Model Output Discussion - 8th - 14th January

[shedhead]

There might well have been plenty of model drama across the last 24hrs, but the latest set of outputs keeps us pretty much where we've been for some time now. Mild/very mild for much of the working week, turning less mild this weekend,then colder (tho not cold) into next week. Anything beyond this remains pure supposition imo, but it's probably fair to say that colder weather looks more likely than milder weather for the final 3rd of January.

Edited January 8, 2012 by shedhead

[Cheshire Freeze]

I would not say a massive step back unless you were expecting the quick advection of cold air to the UK. That is not going to happen with the PV in it's current state. Step one is seeing signs that the jet will not be barreling past the Meridian towards Russia, he rather harder bit Step 2 is seeing the PV back West/break-up.

Ian, you're a breath of fresh air when you're not on the wind up, really knowledgeable. To be impartial is a good trait!

I said last night that this attempt would probably fail, my attention is on the turn of Jan into Feb

[stewfox]

So please, rationally answer me this question;

Where will the cold come from to support a maximum temperature of 0c in London? Post me a chart to suggest otherwise.

Just apologise and move on SM has gone out of his way to show you where you are going wrong

Beckely West Virgina Max temp drops by 9C in one day because cold air 'arrives' its not emedded to the north .

http://www.wundergro...WV/Beckley.html

It then rises 12 c then drops 14c all in a few days.

http://www.wundergro...WV/Beckley.html

You have already posted the chart

Edited January 8, 2012 by stewfox

[Cheshire Freeze]

For those interested Ian F's latest tweet says

"UKMO view is of predominately anticyclonic but eventually chllier (but non-snowy) for South UK in next 6-15 days - more unsettled in North though."

Kudos to the METO if they're correct but I think it's going to be tricky for anyone to say with any certainty what will happen, especially with any height rises around the pole

[Optimus Prime]

Take a look at what happens over in the US during the winter months.Same applies here.

Major difference is North America is situated directly below the well known country of Canada (on the map) where there is (believe it or not) less open water and a markedly greater availability of cold to plunge down. I've seen the apparent simularities between the US cold and UK cold described quite a few times now. It's fundamentally and scientifically wrong.

IMO (and that will not change) an easterly this time around would not bring what most people here want - Sub zero temperatures and widespread and heavy snowfall that will stick around for a few days in the south east. I feel I've proven this with the use of a good selection of charts which support my hypothesis.

• 
  

[cooling climate]

Here is the H 850 temperatures for Jan 17 1947

This is the H 850 temperatures for Jan 24 just one week later.

Edited January 8, 2012 by cooling climate

[Tom Montalbano]

As has been already stated, big disagreements in the models on where we're going in about a weeks time.

Some pressure Ensembles:

http://nwstatic.co.uk/ensimages/ens.20120108/12/prmslAberdeenshire.png

http://nwstatic.co.uk/ensimages/ens.20120108/12/prmslOslo.png

http://nwstatic.co.uk/ensimages/ens.20120108/12/prmslReyjavic.png

Regards,

Tom.

[Cheshire Freeze]

Major difference is North America is situated directly below the well known country of Canada (on the map) where there is (believe it or not) less open water and a markedly greater availability of cold to plunge down. I've seen the apparent simularities between the US cold and UK cold described quite a few times now. It's fundamentally and scientifically wrong.

IMO (and that will not change) an easterly this time around would not bring what most people here want - Sub zero temperatures and widespread and heavy snowfall that will stick around for a few days in the south east. I feel I've proven this with the use of a good selection of charts which support my hypothesis.

• 
  

To be honest OP I think to call it a hypothesis is a trifle generous

[bluearmy]

Having read the last few pages, i must be nutty but I quite like the ECM and ukmo this evening. Any chart that splits the p/v across the NH by T144 is a good chart. Anything can follow that polar profile. That's a split vortex in the reliable timeframe. And that's a vortex which I believe was one of the strongest we've seen for decades ???

Just in case anyone needs reminding, its the 8th of jan

Edited January 8, 2012 by bluearmy

[peterf]

Here is the H 850 temperatures for Jan 17 1947

This is the H 850 temperatures for Jan 24 just one week later.

both look the same to me lol.

[Cloud 10]

So please, rationally answer me this question;

Where will the cold come from to support a maximum temperature of 0c in London? Post me a chart to suggest otherwise.

The chart posted is a good example of how quickly cold pools can build to our east,as just 2

days later there is suddenly a decent area of -10 upper air.

[cooling climate]

This is the chart for the 24 Jan 1947 just one week later.

[Bristawl Si]

Kudos to the METO if they're correct but I think it's going to be tricky for anyone to say with any certainty what will happen, especially with any height rises around the pole

i think this winter their 2 week and monthly forecast have been pretty much spot-on. They also predicted the cold spell for end Nov/Dec 2010 in advance i think. So they're not as bad as some may say IMO.

I think it's in the v short term where my perception is that sometimes they're a bit slow to detect changes - but then that is my perception - it may be unfair and inaccurate.

[ourson]

Matt Taylors forecast on Country file showed a set-up similar to this for Friday

This could go anywhere from here if the cold air to our east shifted west we would be starting to see some much colder weather.

I think IF should be in a larger font here personally.

