Model output discussion 25th Jan onwards

[snowmadchrisuk]

http://www.meteociel.fr/modeles/jma/runs/2014020412/JN192-21.GIF?04-12

 

Decent JMA -  nice chart.

 

Need some of these eye candy charts to get to 72 & 96............

 

S

 

doesn't look that decent at the surface to me Steve , more like more of the same , Wet with snow on hills, Would rather have +5 850's over GL than -25. Can see the split PV but can't see where you see the eye candy ... 

[IDO]

For well over a week now I have been touting a pattern change to one of more blocking or

amplification to the north and lows tracking further south with hopefully a decent continental

feed bringing cold uppers and finally a taste of winter. This is now starting to show in the model

output and is brought about by the ongoing strat warming.

Plenty of changes to come in the output as the models get to grips with this with the strongest

period of blocking probably the last two weeks of the month.

I know if I could take one week of proper cold wintry weather, laying snow etc from this awful

winter I will be happy.

 

I am struggling to see that "change" at the moment. The GEFS for London remain poor for cold: 

 

The mean showing average to above temps. and nominal chance of snow.

 

The surface pressure clusters at the end of the GEFS have 70% zonal, 15% height rises to the NE and 15% with a NW-SE trough: 

 

 

Slightly better than of late but still not leading us anywhere yet.

 

Certainly next week the trend for a slacker flow and possible upper temps being cool for several days remains. But the mean flatlines at 0c to -1c so excitement remains on the back burner for us southerners on low ground as we await the next dumping of rain.

 

GEM at D10 (mid month) not looking like a cold spell is waiting in the wings:  

 

ECM again just average February fare at D10: 

 

This slacker flow may be all we can expect from the recent strat warming (based on the modus operandi of this winter) and that has reversed so it is likely that the PV will regroup all too soon. Certainly the CFS suggests nothing till week 2 of March, when the PV appears to be weary and looking forward,  towards it's Summer Holiday.

[The PIT]

Without putting to much insight into the models there really is high potential for snow & snow cover in the models tonight- again though more especially over the hills of the midlands & pennines etc-

 

ANY shallow low that tracks across the UK in this type of set up-

http://www.meteociel.fr/modeles/ecmwf/runs/2014020412/ECU1-192.GIF?04-0

http://www.meteociel.fr/modeles/ecmwf/runs/2014020412/ECU0-192.GIF?04-0

 

With heights around 508 DAM & thickness around 528 DAM, will always be a recipe for snow over hills-

 

The UKS best chance of the winter for snow presents itself this weekend & more especially early next week.

Also Scotland looks very cold - with circa -4c air, low heights & thicknesses as well with a gentle southerly breeze.

 

S

I think we will need a bit of additional help for that. A bit of evaporative cooling perhaps.

At the moment I'm just interested in the subtle change in the models since last time I looked.

[SMU]

Hi

 

The temp over Greenland is irrelevant on that chart-  Thickness along the 990 contour is exactly 528 DAM

A shallow low with minimal mixing is great if you wont to see snow-

 

Anyway is wont verify like that- however if it did, snow would be on the agenda.-

S

[Stuie]

doesn't look that decent at the surface to me Steve , more like more of the same , Wet with snow on hills, Would rather have +5 850's over GL than -25. Can see the split PV but can't see where you see the eye candy ... 

Saying that Chris, it will be marginal come next Wednesday.

[snowmadchrisuk]

Saying that Chris, it will be marginal come next Wednesday.

 

yes looks like Snow chances next week especially looking at ECM , GFS look's ok next week as well, just have to see what precipitation is available and how heavy it is ... 

[Mucka]

The main reason I raised the topic was that I could not see where the trough disruption quoted by several posters this morning was occurring?

Does anyone else see trough disruption in the GFS output?

Please show me as I am honestly unable to see just where this is happening-that is all I am asking.

 

and to answer mucka, it is the loose and at times incorrect use of some terms that is misleading. Why use the term if others are not sure what you are saying?

