Winter Approaching: Forecast and Model Discussion Commentary

[WYorksWeather]

Big change on the GFS 12z vs. the 6z around the 8th-10th timeframe of interest (as I said, I'm just keeping an eye on developments beyond that for now, no point getting too attached to anything beyond day 10).

Showing more of a toppler. 6z looked better for cold.

[Mcconnor8]

GFS looking like it wants to try and retrogress the high at the end of next week

[blizzard81]

 WYorksWeather The intense storm showing over New Foundland on the 06z has disappeared. Probably why we didn't get the same traction and amplification on our high at day 8 but I think this might be better for prospects going into week two though.

[northwestsnow]

Another bite of the retrogressive cherry ?

Prefer 12z 

Here's 6z

Edited November 30 by northwestsnow

[blizzard81]

And yes, looking better going through week two.

[northwestsnow]

 blizzard81

Very difficult to pin a pattern at the timescales involved,expect lots of variations on the theme.

Let's get that ridge up in the Atlantic and hope for some luck for once ! 

Edited November 30 by northwestsnow

[blizzard81]

 northwestsnow Indeed and what's happened to the PV?

Wouldn't be surprised if we end up with a Scandi high on this GFS run.

[Gregulator]

Question..does the jet stream dictate how/where the highs/lows form or the other way round...or not at all?

[blizzard81]

This is shaping up to be a crazy run!

[blizzard81]

And there's the Scandi high forming as predicted. Probably an outlier but we can hope.

[northwestsnow]

 blizzard81

It's a cracker but you and I know a lot of water is to run under the bridge before we can begin to hope..

[blizzard81]

 northwestsnow Absolutely bud. I certainly don't trust that run lol. Where did it come from? The difference to the 06z is laughable. 

[Scandinavian High.]

and this is the direction want to see .

[Met4Cast]

7 hours ago, Met4Cast said:

Unsure if we're looking at a Greenland or Scandinavian high, perhaps a mixture of both,. albeit I'd probably favour an extension into Scandi initially,

Thank you 12z GFS for making me look like I know what I’m talking about

[blizzard81]

Maybe that GFS run wasn't so crazy after all. I think the Ukmo 168hr chart could easily lead to a Scandi high also.

[feb1991blizzard]

 Scandinavian High. Yes, its certainly the direction of wind i like to see. You can thank me for that, literally you posted it just after i went for a very high cet in the December competition.

[minus10]

Now that is a picture of a 'peturbed' jet...

[WYorksWeather]

 blizzard81 Yep, turned into a very cold run there, not notably so but consistently cold.

[Mike Poole]

Good run from the GFS 12z.  But no surprise, that evolution was very much present on the extended clusters this morning.

More interest up top than we’ve seen for many runs too, T384:

[WYorksWeather]

 Mike Poole Will be very interesting to see the ECM zonal wind chart tonight when it updates.

[Jacob]

The GFS 12z is synoptically good in FI but the uppers only suggest a somewhat cold spell. Hopefully the Synoptics are repeated, but with colder uppers 

[minus10]

Nice cluster going colder on the 12z from day 7 or so...

...the anoms also showing promise with the trough extending south west accross Europe and into Spain while the extensive higher pressure in the Atlantic  allowing for a potential colder pattern...

...lets hope this is a trend that will stick...

[bluearmy]

Geps are interesting late on 

gefs may be headed that way 

ec op day 15 is drifting towards the AI 06z run 

 

[Cambrian]

A dramatic hemispheric shift in the 12z GEFS at day 10 from where we were a day ago at day 11. Yesterday / today.

 

It’s not just given the remnant Scandinavian trough a big heave in favour of positive heights. Look at the difference through northern Greenland and that linkup between Atlantic and western Canada / Alaska heights, cuts the PV sausage in half, and notice too the impact on the eastern seaboard trough, de-energised and pulling back north into Hudson Bay.

Atlantic heights further west, weaker heights heading northeast from the Azores, more now of a push north. Most of all, the European trough, growing in stature with every passing day.

Becoming very interesting indeed - heading into the middle of December, doors are being opened, left, right and centre. 

[bluearmy]

Both ec and gfs ops are not without some mid lat fun end week 2 

given that we’d expect the trop pattern to be responsible, we should not be over attentive to that without some consistency .  However, it shows that the strat pattern remains susceptible to amplification in the trop and that is very difficult to forecast two weeks away