Model Output Discussion:

[Methuselah]

Not strictly on topic, but I've heard the older generations (pensioners mainly) say that if we get an easterly at this time of year, it will last a fortnight. I don't know if history or charts of yesteryear bear that out, but first hand experience must be a basis for saying it?

I suspect it has more to do with 'selective memory' Ribster? I can't remember ANY one-day Easterlies from the 1960s...

[David-kig]

There is no guarantee of retrogression occuring, the gfs 06z doesn't end up with a Northerly, in fact, the 6z tended to become less cold in the later stages, especially in the south.

i tend to agree by looking at the GEFS ens even though it were the milder end of the ens later on it still shows much uncertainty esp after the 17 th

[michail]

Hi all! not a regular poster but with the models hinting at a potentially prolonged cold spell , will there be any exeptionally cold minimums across the country? I would love to see our nearby lake freeze over again. I live in the west of Ireland.

[damianslaw]

Not strictly on topic, but I've heard the older generations (pensioners mainly) say that if we get an easterly at this time of year, it will last a fortnight. I don't know if history or charts of yesteryear bear that out, but first hand experience must be a basis for saying it?

This time of year traditionally sees the atlantic quietening down and blocked patterns more likely to feature, hence an easterly has a much greater chance of lasting a long time now than in Dec or Jan when there tends to be much more energy in the atlantic - there have been exceptions to this, but generally an easterly is more likely to be sustained in February and much more likely to make an appearance. The beauty of this winter is that we haven't had to wait until Feb for blocked winter patterns, whereas in recent years we have as recently as 2008, 2006 and 2005.

February is often a much drier month than Dec and Jan and in some years significantly so. I tend to associate Feb with dry settled cold frosty conditions and snowy conditions - its a true winter month for me even though the sun begins to gain significant strength. In recent winters it has eclipsed Jan by some margin even right to the end i.e. 2004, 2005 and 2006 when the cold lasted into March.

[Lewis]

For those of you wondering about temps and dew points etc, signup to netweather extra and look at the custom skew charts. The 06Z at normal resolution shows dew points sometimes at 0-1c, this is way out and the GFS is also over cooking the temps.

The custom skew charts for kingston upon hull, show the dew point from monday afternoon right through too friday at 0c or below throughout, and temps struggling at 2c during the day.

[nick sussex]

Now that we've got a good idea of the pattern going forward its really the extended outlook that is quite uncertain with how much retrogression of the high takes place and how far north Atlantic weather systems will come. If you want to hang onto the cold then you don't want the high moving too far west towards Canada as this allows lows to the sw to exploit the weak area between the ridge and trough over Scandi.

The GFS in particular is more likely to pull the high further west than the ECM given its pre Xmas reading of the negative NAO.

[Rommy]

looking at the models mainly dry for next week few snow showers in the east as you would expect nothing to great in terms of widespread snow mainly dry and cold.

[SussexmarkyMark]

Well based on the 'main three' models this morning, the intensity of any cold in the coming week seems to have reduced. About 48 hours ago, the sub 528 was being shown quite widely, with some sub 520 air getting into the SE of England. This mornings model runs seem to divert the colder air into central France, and keep us above 532, so nothing particularly severe in the coming week based on this mornings runs and daytime temperatures of around 4 or 5 c seem quite reasonable predictions to me.

[Lincs Observation]

not disagreeing with most of your post Lincs just one small point

Weather models are NOT given 'long term averages'. They are all 'fed' current data as available no averages or whatever else. They then, in somewhat different ways, GFS, UK Met, ECMWF, depending on how their programme has been set up, then work out for every grid point at 1 sec upwards to whatever end of time scale they are set to the basic formulae for thermodynamics-hugely complex that they are. No averages that I am aware of are fed in on any model. programmers do at times 'tweak' the models if they seem not to be responding to events very well. too little or too much moisture, not enough notice of topography, etc.

I Stand corrected John, However i would imagine (At risk of stepping into territory i Know little about) That the current set up from the past few years is if a little different from the norm, Would i be right in saying that its the basic set up that may be the basis for such diversion for each model and it is at that point that maybe some sort of overview would be needed.

Regardless of current data been fed into the system if the set up has been fed to wide a variable at the start, then situations like now are off the mark. I would guess that even minor tweaking ma ynot be enough to offset the errors.

I find it fascinating how this stuff works, i wish id paid more attention in Geography.

