Model Output Discussion - cold spell to end Autumn

[Snowjokes92]

Hi all ! Lurker on this forum since around 2007! Now decided to join the crazy ride of winter 2017/18 and beyond. Im no experct on weather compared to some members of this forum such as GP and tamara etc, however i do feel i have the same basic knowledge as most of the users of the forum.

Also just to add some on topic discussion. That ECM going through the next week has just thrown another piece to the puzzle, in this great and interesting start to the winter. Probably best ecm run recently, for developing a decent scandi high in the longer range output. 

[blizzard81]

3 minutes ago, Snowjokes92 said:

Hi all ! Lurker on this forum since around 2007! Now decided to join the crazy ride of winter 2017/18 and beyond. Im no experct on weather compared to some members of this forum such as GP and tamara etc, however i do feel i have the same basic knowledge as most of the users of the forum.

Also just to add some on topic discussion. That ECM going through the next week has just thrown another piece to the puzzle, in this great and interesting start to the winter. Probably best ecm run recently, for developing a decent scandi high in the longer range output. 

Welcome Snowjokes. Enjoy the ride

[Derecho]

Hello

A lot of attention obviously on Sunday and Mondays events, though I'm also looking to see whether we can sustain the cold. 

Admittedly it will be quite tricky but there seems to be a Scandi high popping up in the operationals again. I'll highlight the key to look out for. First to stop a zonal onslaught, it's vital we prevent the polar vortex from creeping into the Atlantic. Here is the 12z GFS operational later on in the week:



The Polar vortex is held back and heights are allowed to build northwards from the Azores. Whereas the control....



Is poor and we see a return to more familar territory. Thankfully the ECM supports the operational instead. Next step to hold on to the cold can be achieved in two ways; either trough disruption (ECM) or a held back polar vortex over NE Canada (GFS).

                   ECM                                                          GFS operational
 

For good trough disruption cold air over the UK is a big help (as shown by this weekend) so we want to see as much cold pooling as possible on Thursday. The 06z GFS operational was actually very cold with sub zero maxima at times in central and northern areas but that was because of a snow event on Thursday. It will be difficult to get more snow on Thursday though there is still uncertainty about the incoming low.

Overall the 12z's lack the stronger cold later on and would probably result in a CET of around 4.0C by the 18th. They are ok though but the threat of a return to zonality is there later on. Lets hope the Scandi high builds or we get more trough disruption in around 10 days time!

[Frosty.]

The GEFS 12z mean eventually becomes typically zonal (positive NAO) with low pressure to the nw  and high pressure to the sw / south with temperatures recovering closer to average and the most unsettled weather to the nw  with the best chance of fine spells towards the s / se.

[northwestsnow]

Excellent EC tonight-'

yes the cold is going to break down wed - but i think we all accept that- however the NH profile looks tons better than the00z run -

Hopefully not an outlier with its pattern.

Good luck to all sunday- hope as many get some snow as possible!!

[chionomaniac]

1 hour ago, chionomaniac said:

I'm not seeing that. For me it looks like any westerly mild attack get put back with the emphasis more on any mild weather being watered down as we get each run. The trend is definitely cold with short lived mild rather than what we are used to - mild with short lived cold getting watered down as we close in. If we can keep this trend up and then get a Scandi high as suggested by models and GP/Tamara then who knows........

Furthermore to this it may just as well help by backing this up with some facts. So to recap where we are this winter:

We have a descending solar cycle aligned with an descending eQBO - historically most NH blocking episodes and -NAO have been seen during this time - we have previously shown the papers that suggest this.

EDIT I have got this bit wrong - so apologies for misleading - for a descending solar cycle the NAO is mostly positive - but this data was taken with far higher solar max values rather than the subdued cycle max we have just seen - so at the end of the descent the results may be more closely aligned to the minimum rather than the descending phase.

