Model Output Discussion - Colder spell ending, what's to follow?

[Paul]

Please continue with the model chat in here.

As always, please keep it to the models and keep it friendly in this thread. If you spot any issues, please report the post rather than responding to it. If you're wanting to chat more generally about this winter, or maybe have a ramp, please head off to the winter chat thread:

If you're wanting to learn more about meteorology, please take a look at the Learning and Research area.

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[sebastiaan1973]

High pressure, but till 21 december no winter. MJO phase 6,7 in the long term.

[LRD]

Still a dip in the 850s in FI through the GFS spaghetti a la scatterati. Will this move further and further to the left over the next few days?

Control and Op go in very different directions towards the end. 

Edited December 7, 2020 by LRD

[Griff]

Just now, sebastiaan1973 said:

High pressure, but till 21 december no winter. MJO phase 6,7 in the long term.

Is that last one the change since the previous week? Almost made me think a heatwave was coming...  

[Scott Ingham]

11 minutes ago, LRD said:

Still a dip in the 850s in FI through the GFS spaghetti a la scatterati. Will this move further and further to the left over the next few days?

Control and Op go in very different directions towards the end. 

Interesting the colder members start to creep in after the 17th right on cue

[Mike Poole]

The current setup is fascinating on so many levels.  Whilst no immediate cold is on the horizon on the models, i don’t think anyone would disagree that the weather patterns in either the trop or the strat are not in anyway ‘normal’, and by normal I mean the zonal Atlantic stuff that has been our fodder with few exceptions since 2013.

ECM mean T240:

Lows running into the invisible block!  

Strat NAM plot shows once again the trop pattern is affecting the strat in the forecast part of this (it’s the GFS 0z):

Down here, the vortex isn’t getting going anytime soon, which gives us the precious commodity of TIME so we can play the long game, it was fun in 2018, I can envisage a similar chase now given the state of things, but with delivery while still in the winter months...we will see...

Edited December 7, 2020 by Mike Poole

[Scott Ingham]

13 minutes ago, sebastiaan1973 said:

High pressure, but till 21 december no winter. MJO phase 6,7 in the long term.

Big improvement on amplitude from the previous update of the MJO and those temp anomalies sniffing out the WAA expected through the UK and to the East

[bluearmy]

Ext eps mean has high heights spread widely ..... where will the low heights end up ?? The high heights won’t cover that wide an area .... the clusters (just the one) offers little help given that there simply can’t be only one! 
 

so not much added guidance this evening ......

[damianslaw]

Consistency in the models in the very near-time frame, but then a divergence 120 hrs, this time it's UKMO with a more NW-SE aligned trough, whereas GFS and ECM phase the second low coming out of the Eastern USA seaboard and the trough becomes positively tilted. 

The trend then is for the azores high to nose in and we maintain a mild predominantly SW flow, but as others have commented, no sign of a fast ribbon of jet activity, the trough looks like it will come unstuck against building heights nosing in from the south, end result warm air advection which will prop up ridge development up and through the UK.

I said yesterday those who like cold looking charts should perhaps take a break from model viewing for 7 days, as the more medium timeframe is unlikely to show such an evolution. Expecting next few days to show very variable longer range output as the models get to grips with developments over the Pole (strong heights build up), and the interplay between warm air advection and cold air advection, won't be able to get the latter without some of the former first..

[Matt H]

Whenever you need cheering up there’s always a CFS run there ready to do the job.

[STRiZZY]

4 minutes ago, Frosty Winter said:

Whenever you need cheering up there’s always a CFS run there ready to do the job.

Is the pub run ready to do the job again? 

[Updated_Weather]

Just now, STRiZZY said:

Is the pub run ready to do the job again? 

We find out soon

[MATTWOLVES 3]

I'm not seeing anything from tonight's EC46 that suggests major cold will begin appearing in the next few days. If anything going towards the latter part of the month suggests the EXETER update may be onto something with a chance of milder wetter conditions by this time.. Low pressure anchored over Iceland and increasing Heights over iberia... Know significant Heights over Greenland or Scandy... The ural block still in place, and perhaps a tad more displaced South.. Temps around avareage. 

