Winter Model Discussion 12Z 22/1/13 onwards.

[snowking]

I think without a doubt December 2010 has spoiled many people's perception of a decent cold spell. We are not going to get a December 2010 or 1963/47 every single winter. Do you know how much those of us following winters through the 90's and 00's would have given to have had a cold spell like the one that's just passed, with over a foot of snow in the NE and Wales, and several inches of snow over two weeks with many an ice day thrown in too?

I think people do need to temper their expectations if they are expecting 1947 to hit in February. It will turn colder, there will likely be snow. But this constant down talking of the previous cold spell - which was progged by some since November, and by many more since late December - is becoming really rather tiresome.

The weather will do what the weather will do, and no amount of modelling is going to change that, but can we please leave the rubbishing of what was actually, on a UK wide scale (though admitedly not the greatest IMBY - not that that matters!) a very significant cold spell in the grand theme of things, and if people cannot see that then I'm not sure which country you've been living in for the last 15-20 years

Kind Regards

SK

[bluearmy]

Some noticeable differences between 00/06z GFS v 00z ECM with the track of a deepening secondary low (or shortwave as many like to call it) tracking SE late Friday/early Sat. GFS prefers to track the low SE to the SW of the UK across Biscay into Wern France. 00z had a back edge snow event for S Wales and S England as the low tracked into NW France. 06z has the low track towards the Pyrenees! So the precip largely escaping Sern Britain and instead we have a dry cold flow.

ECM, however, has a low to the SW of Ireland deepen and track E up the channel, colder air kept further north as a result, so no back edge snow event would seem likely, rather v. wet and windy for the south:

http://en.vedur.is/w...ntic/#type=prec

Alot of support for the EC deterministic from the EPS:

http://www.ecmwf.int...t!2013012800!!/

So going to be interesting to see what the 12z output does with this low.

looing through those ecm ens, you would tend to trust the ecm solution. shame the shortwave is sourced from so far south. could be interest for the w midlands/welsh border area though. lets see where the 06z gefs want to place the diving energy thereafter

[Methuselah]

Morning peeps...Just been moving some posts into the 'How Was the Cold Spell' thread...

[Jaffusmaximus]

Look at the low heights across S Europe though with the trough.

The outlook is so simple to figure out im struggling to understand why some can't see it. Rather than using just the models we should have more members using their instinct. The 06Z is another clear example of what i've been saying since yesterday morning and that is NW,ly outbreaks followed by a prolonged cold spell beginning around the 10th as we see the PV weaken.

Will there be enough winter left post Feb 10th to get any meaningful cold or is this cutting it close?

[BLAST FROM THE PAST]

It's all well and good saying the charts show promise but we've been hearing those words most of the winter. The last cold spell wasn't nothing spectacular in terms of deep cold, for many places it was simply too marginal for snow either falling or lying for any period of time. The outlook at best suggests transitional cool/cold snaps for the foreseeable, this may change in the coming days but until then I prefer to comment on what the models are showing, rather than hoping.

But it was a decent cold spell, and it was very cold. Lets hunt the cold and see if spectacular comes? We are bearing down now on the period/month where LRFs converge....fingers crossed then.

Definite consistency building here mid term...we step forward.

BFTP

[nick sussex]

Given what the models showed last week then if you're glass is half full then at least theres a chance of some wintry weather.

If you're looking for a big freeze within ten days your glass is half empty. We may at some stage see a more prolonged spell of colder weather if the Canadian vortex can weaken and edge further west with the jet tracking se to the west of the UK , very much like the recent spell of colder weather.

It may not have the blue ribband Greenland high but as we've seen you don't need that to get snow, you just have to make the best of the pattern.

We could spend the rest of the winter bemoaning the lack of that high rather than trying to see what we can manage if that doesn't appear.

So there are some chances of snow later in the week and then depending on whether we see a little retrogression in the pattern further snow as a shortwave dives se'wards.