Paper is here http://onlinelibrary.wiley.com/doi/10.1002/2013JD021343/full

We have a disrupted trop polar vortex that has been ruling the roost over the lower strat vortex - hence the mean zonal mean winds (u winds) at 30 and 10 hPa are significantly lower than we are used to with no signs that any upper vortex intensification (VI) is likely to occur and filter down anytime soon.

The MJO forecasts in a Nina'ish year are surprisingly good http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml and I am sure that @Glacier Point and @Tamara can come and confirm how this affects the GWO.

But if we look at the composites for December for this type of set up then we see this

Without the Nina then these height anomalies are stronger over Greenland.

The trend is definitely for a southerly tracked jet in a NW to SE axis exactly as we are seeing currently and I don't see anything that will change that in the short term to the usual SW to NE axis. That does leave the door open for Scandi height rises so well done to GP and Tamara for suggesting this. But overall the pattern forecast by the models looks 'right' and I would be highly dubious of any that suggest a return to mild zonality for a while.

Now all we need (on a personal note) is for the snow charts for this weekend into next week to include Sussex!

Edited December 8, 2017 by chionomaniac

[Summer Sun]

Looks like a northwesterly from UKMO at t168

[Frosty.]

25 minutes ago, Frosty. said:

The GEFS 12z mean eventually becomes typically zonal (positive NAO) with low pressure to the nw  and high pressure to the sw / south with temperatures recovering closer to average and the most unsettled weather to the nw  with the best chance of fine spells towards the s / se.

I guess the GEFS 12z mean could be wrong but it does tie in with the latest met office update mid range for a milder Atlantic driven phase with the northern arm of the jet flexing its muscles for a time..but I guess that's not what most on here want to hear..

Edited December 8, 2017 by Frosty.

[Singularity]

  

When it comes down to it, we have in the 8-10 day range a not all that strong or flat jet (compared to what it can be... as we're seeing for early next week) coming up against some significant cold pooing in what looks likely (as of this evening at least) to be a pretty slack setup to the E and NE, which has an increasing amount of aid of background forcing as we move between mid and late-Dec.

So not surprising to see the models trying out some trough disruption with the Atlantic being held off. Whether this can actually be achieved without the Atlantic westerlies ever really getting in will depend on a combination of the pattern continuing to look supportive of deep cold pooling next Sat-Mon plus enough of a nudge in the right direction from the tropical teleconnection. There is a Bay of Bengal tropical cyclone that could complicate matters, but today has seen wind shear impeding the system and keeping it weak (https://www.accuweather.com/en/hurricane/indian) which, given an expected poorly-conducive environment for development in the days to come, reduces the likelihood of much impact on the extratropics .

[Ross Andrew Hemphill]

Could we see another March 2013 style track shift of this slider low, this time further North back to Central Scotland???

 

Wishful and selfish thinking maybe, but I guess it could happen... 

[mother nature rocks]

5 minutes ago, Ross Andrew Hemphill said:

Could we see another March 2013 style track shift of this slider low, this time further North back to Central Scotland???

 

Wishful and selfish thinking maybe, but I guess it could happen... 

Wishful thinking indeed ? can’t see all the models being incorrect at this late stage.

[feb1991blizzard]

Overall a decent Extended EPS, not tremendous improvements but just steady, although not great with troughing S.Greenland, there is more defined scandi ridging into the pole, in fact the polar profile is excellent and also much better euro height profile with low anomaly strengthened considerably from last run.

[Man With Beard]

Looking through those (probably overexagerated) snow charts on weather.us - EC 12Z ensembles out to Monday - that slider low is nothing for uncertainty on this new event!! We have up to a foot of snow and no consensus at all on where it's going. Some go SW. Some go central south. A few go SE. Only about 20% fail to produce heavy snow south of the M4. And we're now inside T72!

[Lynxus]

Is that a beasterly i see in the far far far far far FI.. Like.. So far.

