General Model Output Discussion

[johnholmes]

why, what is the matter with that slack spell?

If you look at the T+120 Fax it shows the 528 line on summer holiday in Iberia-the 850 thickness is on much the same plane.

Neil STOP worrying-EVEN if mild air arrived post T+120 which it will not you would still have had almost a week of bitter cold?

For anyone interested in the science of showers off the North Sea-why the Met O probably have heavy snow showers in some of their central and eastern forecasts then perhaps a trip to my last blog may help.

Its about skew-t's this week along with mean temps for this week for my area-a fair example of low level weather for parts of eastern England.

I'm on the point of updating it with comments using the 00z.

enjoy

[Frosty.]

Well it's a bitterly cold outlook judging by all the 00z output this fine frosty morning, the gfs is my pick with very cold weather continuing for the entire 384 hours, ending on a calm anticyclonic note with no mild breakdown to be found. The ecm charts in FI look a bit odd to me but still with a huge mass of cold air covering the uk. Anyway, no let up to the cold spell at least for the next week and there will be plenty of snow in central & eastern britain for most of the coming week, even today has a peppering of snow showers down eastern coasts all the way down to east kent with several cm's of fresh snow. A cold front reaching scotland tomorrow will bring an organised area of heavy snow showers south with even colder air following it.

Edited January 3, 2010 by Frosty039

[Liam J]

why, what is the matter with that slack spell?

If you look at the T+120 Fax it shows the 528 line on summer holiday in Iberia-the 850 thickness is on much the same plane.

Neil STOP worrying-EVEN if mild air arrived post T+120 which it will not you would still have had almost a week of bitter cold?

For anyone interested in the science of showers off the North Sea-why the Met O probably have heavy snow showers in some of their central and eastern forecasts then perhaps a trip to my last blog may help.

Its about skew-t's this week along with mean temps for this week for my area-a fair example of low level weather for parts of eastern England.

I'm on the point of updating it with comments using the 00z.

enjoy

sorry if i missed something, where can i read your blog, please?

[azores92]

from what i can see, and the METO can clearly see too, for a lot of western and central areas the best opportunity for snow will be from the front moving south on tuesday and wednesday, perhaps giving a few cm in areas should it come off. apart from that, essentially dry away from eastern coasts, but bitterly cold, and temperatures really struggling to get above freezing for the most part. GFS and ECM have different ideas for FI, but they both end with the same evolution, less cold, due to the southern arm of the jet getting weaker. GFS sinks the ridge over Iceland down to the UK, which would inevitably mix out the coldest air, whereas the ECM shows a cut off ridge developing over the UK as the scandinavian high retreats eastwards. Both lead to a less cold evolution, though not particularly mild, just more average weather, but this is still FI.

[TEITS]

Another set of stunning models runs.

The general trend continues of a front moving S on Tues giving widespread snow (see attached fax/UKMO precip).

http://www.wetterzentrale.de/pics/brack1a.gif

http://www.wetterzentrale.de/pics/brack2.gif

Beyond and from Tues till the end of the week a NE,ly seems more likely than an E,ly. This means locations such as NE England/E Yorks/E Midlands/E Anglia/Kent are at highest risk which ties in with the Met O warning areas perfectly.

From next weekend onwards the models hint at a stronger E,ly developing which is shown on the GFS/UKMO although the ECM has a slack E,ly.

[NorthNorfolkWeather]

sorry if i missed something, where can i read your blog, please?

It's under the Forecaster Blogs, you'll find John's informative pieces here

[TEITS]

I won't use the word outlier but the ECM in its latter stages of the run was way warmer than the mean.

http://www.knmi.nl/exp/pluim/vijftiendaagse/Data/15DAAGSE_06260_NWT.png

Looking at the synoptics over Holland I imagine the block is further W with the LP further S maintaining a very cold E,ly.

[Tom D]

I won't use the word outlier but the ECM in its latter stages of the run was way warmer than the mean.

http://www.knmi.nl/exp/pluim/vijftiendaagse/Data/15DAAGSE_06260_NWT.png

Looking at the synoptics over Holland I imagine the block is further W with the LP further S maintaining a very cold E,ly.

That's odd because just before it becomes one of the mildest runs it it one of the coldest. It's good to see that most of the ensembles keep the temps very low though.

[nick sussex]

Morning all, very quiet in here considering we're looking at probably the best cold spell since the 70's!

Anyway the latest ecm De Bilt ensembles for the Netherlands are in and show the operational run a mild outlier for days 8-10, i think this is because the ecm brings an onshore flow for that region and this isn't well supported by the rest of the ensemble suite.

http://www.weerplaza.nl/15daagseverwachting/default_pluim.asp?r=midden

So basically theres a chance of an extension to the easterly for eastern and se areas as shown by the ecm, overall the ensembles are brilliant, i think we'll see this easterly before the high retrogresses back towards Iceland with Scandi trough developing, it's not often we can say this but it's cold to very cold for the foreseeable future!