At this range the models may have the pattern too far east so we can hope thats the case.

I should add during my time in the UK even to get one snowfall of a few cms was a success so perhaps expectations by some don't match the general reality of UK winters.

Of course you need better synoptics the later you get into the winter but we've seen many good spells of wintry weather even at the end of February and the start of March.

In the UK you just gratefully accept any snow regardless of when it arrives. There is one positive as we head into February, higher solar energy can produce alot more convection and the sea temps head towards their lowest.

Edited January 28, 2013 by nick sussex

[Jaffusmaximus]

Given what the models showed last week then if you're glass is half full then at least theres a chance of some wintry weather.

If you're looking for a big freeze within ten days your glass is half empty. We may at some stage see a more prolonged spell of colder weather if the Canadian vortex can weaken and edge further west with the jet tracking se to the west of the UK , very much like the recent spell of colder weather.

It may not have the blue ribband Greenland high but as we've seen you don't need that to get snow, you just have to make the best of the pattern.

We could spend the rest of the winter bemoaning the lack of that high rather than trying to see what we can manage if that doesn't appear.

So there are some chances of snow later in the week and then depending on whether we see a little retrogression in the pattern further snow as a shortwave dives se'wards.

At this range the models may have the pattern too far east so we can hope thats the case.

This caught my attention as from my POV I have seen this many times over the January when the models where at their most volatile and chaotic. I am hoping to see over the coming week, the same chaos from run to run post 120 hrs to perhaps give an effect on the models that may be linked to the SSW.

I also recall the fax charts were being adjusted West many times compared to the GFS eagerness to get lows to our shores ASAP.

Seeing as no one knows exactly what will happen over the coming weeks I cannot see the harm in being liberal in predicting what may happen.

Edited January 28, 2013 by Jaffusmaximus

[chris55]

GFS ensembles have been trending colder over the last 5 or 6 runs, below average from the 5th with good agreement (edit - a bit more scatter on the 06z set), the finer details are open to change so we could see a continuing downward trend if the Azores ridge can actually make more of a stand against the Atlantic "toppling "it.

06z (as previous runs) has a few attempts at getting a sustained ridge and finally manages it right out in FI

Overall there looks to be a reduction of the Atlantic energy over Greenland as we head towards day 10ish (strat related??) this may be our best chance at getting the Azores ridge to actually sustain and help establish some high lat blocking.

ECM highlights this as well

Quite a consistent trend and one to watch.

Edited January 28, 2013 by chris55

[Tim Bland]

I think some members are obsessed by seing rare synoptics. Personaly im a fanatic in rare weather IE snow. the cold spell just gone was fantastic IMO and yet the synoptical evolution that took us there was nothing special. Hopefully we see more cold and snow soon. I would rather have a wedge of HP over Scandi causing undercuting lows and bucket loads of snow over a huge omega block if all it results in is the wishbone afeect with wintry flurries down the coasts.

The ensembles continue the downward trend towards or below the magic -5C line and the squigles along the bottom tell us there will be precipitation around so all good for snow lovers for the next few weeks IMO.

Watch out for that channel low on Sat morning... Someone could get a dunpling!

[Evening thunder]

You can tell when the models are grim for cold when you see post showing cherry picked ensembles, nothings changed in the last few days the pattern is flat and low heights over Greenland. Same old, same old, for most of this winter.

The ensembles are quite cold on average actually: http://www.wetterzen..._London_ens.png

Writing it off after Feb 1st- gosh some are fickle... Wait for the next 4 weeks and then we'll talk!

Very optimistic still for the conveyor belt of seaboard heights to stall and intensify, w/ amplification, the polar jet- retrogression gets a few attempts it seems and there is a developing cold pool associated with the upper troughing over Central Europe.

Patience.

Lol, I think I saw a few posts writing off winter nearly before it had begun!