LO

[nick sussex]

Well based on the 'main three' models this morning, the intensity of any cold in the coming week seems to have reduced. About 48 hours ago, the sub 528 was being shown quite widely, with some sub 520 air getting into the SE of England. This mornings model runs seem to divert the colder air into central France, and keep us above 532, so nothing particularly severe in the coming week based on this mornings runs and daytime temperatures of around 4 or 5 c seem quite reasonable predictions to me.

Are you sure you're looking at the right charts, even the fax charts at 72hrs have most of the UK in sub 528 air. Where are you getting this 532 from?

Temps of course colder towards the SE with values in some rural areas likely to be close to freezing once the easterly kicks in.As a better guide to chances for snow you're better off looking at the 850/1000 thickness charts, generally around 128 and below gives a better chance but with other factors needing to be taken into account.

Edited February 6, 2010 by nick sussex

[kent]

Well based on the 'main three' models this morning, the intensity of any cold in the coming week seems to have reduced. About 48 hours ago, the sub 528 was being shown quite widely, with some sub 520 air getting into the SE of England. This mornings model runs seem to divert the colder air into central France, and keep us above 532, so nothing particularly severe in the coming week based on this mornings runs and daytime temperatures of around 4 or 5 c seem quite reasonable predictions to me.

I agree the latest output suggest to me a dreary rather cold and damp week ahead. The suggestion of anything colder imo is still in FI.

[Frosty.]

I agree the latest output suggest to me a dreary rather cold and damp week ahead. The suggestion of anything colder imo is still in FI.

To be fair, the experts, such as darren bett have been very muted about the upcoming cold snap, with only small amounts of snow expected in the east, I can't see a potent blast being shown anywhere in the uk, indeed, it looks fairly benign in much of the uk with pleasant sunny spells but some overnight frost & fog.

[Guest FireStorm]

So the snow is pretty much on its way for next week then if FAX charts hold true??? Tuesday/Wednesday at the latest but impossible to tell how much will fall and the exact locations this far out. We have the cold modelled to be locked in place and all thats left is to wait for the snow

The good thing for this setup - and indeed this winter overall is once a cold spell has settled on the models, They really have locked the idea in each month. December, January and now February.

I am curious how TEITS is managing to suggest snow showers though and what charts are being used to give this suggestion (not a rant or having a go, total interest in how its done. NAE timeline is about my scope lol)

Edited February 6, 2010 by FireStorm

[snow drift]

I agree the latest output suggest to me a dreary rather cold and damp week ahead. The suggestion of anything colder imo is still in FI.

I think your comments are based on where you live rather than the country as a whole. If I remember, you live in Poole just down the road from myself. Down here, something fairly spectacular needs to happen for us to get something memorable. However what the models are showing is that we are heading back into a cold pattern. Some areas will do well from this. I love watching cold approach and how this is handled by the models. Remember last Sunday and what was being shown? I commented at the time that I thought it was advantage "mild". So will it snow, yep, somewhere. where, need to wait to nearer the time.

The last spell had a large snowfall showing for down here and this had been showing for about 24hrs. Then 3/4 hours before it was due to arrive it decided to make a semi circle round us and we ended up with about a cm. The lesson from this is snow ppn will spring surprises. Not all surprises are good.

[johnholmes]

have a look at the blog I did yesterday showing the skew-t and the instability available, ON THAT RUN, 12z Friday, to give snow showers over eastern and some central parts. The subsequent runs show rather less instability but still enough to give some snow showers in those areas.

Precip is notoriously difficult to predict so the best guide is indeed the Fax charts and wait until 24 hours before hand-or even later and track the actual precip on the NW radar.

hope that helps?

Edited February 6, 2010 by johnholmes

[MR EXTREMES]

looking at the models mainly dry for next week few snow showers in the east as you would expect nothing to great in terms of widespread snow mainly dry and cold.

here we go again there will be good model agreement laters it wont be totally settled if the high is futher south and not all models prog this.

as for snow always a now casting situation why the hell people think this silly idear is beyond me.

its getting rather frustrating listening to one liner its over rubbish,

its not over what will be will be,

snow will fall the models will show different outputs tonight maybe suprises maybe not but i think most will be suprised with the up and comming cold spell.

80s style all the way.

Edited February 6, 2010 by badboy657

[johnholmes]

I Stand corrected John, However i would imagine (At risk of stepping into territory i Know little about) That the current set up from the past few years is if a little different from the norm, Would i be right in saying that its the basic set up that may be the basis for such diversion for each model and it is at that point that maybe some sort of overview would be needed.

Regardless of current data been fed into the system if the set up has been fed to wide a variable at the start, then situations like now are off the mark. I would guess that even minor tweaking ma ynot be enough to offset the errors.