[Catacol]

Ho hum - what's happening here....have taken my eyes off these charts recently...

We have a spiking of relative angular momentum somewhat earlier than I expected it...

And EAMT holding up for now rather than falling back, with overall torques remaining high.

This being the case the flattening of the pattern referred to yesterday drops in probability - and in the near term the likely retrogression of the ScEuro high looks more likely. The charts are showing it in the semi reliable up to 120h before usual westerly bias takes over

All very good news. And in the more medium term? More modelling for the end of next week of the same pacific jet streak highlighted yesterday

which if correct (and it seems to be being maintained as a feature at present) would add greater weight to potential wave breaking for Xmas week.

Jumping onto the back of @chionomaniac and his strat posts from the previous thread, the impact of this streak would be to reinforce the split being opened up by tropospheric forcing, and to reinforce the point I like these charts. Modest wave 2 forcing in the lower strat being modelled for the same period (mid to late next week)

while wave 1 forcing from the pacific side builds further in strength. This is now getting close to being a moderate/strong event

What does all this mean?

1. Slightly unexpected maintenance of momentum means more likelihood of amplified patterns and our ridge getting traction.

2. This will be reinforced next week as the pacific jet engages. Not at all what I would expect from a Nina pattern to be honest - everything feels much more "active" than expected - but this works in our favour.

3. The same process, should it create the expected wave break into Xmas week, will reinforce the wave 2 trop forcing attack that Chio referenced.

4. Will this be sufficient to give us some serious strat vortex grief? I notice Amy Butler has touted for an SSW before the first 10 days of January are out. That would be the perfect impact of this process - though I must stick to my early season punt that it will need a third hit to do the job properly later in January. However regardless of whether we get a technical SSW we can expect a further strengthening of northern blocking and a jet stream heading south.

Extremely happy with all this. Let's see what tomorrow brings and whether the 18z churns out any eye candy.....

 

Edited December 7, 2020 by Catacol

[BARRY]

5 minutes ago, MATT said:

I'm not seeing anything from tonight's EC46 that suggests major cold will begin appearing in the next few days. If anything going towards the latter part of the month suggests the EXETER update may be onto something with a chance of milder wetter conditions by this time.. Low pressure anchored over Iceland and increasing Heights over iberia... Know significant Heights over Greenland or Scandy... The ural block still in place, and perhaps a tad more displaced South.. Temps around avareage. 

well average temps is better than the above crap that we have been subjected to.

[Matt H]

T150 a few days ago vs t102 on the GFS 18z now. Just highlights once again how the big bowling ball low scenario was overdone by the GFS irrespective if the developments beyond this. Never understand why some people are so keen to believe the GFS the whole time.

Edited December 7, 2020 by Frosty Winter

[virtualsphere]

I don't think I can quote a post from the old thread but I like the ECM animation posted by @IDO here: https://www.netweather.tv/forum/topic/94764-model-output-discussion-winter-has-arrived/?do=findComment&comment=4313159

Ignore our locale and take a look at the deep purples of the vortex and their direction of travel in this animation, note that at the end around 16-17 Dec the lobe that develops to the west of Greenland over N Canada is actually spinning back west towards Alaska - for me a positive trend away from any potential zonal outlook further down the line.  

Edited December 7, 2020 by virtualsphere

[MATTWOLVES 3]

1 minute ago, BARRY said:

well average temps is better than the above crap that we have been subjected to.

Temps have been below average for a while and quite cold at times.. Average temps do not float my boat one bit. I admire what the strat guys are saying but the 46 at this moment of time is not seeing it. The Long range anomalies are also not seeing it... That's not to say its gonna nail this pattern, but I'm beginning to think a major strat event is gonna be needed to throw the cat amongst the pigeons.. So to speak. 