Just to add - any injection of cold for England will need a good sub -7c air to be brought south,colder if the flow is NE over the north sea-

There are no indications that we can get any flow sustained enough to filter this west- the jet will effectivley work as a sheild across the UK preventing that happening-

Using the Iceland SLP in this instance is no good im afraid....

S

Quite a few of the GFS ensembles beg to differ with that 'no indications' of us getting a flow to filter -7C 850hpa air west though, albeit in FI? http://www.wetterzen..._London_ens.png

Not sure I understand why using the Iceland ensembles isn't any good In this instance thought they would indicate high pressure in that area which is usually a good thing for cold in the UK?

It's all well and good saying the charts show promise but we've been hearing those words most of the winter. The last cold spell wasn't nothing spectacular in terms of deep cold, for many places it was simply too marginal for snow either falling or lying for any period of time. The outlook at best suggests transitional cool/cold snaps for the foreseeable, this may change in the coming days but until then I prefer to comment on what the models are showing, rather than hoping.

but many places did see falling snow, and lying snow for about a week which is a pretty good period of time in the UK..? also the breakdown got delayed and cold/snow upgraded. all I am doing is commenting on what the models show anyway.

Anyway I am not only looking for the 'holy grail', but other weather too. There are suggestions that more cold wintry weather is quite possible as we progress through February, a big improvement from a few days ago. If some want to only chase the 'holy grail' and say the outlook is negative and members should not be optimistic then that's up to them, but I would prefer not spend 19 out of 20 winters being negative/depressed about the outlook if that's ok..

Sorry I don't post in here very often just felt a little compelled to post today.

Edited January 28, 2013 by Stormmad26

[SnowBallz]

Look at the low heights across S Europe though with the trough.

The outlook is so simple to figure out im struggling to understand why some can't see it. Rather than using just the models we should have more members using their instinct. The 06Z is another clear example of what i've been saying since yesterday morning and that is NW,ly outbreaks followed by a prolonged cold spell beginning around the 10th as we see the PV weaken.

Oh, well I couldn't agree more TEITS.

In that case, I take it you've retired from confidently and persistently dismissing the idea of cold returning to our shores - simply because it isn't showing in low-res GFS. Moreover, I'm heartened that you have some newly acquired respect for Chio et al, who advised you not to place so much trust and base your 'predictions' on the mickey mouse low-res output.

Nice to see you finally join the party; it's never too late and welcome aboard.

[chris55]

Reading the model output beyond day 6/7 is all about instinct and experience. Taking output at face value at this range will leave you open to failure. I'm not sure of the exact verification stats from a week or more out but I bet they are quite low, so if people read the models at face value this far out then It is logical that there analysis will be off the mark.

The experienced members will put there knowledge and past history of model watching to use, and this will obviously result in differing opinions, as we have in the thread today. So although all opinions are valid, nothing is set in stone, far from it, either for cold or mild.

[SMU]

The ensembles are quite cold on average actually: http://www.wetterzen..._London_ens.png

Lol, I think I saw a few posts writing off winter nearly before it had begun!

Quite a few of the GFS ensembles beg to differ with that 'no indications' of us getting a flow to filter -7C 850hpa air west though, albeit in FI? http://www.wetterzen..._London_ens.png

Not sure I understand why using the Iceland ensembles isn't any good In this instance thought they would indicate high pressure in that area which is usually a good thing for cold in the UK?

but many places did see falling snow, and lying snow for about a week which is a pretty good period of time in the UK..? also the breakdown got delayed and cold/snow upgraded. all I am doing is commenting on what the models show anyway.

Anyway I am not only looking for the 'holy grail', but other weather too. There are suggestions that more cold wintry weather is quite possible as we progress through February, a big improvement from a few days ago. If some want to only chase the 'holy grail' and say the outlook is negative and members should not be optimistic then that's up to them, but I would prefer not spend 19 out of 20 winters being negative/depressed about the outlook if that's ok..

Sorry I don't post in here very often just felt a little compelled to post today.

