Model Output Discussion - 1st - 7th January

[weathe20]

Still nothing on this mornings charts if you ask me. Just looks a mess with no pattern change in sight. Patience is the key.....apparently.

[Cecil Hogmanay Melchett]

No, the stalemate continues between low heights to the N and NW and a stubborn high over Europe. Still no realistic signs yet of the 'change' on the table, despite the interesting scenarios ECM evolves around t+240.

What an incredibley robust pattern this is proving to be !!

I'm not sure when the pattern locked in but i have a feeling it was mid Nov or even earlier,i would be delighted to see it blasted away in the reliable timeframe but for all the positives out there its just not being traslated into the model output.]GFS ensembles look OK but its only deep FI and ECM operational is into the habot of offering a pot of gold at the end of a never ending raibbow.

Edited January 5, 2012 by happy days

[nick sussex]

I wouldn't be reading too much into the model output past 168hrs, the ECM has gone from one scenario to another this morning.

It's jam tomorrow charts have been common in the last week with these seemingly marooned at 240hrs, yesterday it was hints at a northerly today its a Scandi high, it really want to take the GFS mantle, at least thats been consistent although probably wrong as well!

Although a SSW doesn't guarantee cold it will cause lots of model variability and if this doesn't shake up things nothing will!

http://wekuw.met.fu-...cmwf1/temps.gif

This is just a forecast so bear that in mind and the lag time in terms of its effect on synoptics can often be short with this type of warming so we'll just have to wait and see what happens.

Edited January 5, 2012 by nick sussex

[karyo]

Next week looks much calmer with generally light winds from the west/southwest. To say that it will feel springlike, is an understatement.

Karyo

[johnholmes]

The latest set of data from various sources overnight, short and longer term, is, at best, variable.

ECMWF in its 500mb anomaly chart seems to be trying to link the European high with one way north but the GFS version is pretty different. NOAA last evening was showing the main +ve area aroud 50N 30W. So my caveat about needing continuity between all 3 for several days certainly does apply. Coupled with my very basic look into the Stratosphere at 30mb, its falling again. The AO and NAO are both a bit of a mix. So I would suggest a sit on the fence approach for a few days to see if things become clearer; shall we say in 5-7 days. It is POSSIBLE, its happened before, that cold will suddenly appear but I would not back that one myself.

[shedhead]

Is this getting any closer though? Seems to have been at 240 on ecm for a few days now.

Perhaps only a one liner RD, but an important one nonetheless.

No doubt we are seeing both improved synoptics and the potential of even better synoptics, but as you say they are always at T+240hrs and beyond - a timescale most are ordinarily very quick to dismiss. Of course we need to see them at this timescale initially, but we also need to see the improvments being shown a little closer too. Yesterdays 240hr ECM was good, so if the same could be said of today's 216hr and perhaps even it's 192hr then I'd be far more interested, but again this morning I can't get away from that all to familiar 'jam tomorrow' feeling.

Edited January 5, 2012 by shedhead

[Tim Bland]

Best GFS ensembles I have seen this winter! Let's hope the OP falls inline soon!

[nick sussex]

Pressure

http://www.meteociel...=1&map=1&type=2

Temperature

http://www.meteociel.fr/modeles/ecmwf.php?ech=240&mode=0&map=1&type=2&archive=0

PV that far east on the operational run

http://www.meteociel...=1&map=1&type=0

I don't think so!

Edited January 5, 2012 by nick sussex

[chionomaniac]

Pressure

http://www.meteociel...=1&map=1&type=2

Temperature

http://www.meteociel...ype=2&archive=0

PV that far east on the operational run

http://www.meteociel...=1&map=1&type=0

I don't think so!

I have to say Nick that the ECM ensemble mean is exactly what I would expect to see given the vortex profile.

[shedhead]

Pressure

http://www.meteociel...=1&map=1&type=2

Temperature

http://www.meteociel...ype=2&archive=0

PV that far east on the operational run

http://www.meteociel...=1&map=1&type=0

I don't think so!

There goes to confiture then...

[mcweather]

Perhaps only a one liner RD, but an important one nonetheless.

No doubt we are seeing both improved synoptics and the potential of even better synoptics, but as you say they are always at T+240hrs and beyond - a timescale most are ordinarily very quick to dismiss. Of course we need to see them at this timescale initially, but we also need to see the improvments being shown a little closer too. Yesterdays 240hr ECM was good, so if the same could be said of today's 216hr and perhaps even it's 192hr then I'd be far more interested, but again this morning I can't get away from that all to familiar 'jam tomorrow' feeling.

The reason this potential for a change has been showing around 240 and beyond for a little while is because it is essentially in line with the most sensible lrfs that were issued for the winter.

