Model Output Discussions 12z 01/09/2016

[Tamara]

1 hour ago, Changing Skies. said:

Spotless sun the significance is unknown to me but the marked limited solar activity could be resulting in the lack of versatility (I'm not sure but I recall reading on here, periods of increased solar activity can flare up the Jet Stream).

This Autumn the Atlantic seems to be heavily sedated, it's rather unusual in fact it's quite comparable to 09/10 - enabling recent anticyclonic weather to lock in this Autumn, and perhaps gives a bigger incentive for a cold northern blocking scenario to lock in or sustain? Which we're seeing in the models to different extents. 

Good post Daniel   

The converse is also true and exactly what we don't want to appear this year. Increased solar activity has an invigorating effect on the Hadley and Walker cells through -ve tendency of frictional torques and lowered atmospheric angular momentum . In plain English, this translates to strengthened sub tropical ridges pushed into mid latitudes, lifting and energising of the polar jet northwards - and, as a consequence, negating emerging south and westward advecting cold albedo feedbacks.

Feedbacks which yet again we are watching closely again this year.

The "solar spoiler" is precisely what scuppered "That Easterly" in early winter 2012 after a promising start whereby earliest Eurasian snow feedbacks and an ideal arctic ice profile had benefitted from low solar activity and +ve torques leading to rising angular momentum and resultant poleward Rossby Wave propagation taking advantage of the favourable weak stratospheric profile there was that year.  An untimely spike in solar activity occurred and scuppered some late November and early December cold leading to something even more promising - as extended modelling suites and ECM 32 at the end of autumn had indicated.

This year, encouragingly, overall angular momentum is actually placed at a slightly elevated position to where it was late October/early November 2012. We have seen a rise in GLAAM from the (relatively) lower angular momentum state of September lead by gently rising recovery in frictional torques 

.The rolling SOI monthly index is now actually tanking into -ve territory with some impressive -ve daily returns in recent days.  - much as documented was in progress and in detail in recent posts.

 

https://www.longpaddock.qld.gov.au/seasonalclimateoutlook/southernoscillationindex/

 

We also have MJO tropical convective related activity in the Western Pacific gaining traction across forecasting suites

 

 

 MJO activity into Phases 7/8  suggests further dampening of attempts by La Nina Easterly trades  - and the reward is another boost to angular momentum in the pipeline as fresh tranches of westerly wind momentum are initiated across the Pacific. This sustains amplification flux in the atmospheric circulation well into November and keeps up the ocean/atmosphere disconnect in terms of the ocean attempted weak Nina signature.

It translates to further wave activity propagating poleward to keep the polar vortex weak and unstable as we come closer and closer towards the start of winter.

At present, what is there not to like?

 

 

 

 

[Nouska]

9 minutes ago, Tamara said:

The "solar spoiler" is precisely what scuppered "That Easterly" in early winter 2012 after a promising start whereby earliest Eurasian snow feedbacks and an ideal arctic ice profile had benefitted from low solar activity and +ve torques leading to rising angular momentum and resultant poleward Rossby Wave propagation taking advantage of the favourable weak stratospheric profile there was that year.  An untimely spike in solar activity occurred and scuppered some late November and early December cold leading to something even more promising - as extended modelling suites and ECM 32 at the end of autumn had indicated.

And here is @Tamara's solar spoiler.

..but we got the benefit of the low activity later in the following Spring.

Follow here.

http://www.gfz-potsdam.de/en/kp-index/

[feb1991blizzard]

6 minutes ago, Nouska said:

And here is @Tamara's solar spoiler.

..but we got the benefit of the low activity later in the following Spring.

Follow here.

http://www.gfz-potsdam.de/en/kp-index/

Is there a spanner in the works though with the unexpected return of the W-QBO?, if this were to be continued would it not practically scupper any chance of an SSW this winter?, I thought SSW's are more likely in Solar Max's W-QBO combinations aren't they where as IF we would have the Normal QBO sequence (ie Easterly for this winter) with weak la nina and low solar activity then that would have been the perfect combination.

[blizzard81]

The ECM control run for debilt looks amazing on the ensembles. Very cold and snowy towards the back end.

[Ali1977]

10 minutes ago, feb1991blizzard said:

Is there a spanner in the works though with the unexpected return of the W-QBO?, if this were to be continued would it not practically scupper any chance of an SSW this winter?, I thought SSW's are more likely in Solar Max's W-QBO combinations aren't they where as IF we would have the Normal QBO sequence (ie Easterly for this winter) with weak la nina and low solar activity then that would have been the perfect combination.

