Model Output Discussion - 8th December Onwards

[Snowly does it]

and then it all gets very very messy and revert to type with a magical toppling Greenland PV reload special.

[Jonan92]

PV over Greenland? That makes nonsense

[Gael_Force]

Thank you Snowmad. Yes, exactly, it is such a good example of how this battle can happen. It's been a while since anything similar happened.

There must be a broadly similar pattern now for that month to be second top analog.

[Frosty.]

well it gets there by day 11 after a week of Atlantic attack. Lots of cherry bites required it seems.

4 days of cold weather, a week of average westerlies occasionally milder than average then Siberian HP to the rescue for Christmas? We'll see

No guarantee we will have a week of average westerlies, it's only an op run. I still think we can expect big changes in the next few days because there is a lot still unresolved I M O. We at least have more of a battle ahead compared to yesterday and the north of the uk could become very snowy later in the week.

Edited December 9, 2012 by Frosty039

[Zenarcher]

I've marked out the changes in the UKMO from the 12z yesterday,

[Damp and dreary]

you know what, scrap my earlier comment, cos this either vindicates what I said or simply insults our intelligence!

And so the cycle of never leaving the Net Weather forums continues

Just when i start to think il be watching a bit less (not very likely really) up pops another interesting senario.....

[Panayiotis]

All in all, we have some slight upgrades in the short term and some really good trends in the longer term, looking forward to what the ECM and 18z deliver...

[Ian Brown]

I think we should be happy with the 12z. With the PV relocation to Siberia, the block over Western Russia should not be going anywhere other than perhaps extending heights West or South Westwards depending on how active the jet is in the mid-Atlantic.

We need this consistency to be shown over the coming runs, the METO might be confident of Westerlies and mild weather for the South up to the 23rd, but I'm not !

[LomondSnowstorm]

Another fine run from the GEM in the shorter term:

Less progressive, a better tilted trough and disruption at the southeastern edge of the trough into continental Europe.

Pretty close to a proper undercut at that.

[Gavin Hannah]

A little something for everyone. Running through the 06, and the 12, I have noticed that the major difference is obv the LP and what happens to said LP, will it eject a shortwave? etc.. What is very consistent is the HP over Siberia strengthening and getting closer.

A look at t.144 demonstrates the difference in the LP progging and the consistency of the Siberian HP cell.

[Frosty.]

It's all to play for still, a big improvement on the last few days, models don't just do a complete U Turn but there is now a genuine hope of the cold lasting longer with more snow in the mix and hope remains of further upgrades either by the ecm 12z or tomorrow's 00z. This morning's 00z was a nice surprise, no reason why tomorrow won't be either.

[Methuselah]

Sometimes though, despite all the recent advancements in computer modelling, I sometimes yearn for the olden days: all those mysterious-looking charts that hardly extended past the British Isles; when a HP barely north of Scotland seemed invincible, and a five-day Nor'easter looked as if it might go-on forever?

[Pixel]

I won't post anymore charts, I think they annoy the MODs...

I hope this was tongue in cheek.. the thought of a model thread without folk posting charts to support their opinion is frankly quite scary.. I hope you feel better now after posting more (-;

the jet has definitely taken a southerly dip in recent runs.

I also notice the low in the atlantic is projected to arrive earlier than previously suggested which could be an overestimation - heights are building around Russia and the energy out of the USA is less than previously modelled. Lets see if the next few runs hold back the atlantic low a little.. The result 'could be' a battle ground on our doorstep - east meets west.

There's a dream of a squeezing of 'that' low further south of our shores but I will be watching the next few runs through the fingers of my hand to see if this happens. Maybe we could just end up having the slate wiped clean for another attempt at.... er lets call it an easterly who knows (-:

Certainly very interesting model watching over the next few days.

[Cecil Hogmanay Melchett]

I think we should be happy with the 12z. With the PV relocation to Siberia, the block over Western Russia should not be going anywhere other than perhaps extending heights West or South Westwards depending on how active the jet is in the mid-Atlantic.

We need this consistency to be shown over the coming runs, the METO might be confident of Westerlies and mild weather for the South up to the 23rd, but I'm not !

I suspect the huge Russian high is going to be a hinderance not a help as we move forward.

[in the vale]

The deterministic models are really struggling with this NH set-up. Perhaps not surprising really, these sorts of battered PV and blocking scenarios are uncommon and so the maths behind the much more common atlantic incursions will perhaps have a stronger influence on the predicted outcomes. In effect, although the ensembles are supposed to show sensitivity to input values and slight tweaks to the maths, the dice are all loaded towards a westerly influence. The same with human input (the met are obviously adding their own significant expertise) as this is also flip-flopping to some degree - if in doubt look to the west, in 9 of 10 years that will be the correct outcome. The maths is also based on this no doubt - after all, what else is there to base the model on other than previous outcomes? I know I sound like a stuck record, but if you stand back and look at all the evidence (incl. the atlantic bias) then all I see is ups and downs, but all in all a trend towards cold, easterly-influenced winter weather for this year and the early part of next.

Edited December 9, 2012 by in the vale

[karyo]

All in all, we have some slight upgrades in the short term and some really good trends in the longer term, looking forward to what the ECM and 18z deliver...

