Model Output Discussion - Cold spell ending - what next?

[bluearmy]

The pub run has a bit of the 00z gem about it 

shove a ridge up and then undercut if so that there are heights around svaalbard waiting for that next push

and for good measure, the pub run rotates the Alaskan ridge to try and complete a cross polar ridge!

Edited January 18 by bluearmy

[Battleground Snow]

3 minutes ago, bluearmy said:

The pub run has a bit of the 00z gem about it 

shove a ridge up and then undercut if so that there are heights around svaalbard waiting for that next push

and for good measure, the pub run rotates the Alaskan ridge to try and complete a cross polar ridge!

Trust us to get a HLB that is "too high"

Just one run of course at that range.

[blizzard81]

1 minute ago, bluearmy said:

The pub run has a bit of the 00z gem about it 

shove a ridge up and then undercut if so that there are heights around svaalbard waiting for that next push

and for good measure, the pub run rotates the Alaskan ridge to try and complete a cross polar ridge!

Anybody who knows me on here will know I'm certainly no fan of the pub run nor the gem (in it's entirety lol). However, I am also a great believer in the old adage 'every dog has it's day'.

[bluearmy]

Having lauded the 18z it comes up with a pattern which sets alarm bells ringing for me. I hope this is all trop forcing and not something to do with delayed strat reversal waves above 70N which I see as the big risk in feb for getting the cold as far south and west  as nw Europe (for example - I mean that’s where our interest lies after all) 

Edited January 18 by bluearmy

[Battleground Snow]

Quite a few different versions on of the scandi high at day 11 as you would expect.

It's still out in FI, so best to just keep a watching brief for now over the coming days.

[Don]

1 hour ago, bluearmy said:

Having lauded the 18z it comes up with a pattern which sets alarm bells ringing for me. I hope this is all trop forcing and not something to do with delayed strat reversal waves above 70N which I see as the big risk in feb for getting the cold as far south and west  as nw Europe (for example - I mean that’s where our interest lies after all) 

This hobby certainly isn't for the faint hearted!  Lets hope the GFS is merely playing around with different scenarios (which it will be at that range of course!) and does not become the correct pattern you fear!

[geordiekev]

2 hours ago, northwestsnow said:

GFS like a dog with a bone here.. 

Have to say, I've now seen 1 too many slow run ins of UK HP retrograde to Greeny failures, in the last 3 years to never again be drawn in, so to see an Azores HP retrogression to Scandy appear, which has a better success rate, I'm all in.

Stick yr Azores HP is a Winter killer where the sun aint shining

[syed2878]

3 hours ago, Catacol said:

And so the cold snap ends. Snap rather than a spell - 9/10 for the depth and quality of the cold (I loved the frost free dry cold and then the intense frost that broke the fuel flap on my car!) and I daresay 9/10 for many in Scotland or parts of the NW who love snow. The NW probably viewed a scandy trough dropping in with a sense of "been here before" - and then low and behold the trough developed a curious westerly and many parts cashed in. The wonderful variability of the weather. But the overall 9/10 has to lose 3 points for the shorter than expected duration, and then a further point for the failed channel runner and anything for the south. Those in the east (like me) would probably knock a further 1 off for the absence of any north sea activity. Lands as a sort of 4 or 5/10 for me.

We have been unlucky with events in the strat this season, no doubt about that. First the SSW that failed at the start of the month that could have done much to cement a cold month (and was probably a key factor in suggestions from the MetO) and then a second warming that split the vortex but has turned into a reflection type of warming, where wave forcing bounces off the strat back towards the trop and helps reinforce default westerlies. Laid out nicely in Amy Butler's recent blog. And frankly a frustration....but one we have to live with. Coincides with IO MJO phases and the lagged impacts the elastic band of AAM being at the wrong end of the "ping" have ensured. Hey presto - cold out very fast, violently mobile atlantic arrives. The weather may be chaotic, but it is also broadly predictable once drivers lock in.

And that broad predictability is what lends significant wintry optimism going forward. First of all, the ebb and flow of momentum that is the GWO.

Look at the patterns here. Note that prior to our December snap and again prior to our January snap we saw a rising orbit take hold. This graphical representation of global windflows gives a strong indication as to whether the atmosphere is predisposed to encourage blocking, and to see the next orbit kick in we need a rising momentum profile.

