Model output discussion - heading into 2018

[gottolovethisweather]

I know I promised not to post and remain in lurk mode but, people would be advised to take heed of Man With Beard's post here, when following the daily outputs, never take notice of them in isolation as you need to follow the trends to get a better grasp of what the possibilities are for our little island, say ten days down the road. Take this quote from my post, last Saturday. A lot of you probably thought I was barking mad.

"A Boxing Day wintry breakdown from the NW possibly? Could well be the case, so watch this space! "

Anyways, chill guys, a milder spell will soon become a more turbulent spell from Boxing Day onwards and as the New Year approaches, I reckon it could get most interesting by way of colder scenarios with snow around. Boxing Day itself brings the first bout and there will be other temporary offerings as well. Transient snowfall incoming.

 

[Man With Beard]

11 minutes ago, Paul_1978 said:

Fair play - thank you for explaining, and at least you post the graphics with a robust explanation. Not knocking the other posters who mention these EPS, but sometimes we do seem to get conflicting messages that change day by day, difficult to decipher from a one liner. Cheers!

Thanks - to be fair I wonder if those of us who comment on the EPS are a little guilty of emphasising cold "signs" and "chances" that the overall picture gets missed sometimes. (Like today - we're talking of 10% chances of a Scandi High - perhaps it's easy to forget the other 90% of chances when they don't get mentioned). Me guilty of doing this too at times, probably. Must try harder

[Nick F]

27 minutes ago, snowblizzard said:

High 1036 over Greenland

High 1029 over Northern Europe linking into Scandinavia?

Low pressure heading into Spain

Azores high slipping SW

Encouraging signs or just a temporary position?

 

There's generally always a surface high over Greenland because of the dense cold over the ice sheet covering much of the landmass creating higher pressure (which is adjusted to mslp given the high elevation of the ice sheet) - meanwhile to the south we have a succession of lows barrelling in from the Atlantic across western Europe.

True, the jet is on a southerly track next week, bringing some transient cold and snow risk to northern areas, especially over the hills. But the models are consistently signalling an upper trough amplifying over the NW then mid-Atlantic next weekend onwards, which would amplify the jet north again over the UK downstream. There is the possibility that if the upper trough moving in from the west amplifies further it may undercut resulting ridge  building N toward Scandi downstream - but this potential is too far off in FI land to have any credibility for now. So realistically we are at the mercy of Atlantic lows rolling through next week before any concrete changes away from this pattern may become apparent.

[knocker]

12 minutes ago, Man With Beard said:

Thanks - to be fair I wonder if those of us who comment on the EPS are a little guilty of emphasising cold "signs" and "chances" that the overall picture gets missed sometimes. (Like today - we're talking of 10% chances of a Scandi High - perhaps it's easy to forget the other 90% of chances when they don't get mentioned). Me guilty of doing this too at times, probably. Must try harder

Surely not. No, No, I'm not having that.

[northwestsnow]

Well as posted somewhere above 6z does indeed offer wintry potential for the pennines etc-

Lets call a spade though, the medium to long term is dreadful again- we are probably a thousand miles to far west for any hope of an easterly getting to our shores -(on this run) and most likely on the ens set too...

[Interitus]

50 minutes ago, Nick F said:

00z EC and 06z GFS below showing a heavy snow signal for northern England and Northern Ireland Boxing Day evening/night on northern flank of low pressure system clearing east over central areas. Too far off to know whether the low track will be further north or south though and whether it will be cold enough for snow to fall and settle at lower levels. But some upland areas of the north could see spell of quite heavy and disruptive snow.

Reminds me of an evening in January 1995 when I was in Leeds at the time studying, when a similar system crossing central areas in a zonal flow had some snow on the northern edge and brought the city to a standstill.

Thinking of something similar much more recently than this, again Boxing day evening just three years ago - snow for upland areas and rain to snow for lowland parts from Wales across the north midlands. Not overly promising charts -

From the Met Office December 2014 review https://www.metoffice.gov.uk/climate/uk/summaries/2014/december a satellite image from the 28th -

22 cm of snow recorded at Middleton in Derbyshire.

Edited December 22, 2017 by Interitus

[bluearmy]

54 minutes ago, Man With Beard said:

Thanks - to be fair I wonder if those of us who comment on the EPS are a little guilty of emphasising cold "signs" and "chances" that the overall picture gets missed sometimes. (Like today - we're talking of 10% chances of a Scandi High - perhaps it's easy to forget the other 90% of chances when they don't get mentioned). Me guilty of doing this too at times, probably. Must try harder

Good post earlier - imo,  the eps are the best predictive tool we get to work with for the back end week 2. The gefs res falls off at day 8 and the eps at day 10. Therefore the eps direction of travel at day 11/12 is very important re reliability of patterns cropping up days 13/15.  As you say, one run in isolation is of little value. 

On the Scandi percentages, that’s a broad brush approach which avoids having to trawl through all 50 members !

im sure many of us would love to make in depth posts as BB1962/63 does but time rarely allows 

[Frosty.]