I find it fascinating how this stuff works, i wish id paid more attention in Geography.

LO

I can't answer your para 1 or 2 fully as I've no inside knowledge but I see no reason for it to have changed from when I was involved. Perhaps a search through the Met O web site might give both of us the answer we are pondering on?

[nick sussex]

I agree the latest output suggest to me a dreary rather cold and damp week ahead. The suggestion of anything colder imo is still in FI.

Dd you just pluck that statement out of the air? Where exactly are you getting damp and dreary from? The flow is likely to be the sunny spells and showers set up with most snow showers towards the east and se, to drive the showers further inland we need to see the flow strengthen and theres still some uncertainty regarding this.

[weather eater]

I think perhaps if there is a word that is overused on this forum it is 'severe', nothing on the outlook looks severe. To be severe you would literally need something on the level of 1963 or 1947 - nothing on the chat is anywhere near that harsh.

I have to say I agree with this Steven, I'm not saying that what are seeing could not become severe, the models will change and evolve, but in the same way that IB cannot demonstrate via any model run that the high will sink, the model runs do not show severe weather on the way to the UK, in any kind of reliable time frame. It will of course get cold, but I don’t see low temps like the -15c that we saw in January and snow looks at the moment to be a mainly an east coast affair. That snow will of course cause disruption, let’s be honest it doesn’t take a lot for this to happen in the UK, a small amount will do. However some good signs that things may develop into something more severe as time goes on, but unsurprisingly at this range there is a lack of true model consensus as to what form this will take.

More posts today suggesting that models have struggled more than usual with this pattern, this is really wide of the mark and I think it’s more of a reflection of models being under greater scrutiny at this time of year.

[MR EXTREMES]

Dd you just pluck that statement out of the air? Where exactly are you getting damp and dreary from? The flow is likely to be the sunny spells and showers set up with most snow showers towards the east and se, to drive the showers further inland we need to see the flow strengthen and theres still some uncertainty regarding this.

very true one thing id like to point out with all the experience in here and from the met o weather online joe b two outlook all are saying cold with snow showers with meto pointing to maybe later channel low thease are always a possibility along with trough formation that can happen at anytime even showers can merge together or even become slow moving.

so its game on if you ask me.

[Tristrame]

I am curious how TEITS is managing to suggest snow showers though and what charts are being used to give this suggestion (not a rant or having a go, total interest in how its done. NAE timeline is about my scope lol)

It's a hunch.

He could be wrong.

Teits is making a brave attempt at a forecast based on long time model watching,longtime weather observing and some intuition.

People at the met office probably have more experience but they do the exact same thing.

[Duane S.]

I agree the latest output suggest to me a dreary rather cold and damp week ahead. The suggestion of anything colder imo is still in FI.

Could you give me a link to these charts you have access to that the rest of us don't please.

[hot and cold]

Could you give me a link to these charts you have access to that the rest of us don't please.

I am intrigued by the temperatures today in fact and the upcoming model predictions for temperatures next week.

Presently it's 8 degrees here with a lovely sunny spring like day. As far as I can see the predicted high for today was 6 degrees. Anyone any thoughts on these temperatures and those of the model predictions for this week?

[johnholmes]

I Stand corrected John, However i would imagine (At risk of stepping into territory i Know little about) That the current set up from the past few years is if a little different from the norm, Would i be right in saying that its the basic set up that may be the basis for such diversion for each model and it is at that point that maybe some sort of overview would be needed.

Regardless of current data been fed into the system if the set up has been fed to wide a variable at the start, then situations like now are off the mark. I would guess that even minor tweaking ma ynot be enough to offset the errors.

I find it fascinating how this stuff works, i wish id paid more attention in Geography.

LO

picking up on this again and mods my apologies for it not being directly about what they are showing for today and the next week but for anyone wanting to know some insight into how, in the UK, the centre goes about it, then this link gives a fairly broad cover of how they do it.

http://www.metoffice.gov.uk/science/creating/

If you log on to the NOAA or ECMWF web sites they will show a similar view on how they do it.

All 3 are prety imilar really.

[Ben_Cambs]

I am intrigued by the temperatures today in fact and the upcoming model predictions for temperatures next week.

Presently it's 8 degrees here with a lovely sunny spring like day. As far as I can see the predicted high for today was 6 degrees. Anyone any thoughts on these temperatures and those of the model predictions for this week?

This is what GFS says for Wednesday and Friday

Fridays chart shows temps only reaching 1 or 2C in the East and maybe up to 4C in the west