Model output discussion - January cold spell ending, what next?

[bluearmy]

48 minutes ago, carinthian said:

ECM now develops some cold air into the British Isles next weekend with some fairly widespread snowfall across the east of England.

C

That feature pops up from nowhere .... a small chance it will be there in twelve hours, let alone a week! 

[Tim Bland]

1 minute ago, bluearmy said:

That feature pops up from nowhere .... a small chance it will be there in twelve hours, let alone a week! 

True... its not a small feature though, looks like a front rather than convective...? ️

[Guest]

Although I think lengthy entrenched cold spell is doubtful, I do think we could see some quite memorable or even historic snow events in the not to distant future!

And lets face it Snow is the name of the game!

[nick sussex]

The frustration continues . 

The ECM op really drops the ball later on and delivers a day ten chart that suggests the SSW was an illusion ! 

We seem to be in the chasing the pot of gold at the end of the rainbow mode.

At some point day ten charts need to start counting down and not left marooned at that stage .

 

[bluearmy]

not really sure what to think

the warming has been ongoing for almost a week now. the data is well and truly in the models and today, the starting data has reversal almost down to the trop. the broad picture is of an arctic high driving a part of the Asian vortex towards nw Russia. that will introduce frigid air into scandi and probably e Europe ( these areas are going to b v cold anyway before this vortex movement ) 

the question is how close we can get that air to nw Europe and more specifically the U.K

that will depend on how upstream develops.  The period T96 to T180 very uncertain as a weak Atlantic jet  meanders around, especially so in the 4 to 7 day period. That allows the models to do some strange things in the medium term. and are they likely to be in the right place when that frigid air moves sw???

so we really have to just wait for the mid term to resolve itself before we can gain any confidence in how that surge of cold may affect us 

the Atlantic amplification looks solid but this mornings ops show that any greeny height rise could well come to nought. They may be unsupported in the ens and even outliers but whilst they produce output like this they do keep out feet firmly on the ground.

im staying in the v cold camp beyond the 20th ......perhaps even a couple days earlier. The period has been signposted for some time.  However, if the donkey, tail etc etc suddenly disappear again I won’t be searching around for an explanation....... some parts of the mid lats will have an very wintry period. it may just not be our turn ....

[chris55]

Quite remarkable ensembles from GFS! (they look slightly more exaggerated because the scale is 2degrees not 5degrees.)

But even with all the scatter the mean is pulled right down to -4/-5 and a few dip down to -15/16 :0 !

They look more like  a NewYork set when they have those classic winter storms. Where the boundary between the ice cold and mild is close geographically. 
 

Some places could be absolutely buried if the boundary sets up over the U.K.! 
 

 

Edited January 10, 2021 by chris55

[Tim Bland]

GEM looks good from day 8 this morning..

[MJB]

Don't forget there are other warmings up above in the pipeline - they could just give that extra push

[sheikhy]

5 minutes ago, nick sussex said:

The frustration continues . 

The ECM op really drops the ball later on and delivers a day ten chart that suggests the SSW was an illusion ! 

We seem to be in the chasing the pot of gold at the end of the rainbow mode.

At some point day ten charts need to start counting down and not left marooned at that stage .

 

Best post of the morning mate!!!!as much as some of us are dying for some snow and being positive we gota also be realistic!!i mentioned the same thing yesterday!!we gota really get these charts well below day 10 to even start believing!!!!

[bluearmy]

9 minutes ago, Tim Bland said:

True... its not a small feature though, looks like a front rather than convective...? ️

It’s a developing disturbance that deepens into a distinct feature as it crosses southern U.K. and travels into the low counties 

but uppers go above zero across a large part of the area a few hours after the snow has begun which means it would be a temporary covering.  But we agree not worth much more than the few posts mention this morning .....

[121]

Apologies if this is a IMBY post but thought it maybe of use to echo what other members have said about the models not grasping what is happening right now - I live at sea level and on a freshwater marina (Cardiff Bay). We were forecast 0c for a couple hours by The Organisation last night.
 

I’ve just woken up and the marina is frozen over. First time that has happened in 5 years of living here. Admittedly, this is likely possible due to no wind and Welsh lock down preventing the fishing charters/yachts going anywhere, but may also indicate how long this cold spell has been kicking around for.

[Nick F]

7 minutes ago, Tim Bland said:

True... its not a small feature though, looks like a front rather than convective...? ️

Yes, an Atlantic frontal system moving in from the west, bumping into a retreating cold high ahead of it over the near continent. Snow to rain event. Actually GFS similarly has the frontal system and developing low along it dropping SE into France, but without the preceding snow. May not be replicated on following runs though.

[bluearmy]

2 minutes ago, AvidWinterSpectator said:

Apologies if this is a IMBY post but thought it maybe of use to echo what other members have said about the models not grasping what is happening right now - I live at sea level and on a freshwater marina (Cardiff Bay). We were forecast 0c for a couple hours by The Organisation last night.
 

I’ve just woken up and the marina is frozen over. First time that has happened in 5 years of living here. Admittedly, this is likely possible due to no wind and Welsh lock down preventing the fishing charters/yachts going anywhere, but may also indicate how long this cold spell has been kicking around for.

Was just thinking that the comments above your post about ‘these charts never coming below day 10’ seems to miss the point that we still haven’t finished the cold spell we are currently in where many have seen lying snow and some had temps lower than for a decade .....

Edited January 10, 2021 by bluearmy

[MJB]

This is interesting from Darren ( Retron on TWO) 

I also remember on usw ages ago a suggestion that the sort of thing we have now, i.e. a 10hPa reversal followed by a weak resumption of westerlies aloft helps "push down" the easterlies that bit faster. To then be followed by another reversal would suggest those easterlies, once pushed down, would remain there for quite some time.
 