 

 

Well you have to be aware that other people are not sure what you are saying and yours is the first post I have read to broach the subject, hence the discussion we are now having.

I think it's reasonable for people to question what others mean if they are not sure or if they don't think a term is being used in the correct context as you have, all part of normal forum life.

You say you don't see the trough disrupting, SE against the ridge in the GFS 06z output I posted, that's fine, but for me that is disruption because the low pressure is stalling and energy dissipating as evidenced by the "stretching" of the trough ultimately resulting in the flabby low SW of Greenland at 204.

I selected that because it was the first charts I found in the output at that time where I might use the term but obviously it isn't a classic example of low pressure stalling against a block and energy being stripped away and I guess there are almost limitless combinations of charts that might show a similar process so it is no surprise that that there is some crossover of these terms and one can't really post a chart as the definitive example.

For me though a classic sign on the 500mg charts for our region would be the "stretching" effect rather than just having low pressure bowl its way across the Atlantic.

 

Onwards and upwards.

Certainly a bit more interest for coldies appearing on the horizon but nothing concrete at all. There are however good signs the jet will continue to be South of the UK and slowly weaken. Naturally this gives us an opportunity of a more amplified pattern to our West and more of a chance any blocking taking hold. 

I'm still looking at around mid month before we may see some decent Atlantic ridging toward Greenland and if we get lucky - we are due - we could see high pressure develop over Greenland or perhaps over Iceland. Either offer decent opportunities for cold. It is still a case of keeping a watching brief but any developments should start to come into range of ECM over the next day or two as well. The search for snow (or just something drier) goes on.

Edited February 4, 2014 by Mucka

[Man With Beard]

Tonight's models, for me, show a continuation of the trends of the last few days - after this weekend, the pattern starts to slacken and some lows take on a more southerly route leaving us, at times, more exposed to the northern side of the flow, this being a good example:

 

 

 

Beyond that, with the PV less influential over Eastern Canada, the outlook remains much more flexible. As shown above, the ECM follows up this morning's run with the same trend of heights building from the east, this time they get towards towards Greenland. Some GEFS members show hints of this at T240 although not enough to sink the upper trough south, which stays largely to our west. 

 

Absolutely no signs of a UK freeze yet and no promise that there will be, but the possibility of a last ditch cold snap is increasing a little more.

 

Of course the obsession with -12C uppers may mean missing what is in front of our eyes - with depression after depression passing the UK shortly in -3C uppers and some north/east wrap-arounds, we aren't actually all that far from surprise snow events - to be honest Friday's event wasn't one I was watching for areas away from high ground but when Ian posted about snow potential across the south on Friday, well it just goes to show that snow is actually quite close to falling right now even without great synoptics! Yes looking at the uppers for Friday I can't imagine it would be anything but back-edge snow, still, I'm sure the UKMO or Ian will clarify soon enough, till then I'll keep building my boat...

[Stuie]

Tonight's models, for me, show a continuation of the trends of the last few days - after this weekend, the pattern starts to slacken and some lows take on a more southerly route leaving us, at times, more exposed to the northern side of the flow, this being a good example:

 

 

 

Beyond that, with the PV less influential over Eastern Canada, the outlook remains much more flexible. As shown above, the ECM follows up this morning's run with the same trend of heights building from the east, this time they get towards towards Greenland. Some GEFS members show hints of this at T240 although not enough to sink the upper trough south, which stays largely to our west. 

 

Absolutely no signs of a UK freeze yet and no promise that there will be, but the possibility of a last ditch cold snap is increasing a little more.

 

Of course the obsession with -12C uppers may mean missing what is in front of our eyes - with depression after depression passing the UK shortly in -3C uppers and some north/east wrap-arounds, we aren't actually all that far from surprise snow events - to be honest Friday's event wasn't one I was watching for areas away from high ground but when Ian posted about snow potential across the south on Friday, well it just goes to show that snow is actually quite close to falling right now even without great synoptics! Yes looking at the uppers for Friday I can't imagine it would be anything but back-edge snow, still, I'm sure the UKMO or Ian will clarify soon enough, till then I'll keep building my boat...

