Model output discussion - 5th December 2016 - Into Winter we go

[Iceaxecrampon]

06Z  - OK its +214

HP well and truly battered away.

Blizzards. 

[mountain shadow]

Those GLAAM forecasts look very volatile and unreliable though Catacol. Five days ago we were forecast to be into low AM but are still just North of the line. It doesn't look like a great tool for forecasting to me, but that's just my opinion. It does however look like one of those good tools for explaining why something didn't happen after the fact.

Granted though, the models are pretty firm on getting rid of the useless block and period of colder zonal weather looks likely, this offers up some possible snow prospects for the usual suspects in the North West with a little altitude. If we can somehow garner a little better amplitude behind any passing cold front, then some may see a surprise.

[marksiwnc]

Ian f did mention that they (met)  thought that a zonal period was probable between the high switching from our East to our North East I believe.  I think this might be the way this pans out. Hopefully it would be able to dig a bit further north west..  hope gp puts a post the next few hours to see where he thinks we could be heading.  give us (sacra members) some good news boys 

[northwestsnow]

Poor meto update, sounds more like the flatter Gfs6z to me than the ecm0z..

Was kind of hoping something to suggest a north wester...

[radiohead]

2 minutes ago, Snow Grain said:

Blizzards?  Is that a new word for rain?

I presume he is talking about mountain conditions.

 

[Catacol]

19 minutes ago, mountain shadow said:

Those GLAAM forecasts look very volatile and unreliable though Catacol. Five days ago we were forecast to be into low AM but are still just North of the line. It doesn't look like a great tool for forecasting to me, but that's just my opinion. It does however look like one of those good tools for explaining why something didn't happen after the fact.

Granted though, the models are pretty firm on getting rid of the useless block and period of colder zonal weather looks likely, this offers up some possible snow prospects for the usual suspects in the North West with a little altitude. If we can somehow garner a little better amplitude behind any passing cold front, then some may see a surprise.

Volatile - yes. The interesting bit - which is not easy to show on here - is how the forecast keeps being wrong. You can track back 5 days on the CPC site, but I dont save all the graphics. However without doubt the models are seeing a Nina pattern moving us to a low AAM orbit 1 -2 - 3 when in fact the atmosphere is keen to sustain a Nino signature with accompanied convection led forcing. This is a key component underpinning the forecast of blocking to come. If the weak Nina signal was suddenly to bring the atmosphere into line and force us into a low momentum phase then we would be in trouble.

Therefore the forecasting tool is curiously obtuse but still valid. In other words the models are seeing a less amplified pattern constantly, but in fact the truth of the matter is that the amplification keeps coming. So FI charts are likely to be too flat. This was what led me to believe we might get a high lat block this side of Xmas. In fact, however, both MJO and partially as a result the GWO have gone very quiet at the moment and very neutral. The starter has his flag raised, and the field are nose to tape.... but he is holding them all a long time!!! No noticeable forcing therefore at the moment. But if the MJO stays with a Nino imprint then it will restart - soon - and those GWO orbits will change. And blocking should/may return.

 

[NorthernRab]

2 hours ago, karyo said:

I can't see why anybody who doesn't live on a hilly location would wish for (cold) zonality. I live in the northern half of the country and I am yet to see anything more than sleet/wet snow from cold zonality. As sundog also mentions, cold zonality tends to be brief and before you know it you are back in the long fetch southwesterlies.

With the stratosphere hostile for northern blocking, a mid latitude high is our best chance for a seasonal feel to the weather.

Cold zonality can deliver for most of Scotland, even down to sea level in the likes of Glasgow. 

[KTtom]

9 minutes ago, northwestsnow said:

Poor meto update, sounds more like the flatter Gfs6z to me than the ecm0z..

Was kind of hoping something to suggest a north wester...

To be fair, the Met and other long range tools have been poor so far this winter...blocked and colder than average was predicted up to xmas, no sign of Atlantic dominating was another term constantly banded around and only a week or so ago...after 2 days solid rain today is sunny and 13 c., so I would recommend not taking too much notice, the way the models are chopping and changing and , constantly picking up on new signals anything can Happen! 

