The hunt for cold - Model discussion (late November)

[booferking]

6 minutes ago, AWD said:

Until we lower those heights over Spain/Iberia then there isn't going to be much coming down from the north.

Definitely lower this run than this morning's run keep lowering them bingo.

[Singularity]

Late Dec cold potential is mainly expected to be trop-led based on MJO propagation - which based on recent discrepancies is likely to be more than the current model consensus. However, the vortex displacement may allow for some height rises across the pole which would be a useful modification to what already has a good chance of becoming a negative NAO-friendly pattern as the shift to Pacific tropical forcing makes itself known.

 

After that, might flushing down of zonal winds ahead of a reversal descending be less problematic than it could be thanks to them having already been displaced?

Given the ingredients at hand and the sequence we’ve been though, I’d be shocked not to see a technical SSW and it’d leave me wondering what on Earth prevented it!

[johnholmes]

1 hour ago, BLAST FROM THE PAST said:

I was kidding around with Pete. I’m still staying with my LRF, a pretty cold Xmas with some surprises to be thrown in.  No serious blocking until New Year.  Bitter cold throughout January

GFSp looking good at Xmas Day

BFTP 

So what is it in your water that suggests that please?

No model of any duration, no other lrf makes that much of the probable cold spell in January.

[SLEETY]

1 hour ago, BLAST FROM THE PAST said:

I was kidding around with Pete. I’m still staying with my LRF, a pretty cold Xmas with some surprises to be thrown in.  No serious blocking until New Year.  Bitter cold throughout January

GFSp looking good at Xmas Day

BFTP 

Very unusual to get cold weather patterns persisting for a month in the U.K.,a week maybe rarely more.

What are you seeing that made you say that bold prediction.

[Ladyofthestorm]

1 hour ago, BLAST FROM THE PAST said:

I was kidding around with Pete. I’m still staying with my LRF, a pretty cold Xmas with some surprises to be thrown in.  No serious blocking until New Year.  Bitter cold throughout January

GFSp looking good at Xmas Day

BFTP 

I agree BFTP, this SSW event is looking special. It wouldn't surprise me to see a very cold January. Snow,  I am less sure of but cold I am confident with. 

Is it just me or does the Altantic  patterns look like they are weakening on the GFS run to run?

Xmas  I am pretty confident won't be mild and wet for us. 

[Ladyofthestorm]

10 minutes ago, SLEETY said:

Very unusual to get cold weather patterns persisting for a month in the U.K.,a week maybe rarely more.

What are you seeing that made you say that bold prediction.

Not unheard of though, Dec 1993, Jan 2001,  Jan 2003, We do get them. Usually a blocking area of High Pressure though. 

[Derecho]

1 minute ago, Ladyofthestorm said:

Not unheard of though, Dec 1993, Jan 2001,  Jan 2003, We do get them. Usually a blocking area of High Pressure though. 

They were rather uninteresting months if you ask me.... not exactly bitter cold for a whole month...

[Methuselah]

19 minutes ago, Ladyofthestorm said:

Not unheard of though, Dec 1993, Jan 2001,  Jan 2003, We do get them. Usually a blocking area of High Pressure though. 

I remember January 2003 quite well, as I was staying in the NW Highlands...18C recorded in Banchory; and certainly no month-long cold spell that I can remember...?

But, as you say, not entirely unheard of: 1963, 1981-2, 1985, 1986...2010?

Anywho, back to today - plenty of amplification around; it's good to see the N-S orientated potential block forming, out in the Atlantic, too:

Edited December 16, 2018 by Ed Stone

[That ECM]

From run to run the ridge out west is gaining strength. The output will be very different in future runs past t144 if this continues. Ukmo and gfs not to far apart. 

[Mike Poole]

Just now, That ECM said:

From run to run the ridge out west is gaining strength. The output will be very different in future runs past t144 if this continues. Ukmo and gfs not to far apart. 

The interest in a northerly Christmas week is still there it seems, I'll add GEM T144 to that too.

The form horse still mild for the 25th, but not by a huge margin. 