Namely GP and RJS on here and Brian Gaze over at TWO they all said the change to any colder weather would most likely be around the middle of January ie 15th. At the moment the models are trying to find a way to that change because their numerical input is suggesting the same thing. Both ECM and GFS are going for colder. The operational gfs run may not say so but its ensembles definitely do as the mean drops below average from the 15th (funnily enough) with some clustering around the coldest output for a while after that too.

The change has always been mooted around mid Jan so complaining that it is appearing 10 days away on the 5th of Jan seems a bit picky to me.

Edited January 5, 2012 by mcweather

[nick sussex]

I have to say Nick that the ECM ensemble mean is exactly what I would expect to see given the vortex profile.

Yes looking at your last post in the strat thread the PV should be edging towards Baffin with low heights developing over Scandi and high pressure in the Atlantic, maybe the background warming is causing the models to go a bit AWOL!

[BLAST FROM THE PAST]

Is this getting any closer though? Seems to have been at 240 on ecm for a few days now.

I've seen this before and with all that's going on in the background I suspect some model jumping will go on. I wouldn't at all be suprised if we 'suddenly' get some very encouraging charts pop up at t144 over next day or two. Looking at ECM today compared o previous two days says it all at the moment, big differences and which is right?

BFTP

[recklessabandon]

Is this getting any closer though? Seems to have been at 240 on ecm for a few days now.

I think we began to see this pattern at T+240 around the 31st Dec if I recall correctly, which would confirm what many are saying that this evolution is sliding back and back, as the 31st + 240 hours is next Mon/Tues, when we will now be sunning ourselves in barmy SW breezes....it might be 'jam tomorrow' but I fear the jam will have gone stale by the time we get it looking at the current outputs....

[phil nw.]

My overall impression of the overnight runs is that we are no clearer on any pattern change.

Essentially up to day 10 the status quo is maintained with High pressure to our South and Low heights still around Greenland.

I have put together some data to show this.

First the 00z NH views at T240 for both models.

Now the mean heights taken from both runs days 8-10

The NAAO forecasted 500hPa anomolies for period days 8-14.

The second image was issued 31/12/11-6days ago.

this has changed little over a few days.Stil the stubborn Azores High,maybe a touch further NW than a few days ago,but still a Westerly pattern.

Finally the GEFs 00z ens.graph

There are tangible signs of vortex weakening,well illustrated in the Strato thread and indeed based on latest data things could change very quickly.

Call this fence sitting if you like but for now the present output does not reflect any real change yet.

Edited January 5, 2012 by phil n.warks.

[Harsh Climate]

Pretty poor ECM over night

Although the operational was good, albeit at 240h again

The other 9 perpetrations are mainly all poor, so the main one we saw didn't have much support:

The saving grace being a good set of esembles on the gfs

There are signs of some meaningful blocking in the northern hemisphere in the future, but it still remains doubtfull at this early stage that that will produce cold and snow for us.

[shedhead]

The reason this potential for a change has been showing around 240 and beyond for a little while is because it is essentially in line with the most sensible lrfs that were issued for the winter.

Namely GP and RJS on here and Brian Gaze over at TWO they all said the change to any colder weather would most likely be around the middle of January ie 15th. At the moment the models are trying to find a way to that change because their numerical input is suggesting the same thing. Both ECM and GFS are going for colder. The operational gfs run may not say so but its ensembles definitely do as the mean drops below average from the 15th (funnily enough) with some clustering around the coldest output for a while after that too.

The change has always been mooted around mid Jan so complaining that it is appearing 10 days away on the 5th of Jan seems a bit picky to me.

I don't think the weather conforms with LRF's mcweather, not even those done by GP, RJS and Brian Gaze.. The truth of the matter is a change to colder weather from mid month remains a possibility, it's no more or no less than that, indeed I'd still call it a genuine 50-50 shot based on all the overnight modelling.

I think it probably wise sticking to what we do know with a fair degree of confidence for now, and that is pressure rising from the south across the weekend and into next week. As a result much of England and Wales at least can look forward to seeing a good deal of drier, quieter weather, OK it will be mild, perhaps very mild, but at least some of us down here in the south and west will get a chance to dry out. To be honest I'll be grateful for that at this stage and of course once HP gets established, it generally becomes easier to open a root to colder weather.

Edited January 5, 2012 by shedhead

[Radiating Dendrite]

Pretty poor ECM over night

Although the operational was good, albeit at 240h again

The other 9 perpetrations are mainly all poor, so the main one we saw didn't have much support:

The saving grace being a good set of esembles on the gfs

There are signs of some meaningful blocking in the northern hemisphere in the future, but it still remains doubtfull at this early stage that that will produce cold and snow for us.

Those are just screen shots of the whole ECM op run.

Look at the dates of each one.