Edited January 3, 2010 by nick sussex

[Frosty.]

I won't use the word outlier but the ECM in its latter stages of the run was way warmer than the mean.

http://www.knmi.nl/exp/pluim/vijftiendaagse/Data/15DAAGSE_06260_NWT.png

Looking at the synoptics over Holland I imagine the block is further W with the LP further S maintaining a very cold E,ly.

The ecm 00z op run just looks wrong to me in FI with that cut off ridge and a flabby flow, hopefully we will get that E'ly the following week or that NE'ly the gfs op run shows. What a week ahead of us though I would think there will be heavy, disruptive snow across northern and eastern scotland, ne england, lincs, east midlands, east anglia, and southeast england until the end of the week and even the areas not mentioned could have some flurries.

Edited January 3, 2010 by Frosty039

[Matt Jones]

Another set of stunning models runs.

The general trend continues of a front moving S on Tues giving widespread snow (see attached fax/UKMO precip).

http://www.wetterzentrale.de/pics/brack1a.gif

http://www.wetterzentrale.de/pics/brack2.gif

Beyond and from Tues till the end of the week a NE,ly seems more likely than an E,ly. This means locations such as NE England/E Yorks/E Midlands/E Anglia/Kent are at highest risk which ties in with the Met O warning areas perfectly.

From next weekend onwards the models hint at a stronger E,ly developing which is shown on the GFS/UKMO although the ECM has a slack E,ly.

What would concern me a little bit is that the front from the north on tuesday was forecast for monday a few days ago and I wouldn't be so sure how much precipitation we will get from it, countless times fronts from the north have little on them. GFS looks good today but I have noticed some large holes appearing in the -10C 850's now we are getting into closer range. Have heard lots of comparisons to 85/87 this remains to be seen. My expections remain low from this week, just for now! No doubt somewhere will get a good snowfall but how widespread I'm not sure.

[TEITS]

I love a ramp too, but wish people especially members who know better would not ramp up charts that were 5 days away. You must be realistic!

Equally wouldn't it be boring if we only commented on the models upto +72.

Make no mistake, the comments of the SE shutting down based on that ECM run were fully justified. Now whether members choose to believe them is up to them. My point is there is nothing wrong with posting what the charts show as this is the whole point of the thread.

I have been saying for many days now and I will continue to say that the exact flow, strength is still uncertain. I remember just before xmas how the models progged a very slack E,ly and then within +72 they started to upgrade the strength of that E,ly. Look at the overall pattern rather than the detail and don't make any assumptions about snowfall just yet. The locations I posted are favoured but not exclusively!

[johnholmes]

sorry if i missed something, where can i read your blog, please?

this is the link

http://forum.netweat...0entry1692616

sorry just noticed NW kidly did it for me-thanks

Edited January 3, 2010 by johnholmes

[nick sussex]

LOL - Feb 1986, Jan 1985, Dec 1981, Jan 1987, Feb 1991.

In terms of longevity i expect it to surpass those for the simple reason that the pattern for the moment is in re-load mode, ask members from the ne and Scotland just how good this spell has been so far, since well before Xmas apart from a couple of less cold days in the south it's been cold to very cold.

The pattern will keep repeating itself until theres a major upstream pattern change and theres absolutely no sign of this.

Edited January 3, 2010 by nick sussex

[snowmadchrisuk]

What would concern me a little bit is that the front from the north on tuesday was forecast for monday a few days ago and I wouldn't be so sure how much precipitation we will get from it, countless times fronts from the north have little on them. GFS looks good today but I have noticed some large holes appearing in the -10C 850's now we are getting into closer range. Have heard lots of comparisons to 85/87 this remains to be seen. My expections remain low from this week, just for now! No doubt somewhere will get a good snowfall but how widespread I'm not sure.

Yes hi Matt , I was wondering a minute ago why Tuesday's trough is not really supported at all by the ensembles with the operational being a clear ourlier for precipitation on Tuesday on the 00z Ensembles.

[TEITS]

Tuesday evening is looking very interesting for parts of the E Midlands/Norfolk.

http://www.wetterzentrale.de/pics/Rmgfs633.gif

This is appearing frequently in the GFS output and ties in with the UKMO.

06Z shows a snowfest for S counties due to the SW.

http://www.wetterzentrale.de/pics/Rtavn784.png

Edited January 3, 2010 by THE EYE IN THE SKY

[Iceberg]

A much much better 06Z for southern areas for the tues/wed/thurs, it follows the ECM/METO by providing pressure of 1000mb on Sunday and the clsoed circulation of the south coast. The result is some qutie heavy and persistant snow for 12 hrs or so and some very nice totals indeed.

[Geordiesnow]

UKMO is probably the best for my location and in truthness is probably is the best nationally aswell as it carries on a fairly strong flow for eastern areas and these showers would penetrate inland.

ecm/gfs however has slacker flows nationwide(although the latter currently shows se areas getting a stronger flow) thus showers won't penetrate inland and will stay on the coast.

It does not look like to me the GFS is trending towards the UKMO, it has the flow further eastwards slightly which is not good for me and folk in NE Scotland.

Anyways, whilst the general set up is agreed on, the final details are not settled, like in terms of how long it lasts for, for example.

[East Herts Snow]

A much much better 06Z for southern areas for the tues/wed/thurs, it follows the ECM/METO by providing pressure of 1000mb on Sunday and the clsoed circulation of the south coast. The result is some qutie heavy and persistant snow for 12 hrs or so and some very nice totals indeed.

Indeed this is a cracking run for Southern most counties for snow potential if this run was to varify.

Nice Channel low developing with plenty of ppn tracking along the Southern most counties.

2m temperatures look okay as well.

NB - This is not ramping by me, as I don't live anywhere near these areas and simply explaining what the GFS 6z run is showing at just 3 days out.

Apologies for the back to front order of the attached images (I can't seem to edit them to the correct order).

Edited January 3, 2010 by North Londoner

[kev238]

Mainly dry for most areas away from coastal strips etc today and Monday. Tuesday- Wednesday- snow showers or longer spells of snow for many areas. Thursday and Friday- showers concentrating on the Eastern side of the UK would be my take for the weather of the next week.

Looking at the models most places should at least get a covering with the focus always being on Eastern areas for the largest accumulations.

[Lewis]

Lovely run, but a huge difference from yesterdays models.

A slacker flow, and the easterly for some reason does not come into full swing of things, and the pressure just sinks southwards. A lot of shortwaves and mild sectors on this run, one thing i don't like about the GFS, it's too messy a model.

I hope this does not verify.

Lewis

[West is Best]

with the focus always being on Eastern areas for the largest accumulations.

Hi Kev, not entirely sure about that. Much will depend on orientation nearer the time, but it looks from latest runs as if parts of the north, west and south may have a fair bit too from different aspects of this. Wales has already had a lot and it could get a lot again. North Devon, especially Exmoor, may get a fair bit and then the channel coasts might too. Earlier on northern England looks favoured.

To those still griping, patience. The MTV generation should learn that the best things come to those who wait. The longevity of the evolution is one of the reasons why it also has great potency. Remember: it's January 3rd! We're in for a very interesting week.

My Mother in Norfolk just rang and commented, with their latest snowfall overnight, that it reminds her of the great winters of the past. She lived in Essex during 1962-3 and 1947.

[East Herts Snow]

Lovely run, but a huge difference from yesterdays models.

A slacker flow, and the easterly for some reason does not come into full swing of things, and the pressure just sinks southwards. A lot of shortwaves and mild sectors on this run, one thing i don't like about the GFS, it's too messy a model.

I hope this does not verify.

Lewis

In the medium to long term the High is situated on top of the UK, bringing with it dry cold weather and no sign of the continental low. However as you say the GFS introduces another different run in FI.

Edited January 3, 2010 by North Londoner

[weather eater]

Equally wouldn't it be boring if we only commented on the models upto +72.

Make no mistake, the comments of the SE shutting down based on that ECM run were fully justified. Now whether members choose to believe them is up to them. My point is there is nothing wrong with posting what the charts show as this is the whole point of the thread.

Morning Dave, you're right of course when you say that the point of the thread is to discuss what the charts show, but its also about analysing how likely it is that what the charts are showing will verify, or how close to verifying they are likely to be. It should not be about just shamelessly ramping them and leaving the less knowledgeable to believe what they like. I have to say that one or two members, who should know better, have let their excitement get the better of them and consequently let their objectivity slip. Yes these are the best winter synoptics we have seen but that's not a reason to abandon caution and cool analysis. Its been a good start to winter, I've already seen more days with snow falling than I've seen for a good few years and some cold minima's, however it is still not yet what I would call a truly remarkable winter, that will hopefully cement itself over the next few weeks. Just watching the 06z coming out now, a run which I suspect will dent some confidence in a prolonged easterly, and although I would say the GFS 06z is the poorest performer of the four GFS runs, it does show another alternative evolution a rather dryer one as well.

[Weather-history]

This is what GFS 06z op run last Sunday was forecasting for this Sunday

And from a fortnight ago for this Sunday