[SLEETY]

20 minutes ago, Ladyofthestorm said:

Not unheard of though, Dec 1993, Jan 2001,  Jan 2003, We do get them. Usually a blocking area of High Pressure though. 

really? don’t recall bitter cold lasting throughout the month in any of those months you quoted

[Mike Poole]

1 minute ago, SLEETY said:

really? don’t recall bitter cold lasting throughout the month in any of those months you quoted

Location an issue maybe?

[Weathizard]

Pressure it just too high to our south, doesn’t matter if that ridge in the Atlantic grows in strength the pressure over Iberia and France is humongous and will just flatten the pattern, the ridging attempts in the Atlantic have been omnipresent recently and haven’t done an awful lot.

[Derecho]

6 minutes ago, Weathizard said:

Pressure it just too high to our south, doesn’t matter if that ridge in the Atlantic grows in strength the pressure over Iberia and France is humongous and will just flatten the pattern, the ridging attempts in the Atlantic have been omnipresent recently and haven’t done an awful lot.

Yes, someone needs to pour some salt on the Euroslug. However a definite positive is that there seems to be increasing signs of low pressure forming over the Azores. This will certainly amplify the pattern providing the high to our south shifts east. If it doesn't though we could end up with a February 1998 type pattern.

Edited December 16, 2018 by Quicksilver1989

[Singularity]

The (anticipated to be) over-stalling of the tropical cycle by the models is in the phase that drives an Iberian ridge so if and when the models correct tropically, the Iberian bubble should burst.

Annoying to have to keep that caveat in there but that’s just how it is with the climate system!

 

Upstream looks closer to anticipated developments on GFS 12z as of day 8 (+192 hr). More amplified ridge trough downstream in response but the latter does need the door to open for a move into mainland Europe.

Edited December 16, 2018 by Singularity
GFS notes

[Ice Day]

Slightly deeper Strat warming on this run, peaking around 168hrs.  

[Ice Day]

So here is Christmas morning on the 12z compared to the same time on the 6z.  Each run is gradually moving more and more of the PV away from Canada / Greenland with better Atlantic ridging.  Would be nice to see this continue.

  

[CanadaAl]

1 minute ago, Ice Day said:

So here is Christmas morning on the 12z compared to the same time on the 6z.  Each run is gradually moving more and more of the PV away from Canada / Greenland with better Atlantic ridging.  Would be nice to see this continue.

  

It's encouraging. Hoping for a low to drop s/sw across the channel like seen in the runs a few days ago. 

[Mike Poole]

Just glancing through the rest of the GFS 12z, does anyone else think the pattern of really cold air across the NH at T210 looks really odd:

Looks like a giant wooden spoon.  Hopefully that's not a metaphor for the rest of our winter!

[SLEETY]

could be very interesting fl coming up,not as if it matters though,as they never verify,do they ?

[summer blizzard]

22 minutes ago, SLEETY said:

really? don’t recall bitter cold lasting throughout the month in any of those months you quoted

He's probably thinking of snow events.

[northwestsnow]

I'm liking the trends on the 12zs..

GFS goes onto produce a cold high, and if i'm honest i actually prefer UKMO which has the ridge slightly west of GFS- (better).

[The Northern Ramper]

6 hours ago, SLEETY said:

why are you ignoring the long term forecasts from the meto and others on here.Its end of dec into january that the forecast of much colder weather is being forecasted not dec! ,do you just ignore what the experts are banging on about for the last few weeks.

Because this is model output discussion not meto.

[nick sussex]

A very confused picture .

The big fly in the ointment is the shallow low pressure over the UK. The problem here is as the upstream pattern amplifies the question is whether that clears eastwards as a whole or whether it splits with a separate low pressure amplifying to the west of the UK. The UKMO looks like it might go that way.

If it’s the latter then you’ll rely on pulling the Iberian high northwards , initially that’s going to bring in some milder southerlies .

Until the high gets sufficiently north and north east .

Putting these issues aside , there’s a window now to develop something in towards Christmas week .

Anything could happen , stay tuned!

[SLEETY]

hmm thought the high was going to retrogress towards greenland,then when low res kicks in,gfs decides to display utter junk.Might as well end the run at 240 or whenever low res kick in.