And here it is. This has been sluggish - I thought the gun had been fired a few days ago...but it appears now that 16 Jan was the moment we hit the starting button. Frictional torque distinctly positive

Mountain torque generally positive also

and this produces the awaited beginning of the next surge in momentum illustrated by a positive tendency now in play

This will accelerate, not least because the MJO is coming back to where snow lovers want it - phases 6/7/8/1 broadly speaking

So. We watch and wait with anticipation given GLAAM has remained positive overall and we are in a back loaded Nino context. The atlantic will fizz for the 5 days or so I have flagged before as the likely window, and then we will gradually see the effects of the forcings listed above impact on NWP. There are signs already, as expected catching the eye around 26/27/28 Jan. Note ridging towards Scandy on the EPS for the end of the week

quite pronounced by the end of the weekend

Someone earlier said there was little sign of such developments, and used GEFS 850s as the tool to evidence it. Worst possible source of evidence for extended forecasting possible. Don't get swayed by such stuff.

Disappointing to see the intense cold depart so soon, frustrating that the strat has refused to play ball so far, but winter a long way from done and the mild I suspect will be an interlude rather than a pattern starter. I still see February as blocked and have faith in the recent Glosea, JMA, CMC and other long range models that see a -AO overall. Plenty of time still to roll those dice again and get lucky.

 

 

 I would rather have mild and sunny than the cold spel we had. Models some of them really going for the weekend storm.

[feb1991blizzard]

3 hours ago, Catacol said:

And so the cold snap ends. Snap rather than a spell - 9/10 for the depth and quality of the cold (I loved the frost free dry cold and then the intense frost that broke the fuel flap on my car!) and I daresay 9/10 for many in Scotland or parts of the NW who love snow. The NW probably viewed a scandy trough dropping in with a sense of "been here before" - and then low and behold the trough developed a curious westerly and many parts cashed in. The wonderful variability of the weather. But the overall 9/10 has to lose 3 points for the shorter than expected duration, and then a further point for the failed channel runner and anything for the south. Those in the east (like me) would probably knock a further 1 off for the absence of any north sea activity. Lands as a sort of 4 or 5/10 for me.

We have been unlucky with events in the strat this season, no doubt about that. First the SSW that failed at the start of the month that could have done much to cement a cold month (and was probably a key factor in suggestions from the MetO) and then a second warming that split the vortex but has turned into a reflection type of warming, where wave forcing bounces off the strat back towards the trop and helps reinforce default westerlies. Laid out nicely in Amy Butler's recent blog. And frankly a frustration....but one we have to live with. Coincides with IO MJO phases and the lagged impacts the elastic band of AAM being at the wrong end of the "ping" have ensured. Hey presto - cold out very fast, violently mobile atlantic arrives. The weather may be chaotic, but it is also broadly predictable once drivers lock in.

And that broad predictability is what lends significant wintry optimism going forward. First of all, the ebb and flow of momentum that is the GWO.

Look at the patterns here. Note that prior to our December snap and again prior to our January snap we saw a rising orbit take hold. This graphical representation of global windflows gives a strong indication as to whether the atmosphere is predisposed to encourage blocking, and to see the next orbit kick in we need a rising momentum profile.

And here it is. This has been sluggish - I thought the gun had been fired a few days ago...but it appears now that 16 Jan was the moment we hit the starting button. Frictional torque distinctly positive

Mountain torque generally positive also

and this produces the awaited beginning of the next surge in momentum illustrated by a positive tendency now in play

This will accelerate, not least because the MJO is coming back to where snow lovers want it - phases 6/7/8/1 broadly speaking

So. We watch and wait with anticipation given GLAAM has remained positive overall and we are in a back loaded Nino context. The atlantic will fizz for the 5 days or so I have flagged before as the likely window, and then we will gradually see the effects of the forcings listed above impact on NWP. There are signs already, as expected catching the eye around 26/27/28 Jan. Note ridging towards Scandy on the EPS for the end of the week

quite pronounced by the end of the weekend

Someone earlier said there was little sign of such developments, and used GEFS 850s as the tool to evidence it. Worst possible source of evidence for extended forecasting possible. Don't get swayed by such stuff.

Disappointing to see the intense cold depart so soon, frustrating that the strat has refused to play ball so far, but winter a long way from done and the mild I suspect will be an interlude rather than a pattern starter. I still see February as blocked and have faith in the recent Glosea, JMA, CMC and other long range models that see a -AO overall. Plenty of time still to roll those dice again and get lucky.

 

 

This spell probably struggling top 25, just about top 50 in my life.

[Daniel*]

Now this is much more like it from GFS 00z… old school Scandi high, feels predictable what would follow. Growing idea of pattern change from 28th onwards with the risk of much colder weather coming from the east in the days after. 

[northwestsnow]

GFS still interested !

GEM saying " maybe "...

 

Edited January 19 by northwestsnow

[Lukesluckybunch]

Gem not good this morning..shows a sinking high and all the cold into central europe,this happens time and time in the UK winters..very frustrating!

[AO-]

Good Morning all,

GFS is synoptically great this morning, but not the best as there is hardly any cold captured to bring West. T850s are pretty mild. And probably for England it still is too far east. But again the consistency is just lovely. 

