Winter Model Discussion 12Z 22/1/13 onwards.

[bluearmy]

Shaun picks up on the end of ecm op and the demise of the canadian vortex/low slp, replaced with a block over the vortex. A very odd solution given recent runs and I suggest waiting to read NOAA take on the run. Looking through the gefs and ops, it seems something is afoot. I was beginning to wonder if ecm's apparent fascination with cold zonality and sinking jet might just allow the ever growing scandi trough to encompass us in the end.

This solution is not supported on the mean. The ecm mean shows a mobile west/northwest flow around a slightly displaced azores high into the mid atlantic. The depressions look to be wanting to track through the uk and se into europe. The mean trough in eastern scandi down to eastern europe. A bit more retrogression of the pattern and it becomes a wintry one for us.

Edited January 26, 2013 by bluearmy

[Bobby]

More or less flat Atlantic dominated weather on the ECM and GFS, a bit more interest in the GEM and the UKMO though with a trough digging S, GEM shows an Ely trying to develop at the end of the run as we try to get an undercut. But too far off I think to take too seriously ATM.

GEM +240

Not much support in the GFS ensembles for that kind of evolution though it has to be said, with the mean at day 9 flat flat, the ECM mean is similar

The Atlantic looks quite active with plenty of energy coming out of the NW/Canada and I think any ridge will have a hard time not being flattend/pushed away, so I think the general outlook for the forseeable is wet and windy although probably turning cooler later on as we get more PM influence. We shall see if the GEM/UKMO are onto anything when we get into a more reliable time frame.

Looking pretty wet overt the nex week or so at least with 100-150 mm of rain to come in the W and espcially over the hills so flooding possible.

[bluearmy]

bobby, with the varying clusters from gefs of atlantic ridge, scandi ridge and cool zonal, i guess the mean will be flat. the anomolys would be a better predictive tool at the moment. naefs just out - will have a gander.

[Bobby]

Looks to be a 48 hour Atlantic warm conveyer setting up from Monday (remember Nov 2009 floods) with a constant stream of rain carried on a river of warm moist air sucked deep from the tropics,

So potentially a lot of rain from as this setup can bring big totals to the hills in the W/NW, worth keeping an eye on maybe..

Edited January 26, 2013 by Bobby

[bluearmy]

naefs is interesting in week 2. following on from ecm ens at day 10, there is a gradual sinking of the jet further sw to allow the low euro anomoly to work west and establish itself close to our se. at the same time, a weakish mean upper ridge appears to be intent on strengthening svaalbard/iceland/nw scandi. sound familiar ?? similar timing to jan aswell.

[Methuselah]

Please can we stick to discussing the models, in here? I know that 'Big Joe' can be very 'interesting', but his prognostications are not all that related to model-output; so, moved into the weather/media thread, where dissection can carry on unhindered...

[Summer Sun]

After an unsettled week UKMO tries to build high pressure from the south at the end of its run

GFS does as well but that gets shifted away quickly at t168

At the moment its on its 2 to 1 in favour of UKMO & GFS at t144 ECM is the only one which doesn't agree

Remember this is based on the 00z runs

Edited January 26, 2013 by Gavin.

[Frosty.]

I don't think many of us want to see high pressure building from the south Gavin, it's a winter killer, it will be better if the jet does eventually tilt more towards a nw/se angle and increase the chance of colder shots in FI, high pressure from the south would bring benign and at least initially fairly mild weather which is the last thing most of us want to see with barely 5 weeks of proper winter remaining, however, from the perspective of those in flood risk areas, i'm sure they would take high pressure happily, wherever it came from.

Edited January 26, 2013 by Frosty039

[Isolated Frost]

When we are looking at the retrogressive motion due to a stalled jet trough in E Canada/NE USA- we must look for the SW-NE tinted Atlantic high, with heights moving in the same direction- we want to see the 552dm line moving SW to NE into W Greenland.. This is the important aspect of building any potential cold spell... There is a trend in recent modelling to build this 'positive retrogression' with an anomalous Atlantic high around D9 or thereafter.

[TEITS]

Well I continue to be in a positive mood after viewing this mornings output.

Since I started following the models I have seen cold spells develop at +384 and work their way to +0, sometimes from +240 and also at +144. Now in my opinion this could be one of those occasions where a cold spell suddenly appears at +144 rather than further out. I see a trend towards LP going SE into Iberia with HP developing to our N. This is unlikely to bring a real GH at this stage but this could be enough to bring a return to cold conditions.

So I wouldn't worry about what the models are showing beyond +180 because at the moment they seem to be having issues resolving what happens in the Atlantic around the +120 mark.

[Chris W]

Better warm air advection west of Greenland, ridging in the Atlantic and chances of a northerly on the GFS 06z at T+147 (even if it is a toppler):

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130126/06/147/h850t850eu.png

[bluearmy]

Well I continue to be in a positive mood after viewing this mornings output.

