Model Output Discussion 12z 04/12/2012

[bradymk]

GEFS Control run very similar to its 6z run so far. Great to look at

Ensembles now out to t192, a very impressive ensemble mean, another cold suite looks likely.

Short ensemble diagrams with the mean below -5 at 850, with quite a few runs below the mean at around -8 mark.

Edited December 5, 2012 by bradythemole

[Neilsouth]

The models are ever changing some times downgrades and sometimes upgrades, because of that happening there is no point in looking at local temps and where the snowfall will be.

Have we learnt nothing?, besides there may be troughs in the flow from the north sea, shifts in the wind directions, light or heavy precipitation, I will say this though that IF this goes ahead the further east the better.

[Suburban Streamer]

Even Paul Hudson is doing a mini ramp. Not saying much that we don't already know tho.

This is model related so hope its the right thread

http://t.co/bktvAlvJ

Edited December 5, 2012 by Suburban Streamer

[fergieweather]

Even still.. baffles me how quick people are to jump on whether there will be a slack flow, a NE,E or SE. Either way, it's a week away and the outcome is still quite uncertain beyond T+96

Indeed. Just chatting it through with UKMO. They're still yet to be convinced on the broader evolution and scope of easterly (or not) given the uncertainties early next week to get things up and running (as emphasised by their own GM, albeit we await the modified version), so genesis thereafter open still to innumerable caveats. In short: they sit on the fence - at least right now - as to how things will shape-up into Monday-Tuesday given model divergence, and this profoundly impacts whatever happens thereafter. EC12z awaited with interest by them.

Edited December 5, 2012 by fergieweather

[Glacier Point]

Eye popping -NAO developing on the 12z GEFS.

If you're mithering about GEM, GFS and UKM, consider this trend developing for retrogression signal...

yesterday t192 GEFS H5 anomaly >>

today >>

that contradicts the idea of a slightly stronger sub-tropical ridge extending northward and developing that flow in the Atlantic.

[Suburban Streamer]

You know its times like this I wish I had a time machine so I could send all those who complain back to the winters we have all had to endure!

Agreed. I had a dusting this morning. During many winters prior to 2007 my dusting would have equated to a decent winter!

Oh how things have changed

[ChartViewer]

T96

T120

T144

T168

T192

Europe cooling down nicely!

[Tom Jarvis]

Eye popping -NAO developing on the 12z GEFS.

If you're mithering about GEM, GFS and UKM, consider this trend developing for retrogression signal...

yesterday t192 GEFS H5 anomaly >>

today >>

that contradicts the idea of a slightly stronger sub-tropical ridge extending northward and developing that flow in the Atlantic.

Gp can I ask what this means for us weather wise??

[bluearmy]

it was the depression i meant BA, its just apparently a chunk of the vortex within quite a large LP system. i just thought it might have quite an effect depending on its track

bd, its not a chunk of the vortex. its just a bogstandard atlantic depression. it may have been formed by energy dropping off the vortex but it isnt a chunk of vortex. the colour at the centre may be dark but the thickness is approx 528dam which isnt nearly low enough to be a chunk of p/v.

[pyrotech]

Looking at the essembles Germany (Berlin) is looking very cold throughout the run and for most of the run the extreme cold is agreed by all members. Those cold in Europe have definitely got it.

[bobbydog]

bd, its not a chunk of the vortex. its just a bogstandard atlantic depression. it may have been formed by energy dropping off the vortex but it isnt a chunk of vortex. the colour at the centre may be dark but the thickness is approx 528dam which isnt nearly low enough to be a chunk of p/v.

ah, ok, well we learn something new every day!

i'll get me coat....

[suffolkboy_]

Just having a quick flick through the last few pages, I see a few people are already worried about this possibly being a "dry easterly". I really wouldn't get too hung up on this, I would be more worried about getting the cold here first. I know many get carried away with all the hysteria, thinking the model output is "nailed", but we can see some large changes right down to +72.

Also, I wouldn't get too hung up on what is shown in FI (probably around 4-5 days at the moment).....it's simply weather porn.....it looks very nice and gets us all hot under the collar, but usually you can look....but not touch.....unless we get lucky ofcourse.

Keep a level head, try not to compare output on a run by run basis (as John and others have said, comparing 12z to 12z, 0z to 0z etc. will prove more accurate and have less wild swings in output)

Also, think it may be worth keeping an eye on developments in the closer timeframe. Could quite easily see some more surprise snowfalls before the week is out.

Enjoy the ride all! A great start to winter!

[weather eater]

Eye popping -NAO developing on the 12z GEFS.

If you're mithering about GEM, GFS and UKM, consider this trend developing for retrogression signal...

yesterday t192 GEFS H5 anomaly >>

today >>

that contradicts the idea of a slightly stronger sub-tropical ridge extending northward and developing that flow in the Atlantic.

You do realise Stewart, that if this comes off in the way you have been outlining for the last couple of weeks, you will be elevated to God like status and the Net Weather team will have buy you a Pope mobile to ride around in, better start practicing a special wave if I were you.