As yesterday, the GEFS 6z mean shows a pronounced cold signal for most of next week after xmas day, especially for the north with a risk of snow and frosty, icy nights.

[Summer Sun]

06z ens shows a cool down to be shortlived much milder to start 2018

[SLEETY]

2 minutes ago, Summer Sun said:

06z ens shows a cool down to be shortlived much milder to start 2018

But that’s over a week away,so lot will change in the ensembles,they flip flop all the time,as you should know considering how much you post in the forums 

[lassie23]

I'm expecting a yoyo this christmas, mild, cool, mild, then siberian freeze up into january, wonder if the models will agree

[MR EXTREMES]

2 hours ago, frosty ground said:

A scandi high starts to Build!

I'm afraid that's not the start of a Scandinavia block.

Seriously as I suggested yesterday very zonal northern areas could see a fair few surprises as systems pass through the UK.

Although average to above average temps in the south.

Northern Blocking seems more confined to the other side of the pole although as seen by the models higher heights to our south.

Unless the jet take a much more southerly route then anything sustainable in regards to cold sustained weather type,

is not likely.

But if we could squeeze a Scandinavia block then absolutely we could open the wintry flood gates.

[northwestsnow]

I'm afraid the models are trending milder generally with winds mainly from the west / south west- the metoffice are now suggesting January will be a milder than average month with perhaps a cooler slot mid way through the month.

The 6z ens have trended towards what looks like a euro high after new year.:( which sounds ominously like a euro high with the settled weather initially for the southern uk)  - reflective of the jet riding over the top.

 

Edited December 22, 2017 by northwestsnow

[Dean E]

I personally cannot see a great outlook for coldies in the next 10-15 days (At this stage). If you like mild, gloomy and potentially a little stormy, then you're getting a great Christmas present this year (and the 5/6 years before then!).

A quick snapshot at +192 from the GFS and ECM 0z

GFS +192hr                                                      ECM +192hr

        

I think the ECM is slightly overplaying the Canadian vortex thus producing a manic Atlantic, however this has been watered down overnight, so I believe the GFS is closer to the mark. Westerlies with Atlantic systems moving across the North is currently most likely during Christmas week.

At this point (+192) there is good agreement between the two with pressure rises over Asia/Pacific regions, with signs this pushing into the Pole into FI. One straw of a few to hold incredibly tight on to!

As with the last few winters, Heights over the Mediterranean is relentless. I can not see any sign of prolonged block patterns until this shifts.

[Daniel*]

23 minutes ago, northwestsnow said:

I'm afraid the models are trending milder generally with winds mainly from the west / south west- the metoffice are now suggesting January will be a milder than average month with perhaps a cooler slot mid way through the month.

The 6z ens have trended towards what looks like a euro high after new year.:( which sounds ominously like a euro high with the settled weather initially for the southern uk)  - reflective of the jet riding over the top.

 

ECM D10 is seemingly a long way from southwesterlies. A chilly start to 2018. Similarly GFS I find quite interesting while very mild for a time, with a southerly waft, how many times have we seen it go from very mild to very cold. The Met Office stress the uncertainty, I’d say the reason they’ve gone off a cold January is signs of SSW by their in house models has waned - nonetheless a big warming is not pivotal, we can still scrap reasonably good wintry weather.

 

Edited December 22, 2017 by Daniel*

[blizzard81]

4 minutes ago, Dean E said:

I personally cannot see a great outlook for coldies in the next 10-15 days (At this stage). If you like mild, gloomy and potentially a little stormy, then you're getting a great Christmas present this year (and the 5/6 years before then!).

A quick snapshot at +192 from the GFS and ECM 0z

GFS +192hr                                                      ECM +192hr

        

I think the ECM is slightly overplaying the Canadian vortex thus producing a manic Atlantic, however this has been watered down overnight, so I believe the GFS is closer to the mark. Westerlies with Atlantic systems moving across the North is currently most likely during Christmas week.

At this point (+192) there is good agreement between the two with pressure rises over Asia/Pacific regions, with signs this pushing into the Pole into FI. One straw of a few to hold incredibly tight on to!

As with the last few winters, Heights over the Mediterranean is relentless. I can not see any sign of prolonged block patterns until this shifts.

The ecm op has gone way over the top in its day 7 to 8 overblowing of the pv or Atlantic lows all season now. A bit of a joke really. 

[Frosty.]

35 minutes ago, northwestsnow said:

I'm afraid the models are trending milder generally with winds mainly from the west / south west- the metoffice are now suggesting January will be a milder than average month with perhaps a cooler slot mid way through the month.

The 6z ens have trended towards what looks like a euro high after new year.:( which sounds ominously like a euro high with the settled weather initially for the southern uk)  - reflective of the jet riding over the top.

 

It shouldn't be any surprise, it's what the ensembles have been showing for a while now. Talk of scandi  highs is pure fantasy wishful thinking although I admire those who put forward a good case for it occuring, however, it seems like we are looking at the Atlantic for our weather next month.

Edited December 22, 2017 by Frosty.

[northwestsnow]

7 minutes ago, Frosty. said:

It shouldn't be any surprise, it's what the ensembles have been showing for a while now. Talk of scandi  highs is pure fantasy wishful thinking.

