Winter Model Discussion - Cold Hunting -12Z 03/01/13

[Frosty.]

i dont see a big fail happening here i also see massive swing towards cold alot more so that before christmas and this is from one warming event.

Yes I totally agree, the SSW is a totally different kettle of fish to the major let down we had with the failed easterly, we had a cold stratosphere then and we were lucky to have a cold snap which lasted a week and gave us a few ice days, the upcoming cold will eventually deliver a much more potent cold spell.

[Robbie Garrett]

Greenland high, Scandinavian vortex.... never fails to disappoint.

When compared to high pressure centered 4,000 miles away! 13th still the pattern change date for me.

[weather is fun]

Still got a feeling we may not see any sustained cold into the uk because of the high flux think the cold will head south missing the uk im afraid. Think we will be looking at another fail like dec for the uk. Due to the high flux

[MR EXTREMES]

Greenland high, Scandinavian vortex.... never fails to disappoint.

When compared to high pressure centered 4,000 miles away! 13th still the pattern change date for me.

what vortex wont stand to much more pressure 3 warmings incredible.

and well picked up by the gfs model aswell.

[ITSY]

Matt Taylor on BBC about 1 minute ago: Colder conditions are heading our way with the temperature heading to below average by the weeks end and beyond. Seems to fit with the Model's quite well.

[MR EXTREMES]

what vortex wont stand to much more pressure 3 warmings incredible.

and well picked up by the gfs model aswell.

and i dont think to start with heights around greenland i think iceland scandi the backing west to greenland in time.

but iceland blocking even better im sure 63 had a nice iceland block or inbetween.

5th febuary 1963

[Frosty.]

Yes I agree it is okay to mention the SSW as is part of the weather systems and will have an impact. I think the point being made though is that too much hope is being pinned on an event that may well have no effect at all in this part of the world. It’s being treated as a panacea for all our cold winter (lack of) woes. Let’s talk about it, but not like it's the answer to the world the universe and everything.

I can see where you are coming from but there is an increasing weight of evidence pointing to a significant cold spell ahead of us, big things have small beginnings but I can now see a major cold outbreak in the not too distant future, the colder trend from midweek is only the beginning.

[nick sussex]

Its that time when I pull out one of my paint jobs! For newer members this is how you'd like to see the evolution and what to look for:

So here:

The orange outline is the preferable shape to the troughing, we'd prefer to have this elongated and not oval or football shaped.

The orange arrow showing more energy digging south. You can generally correlate how much of a push north of the Azores high with amplitude and how much digging south of that trough to the west.

Now the black arrows indicate the two highs working collectively to squeeze that residual energy (purple circle) left over the UK.

The purple arrow shows we want to see a shortwave ejected cleanly into the continent.

You start point re cold advection will be how far north you can get the Azores ridge before this topples se.

As this ridge topples on the southern flank will be the coldest air ready to head west.

If the trend to retrogress the pattern by taking the high away to the nw is correct then you might still get a shot of colder uppers as that occurs if you missed out the first time.

If the background signals are correct then we should see pressure falling to the east with high pressure near Greenland and thats when the snow potential increases,of course if the original high is placed further north then this could also give a window of convective snow potential more especially for the east and se.

Much depends on whether we see some deeper low pressure forming over central/southern Europe.

[winterof79]

Yes, we need a high latitude block to get the cold uppers to the3 UK, as things stand on the 06z for example, we would end up being unlucky with the cold air flooding into Southern Europe whilst we remain under High pressure.

As usual i must be missing something as many seem to be wanting more than what is forecast

http://www.meteociel...&mode=1&carte=1 this in 7 days time and this http://www.meteociel...&mode=1&carte=1 in 14.Sod whats happening in southern Europe

May i also add that getting a cold pool established is of priority wether it be a cold high or not.

Edited January 5, 2013 by winterof79

[Loraine Bennett]

Have just seen Chris Fawkes, he was talking about temperatures dropping towards the end of next week, and then said with a twinkle in his eye,' could be the start of something for the rest of the month'. Then Football Focus came on and they said ' we will be looking at the Great Freeze of 1963'.... spooky!

[chionomaniac]

New thread coming soon. Finish up please.

[scottishandy]

I knew someone would mention the stratosphere. Warming there that's set to occur are still forecasted warmings. So if the forecast for that to happen is wrong then the implications to our weather towards a colder outlook may not happen. People always seem to think stratospheric warming and AO Nao and all the other teleconections GP talks about are guarenteed. They are still all forecasts. And as with the weather forecasts they don't always occur

I know this has been responded to a couple of times already but my question in response to this would be, how can we NOT mention the stratosphere as part of a meaningful model discussion?

Just beacuse our exposure to it and knowledge of it are relatively new and basic doesn't mean we shouldn't discuss it. Any computer model will include all levels of the atmosphere from surface to several km up in the air. Stratospheric modelling is fundamental to the whole process as it both interacts with and effects the tropospheric modelling, they are also in contact in reality aswell!

So this time we have big changes and warming within the stratosphere, happening now and modelled for near future, which should promote northern blocking at the surface.

Whereas in Nov/Dec we had a cooling stratosphere and vigourous polar vortex with the tropospheric modelling of easterlies seemingly opposed to it. To me this meant that the tropospheric drivers to blocking were more prone to change as the the stratosphere was opposing them, this time the stratosphere is on out side and should help reinforce the blocking pattern.

Ultimately all computer modelled output must be possible, we just need to try and judge what is more likely.

[chionomaniac]

Closing now, new thread here: