Model Output Discussion - 05/01/2016 18z onwards

[snowray]

Incredible how GFS )perational & Control runs have been the mildest and most progressive ensemble members consistently over the last few day, and now everyone else is towing the line. Well done GFS.

[chrisbell-nottheweatherman]

30 minutes ago, chionomaniac said:

Another good post S. Worth pointing out that so far no SSW has been forecast. The 'crush' on the vortex will also occur prior to a major warming that does not produce a SSW. So you can have the +ve AO pain but not the end game tropospheric disturbances.....Though the strat vortex will be a lot weaker as a result anyway.

Chiono - by this, are you thinking that, if the switch to a +AO does resolves as ECM predicts, that it might stay that way until Spring - hence February being  near-rerun of December?

[Duane S.]

14 minutes ago, snowray said:

Incredible how GFS )perational & Control runs have been the mildest and most progressive ensemble members consistently over the last few day, and now everyone else is towing the line. Well done GFS.

Sorry, you've lost me, well done for what again? Have you travelled back from the future?

[nick sussex]

Basically the strat has done us no favours throughout the winter, the current colder window of opportunity IMO is inspite of it then now when we want to see more amplitude it throws its toys out of the pram due to the current warming and wants to push the AO into positive territory and increase the westerlies.

So in the UK where its painful to get any cold, theres supposed to be more pain in case of some gain at some point in the future!

Enough already with this pain!

 

[Kentish Snowman in Yorks]

29 minutes ago, snowray said:

Incredible how GFS )perational & Control runs have been the mildest and most progressive ensemble members consistently over the last few day, and now everyone else is towing the line. Well done GFS.

Assuming they are right (I believe they are not).

At that range, and we are still talking FI here, whole ensemble suites can flip just as easily and quickly as the op runs.

If we are sitting here bathed in mild temperatures by this time next week, we will then be able to congratulate the GFS - not before.

[Man With Beard]

38 minutes ago, warrenb said:

OK so we are looking at a possible breakdown at 120, so do we have comparative charts for 120 hours ago from the big 3 from the 0Z runs, to compare to where we are right now ?

Here goes. Easily obtainable on meteociel.fr - just find the "archive" link for each model

This is the 00Z chart as it actually turned out

ECM at T120:

GFS

UKMO

Fairly good performance all round except when you look at Greenland, where the GFS was clearly ahead IMO. Interesting.

[karlos1983]

9 minutes ago, nick sussex said:

Basically the strat has done us no favours throughout the winter, the current colder window of opportunity IMO is inspite of it then now when we want to see more amplitude it throws its toys out of the pram due to the current warming and wants to push the AO into positive territory and increase the westerlies.

So in the UK where its painful to get any cold, theres supposed to be more pain in case of some gain at some point in the future!

Enough already with this pain!

 

Not sure what you think Nick, but for me if we don't see a shift towards the GFS from the UKMO, then I will eat my hat, scarf, gloves and shoes if the ECM doesn't make a significant step in the same direction. Also the GFS will need to continue its corrections from the 06z, but it's so far off the UKMO now, I'd be surprised if it flips completely on the 12z, more of a gradual Reluctant stroll towards it. Still 50/50 for me which way this goes and only because of the UKMO dogged stubbornness to stick with its amplified output. 

Yet again, another interesting 12z to come... 

[warmintim]

At this point it's of no use claiming victory for one suite over another. I would guess we will end up with a blend of all, but the emphasis will be which model comes in closest to the actual weather. It's easy to look at the GEFS ensemble and assume that it's 'won' however a small shift in progression can lead to very different outcomes, especially when the target area of interest (broadly the UK, but tbh for most of us the backyard...) is so small. The 12z will gives more of a steer - wasn't it always the case - more modelling required!

[warrenb]

12 minutes ago, Man With Beard said:

Here goes. Easily obtainable on meteociel.fr - just find the "archive" link for each model

This is the 00Z chart as it actually turned out

ECM at T120:

GFS

UKMO

Fairly good performance all round except when you look at Greenland, where the GFS was clearly ahead IMO. Interesting.

I asked this, a it is an unusual pattern and wanted to see how it was handled from a week ago to now. So looking at that, the GFS had the best handle on this.

[nick sussex]

5 minutes ago, karlos1983 said:

Not sure what you think Nick, but for me if we don't see a shift towards the GFS from the UKMO, then I will eat my hat, scarf, gloves and shoes if the ECM doesn't make a significant step in the same direction. Also the GFS will need to continue its corrections from the 06z, but it's so far off the UKMO now, I'd be surprised if it flips completely on the 12z, more of a gradual Reluctant stroll towards it. Still 50/50 for me which way this goes and only because of the UKMO dogged stubbornness to stick with its amplified output.

