All models show a cold North-westerly flow developing over the UK behind a cold front moving South on Monday. This sets up an interesting and cold spell of weather where the models diverge about outcomes quite early in the coming week.

GFS shows Low pressure sinking South over the East of the UKtowards midweek with a cold and showery flow over the UK intensifying into longer spells of rain, sleet or perhaps snow for a time North to South on Wednesday and Thursday. By Friday pressure rises across the UK with the showers dying away with sunny spells but cold weather with frost and freezing fog developing overnight's, slow to clear. Through the extended part of the run tonight an elongated ridge of High pressure persists across the UK with occasional Easterly winds in the South and Westerly winds across the North. Other than that winds are shown to remain light with rather cold conditions at the surface with varying amounts of night frosts and fogs from place to place and night to night.

 

UKMO tonight shows a very cold spell coming up, especially in the South as a cold plunge of NNW winds with wintry showers early in the week give way to more prolonged precipitation for a time midweek, falling as snow over the hills. The end of the week sees Southern and Eastern areas cold and cloudy with rain, sleet or snow at times while the North and West see drier weather with frosts at night. A keen and occasionally strong NE flow will blow across the South later in the week.

 

GEM makes much less of the midweek feature with an initial surge of chilly NW winds and wintry showers becoming replaced by dry, cold and quieter conditions for a time away from the far East and South with overnight frost and fog. Later in the run winds settle SE and strengthen markedly with some rain or sleet at times across the South and West.

 

NAVGEM shows a developing Low slipping South down the heart of the UK midweek with rain and sleet in abundance across the UK with snow over the hills. Needless to say it will be cold and windy too at times and as winds settled into the NE or east across Southern Britain at then end of the week and weekend further cold rain will fall at times while the North and West becomes largely dry but cold with some overnight frosts.

 

ECM tonight shows a cold and unsettled phase through the middle of the week with some wintry showers or rain and sleet at times. This become displaced later in the week, through the weekend and the start of the following week with High pressure ensconced across the UK with cold weather maintained and frost and overnight fog big problems for many.

 

The GFS Ensembles show a short cold period, shortest in the North as Low pressure migrates to the South of the UK and High to the North. This becomes eroded as pressure becomes fairly High over the UK and uppers dilute out. There will be quite a variation at the surface though as low levels of the atmosphere could become jolly chilly under frost and freezing fog. As usual at the end of the run the weather turns much more undecided with various options being shown.

 

The Jet Stream shows the flow well to the North of the UK turning South down over the UK early next week with an eventual settling of the flow across the Atlantic and over the UK late in the period.

 

In Summary tonight the weather is about to turn colder but for how long? The models differ in the evolutions from quite early in the run with differences varying from UKMO's undercutting scenario with the High to the North and NE and Low to the SE to ECM's large UK based and persistent High pressure. All evolutions look like sustaining cold air close to the surface irrespective of uppers as the UK would develop it's own cold pool under ECM's High pressure based outcome. Chances of snow have increased somewhat tonight as there is rather more made of the midweek feature slipping South near or over the UK. Longer term though no particularly cold weather is likely in the more distant future synoptic patterns as shown would provide potential for further cold weather down the line.

 

http://www.norton-radstockweather.co.uk/Model-Analysis(2859336).htm

 

[ANYWEATHER]

Hi Folks! Just viewed the ecm and gfs and there is an amazing difficulty in modelling next weeks weather. Models are really struggling with this scenario, hence the crazy output! Yes the models go for cold , but for how long, how cold and what format...! I think NO model has a grip on next weeks weather entirely, and I think we need another 24hrs at least to see some sort of agreement on the wintry weather ahead.....

[shedhead]

Possibly as these things rarely get corrected westwards at this sort of time range, we have to hope that it's the UKMO who has the best handle on this if it's snow your looking for.

Indeed SI, westward corrections in this kind of set up are like hens teeth, eastward corrections on the other hand are anything but.  Can't help returning to the point made by Ian Brown recently because it's so important for now and also the rest of winter i.e FI is around 72-96hrs on most things progged to come from the north or east and 168hrs + on most things progged to come from the south or west....those were not his exact words, but they form the gist of his point.  

[Tom Montalbano]

On the basis of what the 12z runs are showing, looks to be too much energy around Greenland to allow further retrogression of the Atlantic high, to that area, and we're left with the high meandering around our latitude, for a while. 

