Model Output Discussion

[Ben_Cambs]

GFS 18z has upgraded PPN for Wednesday, but its now about the 850 Uppers....

[snowking]

GFS 18z has upgraded PPN for Wednesday, but its now about the 850 Uppers....

Its not so much even the uppers on the GFS at the moment, its the dew points which are above 0c, which make you wonder what the Met Office are on about

Then you take a look at the UKMO....

And you start to wonder what will show up when the NAE comes into range tomorrow night...

SK

[Eugene]

lol well another run showing the atlantic running out of steam and deep low pressure stalling west of iceland.

Looking blocked next weekend with HP building northwards over us strongly

http://www.wetterzentrale.de/pics/Rtavn1561.png

[cooling climate]

Latest from CPC, although I know it is only computer generated.

This is the 8-14 day range.

http://www.cpc.noaa.gov/products/predictions/814day/500mb.php

[bluearmy]

Latest from CPC, although I know it is only computer generated.

This is the 8-14 day range.

http://www.cpc.noaa.gov/products/predictions/814day/500mb.php

looks a bit like the pub run (which is also computer generated!!) actually, on a more serious note, the 8/14 dayers are now of more relevance as they now include ECM ens input weekdays. was always a weakness before.

and i believe we are due a new GEFS at lower resolution soon. hope it performs better than the new GFS did in its first month.

[LomondSnowstorm]

looks a bit like the pub run (which is also computer generated!!) actually, on a more serious note, the 8/14 dayers are now of more relevance as they now include ECM ens input weekdays. was always a weakness before.

and i believe we are due a new GEFS at lower resolution soon. hope it performs better than the new GFS did in its first month.

It did have its moment - it predicted the mid-December pattern change from about +240 onwards without dropping it, which is more than can be said of any of the other models. However, since it became the operational, it has dropped back down below the ECM and UKMO with the GEM not even being too far off it.

[Duane S.]

It did have its moment - it predicted the mid-December pattern change from about +240 onwards without dropping it, which is more than can be said of any of the other models. However, since it became the operational, it has dropped back down below the ECM and UKMO with the GEM not even being too far off it.

Yeah, I haven't quite got my head around that one. When it was just 'the Parallel run' it was right on the money in the lead up to the start of our cold spell. Way ahead of any other model in terms of consistency. Then when it took over from the existing operational, it also took over its reputation it would seem! Most strange.

[TEITS]

I don't know about anyone else but im finding the model output at the moment fasinating. What we're currently seeing is the complete reverse of our usual winters. What I mean by this is the mild being downgraded once it enters the reliable timeframe.

A fair summary of the outlook at the moment is a snow event on Wed followed by a milder spell from the end of the week into the weekend. Into the following week and the chance of colder weather arriving with January ending on a cold note. However at the moment exactly how this develops and how cold is uncertain.

So far we have experienced a wonderful winter if you enjoy cold temps and snow. However we're yet to enter the period which could bring far more severe conditions and much colder temps. There is a good reason why Febuary is often the coldest month but its the weather patterns during Dec, Jan that determine whether Feb will be colder. What I mean by this is over in Europe they have also experienced plenty of snowfall and very low temps. So if a cold spell does arrive in early Feb with upper temps of -10/15C this will be much colder in the UK than if Europe had experienced mild weather during Dec, Jan. This is down to colder SSTs in the N sea and also the snow cover across Europe. Also worth mentioning that snow cover can also encourage the development of HP.

Despite some suggesting a mild Feb. I still think its possible that during the beginning of Feb a cold spell could bring max temps way below freezing and another Feb 91 is quiet possible. Keep your eyes out on the +144/+192 timeframe over the next few days because its here a cold spell is likely to develop. At the moment based on the model output I would say around 26/27th Jan is when the next cold spell will begin.

Edited January 17, 2010 by THE EYE IN THE SKY

[bluearmy]

the new fi GEFS trend (which not surprisingly shows up in the 12z NAEFS) is for the AH not to retrogress sufficiently. this also shows in the op run with the shortening of the length of the cold snap as the scandi trough recedes east as the high drifts in. i think we have been spoilt over the past month with our two cold periods and maybe this one will be rather more traditionally british - short !!

[LomondSnowstorm]

the new fi GEFS trend (which not surprisingly shows up in the 12z NAEFS) is for the AH not to retrogress sufficiently. this also shows in the op run with the shortening of the length of the cold snap as the scandi trough recedes east as the high drifts in. i think we have been spoilt over the past month with our two cold periods and maybe this one will be rather more traditionally british - short !!