Closer to now... Monday looks like fun still., 850's aint as cold as they really should be

Yet it does still show good for the trailing edge to have a decent amount of snow for midlands south..

 

[feb1991blizzard]

2 minutes ago, FiftyShadesofWine said:

Seeing as 330 million Twitter users have access to the link heres a chart from the ext eps...hoping I don't get found out first....

What the heck then, here's a better version, might as well have one with the actual heights superimposed over the anoms

[LRD]

14 minutes ago, feb1991blizzard said:

What the heck then, here's a better version, might as well have one with the actual heights superimposed over the anoms

Almost perfect. Just the odd tweak needed here and there such as getting that nose of orange out of Spain and Portugal (preferably to the south and south west of the Azores) and also getting the Scandi ridge ever-so-slightly closer to Iceland and bingo! 

Edited December 8, 2017 by LRD

[Delka]

Probably my favourite outcome so far, bringing heavy snowfall to many with the whole of East Anglia joining in on the act too! Unfortunately unlikely to happen but it's some lovely eye candy for some..

[MattStoke]

1 hour ago, BLAST FROM THE PAST said:

The confidence of no snow south of M4 imo is way too high.  This is a volatile and cold set up we are in with further near time adjustments, changes to come.  Indeed snow accumulations that have happened already surprised many imo

I think Madden needs to do the lottery tomorrow.....I saw back in October he highlighted 7-10 of Dec as a disruptive snow period...no lie.

Models for me showing a further adjustment south..all to play for.  Also the Atlantic ridge for mid month, I think it will manifest in blocking being influential and no westerly flattening

 

 

BFTP

I hope this is sarcasm. The guy is a clown. He highlights every part of every winter for disruptive snow, without giving any specific detail, and then claims to be right every time there is snow over the Cairngorms. He's been 'forecasting' snow every week since October.

[Summer Sun]

A cold start next week before the 850's recover to give a few milder days around midweek towards Friday temps drop again but not as cold as this current spell

NE England

Scotland

London

 

[BLAST FROM THE PAST]

Just now, MattStoke said:

I hope this is sarcasm. The guy is a clown. He highlights every part of every winter for disruptive snow, without giving any specific detail, and then claims to be right every time there is snow over the Cairngorms. He's been 'forecasting' snow every week since October.

Sarcasm re lottery.....but the dates were and are specific.  

 

BFTP

[MattStoke]

2 minutes ago, BLAST FROM THE PAST said:

Sarcasm re lottery.....but the dates were and are specific.  

 

BFTP

Really specific when he says it's going to snow every blinking week and has been wrong every time up until now. Take a look at the dates he specifies. They cover the entire winter, with only small gaps of a few days between each period and the caveat that it will be 'in or around' those dates. The guy deserves no praise. 

[BLAST FROM THE PAST]

Just now, MattStoke said:

Really specific when he says it's going to snow every blinking week and has been wrong every time up until now. Take a look at the dates he specifies. They cover the entire winter, with only small gaps of a few days between each period and the caveat that it will be 'in or around' those dates. The guy deserves no praise. 

Enough on that now but he should do lottery tomorrow   

Agree with those re ECM looking good

 

BFTP

[KTtom]

Just as a matter of interest...is there a reason there isn't a winter model thread...strange were all posting in  a 'potential cold end to autumn thread' ? Come on mods

Edited December 8, 2017 by KTtom

[Bobafet]

Whilst scanning the BBC weather website found this interesting article regarding La Niña, I am sure I have read a bit regarding this in this thread, so hopefully of interest to others. Hopefully this is the right thread to post this in.

http://www.bbc.co.uk/weather/features/42251522

[joggs]

35 minutes ago, FiftyShadesofWine said:

Seeing as 330 million Twitter users have access to the link heres a chart from the ext eps...hoping I don't get found out first....

I can see the jet taking a more nw,se  route.

It's going to be a winter of unpredictability and short changes imho.