Although the QBO has broken a 50 or so year pattern and not moved into an E-QBO , I believe it is now slowly changing over .

It is also doing something never witnessed since being monitored mid last century,  so we can't really use it as a tool to help predict the weather this year neither. 

[feb1991blizzard]

1 minute ago, blizzard81 said:

The ECM control run for debilt looks amazing on the ensembles. Very cold and snowy towards the back end.

Here they are in all their glory!

 

[Nouska]

31 minutes ago, feb1991blizzard said:

Is there a spanner in the works though with the unexpected return of the W-QBO?, if this were to be continued would it not practically scupper any chance of an SSW this winter?, I thought SSW's are more likely in Solar Max's W-QBO combinations aren't they where as IF we would have the Normal QBO sequence (ie Easterly for this winter) with weak la nina and low solar activity then that would have been the perfect combination.

I suspect what we are currently seeing is a response to extremely low ice in the Kara/Barents and late season high energy tropical systems piling WAA into the polar regions. I'm not sure about the QBO as it is different things at different levels. Unique, for the record we have, in other words. The met office do not seem to consider the QBO as a significant indicator for second winter NAO forecast according to this recent study.

http://sci-hub.bz/10.1038/ngeo2824

Where it fits in with present winter forecast, I might find out if Aemet publish the winter forecast again this year. I would be a bit more wary of recent uptick in solar geomagnetic activity - belies the spot numbers by quite a bit.

At the end of the day, we are theorising for fun and education and we may be on the right lines or completely out to lunch.

Edit regarding QBO phases and solar cycle - IMO, sufficient variety of combinatons in the record to allow for alternative scenarios.

Edited October 29, 2016 by Nouska

[feb1991blizzard]

2 minutes ago, Nouska said:

I suspect what we are currently seeing is a response to extremely low ice in the Kara/Barents and late season high energy tropical systems piling WAA into the polar regions. I'm not sure about the QBO as it is different things at different levels. Unique, for the record we have, in other words. The met office do not seem to consider the QBO as a significant indicator for second winter NAO forecast according to this recent study.

http://sci-hub.bz/10.1038/ngeo2824

Where it fits in with present winter forecast, I might find out if Aemet publish the winter forecast again this year. I would be a bit more wary of recent uptick in solar geomagnetic activity - belies the spot numbers by quite a bit.

At the end of the day, we are theorising for fun and education and we may be on the right lines or completely out to lunch.

Thanks for replies.

[BLAST FROM THE PAST]

1 hour ago, feb1991blizzard said:

Is there a spanner in the works though with the unexpected return of the W-QBO?, if this were to be continued would it not practically scupper any chance of an SSW this winter?, I thought SSW's are more likely in Solar Max's W-QBO combinations aren't they where as IF we would have the Normal QBO sequence (ie Easterly for this winter) with weak la nina and low solar activity then that would have been the perfect combination.

My thoughts are that this will allow some LP activity but not of the zonal type.  I think we will experience displaced PV episodes and LPs  diving down on NNW to SSE axis.... much as is progged currently

 

BFTP

Edited October 29, 2016 by BLAST FROM THE PAST

[knocker]

Well at least the EPS is getting rid of that pesky trough to the east thus a much more sensible flow from a westerly quadrant with perhaps a move towards more average temps.

[Summer Sun]

A quick reminder that from the 00z's the models will all be 1 hour earlier 

[Frosty.]

Tonight's Ecm 12z ens mean indicates a trend to more unsettled conditions with showers and longer spells of rain and judging by the position of the trough it will be pulling colder air down across the uk so precipitation could turn wintry on northern hills and mountains with some snow..happy days

[johnholmes]

2 hours ago, feb1991blizzard said:

Yes John but the charts for that specific timeframe (312 I think it was) show higher heights North of Lower heights so roughly the flow into Canada is from the East or at least an Easterly quadrant?

no is the brief answer, the contours give you the flow, all the dotted red line tells you is how much higher or lower the actual contour height is relative to the climatalogical height.

This link might help, that is if it will work as it was done several years ago, and my apologies for it being a long entry.

If one of the team can create it into a link I would be grateful as it will save space-thanks

Using the 500mb anomaly charts?

The first rule is remember they are no more than any other prediction-a prediction nothing more. One cannot use them with 100% expectation of accuracy. This is even more the case if, as with all forecasting, one does not use all the available data for a similar time frame.