I wonder if there is anything in the archives for a comparison ?

[northwestsnow]

My two main emotions when looking at the 00z runs  are excitement and apprehension...

Crucial 48 hours coming up ...

Edited January 10, 2021 by northwestsnow

[Man With Beard]

Looking at the clusters D8-D15 

I sense the ECM op is out of kilter with the main thrust of the ensembles. The eventual outcome is a Greenland ridge of sorts by D11, with varying outcomes. 6 clusters. On the T264-T360, the two slightly larger clusters keep a strong ridge to the NW throughout and therefore likely to be very cold. Three other clusters are trending towards west based -NAO so UK cold prospects rely on depth of cold filtered in from the east along with the positioning of the front dividing cold and mild. The remaining cluster weakens the ridge to the NW and would lead to average conditions.

On the whole, cold favoured D8-D15 but not necessarily for all.

 

[Chesil View]

16 minutes ago, Snowmut said:

Although I think lengthy entrenched cold spell is doubtful, I do think we could see some quite memorable or even historic snow events in the not to distant future!

And lets face it Snow is the name of the game!

Same here Snowmut, even with the ssw's taking place I think any up coming cold/snowy spell will more likely be one that waxes and wanes,ebbs and flows etc especially for me way down south however those are often the best for historic/memorable snow events even down south. The great southwest blizzard of Feb 1978 for instance occured because milder air was trying to get in. Without that milder air no stalling front and no historic snowstorm.

 

[mulzy]

Lots of uncertainty in the medium term.  Six clusters on the EPS at day 7 confirms this.  The Det was part of Cluster *five*.

[I remember Atlantic 252]

FI GEFS 1 my favourite ever I think

[bluearmy]

12 minutes ago, MJB said:

This is interesting from Darren ( Retron on TWO) 

I also remember on usw ages ago a suggestion that the sort of thing we have now, i.e. a 10hPa reversal followed by a weak resumption of westerlies aloft helps "push down" the easterlies that bit faster. To then be followed by another reversal would suggest those easterlies, once pushed down, would remain there for quite some time.
 

I wonder if there is anything in the archives for a comparison ?

I doubt it’s a clean one size fits all thing 

what was often the case with a reversal is that when we saw the reverse flow begin to downwell, it pushed the stronger westerlies that normally exist higher up in the strat into the lower strat and then the trop.  of course once those stronger westerlies are removed, any further downwelling waves (which tend to follow an ssw every few weeks) will find it easier to head into the trop as the usual strong westerly scenario won’t have had time to reform high up and inhibit.  That’s very much a generalisation though and each ssw and what follows will be different ......

[chris55]

19 minutes ago, nick sussex said:

The frustration continues . 

The ECM op really drops the ball later on and delivers a day ten chart that suggests the SSW was an illusion ! 

We seem to be in the chasing the pot of gold at the end of the rainbow mode.

At some point day ten charts need to start counting down and not left marooned at that stage .

 

That may be true for -20 uppers and frozen seas lol but there are opportunities for snowfalls between now and day 10!

One of my old tests for upcoming cold spells  back when we had less access to data was the Deblit ensembles, if the Deblit 2m temp hovered around the 0c mark for an extended period the the U.K. was on its way to a cold spell/snowfalls.....Only circumstantial but...

heres Deblit :0  

[Frostbite1980]

4 minutes ago, chris55 said:

That may be true for -20 uppers and frozen seas lol but there are opportunities for snowfalls between now and day 10!

One of my old tests for upcoming cold spells  back when we had less access to data was the Deblit ensembles, if the Deblit 2m temp hovered around the 0c mark for an extended period the the U.K. was on its way to a cold spell/snowfalls.....Only circumstantial but...

heres Deblit :0  

And if there is more of a NE influence then the UK can actually be colder than Debit

[Ladyofthestorm]

 I don't often post on the forum,I just lurk and nod in agreement or mumble maybe not. I just carefully watch the models unravel the secrets. 

Looking at the ensembles  we can clearly see the downward trend of the 850 hpa temps. Tick box. 

It looks s only at the end of the runs that they wildly yo-yo up and down as they fail to grasp the effects of the SSW. 

I'm also noting the ridging (amplification of higher pressure) around the UK and Atlantic .Atlantic is stalling and any attempt by the Atlantic to rattle in deep areas low pressure should be taken with a pinch of salt. This opens the doors to Nly sourced winds. Another tick box. The ensemble forecast for the NAO is to stay negative. 

Reversal of winds still up in the air, but looks like our source of an Easterly air is now on the freezer. A huge tick box. 

Subsequent stratospheric warmings look inevitable, their effect yet to be seen.  

Overall looking good. Just be patient and I agree critical time frame 5 to 7 days. 

 

 

[Chesil View]

6 minutes ago, I remember Atlantic 252 said:

FI GEFS 1 my favourite ever I think

I can see why. Atlantic 252. Awesome run.

[nick sussex]

2 minutes ago, chris55 said:

That may be true for -20 uppers and frozen seas lol but there are opportunities for snowfalls between now and day 10!

One of my old tests for upcoming cold spells  back when we had less access to data was the Deblit ensembles, if the Deblit 2m temp hovered around the 0c mark for an extended period the the U.K. was on its way to a cold spell/snowfalls.....Only circumstantial but...

heres Deblit :0  

The ECM on its way to the tragic day ten chart does throw a few teases in but will they still be there this evening and the UKMO looks totally underwhelming upto day 6.

There is a lot of chopping and changing between runs so hopefully it will change once again !