Winter Model Discussion - 11/01/13 00z Onwards

[SnowObsessor90]

Just a question on the SSW to either reinforce or alter the way i currently regard it...

Is this very simplistic view of it correct....it will help displace the PV so that chunks of it fall over the Northern Hemisphere which gives us a good chance of getting a cold shot from one of these chunks. However, at the same time, it allows areas of warm air to drift up towards the Arctic. Much as we'd like to get caught in a cold chunk getting displaced downwards, there's no guarantee that we won't end up sitting in the middle of the warm air drifting upwards.

This winter's been like trying to play the perfect game of Jenga.... it looks absolutely fantastic until someone decides that perhaps it's possible to pull one more block out.....

Well according Chiono the SSW could well alternate between sometimes favouring us and sometimes not over the coming weeks, if he's right then it'll do absolutely for the sanity of this thread despite it being far from the worse scenario.

Edited January 11, 2013 by Anonymous21

[BarometerBunts]

Reading the model outputs and following this thread , noone can deny it has been a long hard slog. Models, to some extent reached a level agreement for cold, albeit tenuously just in time for the SSW to start making its presence felt at lower levels. I may be wrong but suspect that SSW interaction and uncertain influence is, at least for the next couple of days going to shake things up with models reverting to more extreme variables. My feeling is that whilst there are so many positives for a cold spell, people are now seeking the intricate detail ie: will it snow imby. Too soon imo. The only way to stay sane is to look for trends/patterns for the next few runs until models settle down. It has been said many times on here in Winters past - "let the cold come in first and then see what follows" This is so true. As a mere layperson, I am quietly optimistic that we may just see something special. I could be very wrong but if nothing else, I am happy to have witnessed some spectacular charts over the last couple of weeks which puts us in a far better position than Winters a few years ago.

[Jonan92]

I don't know if we should trust the CMA or not. At least, in 5 days, we will know how accurate this chinese model is

[Wayneywoo]

06z ensembles

Can you believe there is disagreement as close as T+24 !! I've never seen that before... Where do you put FI...

[Summer Sun]

Before any members start to loose faith after this mornings GFS run may I take you back to Midnight and what Ian Fergusson posted

We have reason for concern Monday, then again Tuesday, and later in week too. UKMO closely on case for potential significant snow events in various parts of country based on combined GM, EC & MOGREPS output.

[snowking]

More and more spread appearing on the ECM ensembles attests to the above from Stuart:

General agreement up until Tuesday, and then we start to see our spread of solutions develop.

This is pretty clearly depicted by the ECMWF ens mean too, with what can only be described as almost a resolution decrease by day 7, with the UK left with no clear synoptic signal:

But as Stuart points out, overall anomaly signal remains pressure higher to the north, lower to the south:

Even by day 6 we see a lot of uncertainty around the UK locale:

By day 9:

No point even bothering to look really. Not a surprise that the highest area of spread related directly to where the expected Jet Stream position is, as shown by the GFS:

GFS also exhibits the spread developing at day 5:

SK

[chionomaniac]

Well according Chiono the SSW could well alternate between sometimes favouring us and sometimes not over the coming weeks, if he's right then it'll do absolutely nothing for the sanity of this thread despite it being far from the worse scenario.

Just to add to that - I don't think that we will ever be in an unfavourable position - just less favourable for short periods. More cold 850's interspersed with shorter periods of getting up to average. Conditions on the surface may stay below average throughout apart from the very SW.

[kold weather]

Before any members start to loose faith after this mornings GFS run may I take you back to Midnight and what Ian Fergusson posted

Even IF the GFS runs were to come off and the cold air is blasted away earlier, there is still probably a very good shot at a decent snow event, possibly two between Monday-Wednesday for a fair part of the country.

[Panayiotis]

SnowKings post is one to look at, backed up by charts/models, its a very fair and reasonable post. Very well done!