For those who find it not easy to see where the UK is, copy and paste into mspaint, then click on image, then on flip/rotate, then rotate by angle=90 degrees, and as below the same pair of charts

There are 3 variations on the 500mb theme; two are on the same chart, the two above (with, before flipping them ECMWF on the left and GFS on the right) and that from NOAA, link below and issued in the evening. I’m not sure about the 2 above but Monday-Friday and the NOAA version has a human input, much like the UK Met Fax charts. In my view, perhaps not to others, this makes hardly any difference to the main positions of the ridges and troughs.

The NOAA link I’m showing is the 6-10 day chart and they also issue at the same time each evening the 8-14 day one. So we then have 3 charts covering the 6-15 day period.(NB again if you want the UK in a more familiar position then do as explained above).

What I do every day is copy and paste these charts-why?-as with any computer output the first thing any forecaster is looking for is the ‘trend’, how they appear to show any changes over the subsequent days. Are those changes consistent? Each day I make notes as to how I think they are progressing or not – sample below

From 13 July 2011

Not shown but NOAA 20-26 very similar

Ec-gfs on 14 for 24 july and little sign of any change-both have upper trough over/just e of uk with 500 flow n of west and meridional type pattern

Once that is done then just for a view of how the basic models are dealing with this time frame, check the GFS and ECMWF outputs, I use either the 00z or 12z, to see if they look reasonable at the side of the 500mb outputs. If not then, unless the 500mb charts are not showing consistency then I find one can bin whichever of the runs show something largely different.

Remember that it’s the 500mb flow we are concerned with NOT what seems to be the surface pattern. Until the upper (500mb) pattern seems fairly soundly based it is a total waste of time expecting the surface charts to be anywhere near correct.

If the ECMWF and/or GFS at 500mb appear to show a similar pattern then the surface charts have some credence, (and it’s a good idea IF you have Net Wx Extra to show its 500mb chart for that time period-another good reason to have Extra!)

We can then look at teleconnections further out to see if they suggest that the overall pattern on the 500mb anomaly charts is about right. This will only come with practice as you see cases where they do and do not fit. In meteorology its no disgrace to walk first before trying to run. Take your time at trying to decipher what is happening, read the posts by experienced and respected members of the forum. If you don’t already know them you soon will!

If those teleconnections (tc’s as I call them) do support the overall upper air pattern then one can be reasonably certain that the weather in the 6-15 day time frame is being fairly well represented by the basic synoptic models. DO NOT though expect the surface features to be anywhere near cast in stone. It has always been, easier, no best use the term, less difficult, to get the upper air pattern right some time before getting the surface correct or about 85% correct. Its too complex to try and explain that here but trust me it is true.

I know we all accuse one another of ‘cheery picking’ but just to show how close the 500mb anomaly charts can be look at the example below which I used a day or so ago to illustrate how close they had been at the 10 day mark.

First the 500mb Extra chart for 00/06Z this morning

 Now the 500mb anomaly chart from 10 days ago, IF I can find it!

Well it’s the issue on 5th for 13-19th by NOAA, and the one issued by ECMWF/GFS was very very similar.

What do they each show?

An upper trough over/off the eastern seaboard of the states; a relatively flat flow across the Atlantic with low contour values to the north (Greenland/Iceland) and high values to the south (Azores area) and highly relevant for the UK weather, a marked trough over/not far east of the country. This pattern with the 500mb flow on both actual and forecast showing from north of west and at a reasonable speed would be expected to give what?

Yes sure enough what we have had over the past week, a mix of weather systems with rain or showers on some days, more so the further NW in the country you live.

To me this is a much better way of model watching than taking each GFS run and putting it under a microscope for surface detail. Like I’ve said earlier the surface detail will often be difficult to get right, even at T+48 the experts in UK Met don’t always get it right. Even their interpretation of their own multiplicity of models and ALL the other world models can end up with the Fax chart at T+48/24 being a bit adrift of the actual weather.

Don’t despair though it really is about the best way for us with web access but not into UK/ECMWF technical discussions of getting a pretty accurate feel for the general weather pattern beyond a week ahead and quite often out to a bit over 2 weeks ahead.

Go on try it, keep records of what you have done, show when it worked and when it did not. Come this winter it MIGHT just stop some of the upgrade/downgrade posts after each GFS run, the false hopes raised then dashed for the cold snow lovers. It will give a more realistic view of the most likely weather patterns in the 6-15 day time span.

If at the end of February you feel this is a load of twaddle and have examples to prove it I’ll be very surprised.