Surely too early to think about +300 timeframe and the end of the cold snap before it has even got into the reliable timeframe!

[NorthantsSnow]

Not much support for the 18z operational solution from the ensembles. In fact, there's a 10C departure from the average on the 26th:

http://209.197.11.142/c9s4a5k3/cds/ensimages/ens.20100117/18/t850Northamptonshire.png?dopvhost=charts.netweather.tv&doppl=0f368a9b44652e3544352e6595f0253a44352e8c&dopsig=29bf478548f96645faaa88ec8b5318db

In the shorter term, Wednesday just looks rainy for the vast majority. Back to normal then, eh?

[lorenzo]

I think we have to take note when such projections come from the BBC/METO. They realise this is not your standard winter, a bit late but they got there, and have been giving more weight to cold winning out than mild for the past week or so (relative to what you might expect from them anyway). Personally, I still think the Atlantic will get through eventually (exactly in what guise i'm not sure though) but - when there is a block of that size sat there coupled with even more impressive NAO, AO and MJO projections from today, then the least you can do is have is an open mind.

The NAO and AO are for me the most interesting part of this Winter so far, the CPC review of December highlights a couple of historic moments.

'' This overall pattern reflected the strongest negative phase (-2.4) of the Arctic Oscillation (AO) for any December since 1950 .

Over the Atlantic sector this pattern produced the strongest negative phase (tied with 1963) of the North Atlantic Oscillation.''

The Ensembles are potentially poised to replicate December again for both with the AO in particular looking like it may exceed the -2.4 it valued.

[Frosty.]

Anyone else liking the ECM 00z this morning..thought so

Looks pretty cold to me with more snow potential than yesterday's 00z, I dare anyone to say that run is mild.

[snowmadchrisuk]

Anyone else liking the ECM 00z this morning..thought so

Looks pretty cold to me with more snow potential than yesterday's 00z, I dare anyone to say that run is mild.

Obviously Not , I thought there would be more interest , Also GFS seems to throw in a good Snow chance for the Midlands on Saturday / Sunday as a disturbance from the West comes in and hit's -5 uppers . After this point around +168 the cold air is really trying to get in from the East . Some upgrades to come this week I feel.

[Totoro]

I don't know about anyone else but im finding the model output at the moment fasinating. What we're currently seeing is the complete reverse of our usual winters. What I mean by this is the mild being downgraded once it enters the reliable timeframe.

Agreed. In some ways I find it more interesting than the weather over the past few weeks, simply BECAUSE it's so uncertain and the models, even more than usual, are struggling really badly with it.

Fascinating.

[cooling climate]

One thing I have noticed on the northern hemisphere charts is the reluctance of a +PNA to

set up over western north America in the medium to long range.

Having a +PNA set up would help to lock a cold pattern in sending the jet stream on a more

southerly track which benefits us down stream.

This was a important feature during our last two cold spells.

Having said this if the AO tanks which I am confident it will and the block makes its way to our side

of the pole then I am still very confident of another major cold spell for Europe and the UK.

[full_frontal_occlusion]

Having said this if the AO tanks which I am confident it will and the block makes its way to our side

of the pole then I am still very confident of another major cold spell for Europe and the UK.

Interested to know why you are confident the AO will shift?

Is it just because the indexes are predicting a shift or is there something else that's causing your optimism? Thanks.

ffO.

[nick sussex]

Very unusual to see the model divergence this morning with the GFS and ECM against the UKMO and GEM, the first two disrupt the trough sending a shortwave se through the UK setting up a colder outlook, the UKMO doesn't want to know at all and the GEM brings in a slack continental flow.

We often see an ECM versus GFS difference of opinion but rarely the GFS and ECM together against the others.

[TEITS]

Very unusual to see the model divergence this morning with the GFS and ECM against the UKMO and GEM, the first two disrupt the trough sending a shortwave se through the UK setting up a colder outlook, the UKMO doesn't want to know at all and the GEM brings in a slack continental flow.

We often see an ECM versus GFS difference of opinion but rarely the GFS and ECM together against the others.

I feel we can safely say the outlook is uncertain.

However its a staggering shift from the models over these past few days. Take for example the pool of cold air just to the E on the GFS +168 chart.

http://www.wetterzentrale.de/pics/Rtavn1682.png

Only a few days ago some were saying "no chance of any cold weather for the next 10-15 days". This is simply because the models were too progressive in blasting the block away as we both suggested. A really puzzling outlook because as you say the UKMO does not agree with the ECM/GFS.