Yes i was very suprised to see members expressing an optimistic tone this morning...the models ( and now exeter) are suggesting euro high dross...

Lets hope for a model flip soon.

Lets face it tho...thats looking increasingly unlikely.

[offerman]

2 hours ago, Nick F said:

There's generally always a surface high over Greenland because of the dense cold over the ice sheet covering much of the landmass creating higher pressure (which is adjusted to mslp given the high elevation of the ice sheet) - meanwhile to the south we have a succession of lows barrelling in from the Atlantic across western Europe.

True, the jet is on a southerly track next week, bringing some transient cold and snow risk to northern areas, especially over the hills. But the models are consistently signalling an upper trough amplifying over the NW then mid-Atlantic next weekend onwards, which would amplify the jet north again over the UK downstream. There is the possibility that if the upper trough moving in from the west amplifies further it may undercut resulting ridge  building N toward Scandi downstream - but this potential is too far off in FI land to have any credibility for now. So realistically we are at the mercy of Atlantic lows rolling through next week before any concrete changes away from this pattern may become apparent.

Brilliant Nick,

I didnt know that about the GH thanks for useful info. Also didnt know it was so high up but assuming its more to do with millions of years of Ice snow layered rather than land elevation although im open to correction.

 

I wonder with Global warming if the Altlantic will salinate thus affecting weakening Jet and destabilizing that permanent Azores High to move about a bit.The Bartlett and Euro so much more powerful than any siberian or arctic high. Atlantic more often than not always to strong for cold highs and often power on by warm highs to the south and southwest. 

[ACCOUNT DELETED]

Swansea GEFS 6Z: turning colder again next week, wet and windy at times (nothing stormy showing atm) but the main difference is we should see more in the way of sunshine after this drab cloudy even foggy weather we've had and continuing to have. Rain could hold off until late afternoon on Christmas Day, rain clearing to showers Boxing Day and the chance of a dry day on Wednesday so not too bad. 

[Frosty.]

12 minutes ago, northwestsnow said:

Yes i was very suprised to see members expressing an optimistic tone this morning...the models ( and now exeter) are suggesting euro high dross...

Lets hope for a model flip soon.

Lets face it tho...thats looking increasingly unlikely.

As I said, I really admire those who put a good case forward supporting a cold January but I've been watching the GEFS closely and it clearly trends to a sw / ne jet alignment from the end of next week onwards with a positive NAO signal which is why I will make the most of the window of colder unsettled weather from the 26th to around the 29th / 30th.

[mulzy]

I prefer the Euro high dross to an active jet bringing wet and stormy conditions.

Long live the Euro high.  If we can’t get snow and ice, let’s have mild and benign weather.

Despite the usual hope casting that happens on here, there is nothing wintry in the cards over the next 15 days, bar some transient snow on northern uplands next week.  

The MO update for the middle of January gives me a little hope but apart from that it’s pretty bleak.

Edited December 22, 2017 by mulzy

[bluearmy]

18 minutes ago, Frosty. said:

As I said, I really admire those who put a good case forward supporting a cold January but I've been watching the GEFS closely and it clearly trends to a sw / ne jet alignment from the end of next week onwards with a positive NAO signal which is why I will make the most of the window of colder unsettled weather from the 26th to around the 29th / 30th.

Funnily enough Karl, the gefs AO And NAO have actually been fairly neutral recently on forecasts out to day 16.

the 06z has a bit of a spike around 3 jan but we seem to be stuck in a neutral phase , if anything the gefs leaning slightly negative whilst the eps are slightly positive in trend

not sure how often these verify as fairly neutral or whether this just reflects the uncertainty of later week 2. 

 

[Frosty.]

12 minutes ago, bluearmy said:

Funnily enough Karl, the gefs AO And NAO have actually been fairly neutral recently on forecasts out to day 16.

the 06z has a bit of a spike around 3 jan but we seem to be stuck in a neutral phase , if anything the gefs leaning slightly negative whilst the eps are slightly positive in trend

not sure how often these verify as fairly neutral or whether this just reflects the uncertainty of later week 2. 

 

Well, from what I've seen, the GEFS mean has been / is trending to more of a sw  / ne  jet alignment from around day 6 / 7 which indicates a return of milder though still changeable / unsettled weather from around the end of next week onwards, especially further n / nw whereas height rises to the s / se  indicate an increasing incidence of lengthier fine spells between occasional unsettled intervals towards the s / se as we go further into january..i.e..not the wintry scenario most of us desire!

Edited December 22, 2017 by Frosty.

[Matthew.]

14 minutes ago, bluearmy said:

Funnily enough Karl, the gefs AO And NAO have actually been fairly neutral recently on forecasts out to day 16.

the 06z has a bit of a spike around 3 jan but we seem to be stuck in a neutral phase , if anything the gefs leaning slightly negative whilst the eps are slightly positive in trend

not sure how often these verify as fairly neutral or whether this just reflects the uncertainty of later week 2. 

 

I think the May 2017 NAO was neutral so that’s coincidence