Yet again, another interesting 12z to come...

 

Well I suppose the odds would be on some backtrack from the UKMO but at least the GFS has stopped the rot. Yesterday was just one long slide into a more progressive pattern. Today theres been some small adjustments westwards with a touch more amplitude. Actually the adjustment needed isn't quite as large as one would think, distribution of energy off troughing against a high is tricky. Relatively small adjustments can have rather larger differences in that type of set up.

We'll see this evening how much more mileage there is but we are running out of road, we need to see both the ECM and GFS move towards the UKMO if that manages to hold firm.
 

[chrisbell-nottheweatherman]

14 minutes ago, Man With Beard said:

Here goes. Easily obtainable on meteociel.fr - just find the "archive" link for each model

This is the 00Z chart as it actually turned out

ECM at T120:

GFS

UKMO

Fairly good performance all round except when you look at Greenland, where the GFS was clearly ahead IMO. Interesting.

I would suggest that the GFS, true to form, rather overplayed the depth of the low.

[Alexis]

Yes, the ECMWF looks closest to my eyes?

 

None of them predicted the alignment of our big trough perfectly though. 

[Man With Beard]

7 minutes ago, chrisbell-nottheweatherman said:

I would suggest that the GFS, true to form, rather overplayed the depth of the low.

There's a bit of a theme here. GFS - good at Greenland, not good at Atlantic lows. ECM - much better at the Atlantic but poor with Greenland. UKMO - sometimes brilliant, sometimes awful!

Does that really help us work out next week - no!! 

 

[weather eater]

Yea the GFS has always had a tendency to over deepen LPs at that sort of range. However, it does not tend to over cook blocking which both the ECM and the UKMO do.

[Frosty.]

4 minutes ago, dragonfalls said:

So are we still getting cold Thursday Fri or is it average for Jan 

It's going to be below average for Jan with sub zero nights and very low single digits celsius by day but even average for Jan is lovely following that vile blow torch which dominated December!

[Paul_1978]

24 minutes ago, nick sussex said:

 

Well I suppose the odds would be on some backtrack from the UKMO but at least the GFS has stopped the rot. Yesterday was just one long slide into a more progressive pattern. Today theres been some small adjustments westwards with a touch more amplitude. Actually the adjustment needed isn't quite as large as one would think, distribution of energy off troughing against a high is tricky. Relatively small adjustments can have rather larger differences in that type of set up.

We'll see this evening how much more mileage there is but we are running out of road, we need to see both the ECM and GFS move towards the UKMO if that manages to hold firm.
 

I agree totally, we are running out of road. If the UKMO trumps the others I'll doff my cap to it, but the overwhelming signal is for the GFS to be right and bring in southwesterly's, and also bearing in mind the probable change to +AO. I hope the UKMO is right but I can't see it bearing in mind it's being outvoted by the other main players model wise.

As always though @Steve Murr has that knack of being able to give us all a glimmer of hope. 

[MKN]

In the not to distant future this low crossing us will be a nightmare to forecast, One place could see snow and 5miles down the road see rain, The precip rates and elevation will be the key differences. Hopefully this produces some lying snow for some of us. Still small window for improvements

[mb018538]

I think the whole forum is pinning its hope on the UKMO and Steve's unbounded optimism!

It's either a big win for the ECM/GFS or a cataclysmic win for the UKMO if it ends up being right. Something has to give, they can't both be right!

[Weather Boy]

3 hours ago, Nick F said:

Indeed, dew points 0C and below ahead of the frontal band though snow to rain event, just for fun:

Further corrections to a more negatively tilted trough/frontal alignment approaching UK late Sun/early next week from GFS on the 12z?

Really shouldn't be concentrating in such detail at that range given the uncertainty past t+120, but not a great deal of snow looking likely from this cold snap before then away from Scotland and higher ground.

 

Hi Nick

So have we now written off snow potential for English lowland for Thurs and Friday?  I can see that it's a bit of an outside benefit as the northerly is not very 'clean'.  Just wondering if those with more experience than myself have totally written off the event at the end of the week?

Cheers,

[NO LONGER POSTING]

54 minutes ago, Weather Boy said:

Hi Nick

So have we now written off snow potential for English lowland for Thurs and Friday?  I can see that it's a bit of an outside benefit as the northerly is not very 'clean'.  Just wondering if those with more experience than myself have totally written off the event at the end of the week?