[The Northern Ramper]

I don't think the weather conforms with LRF's mcweather, not even those done by GP, RJS and Brian Gaze.. The truth of the matter is a change to colder weather from mid month remains a possibility, it's no more or no less than that, indeed I'd still call it a genuine 50-50 shot based on all the overnight modelling.

I think it probably wise sticking to what we do know with a fair degree of confidence for now, and that is pressure rising from the south across the weekend and into next week. As a result much of England and Wales at least can look forward to seeing a good deal of drier, quieter weather, OK it will be mild, perhaps very mild, but at least some of us down here in the south and west will get a chance to dry out. To be honest I'll be grateful for that at this stage and of course once HP gets established, it generally becomes easier to open a root to colder weather.

If you are basing your forecast on overnight fi modelling then yes 50/50 is correct.

[Nick F]

I don't think the weather conforms with LRF's mcweather, not even those done by GP, RJS and Brian Gaze.. The truth of the matter is a change to colder weather from mid month remains a possibility, it's no more or no less than that, indeed I'd still call it a genuine 50-50 shot based on all the overnight modelling.

I was thinking exactly the same! A possibility, but it's one thing getting the stratosphere to warm downwards to provide the impetus to displace the PV to more southerly latitudes, but it's another thing getting the right synoptics in place to deliver deep cold and snow to the small island of the UK. Some of our milder winters have seen several stratospheric warmings during them, but it hasn't led on to deliver cold and snow to the UK, so caution required IMO.

I think I will sit on the fence on this one for now rather than praise the LRFers before it has even transpired! Hats off to them if it does come off cold and snowy for the UK after mid-Jan though.

[nick sussex]

I think we began to see this pattern at T+240 around the 31st Dec if I recall correctly, which would confirm what many are saying that this evolution is sliding back and back, as the 31st + 240 hours is next Mon/Tues, when we will now be sunning ourselves in barmy SW breezes....it might be 'jam tomorrow' but I fear the jam will have gone stale by the time we get it looking at the current outputs....

I'd tend to agree with you given the output over the last week, who needs stale jam!

The ECM has been the main culprit which is unusual, its normallly the GFS which goes off into the sunset!

However I think we are approaching that proverbial fork in the road which will tell us which way the second half of winter will likely go. It's impossible to ignore the events going on in the stratosphere, although these are not guarantees of cold for the UK this will likely have some effect on the NH pattern.

The question mark is over Greenland in whether we see proper high pressure build or whether the PV will weaken but not get displaced sufficiently to bring the real cold to the UK.

If you read these comments from NOAA this morning.

BY THE D+8 TIME FRAME THERE IS SOME DISAGREEMENT OVER THE EXPECTED

PATTERN OF HGT ANOMALIES OVER THE PAC INTO WRN NOAM... BUT LATELY

GUIDANCE HAS BEEN REASONABLY CONSISTENT IN SHOWING A CORE OF NRN

ATLC POSITIVE ANOMALIES WHICH TELECONNECT TO A MEAN TROF OVER THE

ERN CONUS OR EAST COAST. MOST MODEL AND ENSEMBLE GUIDANCE LEADS

INTO THIS PATTERN FAIRLY WELL...

The current limpet high to the sw is effected by that trough in the eastern USA, so its unlikely to just sit there, if the upstream trough amplifies this will pull this back westwards and allow pressure to fall into Europe, the question that leaves us with is will the jet just run over the top with a cooler to colder zonality or will we actually see Greenland high pressure.

If you look at the ECM De Bilt ensembles these do not support a Scandi high scenario, you would expect a much colder clustering if that was the case, these look at the moment to prog a cooler/colder zonality with displaced Azores high and energy heading se over the top of this, they also don't shout screaming bitter northerly either so that doesn't really back a strong Greenland block.

http://www.weerplaza...?type=eps_pluim

Of course these can change quickly but I think thats where we're at today, the background variable of the strat warming is however lurking and because of this I wouldn't rule out some big changes in the output as we head towards mid month.

I think we're going to just have wait a bit longer to see how that strat warming effects the models but its certainly a time for being alot more dubious of later output.

Edited January 5, 2012 by nick sussex

[shedhead]

If you are basing your forecast on overnight fi modelling then yes 50/50 is correct.

I'm not, I'm basing it on all available modelling. No one knows, or indeed rarely ever knows where FI begins. It is very subjective, the cut off between the low and high res parts of the GFS run

being the only quantifiable benchmark imo.

[mcweather]

I don't think the weather conforms with LRF's mcweather, not even those done by GP, RJS and Brian Gaze.. The truth of the matter is a change to colder weather from mid month remains a possibility, it's no more or no less than that, indeed I'd still call it a genuine 50-50 shot based on all the overnight modelling.