RE: Iceland- because the SLP measure say at 1030 could mean a transient feature & or ridge or GH-

If you are to use that are you need a spike & a sustained period above ~1035 MB to see something substantial.

On the ensembles I think I can cound 3 maybe 4 from the 06z that go below -7, so 25%.

nothing conclusive just yet- plus its the 06z

...#S

Edited January 28, 2013 by Steve Murr

[Ian Brown]

Interesting stuff from the NWP, low heights over Europe are key to getting repeated attacks from the North as well as some decent ridging towards Greenland.

I think some people are chasing Jan 87 synoptics and if so you are always likely to be disappointed.....

[Man With Beard]

The recurring theme of the models this winter - attempts at Northern blocking at odds with energy coming out of Canada that never wants to give up. ECM T240 a prime example:

www.meteociel.fr/modeles/ecmwf/runs/2013012800/ECH1-240.GIF?23-0

On this occasion, the vortex looks less likely to break through, but it's still there. Weighing up the evidence, firm forecasts for February still require a bit of a punt. My best guess is a couple of transitional 3 days GH blocks giving opportunities for brief Northerlies to sweep down before the Atlantic gets back in. A kind of up and down month.

[Cheshire Freeze]

Interesting stuff from the NWP, low heights over Europe are key to getting repeated attacks from the North as well as some decent ridging towards Greenland.

I think some people are chasing Jan 87 synoptics and if so you are always likely to be disappointed.....

Too true. I think there will be snow for all in the next 4 weeks. Can't help but feel that some of the dispondency from certain members is due to their geographical location more than anything.

I also feel the need to echo the sentiments of others.....the last 5 years or so have really set peoples' expectations to new levels. Pre 2008 ish we would have been salivating at the thoughts of some of what the NWP is currently hinting at.

Edited January 28, 2013 by CreweCold

[Weathizard]

Must say I'm very surprised at some negative posts, I do understand if you are looking for SEVERE prolonged cold in the next 10 days that there isn't any models showing this but I think expectations need to be kept in check slightly given the fact its VERY rare to see winter sypnotics like we saw in 2009/2010, everything needs to fall into place in our favour for this but in order to get some nice cold shots in the time being a mid atlantic high pressure is a helpful feature, at this point we are only looking at transient spells at present however looking d10+ the mean is hovering around -5 which is very decent at this range to have a mean like that, so a certain degree of agreement that it won't be Atlantic driven or mild at least. I'm very much glass half full though to be honest, looking at the models and going on my personal instinct I think something is certainly afoot in the models.

[Ian Brown]

Too true. I think there will be snow for all in the next 4 weeks. Can't help but feel that some of the dispondency from certain members is due to their geographical location more than anything.

I also feel the need to echo the sentiments of others.....the last 5 years or so have really set peoples' expectations to new levels. Pre 2008 ish we would have been salivating at the thoughts of some of what the NWP is currently hinting at.

Very much so - people forget that in some winters a northerly toppler - effectively what the thundersnow event of Jan 2004 was - was the highlight of the winter.

[Frosty.]

A nice Gfs 06z in FI, the weekend cold snap suffers a bit compared to the 00z but the rewards further on make it worthwhile, some decent cold snaps on a nw/se angled jet, the displaced azores high ridges north and temporarily blocks the atlantic with a good arctic blast followed by another and another, synoptically it's still work in progress and far from the finished article but there is promise of snow and severe frost in the outlook but in the short term, lots of wet and very windy weather. We still see a brief cold incursion from the north later this week into the weekend, then briefly milder but most of next week could be cold and wintry with more to follow.

Edited January 28, 2013 by Frosty039

[swfc]

Look at the low heights across S Europe though with the trough.

The outlook is so simple to figure out im struggling to understand why some can't see it. Rather than using just the models we should have more members using their instinct. The 06Z is another clear example of what i've been saying since yesterday morning and that is NW,ly outbreaks followed by a prolonged cold spell beginning around the 10th as we see the PV weaken.

good post teits.im not that clued up on a lot of the background signals ete but after 45 years at looking at the charts ete you do get a feel for things if not very scientific.Old school i guess!