Since I started following the models I have seen cold spells develop at +384 and work their way to +0, sometimes from +240 and also at +144. Now in my opinion this could be one of those occasions where a cold spell suddenly appears at +144 rather than further out. I see a trend towards LP going SE into Iberia with HP developing to our N. This is unlikely to bring a real GH at this stage but this could be enough to bring a return to cold conditions.

So I wouldn't worry about what the models are showing beyond +180 because at the moment they seem to be having issues resolving what happens in the Atlantic around the +120 mark.

i tend to agree dave that a general repeat of the recent pattern looks feasible. not sure where the azores heights will be though. they were completely supressed/displaced well west last couple weeks. i just have a feeling that if we do go down the route you describe, the troughing could be quite widespread across nw europe and s scandi.

[The Weather Dragon]

Very pleasing 06z run post 150h we desperately need a settled anticyclonic spell of weather - whatever the airmass ! - have a gut feeling that we will get this - but the weather will be very much on the average side with no significant cold spell.

[SnowObsessor90]

I'm starting to get impression that something indeed is brewing here, many times before have the models hinted at a high pressure dominated setup only for the end result to be quite different.

Edited January 26, 2013 by SnowObsessor90

[BLAST FROM THE PAST]

I don't think many of us want to see high pressure building from the south Gavin, it's a winter killer, it will be better if the jet does eventually tilt more towards a nw/se angle and increase the chance of colder shots in FI, high pressure from the south would bring benign and at least initially fairly mild weather which is the last thing most of us want to see with barely 5 weeks of proper winter remaining, however, from the perspective of those in flood risk areas, i'm sure they would take high pressure happily, wherever it came from.

And it isn't, if one goes through the UKMO run and looks at the synoptic movement HP isn't building from the south, and its a mild outlook nthat Gavin is seeking? and posting an isolated chart to support that view...its misleading as the pressure to our south is in situ well before then and isn't 'building' and it would do precisely what the GFS does at t168 and squeeze it away, that means it isn't 'building' from the south.

The 06z synoptically just does not look right from 7 days onwards, nothing dominating and sort of all over the place? That could be a good thing as we may see that the models are picking up a change beyond this 6 day mobile spell.

BFTP

Edited January 26, 2013 by BLAST FROM THE PAST

[TEITS]

That could be a good thing as we may see that the models are picking up a change beyond this 6 day mobile spell.

BFTP

That for me is one of the reasons im positive this morning. When I was in my rather depressed mood the model output was consistent with its output of mild SW/W,lys but now im seeing some large differences between the runs and this morning the ECM looks rather lonely at +144.

Im finding it hard to explain in words why im positive because some members post on the model output from a scientific POV but my approach has always been years of following the models and a more instinctive approach. A good example is remember at the start of this current cold spell how snowfall was indicated for many S regions but experience told us this would move further S as we approach D1. Another example is last night when the NAE & GFS disagreed with snowfall amounts. Now history told us the NAE tends to be OTT due to predicting lower dewpoints and that was the case last night.

So in summary as +384 only takes us to the 11th Feb and the fact im expecting a change in the model output around +144/+168 then in my opinion we have alot of winter left yet. Seems such a long season this time round because apart from the xmas period we have had plenty to discuss this winter.

Apologies to members for my rather Jekyll and Hyde behaviour of late but I do confess to having a few mental health issues lately. So if Hyde returns just ignore me!

Edited January 26, 2013 by THE EYE IN THE SKY

[Snowman.]

This thread should start to get a bit more active soon but there is something there in the models just needs some corrections to make it more likely?

Remember January we was going to be under a cell of high pressure but as the time got closer this began to move northwards and formed the block? Same could happen here high forms over or near us then steadily moves north into a favoured position.

[Frosty.]

And it isn't, if one goes through the UKMO run and looks at the synoptic movement HP isn't building from the south, and its a mild outlook nthat Gavin is seeking? and posting an isolated chart to support that view...its misleading as the pressure to our south is in situ well before then and isn't 'building' and it would do precisely what the GFS does at t168 and squeeze it away, that means it isn't 'building' from the south.

The 06z synoptically just does not look right from 7 days onwards, nothing dominating and sort of all over the place? That could be a good thing as we may see that the models are picking up a change beyond this 6 day mobile spell.

BFTP

It's just my observation that Gavin loves high pressure, each to his own but I would like to see a cold unsettled outlook, the 6z in FI is mainly benign with high pressure generally in control, I hope you are right about the 6z, it's not very good.

[BLAST FROM THE PAST]

It's just my observation that Gavin loves high pressure, each to his own but I would like to see a cold unsettled outlook, the 6z in FI is mainly benign with high pressure generally in control, I hope you are right about the 6z, it's not very good.

