Model Output Discussion

[yamkin]

Another festival of northern blocking after+168hrs from tonights gfs 18z.

As soon as it gets past 180 hrs someone throws the winter armageddon switch.!

Very exciting times ahead. Trends have been showing a colder period any time from the 10th Dec. I am confident that we will have a very cold E/NE/SE feed due to the interesting trends.

[snowray]

There does seem to be a different look about the models this year. In previous winters FI used to throw up the odd Northerly here and there that never had a long lasting look about them. This year so far, the models in FI seem to be keen on showing the holy grail type senarios with huge amounts of Northen blocking and bitter North Easterlies reminiscent of the late 70's and early to mid 80's.

Could this be our year at last ?

Thats true, it would be very disapointing if it was to all come to nothing.

Interestingly, I noticed last Winter that when the 18z kept throwing up unlikely new and sometimes bizarre trends in deepest FI, it did indeed turn out as being on the right track on a few ocasions.

Edited December 1, 2009 by snowray

[phil nw.]

Looking East at Berlin 12zEns.

http://charts.netweather.tv/ensimages/ens.20091201/12/t850Berlin.png

The op. run was a mild one in the medium term and many members went Colder further out.

Someone posted Moscow`s earlier here again,

http://charts.netweather.tv/ensimages/ens.20091201/18/t850Moscow.png

Going v.cold v soon.

There will be plenty of cold air to draw from if we get the right setup.

Edited December 1, 2009 by phil n.warks.

[damianslaw]

Many of the models beyond the reliable timeframe keep suggestion of strong heights building to the north and continuation of a southerly tracking jet, however, we still have the very annoying trough just out to our west which as long as it remains in situ will prevent any of the cold settled air bottled up to the north come crashing down our way..

In the short term it remains an unsettled picture, the weekend is looking a potential washout for many and windy to boot, quite mild in the south but cool in the north, the Scottish mountains look like they could be about to see some sustained snow attacks all good for the winter ski season ahead.

As I said yesterday, I'm expecting the fairly unsettled weather to last through next week, nothing unusual as the first 2 weeks of Dec are renown for sustained unsettled weather, but for changes to settled colder weather by mid month when we finally see the trough migrate to the east. Patience for the cold lovers at the moment, but very promising signs albeit at this very early juncture that come mid month a significant pattern change has a high chance of occuring in favour of cold and more settled.

Already the signs are that this is not going to be a typical El Nino winter otherwise we should be staring at an endless south westerly steam train, the signs have been here since early November, the stubborn trough not moving anyway and the resultant record rainfall surely being an indicator that patterns are not normal and other factors are coming into play I feel - interesting times ahead.

[Nick F]

A stalemate taking place over the UK between Atlantic trough just to our W and E European ridge seems the best way to briefly sum the way forward perhaps into the medium range ... the UK trapped under a cyclonic S to SW flow.

But how the stalemate will end is certainly intriguing - given the consistency for both ECM and GFS to build heights over the polar area as per ECM/GFS 8-10 day H500 comparisons:

http://www.meteo.psu.edu/~gadomski/ECMWF_12z/hgtcomp.html

However, we have plenty of energy being thrown at us off the Atlantic, and the jet seems to be heading slowly back N with every run - with a rather prominent block over SE and Eern Europe. I remain sceptical atm that the energy will undercut this block - especially so early in winter ,,, despite the alluring beasterlies thrown up by FI tonight. Though been a while since I've seen such encouraging height builds over the Polar areas this early in the season.

[andy_leics22]

Oh F.I :lol:

[TEITS]

Keep your eyes out for the PV to be underneath the HP towards our NE. There will be an astonishingly cold airmass on the SE quadrant of this HP and I believe this airmass will reach our shores.

The chart below is exactly what I mean't earlier.

http://www.wetterzentrale.de/pics/Rtavn3001.png

I shall repeat myself again and say the 18Z F.I charts are very unusual for Dec. Something is brewing and it ain't my Tyhoo teabag!

[ribster]

Also Just to add to that , Good old Roger Smith has photos of Snow in Southern England during the above spell here : http://davidburrin.fotopic.net/c810883. Also it was the coldest in Southern England since 1740 .

An Interesting quote from a very good article here : http://theweatheroutlook.com/twoother/twocontent.aspx?type=libgen&id=1503

"The interesting thing about the cold spell is the poor performance of the forecast models even up to +72 hours, O.K. computers are better now but I still think they would struggle with a similar chain of events."

I also have some pictures from this period in Norfolk, I must post them up - sorry, slightly off topic I know!