[KTtom]

3 hours ago, feb1991blizzard said:

This spell probably struggling top 25, just about top 50 in my life.

It certainly wont be something we'll be discussing this time next year i think the myth 'surprise features always crop up' can be put to bed now!..put it this way, i think next week will be far more memorable for a large swaythe of the country if for the wrong reasons..and no one forecst whats being modelled a couple weeks ago. 

Some sort of ridge forming to the north east is pretty likely for the following week pretty unanamous agreement, however the modelling of detail makes a massive difference in likely temperature, especially in Kuusamo where im going..the 18z and 00z gfs ops have a 20 c difference for 1st Feb with similar synoptics. Also worth remembering how there was good agreement for a substantial Greenland block until it came within t-144 for this week.

Bit surprised with the GEM comment, looks like its just getting interesting to me

Edited January 19 by KTtom

[LetItSnow!]

32 minutes ago, AO- said:

Good Morning all,

GFS is synoptically great this morning, but not the best as there is hardly any cold captured to bring West. T850s are pretty mild. And probably for England it still is too far east. But again the consistency is just lovely. 

I know about moderation and all but there is a healthy patch of uppers below minus ten so that is hardly mild. I’ve seen far worse cold pools in synoptic charts in recent years and even in the 19th century sometimes! If it was around the -5C mark I’d get it but that looks alright. Anyway, ten days away so worrying about exacts like that is fruitless. The uppers were corrected to be colder for the last spell of easterlies anyway, right up to 1-2 days in advance. 

[carinthian]

38 minutes ago, AO- said:

Good Morning all,

GFS is synoptically great this morning, but not the best as there is hardly any cold captured to bring West. T850s are pretty mild. And probably for England it still is too far east. But again the consistency is just lovely. 

Morning the models moving towards a Scandinavian High is place for the months end. All the upper pressure flow projects indicate that. The early building blocks will start next weekend. Regarding depth of cold, predictions of 850mb temp values are not possible at this stage. Getting the right development for an Easterly flow in place is the important aspect and then the cold will follow and possibly deepen once established..

C

Edited January 19 by carinthian

[AO-]

21 minutes ago, LetItSnow! said:

I know about moderation and all but there is a healthy patch of uppers below minus ten so that is hardly mild. I’ve seen far worse cold pools in synoptic charts in recent years and even in the 19th century sometimes! If it was around the -5C mark I’d get it but that looks alright. Anyway, ten days away so worrying about exacts like that is fruitless. The uppers were corrected to be colder for the last spell of easterlies anyway, right up to 1-2 days in advance. 

Agree, but I think you misunderstood me. There are no-15/-20s  in the northeast. I'm affraid the cold will 'dissolve' with the sun getting more power. 

[Lukesluckybunch]

22 minutes ago, carinthian said:

Morning the models moving towards a Scandinavian High is place for the months end. All the upper pressure flow projects indicate that. The early building blocks will start next weekend. Regarding depth of cold, predictions of 850mb temp values are not possible at this stage. Getting the right development for an Easterly flow in place is the important aspect and then the cold will follow and possibly deepen once established..

C

Let's hope we can nail the scandi high..sooner rather then later..early February is much better then late Feb into march..

[That ECM]

T168 all 4. Overall nhp similar with some differences as you would expect at this time. 
 

It’s what happens beyond that’s of interest. As yet that’s still unsure. You can make a case for “good” or “bad” from a cold pov. Truth is we just don’t know but there’s chances.

[LetItSnow!]

13 minutes ago, AO- said:

Agree, but I think you misunderstood me. There are no-15/-20s  in the northeast. I'm affraid the cold will 'dissolve' with the sun getting more power. 

Not something I’d be concerned about in late January and early February to be honest. If it were a month down the line, perhaps. It could be worse. 

[That ECM]

T168 and T192 spread with gefs. 

[Ali1977]

Day 10s, I think we are staring down the barrel of our next chase - and it isn’t at day 16 on the GFS which is nice!! 
This time we are chasing the easterly or north easterly - rather than getting watered down like a northerly these can often quickly establish into something far colder

[AO-]

EC not there yet at day 10. Rather big difference compared to GFS . 

 

[KTtom]

Lets hope EC continues with its reputation for day 10 charts, because this mornings is a shocker if its cold we're after..its not just our location look at the uppers to the east and north east

[winterof79]

48 minutes ago, carinthian said:

Morning the models moving towards a Scandinavian High is place for the months end. All the upper pressure flow projects indicate that. The early building blocks will start next weekend. Regarding depth of cold, predictions of 850mb temp values are not possible at this stage. Getting the right development for an Easterly flow in place is the important aspect and then the cold will follow and possibly deepen once established..

C