Cheers,

Hi Weather boy, if you jump into the South East thread we are discussing it now.. Good read and un-biased opinions! 

[Geordiesnow]

2 hours ago, Frosty. said:

I don't agree, we are not just going to flirt with cold, it's a proper cold snap with plenty of frosts and increasingly wintry ppn with accumulating snow for some of us.

Yes its a proper cold snap but unfortunately pressure starts to build when the cold actually consistently sets in(i.e no mild sectors) so snow will be limited I feel. Some places will see snow but I think it be the night time minimums for this weekend could be the main talking point, potentially some very low minimums on offer despite a lack of snow cover for the majority. 

I think the ECM has edged more towards the UKMO this morning in the short term and it has slightly delayed any Atlantic influence coming in which is probably a good sign. Lets see what this afternoon's runs bring, as usual, it will be interesting but you still got the favour the Atlantic winning out at this stage. 

[Nick F]

1 hour ago, Weather Boy said:

Hi Nick

So have we now written off snow potential for English lowland for Thurs and Friday?  I can see that it's a bit of an outside benefit as the northerly is not very 'clean'.  Just wondering if those with more experience than myself have totally written off the event at the end of the week?

Cheers,

Not written off any snow potential, just the models are not currently signalling any significant lowland snow on the back edge of Thursday's system crossing England and Wales away from Scotland and the higher ground of England and Wales, lowland England and Wales perhaps seeing some back edge wet snow on Thursday that will unlikely settle given projected temps, though ECM does indicate a spell of lowland snow for northern and eastern England (as far south as Norfolk) Thursday morning, though again may not settle at low levels:

Perhaps some sleet and snow showers for lowland eastern England on Friday, as the cold northerly/northwestelry kicks in behind that low. ECM has sleet/snow shower signal for western coasts too.

Of course, with such marginal situations, rain/snow line and temp to allow snow to settle may change a lot nearer the time, so nowcasting is better to get a feel of where it will snow  ... but as it's a deepish system on Thursday, there maybe too much mixing to allow evaporative cooling to lower the temp enough for snow to settle at lower levels.

Edited January 12, 2016 by Nick F

[Midlands Ice Age]

2 hours ago, weather eater said:

Yea the GFS has always had a tendency to over deepen LPs at that sort of range. However, it does not tend to over cook blocking which both the ECM and the UKMO do.

 

I do not understand many of the preceeding posts discussion....

 GFS is the one that has overstated the Greenland high. Not the other way round.

It was forecasting a high of 1055MB for the Greenie.

Both the ECM and MO had it at 1040.  The ECM was a very flabby affair -  The result was 1045mb.

So the Euros were better at predicting the lower pressure at that stage.

How can you  claim that it is better at not overcooking northern blocking as per the Euros? (from that chart)?

Looking further afield it has the main Euro trough centered over Poland.... Result - it is over The North Sea.

Admittedly it did show a superficial split low - but so did the ECM, and the ECM correctly forecast that the low over Scotland would be the main centre and not the GFS..

None of them spotted the remaining low pressure to the south of Greenland.

My verdict is the Euro's looks better with the overall pattern.

Am I  wrong or simply mis-reading?

 

 

Edited January 12, 2016 by Midlands Ice Age

[Eskimo]

Would you then conclude that this isn't really a 'cold spell', more akin to average if conditions for snow are still marginal? But not just that, the 2m temperature are also around the average. 

Edited January 12, 2016 by PerfectStorm

[chrisbell-nottheweatherman]

3 hours ago, chrisbell-nottheweatherman said:

Chiono - by this, are you thinking that, if the switch to a +AO does resolves as ECM predicts, that it might stay that way until Spring - hence February being  near-rerun of December?

Quoting myself, but, while Chiono is busy in the strat thread, I thought I'd link from that very thread regarding worries expressed here on a move to a +ve AO (bear in mind I don't understand the technicalities of this at all - just passing-on some information which I think will be of interest:

Quote

 

 

In brief, Cohen (a highly respected researcher into stratospheric matters) anticipates a relatively short-lived rebound in troposheric AO values as the warming, whether it qualifies as an SSW or not, gets going.  After this, the warmed stratosphere is anticipated to quite significantly effect the troposhere, which, if the trop. AO is +ve, would possibly send it -ve again.  Obviously, if the vortex is displaced rather than ripped asunder, it might still fall badly for us, but I don't get the impression that we're likely to see a re-run of December right the way from early next week through till mid-March.

Edited January 12, 2016 by chrisbell-nottheweatherman
Correcting typo.