Ok Noah it all.

I agree, this is the closest we have been to actually getting white stuff. As I posted above the wet bulb levels could be good enough also for lowlands and not just the higher ground.

[Gibby]

Good evening. Here is another look at the outputs from the NWP, this time from the 12 noon outputs for today Tuesday February 4th 2014 and lifted from http://www.norton-radstockweather.co.uk/Model-Analysis(2859336).htm

 

All models show very unsettled conditions through the period covered by tonight's output. Intense Low pressure currently moving in towards the UK from the SW will bring severe gales and locally storm force winds with heavy rain followed by squally showers over tonight and tomorrow. By Thursday a new Low threatens Southern Britain with yet more heavy rain with the North escaping from this feature and maintaining a more showery regime. Later on Friday and the weekend sees yet another major storm system rattle in from the Atlantic with a repeat performance of tonight and tomorrow's sequence of events. Through the period temperatures will remain close to average overall offset by the strength of the wind but there could be some colder interludes especially over the North when some of the precipitation may fall as snow.

 

GFS then shows next week as being little different to this one with incessant Low pressure sending spells of rain and showers across the UK in winds somewhat lighter than this week as a small consolation. Temperatures will remain largely close to average but it will steadily turn colder later as High pressure builds to the North and finally cuts off the Atlantic feed for a time at least.

 

The GFS Ensembles show a slight drying process later in Week 2 but until then the same weather patterns prevail with further disruption likely. Temperatures continue to show little deviation from levels currently being experienced.

 

UKMO shows next Monday to be continuing unsettled and wet as the charts show the UK surrounded and covered in Low pressure areas each bringing the risk of sustained heavy rain and showers in close to average temperatures.

 

GEM tonight remains every bit as turbulent as this morning's model run with Low pressure areas continuing to wind their way across the UK from the Atlantic and keeping the regular occurrences of wind and rain going.

 

NAVGEM also shows little relief next week as the proximity of Low pressure is close by with further rain and showers in blustery and sometimes strong winds.

 

ECM is about as ugly and concerning as I think I can remember model watching with virtually all of the Atlantic, the UK and NW Europe covered in very Low pressure next week with separate centres moving East within the general complex each bringing their own spells of heavy rain and occasional gales in average temperatures or maybe somewhat below in the North. The last day of the run shows a little light at the end of the tunnel as the procession of Low pressure is slowed giving somewhat drier gaps in a still basically unsettled period.

 

The ECM 9 and 10 Day mean Charts show a continuation of the theme of the last fw days with most members within the ensemble group showing Low pressure close by to the NW of Britain and maintaining inclement conditions in SW winds and copious rain at times. There is little support for the cessation of the train of Low pressure indicated by the operational run unfortunately.

 

http://www.wetterzentrale.de/pics/Reem2161.gif

http://www.wetterzentrale.de/pics/Reem2401.gif

 

The Jet Stream shows the flow unrelenting in it's quest as it moves East strongly over the Atlantic and across areas of Southern Europe for the reliable future. The only difference of note tonight is a weakening of the flow late in the run which does rub off on tonight's operational in weakening the Atlantic procession of Low pressure in about two weeks time.

 

In Summary tonight there remains a lot of very unsettled and occasionally stormy weather to get through before we see a grain of hope for about 10-14 days time as there is a little indication of a weakening of the pattern late in the output tonight with rather more dry weather between the rain bands in somewhat less windy weather as we approach the second weekend. However, in the grand scheme of things this remains a distant straw to clutch in an otherwise depressing set of output again tonight.

[bluearmy]

Martin, i see the general encompassing of the uk within this large trough as helping re stormy conditions and a general dropping in temps may well relax the rainfall totals although they continue to look concerning over the ten day period with no obvious 'dry' days.