[bluearmy]

ah, ok, well we learn something new every day!

i'll get me coat....

not at all bd - its a learning experience for all of us. even those who appear to know everything have much to learn.

the GEFS seem to eb a dogs dinner in low res after yesterdays apparent clustering on a longer term solution

[Captain Shortwave]

The charts continue to look excellent if you compare to what we usually have this time of year. Even a slack easterly will give a little snow here. Anyway this winter is already better than last year as it's just snowed heavily and there is some on the ground

Before anyone asks about February last year I was in Southampton where we got only one snowfall which could account to being the worst snowfall ever. Icy drizzle

[bobbydog]

Eye popping -NAO developing on the 12z GEFS.

If you're mithering about GEM, GFS and UKM, consider this trend developing for retrogression signal...

yesterday t192 GEFS H5 anomaly >>

today >>

that contradicts the idea of a slightly stronger sub-tropical ridge extending northward and developing that flow in the Atlantic.

encouraging signs GP, however i think i'll save my eye-popping until the snow anomaly in my garden is +3 feet and the radar shows no signs of it stopping!

[Weathizard]

I don't buy that from the gfs,if that block gets in it will take some low to smash it out the way. Within a reliable timeframe I'm happy anyway, awaiting the ECM to throw a spanner in the works!!

A question I'd like to ask about the ecm especially, obviously there is only 2 runs per day 0 and 12z but why are they released at 6AM/PM? Do these computers take longer to process or something?

Edited December 5, 2012 by Weathizard

[Cheshire Freeze]

Eye popping -NAO developing on the 12z GEFS.

If you're mithering about GEM, GFS and UKM, consider this trend developing for retrogression signal...

yesterday t192 GEFS H5 anomaly >>

today >>

that contradicts the idea of a slightly stronger sub-tropical ridge extending northward and developing that flow in the Atlantic.

Quite.Good signal appearing for retrogression in FI..

Further on a signal for trough to sink into Scandi associated with the vortex relocation....

Don't want to sound greedy but I wonder if not only can we see a Scandi-Greenland progression, but a Scandi-Greenland-Scandi progression. OK I'm pushing it I'll get my coat!

Edited December 5, 2012 by CreweCold

[snowmadchrisuk]

apparently, the vortex wants to pay us a visit-

has that ever happened? i'm sure that would get interesting if it took the right track!

it happened in 2010 , you can see it on the chart below :

[Buzzit]

In my opinion the 12z GEFS mean is better than this mornings 6z.

Nothing concerning me with respect to the long range at this stage...

Future output will be looking a lot different come the weekend.

I believe the models are still fidling with the key in the door at the moment.

[bryan629]

HI all, my very first post and have been watching and learning models since last october, been a great journey so far and im fascinated with posts you all put up on here and how `the cookie might crumble` one way or another... i have been keeping a close eye on the trend that is setting up for next week and its looking pretty cold from a model point of view..... However could some one explain why the met office have posted this on the bbc weather website not just 20 minutes ago ... http://www.bbc.co.uk/weather/features/20618018 they seem to think that it may turn milder .

[Phantom2]

Apologies if this is a stupid question.

I have a keen interest in Winter weather and often pop into this thread to have a look at what the models are telling us and to read posts from the more experienced among us. What I would like to know is why if the charts in FI are useless and not worth looking at then why are they published in the first place, surely the computers would be better concentrating their information etc on the nearer time frame rather than 10 days down the line ..

regards Ian

[Glacier Point]

Just monitoring those GEFS means through t192, and the daily ops w/r/t 30 hPa heights, you do get the sense this a very dynamic situation. If the day 8/9/10 forecasts are near the mark, we will have gone full circle from where we were at the end of November. That's not long ago but feels like an eternity.

I suspect many more rapid evolutions around this core theme of a -NAO, until at least we start to see the stratospheric vortex settle a bit, probably towards Siberian sector.

[Polar Maritime]

HI all, my very first post and have been watching and learning models since last october, been a great journey so far and im fascinated with posts you all put up on here and how `the cookie might crumble` one way or another... i have been keeping a close eye on the trend that is setting up for next week and its looking pretty cold from a model point of view..... However could some one explain why the met office have posted this on the bbc weather website not just 20 minutes ago ... http://www.bbc.co.uk...atures/20618018 they seem to think that it may turn milder .

And, they seem to think it's going to turn colder.... But in these set up's as others will know from the past, it really can just flip and go the other way, im not saying it will, but it's something to keep in mind.

Edited December 5, 2012 by Polar Maritime

[nick sussex]

The UKMO continues to play catch up, in this mornings run it was about 1000 miles slower with a low moving towards the ne USA.

This evening it has finally sped up that low but is still slower and does not engage the PV and is much flatter.

This impacts troughing to the west of the UK.

GFS 144hrs:

UKMO 144hrs

Given the fact that the UKMO has continued over the last few runs to edge towards the GFS/ECM solutions then its obviously not dealing with the pattern very well.

Unless the ECM makes some big turnaround then IMO the UKMO operational outputs should be discounted.

Edited December 5, 2012 by nick sussex