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

[Kentish Snowman in Yorks]

6 minutes ago, chionomaniac said:

You’re welcome. I much prefer plain English than verbose gobbledegook lol. Keep it up

Would like to echo this.  I see people talking about MJO Angular Momentum Mountain Torque etc but up until Scott started to explain them in layman's terms I had no more than a vague understanding of what they were.

His recent posts actually explain in simple English how they are linked and how they can affect our Weather.  I actually now think I have a basic understanding of what the more experienced posters are banging on about when discussing teleconnections etc so cheers Scott! 

[Allseasons-Si]

3 minutes ago, Scott Ingham said:

Continues the trend to lower heights into Europe. Much much better 

Yes Scott and i should of mentioned that as this mornings EPS was dreadful in that respect.

[Daniel*]

Better from this morning that’s for sure the Iberian ridge much more out the way. Stronger Atlantic ridge.

>

[BLAST FROM THE PAST]

13 minutes ago, Scott Ingham said:

Thanks Ed. I appreciate them words! Not bad for someone with Dixlexia haha! I think the condition makes me even more aware of writing for all level of readers 

Hi Scott

I’ve had Last week of December as target for some time using my solar forcing method.  Any run showing  a northerly and diving N/S LP to be on near continent and Ridging to NW in time for Xmas has my backing.

Enjoying your posts and going forward I hope you are right

 

BFTP

[Eagle Eye]

Remember everyone, 

These models once we get futrther into the future are less accurate it would be more accurate to look at last years. 

No need to get depressed on t-384 charts they can be Polar opposite

There coupd be something happening with Polar ridges but it's too far out so let's wait and see but 

Remember to not overly look into t+384.

Edited December 13, 2020 by Sheldon Cooper

[Scott Ingham]

3 minutes ago, Kentish Snowman said:

Would like to echo this.  I see people talking about MJO Angular Momentum Mountain Torque etc but up until Scott started to explain them in layman's terms I had no more than a vague understanding of what they were.

His recent posts actually explain in simple English how they are linked and how they can affect our Weather.  I actually now think I have a basic understanding of what the more experienced posters are banging on about when discussing teleconnections etc so cheers Scott! 

Im glad that the posts have helped mate. Itd great when you get to that stage of knowledge and have that basic framework in your head. Now that you understand that you can apply that knowledge to individual runs or extended clusters like the one just posted and you can work out what seems the most likely evolution. Not the exact forecast but the most likely to happen

[Eagle Eye]

26 minutes ago, feb1991blizzard said:

That's an Atlantic low, not a polar low.

You know what I meant I meant coming from the north West

[Kentspur]

1 hour ago, feb1991blizzard said:

Now you're talking with that top one, you would get absolutely buried in Kent in the 24 hours after that chart as the low pulls away turning rain to snow!

Seeing as we're in tier3 we can only hope that this does happen as we can't go out for a meal and drinks anywhere so the sledge and the Downs it is, hope this ensembles called it correctly 

[Scott Ingham]

5 minutes ago, BLAST FROM THE PAST said:

Hi Scott

I’ve had Last week of December as target for some time using my solar forcing method.  Any run showing  a northerly and diving N/S LP to be on near continent and Ridging to NW in time for Xmas has my backing.

Enjoying your posts and going forward I hope you are right

 

BFTP

I hope we are both right BFTP. Ive never put any thought into solar forcing if you find the time drop me some links/reading material and ill have a look next week when I find the time

[sebastiaan1973]

No winter in sight ( weather to be able to skate). Plume De Bilt.

[Daniel*]

Think we should be a bit careful about calling it a cold spell as it stands temperatures look to become more seasonal I suppose it is normal for the cold to be muted given the range we’re taking about, nonetheless a significant cold spell is unlikely this month. The air could be colder than what we had early this month... which would increase snow risk but currently there’s not much to suggest this colder weather has much bite or longevity to it.

[Portsmouth Sun]

2 minutes ago, Daniel* said:

Think we should be a bit careful about calling it a cold spell as it stands temperatures look to become more seasonal I suppose it is normal for the cold to be muted given the range we’re taking about, nonetheless a significant cold spell is unlikely this month. The air could be colder than what we had early this month... which would increase snow risk but currently there’s not much to suggest this colder weather has much bite or longevity to it.

Thank you, finally a reality check. 

 

[Nick F]

Can't complain about these H500 means from 12z EPS tonight. 

Day 12

Day 15

Cold for Xmas day?

[chionomaniac]

14 minutes ago, That ECM said:

What are your thoughts? Would be very interested.

No real change since I returned. We have missed one opportunity at gaining a Greenland block, but tropical and strat conditions still leave us in a great position to have more opportunities. If we look stratwards then we see a far weaker vortex than what we would normally expect at this time of year. Without a period of Vortex Intensification in the strat and that influencing the trop, then any amplification in trop wave activity has a far greater chance of puncturing the trop vortex. So heads should still remain up, because this winter still has potential to deliver before the days lengthen .

[northwestsnow]

2 minutes ago, Daniel* said:

Think we should be a bit careful about calling it a cold spell as it stands temperatures look to become more seasonal I suppose it is normal for the cold to be muted given the range we’re taking about, nonetheless a significant cold spell is unlikely this month. The air could be colder than what we had early this month... which would increase snow risk but currently there’s not much to suggest this colder weather has much bite or longevity to it.

Further North with altitude will likely be 2 or 3 degrees colder i imagine, so no freeze but hopefully more seasonal..