[andy_leics22]

The chart below is exactly what I mean't earlier.

http://www.wetterzentrale.de/pics/Rtavn3001.png

I shall repeat myself again and say the 18Z F.I charts are very unusual for Dec. Something is brewing and it ain't my Tyhoo teabag!

LMAO, I knew i'd find you here after that run mate

Obviously it can go belly up on the next run but it's still nice to see non the less.

[Nights King]

Interesting to see if the meto change there long range forecast for next couple of weeks in a couple of days if the trend continues.

Sometimes i hate Fl always so much hope only to be knocked back down to earth again in a days time. Would get chilly wrapping xmas trees if that came off though

[nick sussex]

The latest ukmo fax chart for 120hrs is quite strange, it doesn't follow the ukmo data, sometimes the duty forecaster modifies it towards the ecm if they're not confident in their own model but it's nothing like the ecm either, all a bit of a mystery, the same can be said for the gfs in the lower resolution part of the output, its like the gfs sponsored by the Twilight Zone!

Overall there is good model agreement for the slow moving low parked near the uk, how long it sits there spinning around and being fed by the now rampant jet stream is really up in the air, it never ceases to amaze me the amount of times we see pressure trying to build in from the east or ne but met with deep troughing near the uk.

Whatever happens patience is going to be needed, often with these patterns you stare at the output coming out and think has it got stuck as the low just sits there for what seems like an eternity.

In terms of the upstream pattern i think its too early to accurately predict the downstream effect so we could see the trough edge a little further east or west.

But i would agree with Nick F, with time the general rule is that the jet stream will edge north and east with pressure rising over Iberia and into southern europe, eventually if the jet slackens and the block to the ne still wants to edge sw'wards then a chance of something interesting but the success rate of an Arctic high directly affecting the UK is not great, of course it has happened in the past and certainly does bring the coldest possible air but its very much a longshot.

Edited December 2, 2009 by nick sussex

[Stu_London]

Another interesting 18z especially in the context of yesterdays 18z

Although the operational runs haven't been too spectacular today, the number of cold members in the ensembles post 11th December 2009 have gradually been increasing.

To early to call a trend, but if looking for upgrades at this range, it is worth doing 24 hours comparison - i.e 00z run to 00z run - and pay particular attention to the ensembles.

There are still so many ensembles where the atlantic wins out or we get a bartlett type situation that I wouldn't be too downhearted if we get some operational runs that are mild.

I still think the percentage call is hugely in favour of the atlantic winning out, however the chance of a severe winter weather event sometime around the middle of the month is probably now more like 5%-10%, whereas a couple of days ago it was probably >2%

[492]

GFS appears to repeatedly initiate with pressure too high over Greenland - probably about 20 mb too high on the 18Z output. No wonder it is showing such extremes in FI.

[Stu_London]

The latest ukmo fax chart for 120hrs is quite strange, it doesn't follow the ukmo data, sometimes the duty forecaster modifies it towards the ecm if they're not confident in their own model but it's nothing like the ecm either, all a bit of a mystery, the same can be said for the gfs in the lower resolution part of the output, its like the gfs sponsored by the Twilight Zone!

That must be a positive - because UKMO and ECM were both pants for cold at 120-144

[ScottSnow]

I find the best thing to look for in FI is the general overall pattern over a number of runs.

The pattern I have noticed is some source of cold coming from our north east later in the month. It may be a shortlived event, it could be something memorable or it may not happen at all but the signs are there. Only time will tell.

[pyrotech]

The fax charts upto the 120hrs has been very accurate so far over the last 26 days. GFS has struggled past 96hrs and ECM has had varied sucesses.

The models are struggling as a huge change in the sunspot cycle now starts to effect global weather ( sceptics note that it has become relevant enough for NOAA to mention)

We will PROBABLY see a 80s style winter, this is where flooding becomes more likely again, but also periods of extreme cold pulling deep down in Europe later in the New year or end of this year.

Hongkong has been unusually cold in November and some states in USA have had colder than normal autumn. yet we throw our dummies out of the pram when we do not see what we want. The MODELS GFS ECM have not suddenly become unreliable in fi its always been that way, its us, we see a run we like and get suckered in. Its trends in fi we should look for over days not just one or two runs.

The next few weeks will see the UK in a very active period with bands of heavy rain, but a back edge of snow to hills and mountains even as far south as Devon. This will leave snow on peaks of mountains like the Brecon Beacons. This is reminisant of 80s, deep low presure draging short duration cold air behind them, allowing sleet and snow to 500 - 800m hills. The fax charts hint at this for end of current week.