[bluearmy]

i suggest ptb 5 from the 06z gefs as being a decent representation of current extended ens modelling. there are colder runs but those tend to build a strong greeny ridge which is currently not widely supported by the week 2 ens.

what is interesting is that in those runs which manage to build a greeny ridge that lasts for only a couple of days, it seems sufficient to allow the euro troughing to get across the uk and deflect the jet further sw. also a cluster of runs whereby the euro trough becomes cut off and the ridge extends into scandi. that then either sinks or keeps us in an easterly flow.

[Catacol]

GFS has moved towards the ECM solution today, placing vortex energy mostly in the Canadian sector at day 10.

ECM ensemble for today still has a lot of energy in the canadian sector, persistent heights to our SW and gentle but persistent troughing to our north:

So no change yet. Atlantic dominated, mild at times in the south and occasional NW incursions bring chances of snow to high ground in the north. Bog standard winter - nothing remarkable.

This is the pure model interpretation of course. Teleconnections suggesting otherwise, but we are yet to see anything like an MJO 7 or 8 pattern emerging in the output, and with spiking AM the models are not yet really picking up a very big increase in wave amplitude if it is coming.

I'm still wondering if this is going to be the winter where vortex displacement actually ended up working against other teleconnections and over riding them in favour of cold zonal rather than blocked conditions. Bar one cold week to 10 days in January it has been mainly cool/average and wet for the last 8 weeks. Nothing yet to make this winter stick in my memory...

A quick comment for those saying "Dec 10 was remarkable - hunting for such events is rather wishful thinking" I'm not sure I agree. I pulled up the CET stats and picked 1959 - 1991 as the website page that popped out in front of me. Looking for months with a CET of 2 or less I found 15 of them - that's 15 cold to very cold months in a 32 year period. One ever 2 years on average. My point is that the last 20 years have made us too quick to assume that cold rarely strikes here consistently. The historical record suggests otherwise.

[phil nw.]

Yes some realistic and sensible posts in here today-no wild hope casting just good assessments of where this pattern may go.

i agree with many that it`s a decent cold outlook into week 2.The Ens show this, drifting towards -5C on the 850`s and it`s a setup that could evolve into something colder.

At the moment it`s very marginal for widespread snow but it doesn`t need much for this to improve.

Certainly no reason for cold seekers to be down at this stage.

[Evening thunder]

RE: Iceland- because the SLP measure say at 1030 could mean a transient feature & or ridge or GH-

If you are to use that are you need a spike & a sustained period above ~1035 MB to see something substantial.

On the ensembles I think I can cound 3 maybe 4 from the 06z that go below -7, so 25%.

nothing conclusive just yet- plus its the 06z

...#S

Oh ok thanks for that, I think I might see what you mean about the Reykjavik (for some reason spelt Reykjavic on the Netweather) mean not being high enough with too much scatter at the moment.

With the ensembles they did change to the 06z just as I posted although I do definitely count more than 4 members that go below -7C at some point for London, with the mean at -6C which I would have thought would be a good trend for that time frame at least, but I agree nothing conclusive at that range as always.

[snowjoking]

It's all well and good saying the charts show promise but we've been hearing those words most of the winter. The last cold spell wasn't nothing spectacular in terms of deep cold, for many places it was simply too marginal for snow either falling or lying for any period of time. The outlook at best suggests transitional cool/cold snaps for the foreseeable, this may change in the coming days but until then I prefer to comment on what the models are showing, rather than hoping.

While i agree with your statement about no deep cold,you are totally wrong about being marginal for lying snow.

The 5cm of snow we had on the ground from Sunday/monday 13/14th January lasted right through until Yesterday.

And i only live 26 miles from you and in North Ribbledale not on the top of a hill.

Edited January 28, 2013 by snowjoking