[Scott Ingham]

7 minutes ago, Catacol said:

Ho hum - what's happening here....have taken my eyes off these charts recently...

We have a spiking of relative angular momentum somewhat earlier than I expected it...

And EAMT holding up for now rather than falling back, with overall torques remaining high.

This being the case the flattening of the pattern referred to yesterday drops in probability - and in the near term the likely retrogression of the ScEuro high looks more likely. The charts are showing it in the semi reliable up to 120h before usual westerly bias takes over

All very good news. And in the more medium term? More modelling for the end of next week of the same pacific jet streak highlighted yesterday

which if correct (and it seems to be being maintained as a feature at present) would add greater weight to potential wave breaking for Xmas week.

Jumping onto the back of @chionomaniac and his strat posts from the previous thread, the impact of this streak would be to reinforce the split being opened up by tropospheric forcing, and to reinforce the point I like these charts. Modest wave 2 forcing in the lower strat being modelled for the same period (mid to late next week)

while wave 1 forcing from the pacific side builds further in strength. This is now getting close to being a moderate/strong event

What does all this mean?

1. Slightly unexpected maintenance of momentum means more likelihood of amplified patterns and our ridge getting traction.

2. This will be reinforced next week as the pacific jet engages. Not at all what I would expect from a Nina pattern to be honest - everything feels much more "active" than expected - but this works in our favour.

3. The same process, should it create the expected wave break into Xmas week, will reinforce the wave 2 trop forcing attack that Chio referenced.

4. Will this be sufficient to give us some serious strat vortex grief? I notice Amy Butler has touted for an SSW before the first 10 days of January are out. That would be the perfect impact of this process - though I must stick to my early season punt that it will need a third hit to do the job properly later in January. However regardless of whether we get a technical SSW we can expect a further strengthening of northern blocking and a jet stream heading south.

Extremely happy with all this. Let's see what tomorrow brings and whether the 18z churns out any eye candy.....

 

Im glad Amy agrees with my ssw forecast end of December start of Jan. Models are continuing to underestimate the tropics. It hadn't the first time. Its a striking feature of this winter. Why im not 100% yet but I have some ideas

[STRiZZY]

1 minute ago, MATT said:

Temps have been below average for a while and quite cold at times.. Average temps do not float my boat one bit. I admire what the strat guys are saying but the 46 at this moment of time is not seeing it. The Long range anomalies are also not seeing it... That's not to say its gonna nail this pattern, but I'm beginning to think a major strat event is gonna be needed to throw the cat amongst the pigeons.. So to speak. 

I think he meant the above avg temps of the previous few seasons. 

Edited December 7, 2020 by STRiZZY

[chris55]

UKMO 144 my chart of the day 

That Norwegian Sea high is in danger of getting cut off from the Russian high with the energy forcing south between the two. 
 

ECM and GFS broadly similar in the long wave pattern, it’s the way UKMO deals with the details to our north that’s interesting.

 

Probably be gone tomorrow, but shows what’s possible. 

[Catacol]

2 minutes ago, Scott Ingham said:

Im glad Amy agrees with my ssw forecast end of December start of Jan. Models are continuing to underestimate the tropics. It hadn't the first time. Its a striking feature of this winter. Why im not 100% yet but I have some ideas

That's a bit like saying Jurgen Klopp agrees with your interpretation of the Gegenpress......

[Mike Poole]

Pub run T144, the red line is the invisible block as I understand things, let’s see what happens:

[Scott Ingham]

Just now, Catacol said:

That's a bit like saying Jurgen Klopp agrees with your interpretation of the Gegenpress......

Hahahaha completely agree! She is new level! Hence it gives me confidence i might be on the right lines! 

[Scott Ingham]

5 minutes ago, Mike Poole said:

Pub run T144, the red line is the invisible block as I understand things, let’s see what happens:

Look at how that low pressure is just filling in situ. Its a shame more energy isn't going South but there's still time for that because as catacol says there's still room for more amplification to be added to the system