The models are showing a definite cooling with 850s of 0 becoming more regular as we head into December.

As the new year nears the models will hint more at deep cold air masses over Europe with the possibility of a Westward flow towards the UK.

This winter will have many similarities to the 80s and its this turn back that is making 5 days fi, for both gfS and ECM. The height builds over Europe are being played with but this is what will happen, but timing is the only thing in question. The lag in the sunspot cycle should allow parts of Europe to become much colder than recent years, The model all play with this, but the right set up needs to be in place to allow it. The potential is there.

We are 19 days away from the shortest day, It is after this that the coldest weather is reached, we all seem too quick to get disapointed when the models do not say what we want, or show it in fi and then dissappear.Its only just December.

The models hint at cold coming into Europe and then retract it. Its a trend thats being held back by a savage jet stream, but it is a expected outcome and likely to be potent and prolonged when it finally arives.

This December has the hallmarks of 1979, a period of years followed with heavy snowfall.

When GFS shows cold sweeping down over Europe within 60 hrs and fi shows it head over the Uk then it will 90% happen, till then anything will be marginal or shortlived.

For those who remember the 80s this is a very typical setup and the outcome was worth the wait.

Edited December 2, 2009 by pyrotech

[londonsnow]

just woke up and had a peek at the pub run. blimey, FI really is living up to its name on the pub run. when was the last time 492 air was so close to our shores. into reality, quite standard charts, fairly average stuff for the immediate future

[VillagePlank]

According to the 18z, nothing spectacular, and, it seems, is reasonably sure of itself

Nothing until the 14th December where, even then, you have to rely on GFS being right down at the bottom of it's standard error to get a few days of-5C 850hPa which is still marginal for the stuff we all want to see.

Longer term, the higher stratosphere, at 5 hPa, looks like warming, shortly, and if this can translate down to, say, 30hPa, then the chances for January not looking too bad. I suspect it will have to be some serious warming to override the ENSO signal expected,though

(Note to mods: any chance we can have the standard deviation added to the NetWeather charts?)

Edited December 2, 2009 by VillagePlank

[VillagePlank]

Not much better on the 00z, either.

[VillagePlank]

Sorry mods, I can't help myself. Will report duly for my seasonal spanking ...

Is winter over?

(Edit: well at least I waited until the second day of winter ....)

Edited December 2, 2009 by VillagePlank

[ScottSnow]

Sorry mods, I can't help myself. Will report duly for my seasonal spanking ...

Is winter over?

(Edit: well at least I waited until the second day of winter ....)

Theres always one !!!

The pattern of cold coming from our north east still persists on the 00z, http://www.wetterzentrale.net/topkarten/fsavneur.html

[Cecil Hogmanay Melchett]

Another superb gfs oz run,unfortnately the ens show it to be a HUGE ouylier.

ukmo is,well,i wish i hadn't looked at it.144h is probably about as bad as it gets,euro high,strong jet= rain and more rain!!

[Iceberg]

A lot of agreement out to 144Z, ECM has the Final very deep(sub 960mb) a little further west. Further out any cold is kept well out except for the GFS ops run, which look very tasty indeed.

However the main aspect is a very very wet and maybe windy 5 or 6 days for the UK and the west in particular.

I am not sure sure what a typical 80's synoptic looks like ?, but the Nov we've just had does not look typical of any month tbh (except perhapes Nov 2000).

Anyway wet, windy and LP is still the order of the day for now.

Sorry I forgot one quick thing to add, despite all the talk of a negative NAO, AO, PNA etc this winter none of these indexes has been below -1 since October, and we all know what started in October.

I am not saying that they won't happen, but remember they are just forecasts that change and are predicted by the very same models that we say don't trust beyond 144Z.

[Frosty.]

The GFS 00z has a real tease later in FI with a bitterly cold snowy/frosty dreamland but reaching that narnia like fantasy world will prove very difficult or impossible in reality. The models indicate that the next 7-10 days will be very unsettled with low pressure near iceland being dominant and further lows spawning in mid atlantic and rushing towards nw scotland such as the vigorous feature next tues/wed, ok it's almost 7 days away but the lp track shown on the gfs & ecm looks realistic given the southerly tracking jet. Temps next week look lowest in the north with a risk of highland snow but nearer average further south and just about on the mild side in southern and sw england, s. wales.

Edited December 2, 2009 by Frosty039

[Nick L]

The GFS really has gone insane this morning. I know it is at the deepest end of FI, but how often do we see the -10 850 line making a bee line for northern Spain?!