Winter Model Discussion - Cold Hunting - 20th Dec

[Gavin Hannah]

ECM again looking not too bad. Some decent cold weather over Xmas and New year looks on the cards.

If only the weather would cease to be so bloody atlantic driven...

[Frosty.]

The models show another brief respite from the torrential rain in the south and southwest but there is another ripple of tropical air heading north with another prolonged spell of heavy rain pushing into the south tonight and tomorrow with more floods. The models then show more spells of heavy rain through the next few weeks as lows track northeast across the uk at regular intervals but at least it will be mild, there is no sign of any snow or cold weather until well into january according to the models.

[bluearmy]

not in the 2x and 4x daily synoptic

the ONLY data is the actual or assigned data at the start, 00, 06, 12 and 18z nothing else at all. The models then chunter away using the basic physics and complex maths to give the charts we see.

If you doubt that explanation then google uk met and NOAA, or send UK Met an e mail and ask if their synoptic models, as opposed to their climat models do different to what I've suggested

That said then I am unsure of what the top level is in their main model, it quite probably goes into the Stratosphere but has no forecast data put into it.

john, are you suggesting that the models run a separate trop and strat model? surely they are on the same 'platform' and the 'kneebone is connected to the thighbone'. i am sure that the strat temp soundings must be fed into the starting data so why would ncep/ecmwf run two models for what is, in effect, the two parts of the atmosphere that drive our weather ?? maybe i didn't understand your post ??

[Winter Monsoon]

Quite a stunning post made by Recretos on strat thread showing that the GFS is, on a whole, very accurate with the start forcast, Im far more confident of it happening than not now, We just dont want any part of the PV setting up shop over greenland really.

[Frosty.]

I think we will all need a boat if the models are correct, there seems no end in sight to the conveyor belt of flood inducing rains and mild temps for the foreseeable future, my goodness it seems a long time since everyone was moaning how dry it was last spring, the weather has had the last laugh.

[nick sussex]

The teleconnections suggest one thing the operational outputs another:

As you can see there the NCEP has the biggest drop in the NAO, the ESRL less so but still into negative territory.

This was from the 22nd so maybe theres been some big turnaround but if these forecasts hold true then the operational outputs aren't really giving an accurate picture.

I should add these forecasts are not just a bi-product of the GEFS, these are separetely done using the MRF which is the specialized medium range ensemble forecasts.

As you can see also a big difference between the ESRL and NCEP regarding the PNA pattern.

[phil nw.]

I think we will all need a boat if the models are correct, there seems no end in sight to the conveyor belt of flood inducing rains and mild temps for the foreseeable future, my goodness it seems a long time since everyone was moaning how dry it was last spring, the weather has had the last laugh.

Yes it looks very unsettled for the rest of the month Frosty.

I think many of us would raise a glass of festive cheer to a even a brief period of high pressure with a bit of frost but even that looks very unlikely at the moment.

[bluearmy]

The teleconnections suggest one thing the operational outputs another:

As you can see also a big difference between the ESRL and NCEP regarding the PNA pattern.

cant be right within two days for the PNA forecasts to differ that much nick ???

[bradymk]

This morning output reinforces that unsettled weather is likely to be the dominant feature until at least the new year. Regarding any colder weather, the GFS is poor along with its ensembles with a flat pattern until new year and beyond but don't take this too literally as this time yesterday, both were trending for a mid-atlantic ridge. The ECM is more amplified, along with the GEM and to some extent the UKMO but this only goes to +144. ECM ensembles are fairly balanced longer term with a clustering for both colder and milder. The 00z op was also in good agreement with the ensemble mean and control out to +240 hours. Bit downbeat in here this morning which is understandable but for me, this period was never shown as very cold and more of a waiting period but hopeful of any northerly outbreaks. Transitional northerly/NW's are still likely if the ECM and GEM are correct with a more amplified pattern but if its sustained cold you are looking for this morning, then maybe its patience until we know what happens with the potential SSW. If you want cold in the mid range (new year) then we want to see a more amplified pattern and hope that NOAA were right with the +PNA.

[Gavin Hannah]

Yes it looks very unsettled for the rest of the month Frosty.

I think many of us would raise a glass of festive cheer to a even a brief period of high pressure with a bit of frost but even that looks very unlikely at the moment.

Indeed it does. But, as many of us have witnessed in the past, HP can creep up out of now where and set up shop for weeks at a time. Lets hope the GFS is overdoing the Atlantic this morning.

