Model Output Discussion; into 2015

[meathead]

Anyone else concerned about the 30 day met office forecasts? pretty much no mention of cold.

[nick sussex]

Just caught up with the outputs and not much change since yesterday. To add to the complications these southern stream lows ejecting out of the southern USA which are a nuisance especially if these phase unfavourably with lows exiting the northern stream.

 

The lack of updates re the MJO also cloud the issue because this signal could be the determining factor for any UK cold. Aswell as this there is no clear trend within a reasonable timeframe to suggest a  pattern change.

 

Regardless of whether the majority of GEFS at some later timeframe show colder synoptics we need to see these move forward and not stuck past T240hrs.

 

Whilst its a positive that the Azores high might displace further west the issue is whether this will amplify sufficiently, PM shots just don't really deliver especially in such a fast moving pattern where before you know it any colds gone.

 

So rather than putting up with a few leftovers we need to see a lot more amplification upstream and  need the MJO to deliver to at least get a better chance of a decent cold spell or even a cold snap that can deliver some cold and snow and not a two hour slushfest!

 

Sorry if my post comes across as a bit negative but theres a danger that any change is being overstated in here when in reality we have a few GEFS and GFS operational runs hinting at some possibilities, the ECM as yet we don't know because its out of range, the ECM ensembles whilst showing a colder cluster do not show anything of note.

 

It probably will turn somewhat colder but we're a long way yet from the type of synoptics that can really deliver what people want to see.

 

That may well happen especially if the MJO can help but I think some realism is needed in here. As everyone knows I love the cold and snow and if I see something interesting I'm not one to keep quiet!

Edited January 5, 2015 by nick sussex

[Hocus Pocus]

I can't help but feel we're being led up the garden path again with regards to any lasting cold spell as the MetO still aren't buying into the GFS solution and one can only assume that MOGREPS and the ECM clusters aren't keen on anything other than TM and RPM weather effecting us for the rest of this month at least.

[karlos1983]

Just caught up with the outputs and not much change since yesterday. To add to the complications these southern stream lows ejecting out of the southern USA which are a nuisance especially if these phase unfavourably with lows exiting the northern stream.

 

The lack of updates re the MJO also cloud the issue because this signal could be the determining factor for any UK cold. Aswell as this there is no clear trend within a reasonable timeframe to suggest a  pattern change.

 

Regardless of whether the majority of GEFS at some later timeframe show colder synoptics we need to see these move forward and not stuck past T240hrs.

 

Whilst its a positive that the Azores high might displace further west the issue is whether this will amplify sufficiently, PM shots just don't really deliver especially in such a fast moving pattern where before you know it any colds gone.

 

So rather than putting up with a few leftovers we need to see a lot more amplification upstream and  need the MJO to deliver to at least get a better chance of a decent cold spell or even a cold snap that can deliver some cold and snow and not a two hour slushfest!

 

Sorry if my post comes across as a bit negative but theres a danger that any change is being overstated in here when in reality we have a few GEFS and GFS operational runs hinting at some possibilities, the ECM as yet we don't know because its out of range, the ECM ensembles whilst showing a colder cluster do not show anything of note.

 

It probably will turn somewhat colder but we're a long way yet from the type of synoptics that can really deliver what people want to see.

 

That may well happen especially if the MJO can help but I think some realism is needed in here. As everyone knows I love the cold and snow and if I see something interesting I'm not one to keep quiet!

 

Good post Nick, it is extremely difficult to argue with anything you say to be honest. It does seem at the moment everything possible is going against the UK getting what I would call "Real Cold".

[nick sussex]

Good post Nick, it is extremely difficult to argue with anything you say to be honest. It does seem at the moment everything possible is going against the UK getting what I would call "Real Cold".

Thanks, it's been like that for the last two winters, although at least this winter has seen a few decent frosts and a few saw snow after Christmas.

 

Unfortunately Karlos in here mentioning colder can then morph into severe cold, ice days and snow. The whole thing snowballs so that suggesting something colder gets taken as 5 star synoptics.

 

If the Azores high displaces it will allow more digging of low pressure into mainland Europe so that's a small step in the right direction, after that really a lot of uncertainty.

[Frosty.]

Another Beautiful GEFS 06z perturbation, and there have been many like it in recent days..P3 would be very nice as a new pattern beyond mid month. :-)

[Mucka]

Seems to be a lot of NIMBY posts around again today making comment on no cold etc.

Reality has a mean of - 6/7c uppers with plenty of ppn for the weekend for Northern England but nothing wintry in the charts? 

After this week there will be good snow chances even to low levels in Northern areas with sleet and snow showers pushing quite far in land over the weekend (Cheshire gap) IF the current output is about right.

England is not confined to the SE.

 

As for the pattern change possibilities still fairly low but persistent signal for changes around mid month but certainly nothing to suggest it is imminent.