As a suggestion

To those with little knowledge of these charts

Ignore the + (red) and –ve (blue) areas and concentrate on the green lines, they are the contour lines, if you like isobars at 500mb.

For those who feel confident with that part, then be very careful in trying to work out just what the + or – may mean to the forecast.

In simple terms all they show are the areas which are above (+) or below (-) 500mb height values compared to the averages for the dates shown.

The use of AO and NAO, again with caution, can sometimes help decide where contour heights may either fall or rise on subsequent charts. Further out then the MJO forecast (I find that about as easy as finding a needle in a haystack) along with the overall ENSO assessment from the IRI site can also give reasonable guidance in about 65+% of occasions I find.

Anyway enjoy and hopefully build up your skills at model reading.

jh

 

Edited October 29, 2016 by johnholmes

[feb1991blizzard]

1 minute ago, johnholmes said:

no is the brief answer, the contours give you the flow, all the dotted red line tells you is how much higher or lower the actual contour height is relative to the climatalogical height.

Thanks, but you are refrerring to anomaly charts surely, Nouska and yourself cleared that one up the other night, but this chart I'm talking about is the meteociel H500 +slp chart for a specific time, theres no red dotted lines on those, Take this chart here for example.

 

Notice the Trough over Scandi / Eastern Europe, surely the flow is counter clockwise around that both at surface and 500mb level, so basically, the flow on the Western flank is surely Northerly and on the Eastern flank its a southerly flow (give or take a bit, I know theres about a 15 degree difference between isobars and flow).

[shaky]

Another slight upgrade on the gfs 18z!stronger ridge in the atlantic at 138 hours!!

[Ali1977]

On 29/10/2016 at 23:15, shaky said:

Another slight upgrade on the gfs 18z!stronger ridge in the atlantic at 138 hours!!

I agree , stronger WAA into all the right places although it's toondifferent from the last run to know what is right or wrong. Big differences west of Greeny

Edited October 29, 2016 by Ali1977

[Ravelin]

Getting away from criticizing @knocker for posting charts that back up his particular preference, when most of us are equally as 'selective'in the other direction....

GFS 18z looks marginally better at t138 compared to it's predecessor at the same time on the 12z....

  

Small margins at this stage though.

[johnholmes]

7 minutes ago, feb1991blizzard said:

Thanks, but you are refrerring to anomaly charts surely, Nouska and yourself cleared that one up the other night, but this chart I'm talking about is the meteociel H500 +slp chart for a specific time, theres no red dotted lines on those, Take this chart here for example.

 

Notice the Trough over Scandi / Eastern Europe, surely the flow is counter clockwise around that both at surface and 500mb level, so basically, the flow on the Western flank is surely Northerly and on the Eastern flank its a southerly flow (give or take a bit, I know theres about a 15 degree difference between isobars and flow).

Yes I was referring to a post some time back (Zakos I think) using an anomaly chart, the chart you show and comment on I have no argument against what you say.

 

[Ravelin]

Getting back on track, massive differences over Canada and Greenland by t168...

  

Edited October 29, 2016 by Paul

[Barry12]

Looking a bit chilly...

[Paul]

Can we drop the personal comments please. If you want to have a conversation with someone which isn't related to the model output, then please take it to the relevant thread, or pm.

[Kieran]

18z is another good run for cold for all parts. 240+ onwards is setting up another reload of cold (similar to the 12z). I hope this pattern continues tomorrow...

[Ravelin]

Someone more experienced then me is going to have to work this one out but the differences at d10 between the GFS 18z and 12Z are massive.

  

I suppose we'll have to wait until tomorrow to see if this is a trend or a rogue run.

[feb1991blizzard]

2 minutes ago, Ravelin said:

Someone more experienced then me is going to have to work this one out but the differences at d10 between the GFS 18z and 12Z are massive.

  

I suppose we'll have to wait until tomorrow to see if this is a trend or a rogue run.

I would take the 12z and thought so from quite early on in this 18z, 12z is miles better.

 

The upper ridge wasn't sharp enough on this run.

Edited October 29, 2016 by feb1991blizzard

[Kieran]

4 minutes ago, feb1991blizzard said:

I would take the 12z and thought so from quite early on in this 18z, 12z is miles better.

I agree but both runs give us a good shot of cold with similar uppers. The 12z prolongs the cold for abit longer though. However both runs give us a second shot of cold so both runs are great IMO.

Edited October 29, 2016 by Kieran