Nowt wrong with any favoured pressure or weather type, it just didn't sum the run up correctly. But look at the 06z run again...have you really seen an outlook pan out like that? It gives the impression of not knowing which way to go, to me that shows uncertainty, a lot of it and that is positive compared to 'certainty' that was being showed up to yesterday morning.

This is more of what I want to see develop. Look at the LP on southern tip of Greenland....its negatively tilting. This starts the movement of any LP NW/SE and undercutting pattern. Yes please.

BFTP

Edited January 26, 2013 by BLAST FROM THE PAST

[shotski]

It's just my observation that Gavin loves high pressure, each to his own but I would like to see a cold unsettled outlook, the 6z in FI is mainly benign with high pressure generally in control, I hope you are right about the 6z, it's not very good.

Hi Frosty

Looking back in the archives to the winter of 1947 and the month of Feb more importantly the synoptic set-up was very much like

what we have at present with a split pv with most of the energy over northern Canada. Its worth taking a look on the archives from the

1st of Jan to the middle of Feb. Was there any sort of SSW in 1947 ?

[Frosty.]

Apologies to members for my rather Jekyll and Hyde behaviour of late but I do confess to having a few mental health issues lately. So if Hyde returns just ignore me!

I had big problems with that last year dave, I got it under control now though, brave of you to say it openly, hope you get better soon.

As for the models, I think we are still trending towards a colder pattern after the middle of next week but a gradual change, jet digging further south, better jet tilt towards nw/se, frosts returning and maybe some wintry ppn from T+144 at times. I still feel we could see a sudden change in the output when the next downwelling phase impacts, hope GP still thinks a cold blast from the NE is still on.

[Bobd29]

That for me is one of the reasons im positive this morning. When I was in my rather depressed mood the model output was consistent with its output of mild SW/W,lys but now im seeing some large differences between the runs and this morning the ECM looks rather lonely at +144.

Im finding it hard to explain in words why im positive because some members post on the model output from a scientific POV but my approach has always been years of following the models and a more instinctive approach. A good example is remember at the start of this current cold spell how snowfall was indicated for many S regions but experience told us this would move further S as we approach D1. Another example is last night when the NAE & GFS disagreed with snowfall amounts. Now history told us the NAE tends to be OTT due to predicting lower dewpoints and that was the case last night.

So in summary as +384 only takes us to the 11th Feb and the fact im expecting a change in the model output around +144/+168 then in my opinion we have alot of winter left yet. Seems such a long season this time round because apart from the xmas period we have had plenty to discuss this winter.

Apologies to members for my rather Jekyll and Hyde behaviour of late but I do confess to having a few mental health issues lately. So if Hyde returns just ignore me!

Experience and a clear understanding of how to read all the charts and interpret their nuances are extremely valuable as an addition to the pure scientific approach of some of our valued members. Your posts Dave are among the ones I always seek and read, keep on with your style of analysis many find it very enlightening; regards Bob...

[Jaffusmaximus]

@ The Eye In The Sky

I often get very frustrated reading your posts but I guess its only because you are calling what you see. I will continue to look forward to being annoyed by your posts in the future because the truth hurts sometimes!

[Duane S.]

Models certainly starting to back away from any prolonged zonal onslaught predicted by many. I suspect we are going to get some interesting charts to look at soon and not necissarily at +384!

For me there is often a big difference between the vortex being centred N / NW Greenland as opposed to the South of it. In my opinion we have actually been very lucky through January to get the snowy weather we did as the energy was situated S. Greenland, often the death knell for winter weather for us but other factors went in our favour and it ended up providing us with some lovely slider LP systems.

Now, to me it looks like the tendancy is for the dominant vortex to remain around Greenland not to the NE despite hints otherwise but, although it will be a fairly strong wound-up vortex I can also see it centring NW of Greenland allowing an Atlantic ridge to eventually build, perhaps with an initial G/L high but then migrating the heights over Scandi bringing us cold from the NE.

Could be a classic month ahead

[J10]

Greenland highs can deliver severe cold, they often bring very clear skies to western parts in particular - take Dec 2010 as an example coastal parts of Merseyside which don't usually see cold temps got down to -17 degrees, albeit thanks to deep snow cover. I agree they don't tend to bring uppers much lower than -10 degrees, unlike easterlies which bring the coldest uppers, but if we have clear skies, very low minima can easily be achieved.

Dec 95 brought a ridge down from the arctic over east Greenland and we saw record cold temp in the Highlands. From an imby perspective I would rather have a greenland high than a russian/scandi high, those in the south and east who like cold probably prefer the latter, but for anyone in the north and west who wants crisp cold frosty weather and chance of polar lows they are superb.

Cannot really disagree, for the severe cold I was more talking about down south, and while it can bring heavy snowfalls for us down here and has done quite a few times in the past. Easterlies do bring colder weather. although I do take your point about Scotland.

Edited January 26, 2013 by Jackone