I will say though that the colder members on the ECM ensembles have certainly grown overnight.

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

[nick sussex]

I feel we can safely say the outlook is uncertain.

However its a staggering shift from the models over these past few days. Take for example the pool of cold air just to the E on the GFS +168 chart.

http://www.wetterzentrale.de/pics/Rtavn1682.png

Only a few days ago some were saying "no chance of any cold weather for the next 10-15 days". This is simply because the models were too progressive in blasting the block away as we both suggested. A really puzzling outlook because as you say the UKMO does not agree with the ECM/GFS.

I will say though that the colder members on the ECM ensembles have certainly grown overnight.

http://www.knmi.nl/exp/pluim/vijftiendaagse/index.html

Morning Dave

Yes it's very unusual to see the ECM and GFS against the other global models, I can't really remember the last time this happened, and as for the ECM ensembles agreed theres been a big shift overnight especially with the control run, I find it hard to back against the ECM now that its got support from the GFS, its hard to imagine that they've both picked up on a wrong signal, if it was just one model then i'd be very dubious, lets hope the UKMO comes on board this evening.

[TEITS]

Im beginning to doubt the Wed snow event will even reach me on Wed.

http://www.wetterzentrale.de/pics/Rtavn481.png

Again as some of us suggested the block is further W than intially progged. This means the SW will track SE and the precip will only affect W areas.

[MR EXTREMES]

ok i noticed a comment made to me yesterday about me being against the cold returning,

its not that i dont want cold its that things are slow swinging towards a more disturbed type of weather,

if you been reading gp post on the teleconnections then he himself is not certain either and also feels the feb will be mild,

of coarse he could be wrong but from looking at thease factors it seems to me change is close.

the only reason why people are optimistic of another cold outbreak is because its there waiting.

but im skeptical i dont think the high to our east is about to slip into greenland,

i do however think it could effect us a little,

but nothing interms of big freeze or snow drifts.

and the models are finding it hard to come to terms with the block to the east and low pressure to the west,

its also intresting to see after wed when a front moves through double figures will be with us,

remember the mild air won because by saturday double figures are with us and then the next front is ready to move in with a fairly active alantic a return of the jet.

id be suprised of any kind of sustained cold remember i also felt it would be baack last week of jan into feb im not optimisitc now.

but its been a great winter fantastic.

Im beginning to doubt the Wed snow event will even reach me on Wed.

http://www.wetterzen...cs/Rtavn481.png

Again as some of us suggested the block is further W than intially progged. This means the SW will track SE and the precip will only affect W areas.

thats why i cant understand the met o widespread warnings.

some will get snowfall but its not a major event but then the meto must try to maintain professionalism,

id like to add they to have found it hard to deal with patterns this winter.

but i still have respect for there shortem forecast.

Which bloke is that then?

lol that teach me i do this alot i do read through my post thanks good spot sorry mods.

Edited January 18, 2010 by Coast

[cooling climate]

Interested to know why you are confident the AO will shift?

Is it just because the indexes are predicting a shift or is there something else that's causing your optimism? Thanks.

ffO.

Long range guidance from the NWP models including NAEFS show high pressure ridging into the Arctic + of course

the MJO and convection that is situated around the date line which bodes well for our neck of the woods.

On top of this we have what looks to be an impressive MMW (major midwinter warming) in the stratosphere

(see stratosphere thread) and also the CPC AO and NAO outlooks agree with all of this.

Edited January 18, 2010 by cooling climate

[NorthantsSnow]

Im beginning to doubt the Wed snow event will even reach me on Wed.

http://www.wetterzentrale.de/pics/Rtavn481.png

Again as some of us suggested the block is further W than intially progged. This means the SW will track SE and the precip will only affect W areas.

Same. But this is good news in a way surely as it means the block is stronger and more robust than originally thought?

Short time pain, long term gain, perhaps. But like I said last night I'm not buying into any easterly at the moment.

[andymusic]

GFS 06z has backtracked quite a bit on where the front for wednesday will be and also considerably on temps for wednesday as well - so much so that I'd love to know which other models the meto were keeping an eye on to have confidence that they needed to issue a warning at all for this coming wednesday? - (even with the fact - it's not gonna be a major snow event - not when compared with what we've just been through)