[fergieweather]

2 hours ago, Gael_Force said:

Is that not what they were discussing on Monday? ie. switch of emphasis on the daily ensembles from blocking over us to trough situation instead. The EC 46 would have been initiated when the bulk were in favour of the high holding on and hence the positioning of the anomalies. 

Yes, but it's the evolution on into January that is a focal point of ongoing interest (certainly at Exeter), with GloSea5 continuing each run to support Monday's ECMWF theme of migrating height anomalies westwards during week1-2 of Jan, with lows tracking much further north over this. The net result is a generally blocked output 1st half Jan, with switch from mean SW or at times perhaps NW flow (Xmas period) to E'ly into Jan and resultant higher likelihood of colder outbreaks. Confidence is of course very low at this lead time and not least - as UKMO point out - hindered by a lack of clear global teleconnections into that period.

Edited December 14, 2016 by fergieweather

[Matthew.]

42 minutes ago, mountain shadow said:

Those GLAAM forecasts look very volatile and unreliable though Catacol. Five days ago we were forecast to be into low AM but are still just North of the line. It doesn't look like a great tool for forecasting to me, but that's just my opinion. It does however look like one of those good tools for explaining why something didn't happen after the fact.

Granted though, the models are pretty firm on getting rid of the useless block and period of colder zonal weather looks likely, this offers up some possible snow prospects for the usual suspects in the North West with a little altitude. If we can somehow garner a little better amplitude behind any passing cold front, then some may see a surprise.

Useless Block?  Much better than gales and heavy rain surely? Agree with the cold zonal loooking likely from the models now and yes snow to higher ground for northern hills. As you say we need more of a Nw'ly for -8 uppers to flood the Uk. I think this has been the kindest 1/6 of winter i can remember- no snow/gales/heavy rain. The Atlantic storms are truly leagues to the Nw

[Man With Beard]

With regards this zonal malarky, are we getting way, way ahead of ourselves here anyway? There's enough disagreement at just T144 this morning.

      

Sure the big picture is fairly consistent, but heights over different parts of Europe vary considerably - the UKMO in particular. Not enough confidence yet for me to say the Atlantic will break through.

 

[Seasonality]

6 minutes ago, fergieweather said:

Yes, but it's the evolution on into January that is a focal point of ongoing interest (certainly at Exeter), with GloSea5 continuing each run to support Monday's ECMWF theme of migrating height anomalies westwards during week1-2 of Jan, with lows tracking much further north over this. The net result is a generally blocked output 1st half Jan, with switch from mean SW or at times perhaps NW flow (Xmas period) to E'ly into Jan and resultant higher likelihood of colder outbreaks. Confidence is of course very low at this lead time and not least - as UKMO point out - hindered by a lack of clear global teleconnections into that period.

Hello Ian, once again many thanks for your invaluable contributions and the insider knowledge you give us on the workings of the met office. If I am reading what you say correctly, could it be said today's ECM 00z evolution is a genuinely feasible outcome, albeit with low confidence and possibly less extreme?

[nick sussex]

It's a bit of a catch 22 for those wanting rid of the block. Because of the lack of upstream amplitude the only way to force the jet se near the UK is to have the block to the ne. Otherwise the rampant PV will just blast the jet right through , eventually you end up with the Azores high ridging ne and mild sw mush. You need something to help lock in lower heights over central Europe. 

[bluearmy]

10 minutes ago, fergieweather said:

Yes, but it's the evolution on into January that is a focal point of ongoing interest (certainly at Exeter), with GloSea5 continuing each run to support Monday's ECMWF theme of migrating height anomalies westwards during week1-2 of Jan, with lows tracking much further north over this. The net result is a generally blocked output 1st half Jan, with switch from mean SW or at times perhaps NW flow (Xmas period) to E'ly into Jan and resultant higher likelihood of colder outbreaks. Confidence is of course very low at this lead time and not least - as UKMO point out - hindered by a lack of clear global teleconnections into that period.

with this set up, we continue to run the risk of the block sinking if the jet strengthens for any reason (as we see upcoming). to deliver a deep cold wintry period, we require the flow to split and get some low heights into Europe. failing that troughs dropping in through the back door though even that remains tricky without any lowering of euro heights

[feb1991blizzard]

 

16 minutes ago, fergieweather said:

Yes, but it's the evolution on into January that is a focal point of ongoing interest (certainly at Exeter), with GloSea5 continuing each run to support Monday's ECMWF theme of migrating height anomalies westwards during week1-2 of Jan, with lows tracking much further north over this. The net result is a generally blocked output 1st half Jan, with switch from mean SW or at times perhaps NW flow (Xmas period) to E'ly into Jan and resultant higher likelihood of colder outbreaks. Confidence is of course very low at this lead time and not least - as UKMO point out - hindered by a lack of clear global teleconnections into that period.

Are they discussing the possibility of the high being far enough North to bring in an unstable potent easterly (obviously I know you cant forecast uppers at that range for certain but just talking about the positioning of the high being far enough North to allow for such an outcome) or one that's only just to the N or NW which in itself could still be very cold if not feeling as cold as the aforementioned possibility but being more of the still fog and frost variety?

Edited December 14, 2016 by feb1991blizzard

[fergieweather]

12 minutes ago, Seasonality said:

Hello Ian, once again many thanks for your invaluable contributions and the insider knowledge you give us on the workings of the met office. If I am reading what you say correctly, could it be said today's ECM 00z evolution is a genuinely feasible outcome, albeit with low confidence and possibly less extreme?

Current thinking for festive period via ENS is 60% likelihood HP remaining proximal to SE/E (more settled); more unsettled to NW/W.  Alternative is 40% probability more widely unsettled with cyclonicity spreading across entire UK for Christmas, with resulting temps ranging normal to a bit below (showery; some wintry).

[Nouska]

14 minutes ago, fergieweather said:

Yes, but it's the evolution on into January that is a focal point of ongoing interest (certainly at Exeter), with GloSea5 continuing each run to support Monday's ECMWF theme of migrating height anomalies westwards during week1-2 of Jan, with lows tracking much further north over this. The net result is a generally blocked output 1st half Jan, with switch from mean SW or at times perhaps NW flow (Xmas period) to E'ly into Jan and resultant higher likelihood of colder outbreaks. Confidence is of course very low at this lead time and not least - as UKMO point out - hindered by a lack of clear global teleconnections into that period.

That's interesting because the JMA has done a fairly quick change between the output on the eighth of the month to that of the twelth. Albeit, one is weekly and the other is monthly the indication was more of the same for first two weeks of January.

Latest seasonal for January 'might' depict what you are seeing in your models?

At least, it is the first indication of low height anomaly to the south - an artefact of the digging trough leaving residual cut-off troughiness in the westerns Med?

http://ds.data.jma.go.jp/gmd/tcc/tcc/products/model/map/4mE/map1/zpcmap.php

 

 

 

 

[Dennis]

A very heavy blocked situation

[Seasonality]

1 minute ago, Dennis said:

A very heavy blocked situation

Interesting Dennis, still shows a strong Baltic centred high. A bit like the GFS runs a couple of days ago.

[Weather Boy]

2 minutes ago, Dennis said:

A very heavy blocked situation

I know that's an anomaly, and so shouldn't be read like a pressure map, but comparing with the anomalies yesterday and previously, that's a lot further east, with the highest around Finland.  Previous efforts had HP mostly around North Sea or SW Scandinavia.

[fergieweather]

5 minutes ago, Nouska said:

That's interesting because the JMA has done a fairly quick change between the output on the eighth of the month to that of the twelth. Albeit, one is weekly and the other is monthly the indication was more of the same for first two weeks of January.

Latest seasonal for January 'might' depict what you are seeing in your models?

At least, it is the first indication of low height anomaly to the south - an artefact of the digging trough leaving residual cut-off troughiness in the westerns Med?

http://ds.data.jma.go.jp/gmd/tcc/tcc/products/model/map/4mE/map1/zpcmap.php

 

 

 

 

It's hard to fathom any semblance of favoured direction, isn't it!? I'm awaiting what UKMO Seasonal meeting on Monday makes of it all (they're discussing J-F-M in entirety). Of course, any possible SSW in Jan would throw everything akimbo anyway.

[fergieweather]

6 minutes ago, Weather Boy said:

I know that's an anomaly, and so shouldn't be read like a pressure map, but comparing with the anomalies yesterday and previously, that's a lot further east, with the highest around Finland.  Previous efforts had HP mostly around North Sea or SW Scandinavia.

....albeit ECMWF has it focused in exact same area (bear in mind these are 500hPa GPH anomalies in both charts: not MSLP)

[blizzard81]

9 minutes ago, fergieweather said:

....albeit ECMWF has it focused in exact same area (bear in mind these are 500hPa GPH anomalies in both charts: not MSLP)

Hi Ian, at what timescale is that chart covering?

[Tamara]

I genuinely don't understand why the slavish fixation, day in day out, with face value model operational output creates total amnesia towards the wider perspectives given by many on this thread each day. Its highly frustrating to say the least

I must be looking at different data because both the complexity of the factors at hand, and the possible outcomes ahead hold greater promise and interest than some of the highly inward posts today and most other days

Why not focus on this instead of needless emotional reaction to every deterministic roll out? For my own part with that in mind, there is nothing further to add, today, to previous days summaries. Suffice to say the retrogressive blocking signals involved tally with posts made since the weekend. No further repeat needed of those and therefore definitely also no need on that basis for short term transfixion with zonality continuing till the Spring equinox.

Watch, wait, find answers at each natural corner and, at the same time trying to read between the lines using the information and tools available to gain clues in anticipation of what is ahead.

For what it is worth, I can find various things in todays operational output anyway that are highly consistent with recently (and not so recently!) explained longer term guidance. It further underpins confidence in the GSDM as a highly valuable long range tool. So I would disagree that this methodology is hindsight based. It gives significant clues as to the possible directions and future evolution of NWP.

What is can't always do however, is make it snow over any town close to you, at a given x/y point in time

@Seasonality  I totally understand the difficulty of not being able to understand complex information. Its something I. like most all others experience. But that information is freely available and one of the benefits of a community is being able to ask questions. Better that, than ignoring the guidance given by so many of this thread who will happily answer those questions and make face value reaction to NWP less necessary

 

Edited December 14, 2016 by Tamara

[Seasonality]

2 minutes ago, Tamara said:

I genuinely don't understand why the slavish fixation, day in day out, with face value model operational output creates total amnesia towards the wider perspectives given by many on this thread each day. Its highly frustrating to say the least

I must be looking at different data because both the complexity of the factors at hand, and the possible outcomes ahead hold greater promise and interest than some of the highly inward posts today and most other days

Why not focus on this instead of needless emotional reaction to every deterministic roll out? For my own part with that in mind, there is nothing further to add, today, to previous days summaries. Suffice to say the retrogressive blocking signals involved tally with posts made since the weekend. No further repeat needed of those and therefore definitely also no need on that basis for short term transfixion with zonality continuing till the Spring equinox.

Watch, wait, find answers at each natural corner and, at the same time trying to read between the lines using the information and tools available to gain clues in anticipation of what is ahead.

For what it is worth, I can find various things in todays operational output anyway that are highly consistent with recently (and not so recently!) explained longer term guidance. It further underpins confidence in the GSDM as a highly valuable long range tool. So I would disagree that this methodology is hindsight based. It gives significant clues as to the possible directions and future evolution of NWP.

What is can't always do however, is make it snow over any town close to you, at a given x/y point in time

 

 

I think there are several reasons for the slavish fixation, some fall into different categories.

1: Those who enjoy the fun and post accordingly. They understand the broader signals but get pleasure in reacting to each new roll of the dice.

2: Those who don't (yet) have sufficient knowledge to understand the complex factors at hand

3: Those who lack the capacity to understand the complex factors at hand

4: Those who do understand to some extent the complex factors at hand but post in a manner that is designed to provoke a reaction

5: Those who do understand to some extent the complex factors at hand but are too shy to speak out for fear of being shot down in flames