[Jason M]

I would not say a massive step back unless you were expecting the quick advection of cold air to the UK. That is not going to happen with the PV in it's current state. Step one is seeing signs that the jet will not be barreling past the Meridian towards Russia, he rather harder bit Step 2 is seeing the PV back West/break-up.

Yep, a bit over dramatic to be fair. What I mean't was that the positive trend from yesterday hasn't been maintained. Plenty of northerlies and easterlies in amongst the ensembes though so all options are on the table. The only trend really is uncertainty, which is obvoiusly better than where we were on Friday evening.

[Tim Bland]

When the GFS OP and control are opposite ends of the spectrum (as they ate tonight) it shows how much volatility and uncertanty there is. The op was a mild otlier in the south (FI) A positive is that all models agree on a weaker PV and more heights to our north than we have seen for a while.

Edited January 8, 2012 by Tim Bland

[nick sussex]

Having read the last few pages, i must be nutty but I quite like the ECM and ukmo this evening. Any chart that splits the p/v across the NH by T144 is a good chart. Anything can follow that polar profile. That's a split vortex in the reliable timeframe. And that's a vortex which I believe was one of the strongest we've seen for decades ???

Just in case anyone needs reminding, its the 8th of jan

I think you must be in a minority of one.

After this mornings ECM tonights is a bit like being promised two weeks holiday on the Cote D'Azur and then finding out instead you're on the way to a fortnight of frivolity in Tehran!

I get your point re the split PV apart from that the ECM is a shocker, of course its still got the Arctic high but really I think I speak for most in here, the time for potential is over, we want action and we want it now!!!!

Edited January 8, 2012 by nick sussex

[snowray]

Strange realy how the GEM introduced that Easterly and a Scandi high out of nowhere and every other model followed suite apart from UKMO, LESS than 24 hours later GEM have dropped it and so has everyone else, ECM has been shocking in fact in this turn around. There must have been a decent enough signal there yesterday though, what has changed so fast?

UKMO remains top notch.

[bobbydog]

not sure if anything like it exists already but it would be interesting to see an 'ensemble style' chart showing only the op runs from the past week or so. it might be good for showing any emerging trends. maybe a little challenge for anyone who's good at making stat charts?....

[john mac]

Lol the models tonight make me laugh, its like taking a packet of sweets away from a kid, plenty to be positive about especially the fact that there is plenty of disagreement in the models as early as 120hrs. If they were all singing from the same song sheet then i would say order in the prosac off nick s. lol

[cooling climate]

Just like to add that when you see the progression of the synoptics from the 17th Jan 1947 to

the start of the infamous cold spell 24th Jan 1947 you realise that anything is possible with the

charts we are seeing at the moment.

The H 500 chart for Jan 17th 1947

There is no way I would have forcast one of the coldest and snowiest spells to come

from a chart like this just a week later.

Now here is the H 500 chart a week later.

So you just never know, although personally I think we will have to be a bit more patient for a couple

of more weeks.

Please see below for the H500 chart for 17 Jan 1947

Edited January 8, 2012 by cooling climate

[Cloud 10]

Strange realy how the GEM introduced that Easterly and a Scandi high out of nowhere and every other model followed suite apart from UKMO, LESS than 24 hours later GEM have dropped it and so has everyone else, ECM has been shocking in fact in this turn around. There must have been a decent enough signal there yesterday though, what has changed so fast?

UKMO remains top notch.

The UKMO only goes out to +144 so never had a chance to show the easterly.

Can't argue with the verification stats of it,but i do wonder if it would get so much love

if it went out to +240.

[nick sussex]

yes how on earth can the ecm be considered enjoyable its atrocious for cold prospects !!!

I started to fear the worst when i viewed ukmo and gem.

Back to the drawing board with huge PV limpeted over greenland on ecm .

The UKMO is better than the ECM and its very typical that just as one improves the other implodes, it is a strange coincidence though that the two most bullish outputs the ECM and GEM have both jumped ship at the same time.

[damianslaw]

The UKMO model is always worth watching when we have differences between ECM and GFS within the reliable timeframe as we were seeing earlier today. Often in such set ups it is worth seeing which model UKMO is more aligned too as a good indicator of which one is most likely to verify, mind it can also show different set ups to both GFS and ECM but rarely to the same extremes.

The UKMO model is much more in line with what GFS has been showing today than what ECM was showing earlier, so perhaps no surprise to see ECM now backing off its easterly idea.

UKMO this evening suggests a cooler interlude later in the week thanks to heights ridging north over the country, with maxima closer to average and the return of ground frost and possibly some fog by Friday, something we have seen very little of so far this season. I was surprised BBC countryfile had as one of its headlines that the week ahead will be milder than that just gone, it looks preety similiar, with temps getting as high as 11 degrees Wed at best.

[johnholmes]

the time for potential is over, we want action and we want it now!!!!

all anyone taking a measured look at the models can respond to that is tough Nick.

They do not and never have promised some of the things that have been posted in here Like I said earlier today let's have some realism.

The most likely happening is for high pressure at the surface to quieten things down, especially in the south (ridge/high) most probably close by the west or SW of the country. West of the country, IF that is where it decides to be, would mean the prob of some brief northerly type shots. Nothing is being predicted by anything that I can see better than that out to at least the 3rd week of January if not further.

Edited January 8, 2012 by johnholmes