I think it probably wise sticking to what we do know with a fair degree of confidence for now, and that is pressure rising from the south across the weekend and into next week. As a result much of England and Wales at least can look forward to seeing a good deal of drier, quieter weather, OK it will be mild, perhaps very mild, but at least some of us down here in the south and west will get a chance to dry out. To be honest I'll be grateful for that at this stage and of course once HP gets established, it generally becomes easier to open a root to colder weather.

I definitely agree with you about getting a chance to dry out shedhead. However I do think that the coming days will see the models firming up on our way out of the mild and into something colder. At this distance ( ie still ten days out) I wouldn't expect it to look like anything more than 50/50 but I think those odds will start to fall a lot more firmly in favour of cold over he coming days.

[Glacier Point]

ECM ensemble mean at day 10:

...shows positive height anomalies in the expected places, most interest to us being the ridge in the Atlantic becoming amplified and the downstream trough over Scandinavia, becoming sharper and further west in time. Note also the trough over eastern North America phasing with the polar vortex and pulling some of the energy southward. A good sign for cold evolution.

The operational ECM is inconsistent with this mean in a number of areas, most notably heights over the Arctic and the troughing into Scandinavia and is therefore rejected.

GFS Sphaghetti plots for the AO:

Consistently advertising a switch to negative around the 13th January. Only two members manage to break zero in the extended range and the trend over the last few runs has been to deepen the forecast magnitude of the AO in time.

Both ECM and GFS are largely neutral with the NAO for the time being although given the gathering momentum on the AO becoming strongly negative, it should only be a matter of time before that index is forced negative.

Angular momentum looks to me to be about to drop significantly sending the Global Wind Oscillation into a phase 8-1 type evolution which is sound for blocking over Arctic and low major trough development over Europe and eastern North America.

Add to that we have one stratospheric warming lagged from Christmas, another now in progress and a much larger event looming for around mid to late January. Wave on wave on wave and the AO could potentially beat the record low set last year in the latter part of January or early February.

Re Jam tomorrow - if you've followed the postings, mid January has always been touted as the earliest possible window of opportunity. That's ten days from now. Only if you bought into ECM height rises over Scandinavia or possible progressive ECM operationals of the last few days could you consider this to be dwelling in la la land.

[recklessabandon]

I'd tend to agree with you given the output over the last week, who needs stale jam!

The ECM has been the main culprit which is unusual, its normallly the GFS which goes off into the sunset!

However I think we are approaching that proverbial fork in the road which will tell us which way the second half of winter will likely go. It's impossible to ignore the events going on in the stratosphere, although these are not guarantees of cold for the UK this will likely have some effect on the NH pattern.

The question mark is over Greenland in whether we see proper high pressure build or whether the PV will weaken but not get displaced sufficiently to bring the real cold to the UK.

If you read these comments from NOAA this morning.

BY THE D+8 TIME FRAME THERE IS SOME DISAGREEMENT OVER THE EXPECTED

PATTERN OF HGT ANOMALIES OVER THE PAC INTO WRN NOAM... BUT LATELY

GUIDANCE HAS BEEN REASONABLY CONSISTENT IN SHOWING A CORE OF NRN

ATLC POSITIVE ANOMALIES WHICH TELECONNECT TO A MEAN TROF OVER THE

ERN CONUS OR EAST COAST. MOST MODEL AND ENSEMBLE GUIDANCE LEADS

INTO THIS PATTERN FAIRLY WELL...

The current limpet high to the sw is effected by that trough in the eastern USA, so its unlikely to just sit there, if the upstream trough amplifies this will pull this back westwards and allow pressure to fall into Europe, the question that leaves us with is will the jet just run over the top with a cooler to colder zonality or will we actually see Greenland high pressure.

If you look at the ECM De Bilt ensembles these do not support a Scandi high scenario, you would expect a much colder clustering if that was the case, these look at the moment to prog a cooler/colder zonality with displaced Azores high and energy heading se over the top of this, they also don't shout screaming bitter northerly either so that doesn't really back a strong Greenland block.

http://www.weerplaza...?type=eps_pluim

Of course these can change quickly but I think thats where we're at today, the background variable of the strat warming is however lurking and because of this I wouldn't rule out some big changes in the output as we head towards mid month.

I think we're going to just have wait a bit longer to see how that strat warming effects the models but its certainly a time for being alot more dubious of later output.

I have been mulling over the concept of a move to cooler or even cold zonality in the medium term as an evolution for a little while now on a personal basis, with the downstream effects of stratospheric warming coming in later february or even march an manifesting as a northerley or north easterley flow similar to Feb/March 2007 I think. This is something I am looking out for, but don't have enough experience or knowledge to identify the signals yet that I should be looking for. I do think this maybe is where we will head though having being watching the models fairly closely this winter.