For my area the ensembles are ok with the mean never reaching above the 0C so we can say, at least it will average for Fi on this run also snow chances are there starting from tomorrow until the end of the ensemble which is great even if they show the chances of it snowing is 5%!

Edited January 11, 2013 by Panayiotis

[pyrotech]

The jet stream is driven by exactly the same symnotics that have the greatest uncertainty, The polar Vortex being disrupted will influence that rather acutely and so it could end up much further South and weaker than shown, which will make the outcome accross the troposphere very different.

I expect huge uncertainty and inconsistancy in the models especially beyond 4-5 days to continue.

[EML Network]

We seem to be in a position where by we can almost say with confidence what is going to happen at day 4 (+96), but for the past 7 days now, when looking at day's 5-7 (+120 - 168) there has consistently been either a split, blend or every variation under the sun of a theme.

If what Chino has posted is correct then I expect this will continue for the forseeable future and we will all go bald :-)

People say not to take each run as gospel and I think now more than ever is something we should heed (and I'd say to a degree this should extend to the Ensembles).

To some degree having regular bouts of cold interspersed with milder shots, increases the chance of some battleground type sets ups too, so if this happens some areas could find that they get a couple or more significant snow events...anyway...it's all a long way off just yet.

Let's get the cold in first today and tomorrow and see where we go from there.

good ...if somewhat brain melting times ahead

[Timmytour]

I don't know if we should trust the CMA or not. At least, in 5 days, we will know how accurate this chinese model is

5 days, we'll know what the end of its current run is!

[Polar Maritime]

Well, we are still no closer to any detail as to what to expect from the current chart's, something we will have to get used to over the next week or two, very uncertain times ahead.. one thing for shure is, we are now entering the predicted cold spell, with the cold set-up in place and the SSW predicted the models are just everywhere, with FI at around t74hr.

Latest MET update call's for battleground snowfall situations over much of the country next week, with ice days and sharp frost's, hopefully the cold will win out bringing severe cold if the background signals are taken into consideration...

This winter must be one of the most interesting here on NW for model watching i have ever witnessed, very complicated synoptic's indeed.

[Bobby]

The models are most certainly a total mess this morning, though they have been for a while really. But overall I find it difficult to see where a prolonged cold spell is going to come from with the way things are looking. Where's the northern blocking gone? And with the Atlantic having plenty of energy I can't see how the cold can be sustained for long. Of course we're now looking further out but that's how I see it going into later part of next week.

However in the shorter term there is plenty of interest at least and I'm sure a many here will get a lot of snow over the next few days although just exactly where is uncertain at the moment, these battleground scenarios are nightmares to forecast. Personally if I get a few good dumpings of snow before mild Atlantic weather returns later next week I'll be happy enough.

Central areas look to get a lot of snow on this GFS

GEM would gives the West lots of snow

[Frosty.]

Well, we are still no closer to any detail as to what to expect from the current chart's, something we will have to get used to over the next week or two, very uncertain times ahead.. one thing for shure is, we are now entering the predicted cold spell, with the cold set-up in place and the SSW predicted the models are just everywhere, with FI at around t74hr.

Latest MET update call's for battleground snowfall situations over much of the country next week, with ice days and sharp frost's, hopefully the cold will win out bringing severe cold if the background signals are taken into consideration...

This winter must be one of the most interesting here on NW for model watching i have ever witnessed, very complicated synoptic's indeed.

Yes PM I fully agree, i'm encouraged by what GP says and the meto update and am not concerned by individual op runs, the bigger picture is exploding with potential, we have come so far since the mild boring weather over christmas and new year..bring it on

[chionomaniac]

Here is one of the great images from NW extra - slp spread and mean ( cheers Paul) which highlights the uncertainty of the GFS ensembles at T+144. I guess the 'Shannon entropy' is greatest where the red area is and this is the area we are most likely to see most changes in the future output (yes it is the UK)

Edited January 11, 2013 by chionomaniac

[andy_leics22]

Still a huge scatter as early as 5-6 days time, the models still don't have much of a hold on this situation! Can't ever remember seeing the models this unsure before. They've had wobbles in the past similiar to this one but not quite this bad!

