Model Output Discussion - 8th December Onwards

[Gavin Hannah]

Just caught the Countryfile forecast 20 mins ago. As stressed by the presenter, Susan ... (?) Wed onwards could be subject to some changes, even this close out. What I will say however is that Thur and Fri were shown as having Easterly winds across the northern half of the UK, and westerly winds across the southern half. The LP center was out to the west and it was being stretched out under the high pressure to our East.

The Beeb forecast matches neither the 12Z or the 06Z. Nor the ECM.

Edited December 9, 2012 by IBringTheHammer

[Summer Sun]

Just caught the Countryfile forecast 20 mins ago. As stressed by the presenter, Susan ... (?) Wed onwards could be subject to some changes, even this close out. What I will say however is that Thur and Fri were shown as having Easterly winds across the northern half of the UK, and westerly winds across the southern half. The LP center was out to the west and it was being stretched out under the high pressure to our East.

The Beeb forecast matches neither the 12Z or the 06Z. Nor the ECM.

Susan Powell it was, yes the forecast is highly uncertain beyond Wednesday, Freezing fog could be a big problem in the west at times as well

[bryan629]

yep i saw country file too... clearly dont know for sure whats going to happen beyond thursday for sure...their charts showing arrival of atlantic painfully slower than the gfs... why are the models so inconsistent with each other or should i say erratic at the moment.

ps im still learning

[Froze were the Days]

The might of the Russian high even if it was on steroids wouldn't manage that, its actually bulleted that low se into Italy quicker than the rush to the doors at the Harrods sale!

And as we see later the Russian high teases and then wants to go home. Generally in this set up if its going to happen the models will deliver it quickly as the PV forces some westwards retrogression as it heads to Siberia.

I have a rule for these Russian highs, three strikes and you're out, basically we see many of these modelled which hang around never quite make it and then head away.

So if its going to happen the models will go to that solution quickly, give it a few days and lets see whether we see some retrogression in the pattern.

Totally agree with your post regarding '3 strikes and your out' Re: The Russian HP, I posted this just a moment ago about maybe 3 attempts by LP to displace the block before reading your post, this has happened a couple of times in the past (can't remember the years) but this is generally the case, I'll be surprised if the HP makes retrogression westwards and best I think we'll see maybe a weak ridge but the form horse is eventually the Atlantic sorry to say. Could take until xmas or just before until we see this resolved.

[Craigers]

Also on the country file forecast the chart showed a "potential breakdown" of the cold. These words used from the bbc forecaster! so still uncertain of the setup!

[BARRY]

Totally agree with your post regarding '3 strikes and your out' Re: The Russian HP, I posted this just a moment ago about maybe 3 attempts by LP to displace the block before reading your post, this has happened a couple of times in the past (can't remember the years) but this is generally the case, I'll be surprised if the HP makes retrogression westwards and best I think we'll see maybe a weak ridge but the form horse is eventually the Atlantic sorry to say. Could take until xmas or just before until we see this resolved.

why is the Atlantic the form horse if even the met wont commit from wed

[Jason M]

Wow ECM from T216 (obvious FI):

Feed of very mild air heading our way.

Not neccersarily a bad thing though as it could cause height rises over scandi if it gets far enough north and with all that cold air to the east. That said, its 10 days away so has next to no chance of verifying.

[matty lfc]

Isn't it amazing that the difference between a very wintry ending week with lots of snow or a very mild ending week with gales and heavy rain is all down to the low moving a couple of hundred miles to a more favoured position or the position of it stalling against the block.

All the charts, data etc and really it just boils down to something as simple as that.I honestly dont think the charts/METO have a got a clue beyond Thurday,possibly Wednesday.

Is it fair to say to say that most weather data centres struggle forecasting blocking around the UK?

I

[Summer Sun]

Tonight's country file forecast for those who didn't see it

What we end up with by Friday who knows

[phil nw.]

I didn`t see the CF forecast but going by comments and looking at the UKMO raw output what was showing on the TV would match pretty well.

I think the uncertainty expressed would likely be down to the timing and extent of any snowfall more than the cold holding on totally.

I hope i am wrong but the operational mean outputs for days 7-10 are pretty close in their modelled pattern for early next week.

The Upper trough close to the UK which would push those south westerly`s through eventually further north and east.

No real mild uppers -more around average -as the ens graphs indicate.

[I remember Atlantic 252]

Tonight's country file forecast for those who didn't see it

What we end up with by Friday who knows

Saw it, and I think the snow for the SE is being underesimated mon night to wed night, SE areas look to see a few inches I think, and even E and NE areas

[Frosty.]

At least most of the week ahead looks cold with widespread frosts and some freezing fog forming as winds fall light for a few days, as the orientation of the high changes on tuesday, some snow showers look likely for northern scotland and down some eastern coasts of the uk but most areas, especially inland look dry, cold and sunny with the frosts not really lifting, in the shade at least. From midweek it looks very complex as a SEly develops and strengthens, rain pushing north and east and turning to snow as it hits the cold air, a spell of snow for most areas but turning back to rain in southern and central areas as we lose the colder uppers but we do retain surface cold so it's not going to become mild, currently, the major snow risk after midweek looks highest for scotland, especially further north, a slow moving band of heavy snow pushing further north with strengthening ESEly winds but by the end of the week ,even scotland loses the colder uppers but remains with surface cold. If the russian/scandi high can continue to edge further west, there is a chance the snowier spell in the north could end up a more widespread event, it's the trend within the reliable which is key and things are slowly improving in that respect, i'm not concerned about deep FI on the Ecm 12z because that will change many times, and I think towards a colder pattern.

Edited December 9, 2012 by Frosty039

[Froze were the Days]

why is the Atlantic the form horse if even the met wont commit from wed

Eventually from this synoptic and I'm largely basing this on the ECM output and past history the Atlantic will eventually erode the block after several attempts, Atlantic WILL be the form horse over retrogressing HP's to the east and this is no different. As mentioned we need sustained heights to the north for any chance of cold getting here, I can't see it happening based on that output.

[Robbie Garrett]

In the reliable time-frame. Low pressure to our west is stalling against the block. Models probably not agreeing with anything past 15th December at the moment.

Agreement here for us to go less cooler, as next week rolls on..... but hints at a return to lower temperatures.

There is a great deal of uncertainty in the forecast, but there are indications of more unsettled weather during this period. Temperatures will generally be a little below average for the time of year, although they may recover to nearer normal by the New Year. The signal for rain and snowfall amounts and distribution shows a high degree of uncertainty. On balance, it seems most likely that many areas will receive average amounts of rain.

At the moment, I don't think a cold spell this site of the winter will be as we expect I am afraid... and that's just based on the current output and long-term trends that I am looking at. If we get any snow, it is likely to be the week beginning Christmas, ensembles seem to agree.

[Jason M]

The CF forecast did also say 'there will be mild air ahead of the front so we are not too concerned about the risk of snowfall'

The issue as stated by Phil is simply timing. To avoid it happening we would need a turnaround of.... Well last weeks magnitude :-)

Looking on the bright side going forward things are a lot more encouraging than they were this time last year. At least we're in he game at the moment!

Jason

[Nick F]

12z GFS and ECM ensemble means all pointing to a cyclonic southwesterly flow t+120 - 240. Russian high very steadfast though, which suggests lows not getting very far east of the UK - which may mean excessive rainfall could become an issue yet again. And potential for deep secondary lows heading towards Sern UK, as a strong jet streak moves across the Atlantic towards western Europe.

Towards the end of this week, uncertainties over timing of the breakdown, but unfortunately for southern UK it seems likely atm that milder air moves in ahead of the frontal precipitation - so when the fronts arrive what will fall will most likely be rain. Though northern areas much more favourable to hang on to cold enough air long enough to see some snow as fronts arrive before turning to rain too.

Edited December 9, 2012 by Nick F

[Gavin Hannah]

It's time to hang on to your hats guys n gals. Eagerly awaiting the 18Z and tomorrows output. I would love to see this Low become a slider and undercut the HP as we progress through the week. That would just be like all my Xmases rolled up into one lol.

[iowpompeylee]

Saw it, and I think the snow for the SE is being underesimated mon night to wed night, SE areas look to see a few inches I think, and even E and NE areas

looks just like the odd shower.cant see much precipitation myself.hope your right though lol

[stainesbloke]

Isn't it amazing that the difference between a very wintry ending week with lots of snow or a very mild ending week with gales and heavy rain is all down to the low moving a couple of hundred miles to a more favoured position or the position of it stalling against the block.

All the charts, data etc and really it just boils down to something as simple as that.I honestly dont think the charts/METO have a got a clue beyond Thurday,possibly Wednesday.

Is it fair to say to say that most weather data centres struggle forecasting blocking around the UK?

I

Most definitely. Blocking trends can be picked up quite far in advance but its the details which are pretty much unforecastable until very close to the event itself. As we know the details changing can have big implications for the UK...some interesting weather coming up though I haven't got a clue as to exactly what!

[Grimsby Snow Lover]

What I can't seem to get out of my mind is that the metoffice seem to think that there will be no significant cold after this week for the foreseable. Surely they have more info and data than we can see. It must be said though that the Atlantic push does seem to have slowed some what. COULD the met's view change?

Edited December 9, 2012 by Grimsby Snow Lover

[Snowman.]

I also do believe that we will see maybe one more attempt of blocking this side of winter probably around the festive period how cold/snow to be given from this if any at all is beyond me.

[hilldweller]

What I can't seem to get out of my mind is that the metoffice seem to think that there will be no significant cold after this week for the foreseable. Surely they have more info and data than we can see. It must be said though that the Atlantic push does seem to have slowed some what. COULD the met's view change?

It can and will change , nothing is over yet !!

[Cheese Rice]

What Model is this from does anyone know? It's on the Daily Mail article but I can't tell which model its of.

[Gavin Hannah]

What Model is this from does anyone know? It's on the Daily Mail article but I can't tell which model its of.

That looks like todays or tomorrows chart. Likely GFS.

Edited December 9, 2012 by IBringTheHammer

[Frosty.]

What I can't seem to get out of my mind is that the metoffice seem to think that there will be no significant cold after this week for the foreseable. Surely they have more info and data than we can see. It must be said though that the Atlantic push does seem to have slowed some what. COULD the met's view change?

Yes because even they don't know whats going to happen on thurs/fri yet, as they just said on tv. This is going to become very interesting over the next day or so, we are definately in with a chance of significant upgrades if the models have underestimated the cold block in any way at all. Human error and computer error could still tip the balance in our favour.