Even if we manage to squeeze the best possible scenario out of the coming synoptics, expectations of any significant snowfall should be tempered.

Apart from 2010, 1965 and to a certain extent 2005, you'd be pushed to find archive reports of much settling snow, at this time of the year, certainly in the southern part of the UK, of course further north it's a different matter, especially over higher ground.

It's important for some of our recently registered members, joining the feeding frenzy of every model run, not to get hung up on each twist and turn of the output. Think about the general overview of what the UK can expect in terms of snowfall, in the last 10 days or so of November, keep that in perspective and you wont be disappointed.

Enjoy the developing synoptics, that's always interesting and after all it's still officially Autumn, we could be into the second half of February, after a snowless Winter, thankfully that's not the case.

 

Tom.

Edited November 16, 2013 by Kentish CZ

[ChartViewer]

Like the BOM

 

[Snowman.]

I don't know why people are obsessed with very cold uppers, during 63 winter the really cold uppers stayed to our northeast. What we had was sustained cold, therefore the cold became entrenched and day by day got colder. Some models are pointing towards a prolonged cool/cold spell, so you never know.......

tbh where not sure what happens after 120 we have the rough idea of pressure remaining north but details are limited.

 

Westerlies are out of equation but southerlies, easterlies and northerlies aren't 

[Smiler1709]

tbh where not sure what happens after 120 we have the rough idea of pressure remaining north but details are limited. Westerlies are out of equation but southerlies, easterlies and northerlies aren't

I think with Europe currently warmer than normal I'm not really fussed about what we get, there's still all winter to come and I'd rather have Europe in the freezer next time we get these charts. As stated already it only takes 24 hours and most of Europe could be frozen, if we go by the ukmo then we could really hit a good cold spell, with a nice block to our northeast we could keep our 2m temps below average, then once Europe is cold we could tap into some real freezing weather. It's really exciting model watching and one that's keeping us all guessing.

[ANYWEATHER]

Not a model I view very often but the GEM shows reloads of cold down from The Artic 

[radiohead]

A few very good GEFS members. The best :

 

[snowmadchrisuk]

Gfs isn't all that bad , I mean on the chart below , a little more energy under that high pressure and we would be seing BOOM charts .. If that low over Iceland could get under the block we would be laughing... 

 

[SMU]

Last one-

 

based on the UKMO & a what I have seen from the suites over the last couple of days-

 

The BOM is the first model ( operational ) to present vertical advection over Western Greenland ( a La 2010 )

 

http://modeles.meteociel.fr/modeles/bom/runs/2013111612/bomnh-0-240.png?12

 

Its a simple transition in theory & the downstream pattern has been modelled very similar for the last 24 hours ( around day 8/9) which is the flat sausage shaped Scandi high-

 

The upstream pattern is more complicated & the BOM is a choice of evolutions, however this evolution becomes ever likely if the projected energy in the northern arm of the jet has been favoured by the models by mistake- ( NB: tonights ECMs failings) should we see more energy moving back into the southern branch of the jet then the retrograde block becomes favoured...

 

I hear the uproar that the BOM is being picked over the ECM- its a rare thing but the BOM could have fluked the right solution alongside the ECM which I think is very poor in its modelling tonight.

 

UKMO + BOM ( ironically the BOM has the UKMO starting package)Look the form couplet tonight...

 

cheers

S

Edited November 16, 2013 by Steve Murr

[snowmadchrisuk]

It's unfortunate but one can definitely sense the air of despondency that has undoubtedly descended on the forum tonight. We talk of lowering ones expectations so as to avoid disappointment when charts fail to deliver but with the memories of Dec 09/Jan 10 and Nov /Dec 10 still etched on our minds it's nigh on impossible.

It would seem we need to stop viewing the models through rose tinted glasses and be open if indeed not accepting the fact we're unlikely to witness such an historic weather event again, for that's exactly what it was, HISTORIC with the exception of '47 and '62/63 of course 

LOL , Maybe it is global cooling... European Winters have been getting increasingly Cooler 08/09/and 10 were all very Snowy Winters.

[Frosty.]