Currently looks like there will be some form of attempt for an Atlantic ridge to build, could still be some widespread snow around if low pressure is far enough South and Atlantic loses momentum in this phase. Thereafter blocking or Atlantic to establish dominance last 3rd of Jan.

 

12z Op has a more prominent Azores high than recent runs and that could still play spoiler but hopefully not for those in NW England. 

Edited January 5, 2015 by Mucka

[karlos1983]

Seems to be a lot of NIMBY posts around again today making comment on no cold etc.

Reality has a mean of - 6/7c uppers with plenty of ppn for the weekend for Northern England but nothing wintry in the charts? 

After this week there will be good snow chances even to low levels in Northern areas with sleet and snow showers pushing quite far in land over the weekend (Cheshire gap) IF the current output is about right.

England is not confined to the SE.

 

As for the pattern change possibilities still fairly low but persistent signal for changes around mid month but certainly nothing to suggest it is imminent.

Currently looks like there will be some form of attempt for an Atlantic ridge to build, could still be some widespread snow around if low pressure is far enough South and Atlantic loses momentum in this phase. Thereafter blocking or Atlantic to establish dominance last 3rd of Jan.

 

12z Op has a more prominent Azores high than recent runs and that could still play spoiler but hopefully not for those in NW England. 

 

nor is it confined to the Cheshire Gap or N England for that matter Mucka. -6/7C Uppers in a North Westerly flow won't cut it for the majority of the UK, unless you are at elevation. so IMBY is no better than Not.

[nick sussex]

nor is it confined to the Cheshire Gap or N England for that matter Mucka. -6/7C Uppers in a North Westerly flow won't cut it for the majority of the UK, unless you are at elevation. so IMBY is no better than Not.

True and PM shots normally get downgraded nearer the time as the models tend to overdo the cold advection south at longer range.

 

The one currently modelled is a blink and you'll miss it affair, it might give a few hours of excitement for some lucky areas but overall a damp squib unless the outputs can find some last minute upstream amplification.

[Mucka]

nor is it confined to the Cheshire Gap or N England for that matter Mucka. -6/7C Uppers in a North Westerly flow won't cut it for the majority of the UK, unless you are at elevation. so IMBY is no better than Not.

 

Hi Karlos

Having lived in the area all my life I can tell you this mornings 00z runs would bring snow showers that would penetrate even the the South Manchester snow shield.

Anywhere with elevation will take a pasting with showers likely to be frequent and heavy in such a strong west/NW flow.

We will have to wait and see what the actual charts are like for the weekend and discuss it then. TWT.

[karlos1983]

Hi Karlos

Having lived in the area all my life I can tell you this mornings 00z runs would bring snow showers that would penetrate even the the South Manchester snow shield.

Anywhere with elevation will take a pasting with showers likely to be frequent and heavy in such a strong west/NW flow.

We will have to wait and see what the actual charts are like for the weekend and discuss it then. TWT.

 

I can imagine with a chart like this, you could well be correct. I genuinely hope so. 

[Mucka]

True and PM shots normally get downgraded nearer the time as the models tend to overdo the cold advection south at longer range.

 

The one currently modelled is a blink and you'll miss it affair, it might give a few hours of excitement for some lucky areas but overall a damp squib unless the outputs can find some last minute upstream amplification.

 

Disagree Nick. I remember we had a discussion (I think it was with you) about another Nwesterly a couple of years ago or so. That time I was actually in the opposite camp because the flow wasn't long fetch nor sustained for 24h+ and was proved right. If this mornings output is about right we wills see snow showers in the NW to low levels.

Any accumulations will very likely require elevation though heavy showers in the cold of dawn could well give temporary coverings for places like Oldham.

Guess this needs to be regional.

 

EDit.

 

I do agree GFS can overplay these things, think I mentioned that a couple of days ago but it is also showing on UKMO and ECM.

Still time for the AH to do its think and kill it but currently looks promising for snow showers to me.

Edited January 5, 2015 by Mucka

[Captain Shortwave]

Hi Karlos

Having lived in the area all my life I can tell you this mornings 00z runs would bring snow showers that would penetrate even the the South Manchester snow shield.

Anywhere with elevation will take a pasting with showers likely to be frequent and heavy in such a strong west/NW flow.

We will have to wait and see what the actual charts are like for the weekend and discuss it then. TWT.

Very short window though, just Saturday night looks like holding potential before the 850s warm out and the showers die away before the next front moves in. Still better than nothing. Potency may change but given the strong westerly pattern, that colder flow has probably a 95% chance of verifying. The parallel is very similar but the UKMO would eek the whole of Sunday for a fine day with showers in the west, though 850s are very marginal and the crucial chart (Saturday) hasn't turned up.

