Hunt For Cold: Model Discussion - Heading Into Christmas

[blizzard81]

Just think this is one of those occasions when we need to hold our nerve. The ecm and ens will be interesting tonight. 

[Seasonality]

18 minutes ago, More Snow said:

Its Gin time!!!

Good man. Hope the weather gives you some more snaw to go with it soon. European cold now looking very likely, I'll set up a few industrial fans to try push it west for you. 

[Banbury]

GFS at 180 looking to storm the Atlantic in

[Reversal]

12 minutes ago, Nick F said:

There is a danger of assuming that the upcoming major SSW and forecast split will couple with the tropospheric circulation, unfortunately not all do, a recent study by Karphechko et al. (2017) suggested that 43% of SSWs do not strongly couple to the trop circulation. We've been lucky that in recent years that some of the major SSWs (Jan 2009, Feb 2010, Jan 2013 and Feb 2018) have downward propagated and given us the goods. Credit to Simon Lee: https://simonleewx.com/2018/12/27/not-all-ssws-were-created-equal/

However, there is a great deal of uncertainty how this SSW will affect the trop if at all, so a waiting game to see, given that it can take 10-14 days for the troposphere to respond from the date of the SSW. The ECWMF ops recently to varying degrees have been hinting at perhaps a response from the trop by building a ridge north over the N Atlantic while deep cold pushes south over NE / E Europe. GFS ops not really been keen at all, rather showing deepening and expanding trop PV to the north and strong westerlies, though jet stream tracking further and further south with potential for NW'ly or N'ly incursions.

We could also see the trop pattern respond to poleward wave propagation of the MJO wave if it goess through 7-8-1 at a decent amplitude too, so if the SSW doesn't have an impact on changing the pattern the MJO could do it.

Frustrating I know, when the models are not hinting with any confidence and continuity a pattern change to bring deep cold and wintry weather atm. So more sitting on the fence from me.

And exactly why we shouldn't be saying so certainly that the models are yet to smell the coffee because the trop isn't mirroring the forecasted strat profile the way we would like it to 

It's has been suggested repeatedly that the models are yet to "smell the coffee". This coffee being the strat or MJO output of those same models.

Is there any truth to the notion that models don't take account of the feedback of the very events they are forecasting? It doesn't seem likely that NWP would have a less holistic view of the atmosphere when compared to wx enthusiasts looking for one type of weather in one part of the globe 

[Sir Mim]

1 minute ago, Banbury said:

GFS at 180 looking to storm the Atlantic in

So far it's looking almost exactly the same as the 06 run...  

[Methuselah]

If the SSW doesn't show its hand soon, it might be too late - this run is already half-way down the crapper!

[blizzard81]

I'm not holding my nerve anymore. Just going to emigrate to colder climes lol. 

[Decemberof2010]

Mmmm. GFS was getting a lot of stick this morning. Of course it may still be wrong, I hope it is. However, the ICON has trended away from its 6z run. Let’s see what the GEFS and ECM show. 

[warrenb]

Ssw lead time can be 2 to 3 weeks. So stop writing it off based on charts based a week away

Edited December 27, 2018 by warrenb

[Banbury]

1 minute ago, Ed Stone said:

If the SSW doesn't show its hand soon, it might be too late - this run is already half-way down the crapper!

What are you on about 

Nothing is going to happen until Midnight on January 14th 

[Summer Sun]

GFS v UKMO at t144

[blizzard81]

Real cold zonality on the 12z gfs. 

[Sir Mim]

2 minutes ago, Summer Sun said:

GFS v UKMO at t144

I always preferred the UKMO anyway.  Much more reliable.  

[Summer Sun]

Certainly a stormy looking GFS this afternoon maybe we need to look to the west for cold air and not the east

[Kentspur]

9 minutes ago, blizzard81 said:

I'm not holding my nerve anymore. Just going to emigrate to colder climes lol. 

Turkey would be perfect 45c in summer snowed in in winter!

[Weathizard]

2 minutes ago, Summer Sun said:

Certainly a stormy looking GFS this afternoon maybe we need to look to the west for cold air and not the east

This sort of cold zonality would be rain and wind for 99% or the UK, who wants that?! Good for peaks and Scottish ski resorts that’s about it.

Be interesting to see if FI builds a ridge in behind the big system 

Edited December 27, 2018 by Weathizard

[Paul_1978]

8 minutes ago, Ed Stone said:

If the SSW doesn't show its hand soon, it might be too late - this run is already half-way down the crapper!

Met Office update suggests a wet and stormy early January so this shouldn't be a surprise. 

Only after week 2 does the update suggest a potential change to cold. 15th Jan is 456 hours away yet.

We won't be getting 15th Jan in model range (at T+384) for another three days yet. 

So for me, in the "hunt for cold" there is no point in worrying about model output for at least another 7-10 days yet until mid Jan starts to get into a semi-reliable timeframe. 

I'll keep taking a cursory glance at the models until then just in case anything unexpected happens in the meantime.

[Bruegelian]

Seriously though, might Fawkes be right even thought most of us hope he's wrong? Why would the SSW struggle to affect the troposphere? Of course SSW is not a silver bullet.

Edited December 27, 2018 by Bruegelian

[winterof79]

"Whatever" GFS

12Z

06z

It is all over the shop. Turkeys either frozen or cooked 

Edited December 27, 2018 by winterof79

[blizzard81]

1 minute ago, Weathizard said:

This sort of cold zonality would be rain and wind for 99% or the UK, who wants that?! Good for peaks and Scottish ski resorts that’s about it.

Might see the odd fleeting sleet shower lol. 

[Johnp]

7 minutes ago, blizzard81 said:

Real cold zonality on the 12z gfs. 

Someone's going to mention the Scottish ski resorts soon. Then we know we're scraping the bottom of the barrel.

[Polar Maritime]

The Jet really ramping up on this evening's run, With Severe gales and hill snow from a PM flow. Something seasonal/interesting at least.. or last! And in line with Meto Extended.

 

Edited December 27, 2018 by Polar Maritime

[feb1991blizzard]

4 minutes ago, Bruegelian said:

Seriously though, might Fawkes be right? Why would the SSW struggle to affect the troposphere?

He certainly could be - it certainly looks to be taking its time and having a think about it in GFS FI - certainly slow response compared to Jan 13 off the top of my head for example.

Edited December 27, 2018 by feb1991blizzard

[Nick F]

The GFS operational outputs have been pretty consistent in the strong westerly signal and although not everyone's cup of tea, especially us down sarf., they have been hinting at 'cold zonality' for early January, which offers up some hill snow for sure and perhaps lower levels at times for the north, the 12z indicating this potential:

However, UKMO's (and EC on it to) strong NW Europe block signal at day 6 hardly inspires confidence of model guidance beyond day 6 ...

[booferking]

10 minutes ago, Weathizard said:

This sort of cold zonality would be rain and wind for 99% or the UK, who wants that?! Good for peaks and Scottish ski resorts that’s about it.

Be interesting to see if FI builds a ridge in behind the big system 

528 dam line through the country some low lying areas would see snow also.

Edited December 27, 2018 by booferking