[Tim Bland]

5 minutes ago, Daniel* said:

Think we should be a bit careful about calling it a cold spell as it stands temperatures look to become more seasonal I suppose it is normal for the cold to be muted given the range we’re taking about, nonetheless a significant cold spell is unlikely this month. The air could be colder than what we had early this month... which would increase snow risk but currently there’s not much to suggest this colder weather has much bite or longevity to it.

Are these available for locations other than London City Airport ? It’s always a bit warmer in the city

[Scott Ingham]

5 minutes ago, chionomaniac said:

No real change since I returned. We have missed one opportunity at gaining a Greenland block, but tropical and strat conditions still leave us in a great position to have more opportunities. If we look stratwards then we see a far weaker vortex than what we would normally expect at this time of year. Without a period of Vortex Intensification in the strat and that influencing the trop, then any amplification in trop wave activity has a far greater chance of puncturing the trop vortex. So heads should still remain up, because this winter still has potential to deliver before the days lengthen .

Summed up perfectly! 

[Daniel*]

14 minutes ago, northwestsnow said:

Further North with altitude will likely be 2 or 3 degrees colder i imagine, so no freeze but hopefully more seasonal..

I think there’s a real chance of some snow in final week of December in northern areas especially but people shouldn’t be expecting ice days or anything substantial imo. I’d take it a bonus. It seems the greatest chance of significant winter is more likely to feature in second half of winter mid Jan onwards. 

and well @Tim Bland the 4 corners of U.K. or anywhere in world Edinburgh for example..

 

A new trend has emerged in that GFS continues to be quite aggressive with a Siberian warming in FI I know, but the models model the stratosphere better. Potentially wrapping towards the pole? And that could become very interesting I see  Dr. Judah Cohen is watching... more hints of a SSW in January. PV already been or set to become more destabilised so it is intriguing... we’re clearly not following winter 2019-20 in this regard.

 

 

 

[Catacol]

2 hours ago, feb1991blizzard said:

Is this what is driving the strat warming in GFS 12 FI?  feel that it will fall short of an SSW this time but ripe for the taking around 20th to 30th Jan.

We are seeing ongoing signs of amplification despite the failed attempt for high lat blocking here in a week’s time. Pacific jet forecasts show more in the way of momentum being fired into the system. Jet extension this week

and more jet extension in the mix for Xmas week.

Such forecasts are linked to the next rise in AAM which is now underway. Frictional torque between earth and atmosphere is increasingly sharply now

and what we need to look for is a rise in mountain torque that would typically follow afterwards. Mountain torque is currently strongly negative but it won’t stay that way.

Those GFS pacific jet charts are suggesting that it won’t be too many days before this happens, and +EAMT will be a key ingredient in the overall increase.

On the ground for us what does this mean?

1. The optimism around the run in to Xmas should not fade too much because the impacts of the next cycle are on the horizon.

2. Slightly at odds with some of the MJO enthusiasm in here today I would say that this will happen regardless of whether the MJO makes it to the Nino phases of 7-8-1. It would be good to have MJO support for the spike and if we get that then the likelihood is the spike will be greater...but it isn’t the be all and end all.

3. As momentum spikes and engages mountain torque the pacific jet fires up, and ahead of it encourages wave breaking in form of ridges that give us our chance of a higher let block.

Can we get one of these ridges to get traction to the north of the U.K.? Here we need to hope for timing to click. The outer edges of the ECM strat forecast see the core of the upper trop vortex sitting over Greenland on the 22nd. 

From this position we can see that substantive height rises in the days before Xmas are a long shot (the misery of the last 24 hours!) but beyond Xmas? Notice the vortex is still split on this forecast - a better position than was being touted 2 days ago and so the damage being done right now as wave 1 and wave 2 forcing happens for the next few days may actually be ramping up. So it is not beyond the bounds of possibility that the vortex is left quite weakened, and if the core of the vortex can find its way back across to Siberia then I’d say - yes - chances of a high lat block return for the period leading up to New Year.

So - things to look out for

- Gradient of mountain torque increases over the next 7 days. Big +EAMT would be ideal.

- Any concurrent support from MJO progression.

- Signs of the vortex remaining weakened and perhaps shifting away from Greenland towards Siberia.

Plenty to keep the forecasting pot simmering!

 

As for a SSW? I’m in your camp. I remain cautious about activity in the New Year being enough to bring it down, but later in January - yes...

Edited December 13, 2020 by Catacol

[Allseasons-Si]

Well if the CFSv2 is showing this for Xmas day....

...then it's on

[Griff]

25 minutes ago, Allseasons-si said:

Well if the CFSv2 is showing this for Xmas day....

...then it's on

Doesn't it always! 

Last time I had a chance to glance in here was 13 hours ago and 12 pages since of very interesting and somewhat excitable comments... 

Wowzers the potential!*

 

 

*and for absolutely huge disappointment. 

[Allseasons-Si]

Just searching afield to see what the pressure is forecasting for Iceland...

and you can clearly see a pressure rise there for Xmas week,this bodes well for us

now onto the 18z...

....FOR SOME SNOW

 

[lamppost watcher]

[Allseasons-Si]

The ICON slightly more amplified in NE states at 120 thanks to downstream trough into central states

18z 120 v's 12z 126

more info,there seems to be uncertainties with Wed nights storm track,so one to watch...

 

 

Edited December 13, 2020 by Allseasons-si
typo

[Griff]

Possible amplification (ramplification) alert...

Watch it go pear shape now I cursed it...