 

GFS low res - Just a brief toppler on the 16th/17th before high pressure builds in (or at least tries too)

Edited January 5, 2015 by Captain shortwave

[karlos1983]

That low coming of the southern east coast of US is a pain in the plums! Puts a halt to the Ridging in the Atlantic.

 

Temporarily if the GFS is to believed. serious model fatigue kicking in now 

Edited January 5, 2015 by karlos1983

[Mucka]

I can imagine with a chart like this, you could well be correct. I genuinely hope so. 

 

 

Yes that would do it but I accept the Azores high could easily change the outlook to something more mundane.

[terrier]

Looks like we could see a 945mb low hitting Scotland and Northern England fri/sat on latest output. This would bring gusts in the range of 80mph and heavy rain. Think with the cold chasing we could be missing the nearer term. Looks like it could be very nasty stay safe. And hopefully models will downgrade it over days ahead.

[Betleyblizud]

Seems to be a lot of NIMBY posts around again today making comment on no cold etc.

Reality has a mean of - 6/7c uppers with plenty of ppn for the weekend for Northern England but nothing wintry in the charts? 

After this week there will be good snow chances even to low levels in Northern areas with sleet and snow showers pushing quite far in land over the weekend (Cheshire gap) IF the current output is about right.

England is not confined to the SE.

 

As for the pattern change possibilities still fairly low but persistent signal for changes around mid month but certainly nothing to suggest it is imminent.

Currently looks like there will be some form of attempt for an Atlantic ridge to build, could still be some widespread snow around if low pressure is far enough South and Atlantic loses momentum in this phase. Thereafter blocking or Atlantic to establish dominance last 3rd of Jan.

 

12z Op has a more prominent Azores high than recent runs and that could still play spoiler but hopefully not for those in NW England. 

 Yes Mucka the potential on the current output for say Lancs, Cheshire, North Wales and North Midlands to see some significant snow is there. Of course it may not last that long  and it is fair to say that, generally, easterley winds tend to bring longer and deeper cold spells. Of course because this can effect the South East significantly we hear more about it. Crewe Cold will remember a xmas around 2004/2005 when up to 4/5 inches of snow fell in Cheshire on xmas day but the charts were "rubbish", "useless" and "Bartlett type" as nothing fell south of London.

 

Perhaps something for 'newer' visitors to consider. Look at the chart for your own area rather than relying on someone elses comments as there will naturally be a IMBY bias. Also another top tip. When we do, finally, get a real cold spell expect posts within 30 seconds of the models coming out and at 'T10 minutes' stating "The azores high is 2 miles further west this is going to be a bad run" and by T24 "This going to be a big backtrack as its not quite as blue over the UK". Its a great thread though!!

[johnholmes]

That low coming of the southern east coast of US is a pain in the plums! Puts a halt to the Ridging in the Atlantic.

 

 

Temporarily if the GFS is to believed. serious model fatigue kicking in now 

not unexpected though when looking at the 500mb anomaly charts?

Edited January 5, 2015 by johnholmes

[The Eagle]

All aboard the Polar Maritime train....snow showers for some, miniature flags for others

 

[nick sussex]

Both GFS's are flatter upstream at T186hrs, not a great sign really, even though the GFS finds some amplification in its lower resolution the fact that its not till the drop in resolution would be a concern.

 

The GFS P has lost that amplified wave that worked east amplifying the ridge ahead of it. Overall disappointing, lets hope the ECM can raise spirits because both GFS's are seriously underwhelming.

[Mucka]

Transient snow chances for the NW aside.  No eye candy on the Op but at least the signal for Atlantic ridge is there for the glass half full types.

Be a few days yet before we have good idea of what will happen but some form of toppler is currently favourite I guess?

 

[mountain shadow]

As expected, GFS op drops any HLB and delivers a Euro high instead..

 

http://max.nwstatic.co.uk/gfsimages/gfs.20150105/12/372/h500slp.png

 

Think we can write anything off for January.

[nick sussex]

You can clearly see here how it all goes pearshaped upstream:

 

The GFS P 06hrs run to 204hrs:

 

 

The GFS P 12hrs to T198hrs:

 

 

The latter much flatter upstream, without that amplitude theres nothing to help interact with low heights over Greenland to pull the PV further to the nw.

 

And because of that you don't develop the more amplified ridge ahead of the upstream low.

 

 

 

 

[Mucka]

As expected, GFS op drops any HLB and delivers a Euro high instead..

 

http://max.nwstatic.co.uk/gfsimages/gfs.20150105/12/372/h500slp.png

 

Think we can write anything off for January.

 

The Op and parallel are poor this evening but that is a bold forecast. 

[karlos1983]

not unsexpected though when looking at the 500mb anomaly charts?

 

Hi John, anomaly charts are my summer 2015 homework for next winter. Not really got my head round them, but I have saved a fair few of your posts/PDF which I will be reading when my model watching comes to an abrupt end in Summer. So keep them coming