[karyo]

Dec has just got worse and worse as its gone on,and it almost certianly will end a completely snowless month for many.The real worry is the pattern looks well set to head into the New year and im at a loss to see were any cold is going to come from.What is driving this conveyor of Atlantic lows,its becoming ridiculous.

We will probably end up like last year - 2,5 mild and rainy months and then a 2 week cold spell in February before spring arrives.

Karyo

[Frosty.]

Yes it looks very unsettled for the rest of the month Frosty.

I think many of us would raise a glass of festive cheer to a even a brief period of high pressure with a bit of frost but even that looks very unlikely at the moment.

Yes phil it's very worrying, I can see plenty more flooding misery in the next few weeks with just an occasional bit of respite, like on xmas day and boxing day.

[Methuselah]

john, are you suggesting that the models run a separate trop and strat model? surely they are on the same 'platform' and the 'kneebone is connected to the thighbone'. i am sure that the strat temp soundings must be fed into the starting data so why would ncep/ecmwf run two models for what is, in effect, the two parts of the atmosphere that drive our weather ?? maybe i didn't understand your post ??

The way I see it BA, is that, as the connections between SSWs, Northern Blocking and cold weather are part of a relatively new branch of atmospheric science, it'll be a while yet before the everyday running of the computer models will be tweaked accordingly...It would be a wee bit premature, IMO, to rush into mass algorithmic-modification at such an early stage in proceedings?

Having said that, nothing (that I can see, anyway) precludes the current methodology picking-up on things independently?

JH, Snowballz et al?

[phil nw.]

The way I see it BA, is that, as the connections between SSWs, Northern Blocking and cold weather are part of a relatively new branch of atmospheric science, it'll be a while yet before the everyday running of the computer models will be tweaked accordingly...It would be a wee bit premature, IMO, to rush into mass algorithmic-modification at such an early stage in proceedings?

Having said that, nothing (that I can see, anyway) precludes the current methodology picking-up on things independently?

JH, Snowballz et al?

We do see modelling of the Stratosphere in the GFS runs at various levels and we can view these on Net Weather Extra at 10,30 and 100hPa as well as at 10hPa on Meteoceil.

I assume therefore Pete that the trophospheric charts that are produced would include those calculations.

Well it`s sounds logical to me although i could be wrong in this assumption.

[carinthian]

Well our weather service providers are amazed as many others how the long predicted cold spell failed . The run up to and even beyond Chistmas is not good for the Alps generally. The slow moving WARM FRONT is now making an impact across our region with a warming of all layers of the atmosphere with the 2000m temperatures rising from the present -2c to +5c by this time tomorrow and with a continuation of very mild SWly into the holiday period. +13c in the higher valleys for Christams Eve. The hair dryer has replaced the beast from the east in just a matter of hours. At least we do not have the rinse hold conditions you are suffering back in the UK.. Lets hope the latest set of models do a turnaround again between Christams and New Year, especially you guys, you need a break from that never ending dross!!

C

[Frosty.]

Snowballz

snowballz chance in hell of any cold snowy weather in the uk for the next few weeks at least, but as for rain and floods, the models are full of mild air and lows bringing spells of heavy rain and some very windy spells but temps above average for just about all of the uk in the next 2 or 3 weeks according to the models and the met office, no sign of high pressure settling things down in that period either. So snow seekers need to head for lapland for festive fun.

[Summer Sun]

Yes phil it's very worrying, I can see plenty more flooding misery in the next few weeks with just an occasional bit of respite, like on xmas day and boxing day.

There are weather warnings out again for Xmas day in the south west and Wales with further heavy showers expected leading to the possibility of further localised flooding

GFS 06z ensembles

[cooling climate]

The teleconnections suggest one thing the operational outputs another:

As you can see there the NCEP has the biggest drop in the NAO, the ESRL less so but still into negative territory.

This was from the 22nd so maybe theres been some big turnaround but if these forecasts hold true then the operational outputs aren't really giving an accurate picture.

I should add these forecasts are not just a bi-product of the GEFS, these are separetely done using the MRF which is the specialized medium range ensemble forecasts.

As you can see also a big difference between the ESRL and NCEP regarding the PNA pattern.

Of course it could be that as we get nearer to Christmas there is insuficent data fed into

the model ouputs therefore, lol no I should not joke about that old chestnut.

Seriously though perhaps it could be that we will see the NWP models suddenly do a big flip

in the next few days because as you say there is nothing to suggest it in the models at the

moment.