The GEFS 12z perturbations are overflowing with very wintry charts covering the next few weeks and beyond, some absolute stonkers in there which include 1070 mb Greenland High's and bitterly cold arctic blasts with snow fests and ice days through to scandi highs and a cold ese flow off the continent, there are not many zonal outcomes in there at all, on balance, the GEFS 12z mean is pointing firmly and decisively towards a cold outlook with frost and wintry precipitation, we could be flirting with some very cold outcomes in the weeks ahead. The bottom line is, the mean is still cold at T+240 and even by 30th Nov the temps remain below the seasonal average.   ..BOOM 

[The Northern Ramper]

For me despite the models flipping back and forth what is happening to the north west of us, what interests me is the cold uppers flooding down to our east. Remember two days ago we were being told at 192 the continent was warm, yet at 120 tonight cold is flooding down..........kind of proves a point me thinks.

[Captain Shortwave]

T96-120 is the crucial timeframe here, the ECM was never going to undercut from there, period.

All down to the shortwave in the west Atlantic

UKMO

Notice how it's already undercutting the Atlantic ridge, the following low can dig south unhindered and then undercut the wedge of heights stretched from Scandi to broadly the Iceland region. Even by this chart it's job done as the ridge shields the shortwave from the next trough.

ECM

Notice how it's not undercutting the ridge here, this slows the shortwave down and then gets phased with the upcoming trough, this phasing cause the energy to barrel around instead of going south/south east hence the worse solution.

At T96 there is no model bias here, simply one is right and one is wrong

ECM ens look better than the op, primary due to probably less pressure from the north with that vortex lobe trying to drop into Scandinavia. But again it's probably worthless considering the mean is yet again completely different to this morning.

Lols the mean is an absolute beauty, best of the season so far.

Edited November 16, 2013 by Captain shortwave

[Matty M]

ECM ENS mean is quite different to the operational and probably closer to the UKM.

[Summer Sun]

ECM ensemble continues to support a pressure rise from Thursday not to the extent of the Op but it would still become drier some frosts and possibly fog would be more common overnight linger into the day in places

 

[SMU]

frame 10 of the ECM ensembles screams BOM scream retrograde.....

 

underpinning the thoughts from earlier-

 

s

[stewfox]

Problem is, (well for me anyway). I am pretty sure I'm veiwing the models neutrally. But when for the best part of a week its saying next week will be a freezer. All models agreeing, all runs agreeing. Then suddenly BANG, 4 massive downgrades in a row. It's difficult not to get disappointed. Nothing to do with rose tinted glasses. The models said what they said and then massively downgraded.

 

No models have been saying in the last week that by next week, we will be in the freezer. I dont see any massive down grades. Places that were marginal for sleet snow may now show more rain. Models still show a below average temps next week,  with a cold pattern and no sign of a return to mild zonality (which we saw for the most of October and first part of November) or the Atlantic firing up. A lot of members were also writing off December a few weeks ago. Thank god for model uncertainity !

 

For the 3rd week of November not touching the Prozac just yet and given FI is still within T144 the Prozac remains firmly locked away.If I see a raging Barlett in the next update I will think about it unless SM says bin.

Edited November 16, 2013 by stewfox

[radiohead]

It will be interesting to see if the FAX charts are modified towards ECM or are left showing the UKMO GM output. Should be a good indication.

[Cheshire Freeze]

ECM ensemble continues to support a pressure rise from Thursday not to the extent of the Op but it would still become drier some frosts and possibly fog would be more common overnight linger into the day in places

 

 

Excellent ensemble mean (if it's cold your after)

[tinybill]

http://www.meteociel.fr/modeles/gefs_cartes.php?code=16&ech=192&carte=&mode=0

 

 

i know  people cant get to  grips to how  cold it could get its looking  cold for at least 2  weeks  the  last frame in f1 is looking nice lets see  what the  pub run brings  to us  when we  wake  to in the  morning

[UV-RAY]

Deary me people being despondent because we may not get Nov/Dec 2010 synoptics, look at the bigger picture which is the NH profile. Add to that the projected temps for next week and if anyone doesn't think 2-4c isn't cold for the time of year then a reality check is much needed. Rant over and for me the potential for a substantial cold spell is still alive and kicking, yes the short term may not bring blizzards and sub zero temps but then again these were never forecasted, lots of mouthwatering charts for the foreseeable what more could one ask for in November.

[radiohead]

Not bad at all.