The hunt for cold - Model discussion (late November)

[fromey]

Not looking to shabby!

[Mike Poole]

Just to carry on with this Arctic high theme, and put forward a few wider thoughts.  First here's the December mean surface pressure anomaly from the last 8 CFS runs:

I've posted these from time to time, always as a group of runs, one CFS run on its own is meaningless.  Ignoring the UK for a moment, all 8 of these charts show a significant negative AO for December, so it's no surprise to see similar signals now appearing in the ops and ensembles,

I think it is all coming together.

Various people are making arguments for cold upcoming, but based on arguments from completely different directions, mine - model output, others though are MJO, GWO, Ice extent, QBO, stratosphere, solar output, SST, ENSO, Modoki El Niño etc.  I believe all the weather is connected (except probably solar) and all are partial predictors, but anyone who claims any single one of them are the be all and end all are deluding themselves, in my opinion. What is promising, is that there are positive signals for a cold winter from expert views from most of these perspectives.

A harder question is whether the UK, small islands as it is, will be well placed.  Hope so.

Edited November 23, 2018 by Mike Poole

[feb1991blizzard]

I can cast iron guarantee who i know would be posting about the Icon and GFS 18z runs but he's on a plane half way across the Atlantic - big Westward correction.

[Mike Poole]

I think there's a storm coming in, but maybe slower than earlier runs, GFS 18z at T108:

Yes,  but the NH picture looks anything but zonal...

We just have to sit this low out, and maybe one more.

Edited November 23, 2018 by Mike Poole

[Geordiesnow]

5 minutes ago, Mike Poole said:

I think there's a storm coming in, but maybe slower than earlier runs, GFS 18z at T108:

Yes,  but the NH picture looks anything but zonal...

We just have to sit this low out, and maybe one more.

Going to be the usual uncertainty with this low as its origin is in the tropics in the Atlantic and how it deepens and its final position will be down to the jet stream and the mixing with that tropical air and the colder air. 

Either way, the potential for Wednesday to be a disruptive day is certainly there and the next named storm could be making the headlines soon, more runs are needed to firm the details up. 

[Rocheydub]

10 minutes ago, feb1991blizzard said:

I can cast iron guarantee who i know would be posting about the Icon and GFS 18z runs but he's on a plane half way across the Atlantic - big Westward correction.

True, but it's an inevitable storm, only slightly changing the outcome. In fact, the heights don't rise as well into Greenland after as a result. Not every change is a positive one.

[feb1991blizzard]

1 minute ago, Rocheydub said:

True, but it's an inevitable storm, only slightly changing the outcome. In fact, the heights don't rise as well into Greenland after as a result. Not every change is a positive one.

 Ridge nearer to Greenland at 156 than it was on the 12z and ridge to the East nearer.

[northwestsnow]

Good things happening on this run, seeing signs of the energy splitting at 156..

[feb1991blizzard]

In any case though - i'm not really interested in what happens in the first part of the run, im actually far more interested in the GEFS  and EPS ensemble means/clusters at 300+

[Mike Poole]

OK, pub run T192:

Is that ridge way to our east going to head towards and connect with a polar high?  I think so, would fit with other output this evening.

[thetipster]

GFS 3D POLAR VOTEX + ENSEMBLES

[feb1991blizzard]

7 minutes ago, Mike Poole said:

OK, pub run T192:

Is that ridge way to our east going to head towards and connect with a polar high?  I think so, would fit with other output this evening.

2 wave squeeze and subsequent cross polar flow could happen on this run, watch the Atlantic and Pacific sectors.

[feb1991blizzard]

4 minutes ago, thetipster said:

GFS 3D POLAR VOTEX + ENSEMBLES

What is the potential temperature please? or what is its implications?, im used to looking at those 3D strat charts with GPH.

[Mike Poole]

15 minutes ago, feb1991blizzard said:

2 wave squeeze and subsequent cross polar flow could happen on this run, watch the Atlantic and Pacific sectors.

Yep, looks possible, some tidying up will be needed over the polar region, but quite possible from here. GFS T240:

Edit, T348, the vortex might be dismembered  from closer to home.

Edited November 23, 2018 by Mike Poole

[thetipster]

7 minutes ago, feb1991blizzard said:

What is the potential temperature please? or what is its implications?, im used to looking at those 3D strat charts with GPH.

just showing the uncertainty of the pv

[Man With Beard]

Clusters D14

All I get from this is ridging likely pushing northwards in the Atlantic between 6th and 9th December, which suggests a downturn in temperatures for the UK once again, but chances of big cold still on the lower side - for now. 

[Rocheydub]

46 minutes ago, feb1991blizzard said:

 Ridge nearer to Greenland at 156 than it was on the 12z and ridge to the East nearer.

Fair point, and I probably should have pointed out, I was remarking from the last run I watched, which was the 00z. As a shift worker, I'm often on a different planet to most on here! 

 

Fact remains though, and I doubt it's up for debate, we are in for zonal after this cooler spell. We are also not in line for anything like what we all want (on this thread) for the foreseeable future. Yes, FI and PV disruption is very eye catching, but we've all been down this road before. Hopefully it's as productive as last Spring!!!

[feb1991blizzard]

20 minutes ago, Rocheydub said:

Fair point, and I probably should have pointed out, I was remarking from the last run I watched, which was the 00z. As a shift worker, I'm often on a different planet to most on here! 

 

Fact remains though, and I doubt it's up for debate, we are in for zonal after this cooler spell. We are also not in line for anything like what we all want (on this thread) for the foreseeable future. Yes, FI and PV disruption is very eye catching, but we've all been down this road before. Hopefully it's as productive as last Spring!!!

No, in the next 10 days probably 15, there is zero chance of what we all want on here, hence why i said that i am far more worried about the ens mean, 10-15d anomaly charts and the strat and teleconnections, caveat being that the near time charts don't change significantly enough to scupper the long term ambitions of course.

[feb1991blizzard]

Underwhelming ending to the day with a flat GEFS.

[Man With Beard]

59 minutes ago, Man With Beard said:

Clusters D14

All I get from this is ridging likely pushing northwards in the Atlantic between 6th and 9th December, which suggests a downturn in temperatures for the UK once again, but chances of big cold still on the lower side - for now. 

FV3 18z bang on what I would have expected from these clusters 

[swilliam]

7 minutes ago, feb1991blizzard said:

Underwhelming ending to the day with a flat GEFS.

Flat?

 

This is the mean at 348.

 

[feb1991blizzard]

4 minutes ago, swilliam said:

Flat?

 

This is the mean at 348.

 

This is flat compared to previous runs.

[cheeky_monkey]

31 minutes ago, feb1991blizzard said:

Underwhelming ending to the day with a flat GEFS.

Looks brutally cold for my location towards the end of the run.

[Dave Kightley]

Interesting GFS Fl with height rises over or just North if the UK and great for the USA which i suspect would be very cold! In short to medium turn with Low pressure to our West for a lot of it! Probably quite unsetted 

Edited November 24, 2018 by Dave Kightley

[CanadaAl]

Yes it's certainly looking like north america is getting a big bite of the cherry but also with sniffing of a Scandi high in the FI, it's far away but appears to be appearing more frequently. Could be a trend, could not. I expect my locale to be going right into the freezer that first week of dec