I can't see where the slight upgrades are.

If we take the 12z output so far (UKMO and GFS) up to 144 hours compared to the 0z, then we have a faster breakdown of the cold spell and less chance of snow.

All and all a step in the wrong direction so far.

Karyo

[Snowman31]

I am confident of another Chance of a serious cold spell in the near future as long as we keep the Russian high too our west, and I think the strength of the atlantic is being overestimated.

I hope all of you up north get some snow later in the week, but I am personally.more interested in for the hope of a bigger cold spell then transient snowfall, although it would ne nice.

I don't trust the ukmo long range forecasts that much to be honest. I remember before I found this forum I used to check them daily every winter and they would change their tune on a regular basis.

Edited December 9, 2012 by Snowman31

[John Cox]

I think we should be happy with the 12z. With the PV relocation to Siberia, the block over Western Russia should not be going anywhere other than perhaps extending heights West or South Westwards depending on how active the jet is in the mid-Atlantic.

We need this consistency to be shown over the coming runs, the METO might be confident of Westerlies and mild weather for the South up to the 23rd, but I'm not !

By the way Ian....

I said I would get back to you if our Met Office got it wrong with regards to the cold and snow this week.... They did

[Ian Brown]

I suspect the huge Russian high is going to be a hinderance not a help as we move forward.

Possibly not in this case, it can be if the PV is over Greenland and depressions can't pass the Meridian because you can send up stuck in a rut on the wrong side of the cold air, here we are seeing the potential for Atlantic systems to run out of steam and/or possibly undercut to retrogress the heights at Northern latitude.

[Jason M]

I suspect the huge Russian high is going to be a hinderance not a help as we move forward.

There is certainly a risk that that could happen. If the high doesn't back west we will be left in no mans land with predominantly southerly winds. This would be a disaster for the West Country as it would involve massive amounts of rain for weeks on end.

Jason

hopefully Ian's optimistic take is correct :-)

Edited December 9, 2012 by Jason M

[BLAST FROM THE PAST]

Sometimes we see very stubborn blocking systems and indeed many times they can be a hindrance. This coming block as no intentions of moving very far and this will see the Atlantic get held, and it looks like over or close to us. This really sets us up for a potential soaking, and probably some pretty stormy weather too. The real cold is not going to get a chance to move over us and thus any snow will be shortlived, indeed I suspect most of us won't get any. It'll be and feel cold yes...

Where do we go from here, well there's RJS thoughts, MetO thoughts, maybe a sobering and realistic thought. GP suggested too that the tank will need refuelling as the first spillage of serious cold will take time to replenish from the north before another surge......well the deep cold isn't looking like even reaching us so I think we got some waiting to do.

BFTP

[Jonan92]

Sometimes we see very stubborn blocking systems and indeed many times they can be a hindrance. This coming block as no intentions of moving very far and this will see the Atlantic get held, and it looks like over or close to us. This really sets us up for a potential soaking, and probably some pretty stormy weather too. The real cold is not going to get a chance to move over us and thus any snow will be shortlived, indeed I suspect most of us won't get any. It'll be and feel cold yes...

Where do we go from here, well there's RJS thoughts, MetO thoughts, maybe a sobering and realistic thought. GP suggested too that the tank will need refuelling as the first spillage of serious cold will take time to replenish from the north before another surge......well the deep cold isn't looking like even reaching us so I think we got some waiting to do.

BFTP

In the last GFS runs the strong atlantics influende did just last 4-5 days, after that GFS keeps showing highs rising again

[Stu_London]

Dreadful 12z GFS for snow lovers in the reliable time frame.

Temps will be a bit below average but by the time the ppn moves in everyone except scotland and highest part of pennines on the wrong side of marginal.

Not a great FI (06z was much better) but plenty up for grabs if teleconnections can be believed.

[EML Network]

Running through each of the GFS runs, we look to have much more agreement now about the orientation and angle of approach of the incoming Low Pressure system in the Atlantic.

All the runs have the system flattening as it approaches the UK, some runs have it further South than others, but I don't see it undercutting the UK.

The majority of the runs have the center of the system sitting close to Scotland at + 180, with the Russian High holding it's ground and all runs have some form of Azores High, which I think will become the major player there after, how the Azores interacts remains to be seen.

Run 12 sit's pretty much in between all the other variations, and is more likely to be closer to the mark, if one was to take this run at face value (Which by the way I am not doing, I am simply making a post in the 12z run as things stand currently)

[Cecil Hogmanay Melchett]

Possibly not in this case, it can be if the PV is over Greenland and depressions can't pass the Meridian because you can send up stuck in a rut on the wrong side of the cold air, here we are seeing the potential for Atlantic systems to run out of steam and/or possibly undercut to retrogress the heights at Northern latitude.

hmmm gfs and ukmo both have a super strong jet pulse and associated energy spilling across the Atlantic and even a block like thew one to the NE is getting shunted east ian.

FWIW i think we are looking at a protracted spell of zonality this side of christmas and posibly beyond,although to be fair id go for alternating between pm and tm air not exclusively mild sw based,in reality though thats carp to 99% of the UK as unless your high up on a mountain ooop north i think your chances of seeing snow are pretty poor in the short to medium term.