[MR EXTREMES]

firstly i thought this was the models forum..... secondly its amazing how a northerly or a north west flow cant produse cold and snow even if its as pressure systems move over the uk.

i dont see and extreme run of blow tourch sw flow i see average temps and lots of wind and rain but also chances of snow mostly to the west north west and north.

[Ian Brown]

i think some of you need to 'pinch yourselves'. we are over two thirds through december and returning a below av CET. that is likely to continue to tick upwards and given we look likely to have a cold first half and mildish second half, an av CET seems likely now (high min returns over the next week the main reason we will avoid a cold return overall).

we have avoided a cold snowy spell by a slim margin. we are now in a mobile flow for the foreseeable. yesterday morning, the theme was a mid atlantic block in the mid T200's from gfs/ecm/gem. 24 hours later and that has drained away. it might be back tomorrow? no point in guessing and we go on what the output is consistent on. that is mobile and westerly in general though the current gfs trend is definitely to lift heights in nw europe week 2. that would be a welcome relief.

It would but we are now looking at a pattern as progressive as it can be, a fast flowing flat jet and increasingly low heights to the North with downstream HP over Europe.

I think the only way out to relieve the flooding situation is if we can see HP extending North over the UK as the jet heads further North, but the sort of pattern we are entering, at least in the last 25 years has often lasted 4-6 weeks when established in the winter months.

[Frosty.]

There are weather warnings out again for Xmas day in the south west and Wales with further heavy showers expected leading to the possibility of further localised flooding

GFS 06z ensembles

ok boxing day might be the driest day then before the next lot of flooding rain arrives, still no sign of any cold weather so the poor winter continues with no end in sight.

[nick sussex]

cant be right within two days for the PNA forecasts to differ that much nick ???

Yes it does seem rather strange.

Also I think I had a senior moment and now that I've woken up theres a bit of confusion with my previous post LOL, the NCEP would seem to come off the GEFS although its bizarre because it said the MRF comes off 15 ensemble members to provide that NAO but there are 20 GEFS excluding the control.

The ESRL is the Earth System Research Lab, that is definitely a completely separate entity to the GFS although I think its a division of NOAA.

You're right you cant have that bigger difference between the two at that timeframe. I think I need an emergency infusion of caffeine as my brain seems to have gone into meltdown!

Edited December 23, 2012 by nick sussex

[Methuselah]

We do see modelling of the Stratosphere in the GFS runs at various levels and we can view these on Net Weather Extra at 10,30 and 100hPa as well as at 10hPa on Meteoceil.

I assume therefore Pete that the trophospheric charts that are produced would include those calculations.

Well it`s sounds logical to me although i could be wrong in this assumption.

Indeed, Phil. But how can models make computations, utilising equations that may not have been formalized yet?

We all know that there gaps in understanding somewhere; the recent BFTE no-show was, I think, a perfect example of this?

Of course I may be typing bullocks!

[johnholmes]

john, are you suggesting that the models run a separate trop and strat model? surely they are on the same 'platform' and the 'kneebone is connected to the thighbone'. i am sure that the strat temp soundings must be fed into the starting data so why would ncep/ecmwf run two models for what is, in effect, the two parts of the atmosphere that drive our weather ?? maybe i didn't understand your post ??

not two models ba, looks like I did not make myself clear in my attempt to discount the idea that gets floated at times that the models are 'fed' forecast data-they are not.

I'm about to leave for my Xmas break so not time to check the Met O area giving input details of their global model. What I was trying to say is that the global model has its 'top' well into the Stratosphere as far as I am aware so Stratospherici ACTUAL data the same as Tropospheric actual data is all it gets.

hope that helps clear up any confusion?

just to stress again data fed in as ACTUAL not predicted at ANY height for ANY forecast run?

Edited December 23, 2012 by johnholmes

[phil nw.]

Yes it does seem rather strange.

Also I think I had a senior moment and now that I've woken up theres a bit of confusion with my previous post LOL, the NCEP would seem to come off the GEFS although its bizarre because it said the MRF comes off 15 ensemble members to provide that NAO but there are 20 GEFS excluding the control.

The ESRL is the Earth System Research Lab, that is definitely a completely separate entity to the GFS although I think its a division of NOAA.

You're right you cant have that bigger difference between the two at that timeframe. I think I need an emergency infusion of caffeine as my brain seems to have gone into meltdown!

These are from an American site and are from the 00z outputs Nick the ops and ensls,

Not great for cold lovers it must be said.

Link here http://raleighwx.ame...onnections.html

Just a note they don`t include the ECM on some of those Nick.