[Tim Bland]

Not much talk of snow from Martin / Gibby. Very boarder line i think. More runs needed and let's hope they drop the temp a degree or two

[itsnowjoke]

Not much talk of snow from Martin / Gibby. Very boarder line i think. More runs needed and let's hope they drop the temp a degree or two

rather bland if you ask me

[Snow Grain]

Not much talk of snow from Martin / Gibby. Very boarder line i think. More runs needed and let's hope they drop the temp a degree or two

As I mentioned yesterday, wintry prospects will start showing on the models and will increase as the week goes on. Eye candy charts to come and they will verify!

[Captain Shortwave]

As I mentioned yesterday, wintry prospects will start showing on the models and will increase as the week goes on. Eye candy charts to come and they will verify!

There isn't any cold air in our general part of the world, just a lot of cool mixed out airmasses, tough ask if you ask me to get anything better than a cool cyclonic pattern for the foreseeable. Good for higher ground, rather doubtful elsewhere though with rainfall being the biggest concern for many.

There is a good chance for some good convective activity with a cool unstable airmass and plenty of disturbances developing in the Atlantic. Away from frequent frontal systems there could be some interesting weather of the showery kind. Top up the thunderstorm counter perhaps.

[Purga]

For the bulk of the UK any talk of worthwhile snow within the forseeable future is specious.

[winterof79]

Looking rather more interesting now

http://modeles.meteociel.fr/modeles/gfs/runs/2014020418/gfs-0-60.png?18

http://modeles.meteociel.fr/modeles/gfs/runs/2014020418/gfs-2-60.png?18

[bluearmy]

For the bulk of the UK any talk of worthwhile snow within the forseeable future is specious.

As is your post purga !

[Summer Sun]

For the bulk of the UK any talk of worthwhile snow within the forseeable future is specious.

 

The ensembles back you up as well nothing overlay cold in sight

 

[Eskimo]

Storm on Saturday deeper on the 18z!

Edited February 4, 2014 by PerfectStorm

[Captain Shortwave]

The GFS has taken the low for Friday even further north, so much so that the southern half of the UK is mild with 850's reaching +4C 

Saturdays low looks like it's been cranked up a notch too.

Edited February 4, 2014 by Captain shortwave

[Cloud 10]

Looking rather more interesting now

http://modeles.meteociel.fr/modeles/gfs/runs/2014020418/gfs-0-60.png?18

http://modeles.meteociel.fr/modeles/gfs/runs/2014020418/gfs-2-60.png?18

 

Yes,the 18z has shifted the thursday/friday low further north,which would mean Northern England

gets a share of the rain and possible hill snow.

 

[bluearmy]

The ensembles back you up as well nothing overlay cold in sight

 

 

 

uppers dont look particularly cold gavin but under a slack deep trough, the 0c isotherm is closer to the surface. also, the wz london ens are for a gridpoint somewhere near the isle of wight so can be slightly unhelpful at times.  whatever transpires re surface conditions, we look like seeing very low heights next week.

[Purga]

As is your post purga !

OK BA show me the worthwhile snow for the bulk of the UK and I'll admit defeat.

[Purga]

uppers dont look particularly cold gavin but under a slack deep trough, the 0c isotherm is closer to the surface. also, the wz london ens are for a gridpoint somewhere near the isle of wight so can be slightly unhelpful at times.  whatever transpires re surface conditions, we look like seeing very low heights next week.

Sorry BA but WZ gridpoint is Lat 51N 0W which is actually in the Weald of East Sussex which can get pretty chilly and is more representative of Southern England than the heat Island of London.

http://www.distancesfrom.com/51n-0w-latitude-longitude-51n-0w-latitude-51n-0w-longitude/LatLongHistory/2276570.aspx?IsHistory=1&LocationID=2276570

 

This 'Isle of Wight' malarky is a commonly quoted fallacy.