Model output discussion - proper cold spell inbound?

[bradymk]

Iceland going from a pretty slack light air to a deep low at just 72 hours!! Is that unusual or just me?

6z

12z

[MattStoke]

GFS now going with a rain to snow event on Tuesday. Something the BBC have been showing and I think a poster on here mentioned it the other day.

[karlos1983]

UKMO at 144 looking good!

PV Purples backing west which should allow for heights to rise to our north!

Edited February 10, 2018 by karlos1983

[Met4Cast]

2 minutes ago, MattStoke said:

GFS now going with a rain to snow event on Tuesday. Something the BBC have been showing and I think a poster on here mentioned it the other day.

The APERGE whilst not quite as snow excessive as the GFS, also sees a rain > Wintry mess of a mix and snow

Looking at the GFS precip charts and then the APERGE just shows how much of a difference the higher resolution of the APERGE makes.

[Bazray]

1 hour ago, Ali1977 said:

As mentioned in this tweet, effects from the SSW just aren’t being modelled correctly yet.  So, maybe a few days to push before knowing where we go, how quick we see a response and which part of the world gets hit by a freeze etc....V interesting period ahead. 

And to expand on that a little, here is a quote from the Netweather article regarding SSW and the effects on our weather.

"Quite often the models will chop and change when a large atmospheric driver flips and causes a pattern change in the lower atmosphere and this has been the case over the last few days. But as the SSW impacts start to come in the high resolution part of the models, i.e. out to 10 days with most models, then we may start to firm up on what lies in store and whether indeed we will see high latitude blocking manifest to our north and northeast to bring a cold end to the month. But there is no guarantees of such a pattern transpiring, given what I’ve already described about not all SSW events leading to colder and snowy weather."

Guess we will be in for an really fantastic period of model watching, and hopefully the end result is we all get too see some of the white stuff!

[Weathizard]

Not a fan of the higher pressure over Iberia and Southern Europe at 168, broadly similar but messier than the 6z

[Ice Day]

Decent consistency from the GFS out to 174.  Better cold pooling to the north east on this run as well.

 

[Great Plum]

Are we finally getting some sort of consistency?

[Ice Day]

Getting very interesting at 192.  Cold advancing with an easterly setting up!?  Cracking start to the 12zs

 

[SMU]

GFS plot @192 looks a fair shout at the evolution which has been signalled for 48 hours now-

Just the start really....

[bradymk]

Best GFS run yet! Easterly set in and heights pushing into Greenland now!

[Ice Day]

Then at 210 

 

Close to dream synoptics these.  The next few frames should be good!

[Singularity]

Just take a moment to consider how bizarre the pattern is in 6 days time; vast areas of fairly slack pressure gradients as the troughs in the Atlantic have the life drawn out of them while the blocking has yet to really focus itself anywhere. 

 

With GFS weakening the trough much quicker on this run but also keeping the upstream pattern flatter, so marking a shift to an accelerated version of ECM's recent runs, we are left looking at a situation in which we need enough of the remnant lower heights drifting down across Scandinavia to prevent the mid-Atlantic ridge from simply getting shunted right across the UK.

It is looking rather finely poised on the 12z GFS but a much better effort than the 00z ECM, seemingly due in large part to the trough weakening height rises starting earlier (quicker deceleration of zonal winds on this run?) with results going into day 8 that are comparable to the 12z GFS and GEM of yesterday but slightly sooner in time;

 

 

The 00z ECM left me baffled with much lower amount of zonal wind deceleration. By day 10 you could see it trying to establish the blocking to the NE anyway but the earlier progressiveness had really set things back in that regard.

There's been much wonder about the AO not showing much sign of going negative during the first week after the SSW - seems to me that this is due to the focal point of height rises quickly moving from cross-polar to sit across Asia; the tropospheric height rises should therefore occur offset from the pole toward Eurasia - much as GFS has been playing around with for a number of runs now. 

It could well be that the lack of clear AO response is making the first-week impacts even more challenging for the models to capture.

Liking this GFS run a good deal; plenty of cold air ready to the east and the Canadian vortex already in tatters. Over the following week I can see a route (based on this run) for a fragment of that vortex cross Svalbard and then drop down through Scandinavia or W. Russia... but that's just speculation for the fun of it .

[Frosty.]

I love where this Gfs 12z is going!

[SMU]

216 shows a strong Easterly flow & snow showers

waiting for the Greenland High....

[ICE COLD]

The cold is coming ?

Edited February 10, 2018 by ICE COLD

[Daniel*]

A quite snowy easterly for Southern England with quite low heights I like it a lot. 

[bobbydog]

GFS keeps the dream alive-

 

[Daniel*]

Run of the winter so far I’d say. Exquisite. 

 

[Captain Shortwave]

Absolutely textbook from the GFS, what a beautiful run during the middle stages of the run with an easterly developing with showers piling into the east which turn increasingly to snow. 

That said for balance, the GEM wins the Murphy's law award, the tropospheric response is probably too strong with the trough simply sinking and we end up blocked but still under the influence of a deep Atlantic trough with the block unable to gain momentum to turn us properly cold.

If this happens then at least for the time being then we would be terribly unlucky.

[Singularity]

 

Peak of the second phase of warming is nearer Greenland on this run, with that pesky Eurasian remnant vortex kept further east.

There goes that fragment from the Canadian vortex across Svalbard (well, partially anyway). The hemispheric setup doesn't really get any better than this for both ongoing conditions and prospects going forward.

[Met4Cast]

Remember a few hours ago when everyone was a little downbeat at the poor overnight/morning model runs? Well..

Probably the best run from the GFS yet, very smooth transition, no headaches, cracker of a run

[Ice Day]

Best run of the winter.....lots to change but this is brilliant to see.  The cold will just keep on coming here 

 

[Daniel*]

1 minute ago, Daniel Smith said:

Remember a few hours ago when everyone was a little downbeat at the poor overnight/morning model runs? Well..

Probably the best run from the GFS yet, very smooth transition, no headaches, cracker of a run

It’s sensational it gets going in a semi reliable timeframe too. A very clean evolution that would get the cold and snow troops out in mass.

[Met4Cast]

Wow. This chart wouldn't look out of place plucked from a few classic winters.

Heavy snow/blizzards into Southern England at 264