[Panayiotis]

Here is one of the great images from NW extra - slp spread and mean ( cheers Paul) which highlights the uncertainty of the GFS ensembles at T+144. I guess the 'Shannon entropy' is greatest where the red area is and this is the area we are most likely to see most changes in the future output (yes it is the UK)

Nice, also notice the upstream pattern has a lot of uncertainty, for me this is more important as it can change where heights are going and where the jet stream is going.

[stainesbloke]

Well, we are still no closer to any detail as to what to expect from the current chart's, something we will have to get used to over the next week or two, very uncertain times ahead.. one thing for shure is, we are now entering the predicted cold spell, with the cold set-up in place and the SSW predicted the models are just everywhere, with FI at around t74hr.

Latest MET update call's for battleground snowfall situations over much of the country next week, with ice days and sharp frost's, hopefully the cold will win out bringing severe cold if the background signals are taken into consideration...

This winter must be one of the most interesting here on NW for model watching i have ever witnessed, very complicated synoptic's indeed.

Indeed, so much uncertainty. We need that jet going south and the cold should then become entrenched across the UK. Some potential for large snowfall totals I reckon.

[chionomaniac]

Nice, also notice the upstream pattern has a lot of uncertainty, for me this is more important as it can change where heights are going and where the jet stream is going.

Would agree there. I have a suspicion that the jet stream is being overestimated somewhat over America.

[bobbydog]

Here is one of the great images from NW extra - slp spread and mean ( cheers Paul) which highlights the uncertainty of the GFS ensembles at T+144. I guess the 'Shannon entropy' is greatest where the red area is and this is the area we are most likely to see most changes in the future output (yes it is the UK)

hi chiono, have a look at my 'ramblings on the previous page, post #224. what do you make of my 'theory'?

[kold weather]

Hopefully the models will move away from the idea of an area of energy slipping across the Atlantic like they do on quite a few of the 00z and 06z runs, that is what terminated any real deep cold/snow in December, same set-up cropping up on the 06z GFS op run. The ensembles suggest that the op run is a good deal too progressive, but by in large both the ECM and the GFS op run are heading down a similar route with regards to the placement of the jet.

What I will say that is good news, deffo increased confidence on that band on Monday/Tuesday at the moment

[Polar Maritime]

Yes PM I fully agree, i'm encouraged by what GP says and the meto update and am not concerned by individual op runs, the bigger picture is exploding with potential, we have come so far since the mild boring weather over christmas and new year..bring it on

Yes Frosty here it comes at last was certainly worth the wait ! CPC charts have been very solid and continue to be on the upcoming cold spell

[chionomaniac]

hi chiono, have a look at my 'ramblings on the previous page, post #224. what do you make of my 'theory'?

Would agree entirely. The pattern is being driven by the the big global teleconnectors presently of which the biggest is the strat. The positioning and strengths of these vortices is dependent on the wave feedback from the trop and subsequent warmings. A slight shift to the vortex 'upstairs' will have a slight shift to the vortex 'downstairs' and this will have a determination over surface ridge and shortwave formation. Which is critical when we are right on the border of the cold mass that one little shift can predetermine whether we will see rain or snow.

Edited January 11, 2013 by chionomaniac

[nick sussex]

NOAA expect a colder pattern to set up for the eastern USA , this is in relation to that PV lobe dropping into Canada.

Without a signal for a pressure rise to the north or ne then a pile of energy will just move east and flatten the pattern over Europe. The subject of that seems to have come up over recent long term discussions with the teleconnections saying one thing but the models saying something else.

Historically NOAA cant find a match for what the models had originally suggested and perhaps we're seeing that play out ie east Pacific ridge and Greenland high mismatch.

Of course history doesn't mean it can't happen, theres always a first time !

Looking at all the output so far today I think we just draw a blank in terms of having any certainty as to what the weather might be like in a weeks time.