Model Output Discussion - Into Winter

[Northwest NI]

1 minute ago, MJB said:

Belter 

[Northwest NI]

2 minutes ago, minus10 said:

There are no words...

There is a real sense this year that all of this, including our recent “taster” cold snap, is building up to something.

[Big Gally]

5 minutes ago, MJB said:

Belter 

[alexisj9]

46 minutes ago, rwtwm said:

No, it doesn't. But it's worth noting that ECM doesn't foresee a high amplitude MJO through phase 7/8, so I wouldn't expect the consequences to be reflected either.

This is yesterday's ECM.

There has been discussion up the thread of amplitude decay being a known bias of MJO forecasts. 

Well luckily it seems that the ECM page from which I've drawn the above has a recent history.

ECMWF | Charts

CHARTS.ECMWF.INT

 

Below is the same chart from Nov 28th and Dec 2nd:

 

 

Note the change of the amplitude in phase 5 (in particular) as we move from 1 week ago to today. Bear in mind of course that previous performance is no guarantee of future success. In the same way that if the first 3 lows miss us to the south, doesn't mean the next will.

The BOM has been posted a few times, but for quick reference, here it is again...

I've been sympathetic to the thought that highlighting the BOM feels a bit like 'cherry picking'. But I have to concede it's been consistent with this. I can't find a BOM 240 chart for our part of the world to compare (do they exist?) but that's where if be looking to test the impact of phase 7/8 on our weather, that's where I'd look.

Could be well wrong here, but perhaps BOM mjo is the southern hemisphere pattern?

[johncam]

3 minutes ago, Northwest NI said:

Yep thats what we sre looking for 

[snowsummer]

2 hours ago, E17boy said:

Dear High pressure

I am writing with reference to your movement and travels in the coming days. As you know with the news that you are heading to our shore , I would just like to put a special request in for your direction of travell. Many coldies like myself are waiting and watching you as this will have huge future impacts as to where our goods come from in the coming days.

We have many wintry products including ice, severe cold and heavy snow that are in huge demand by the coldie market here in the uk. Our main suppliers East wind in located in Siberia and NE wind in Scandinavia need a good transport infrastructure  in order to send these products here.

With all this in mind your role in where you sit will be very important. It is advised that if you could possibly set up base in Scandinavia or Greenland this will open the way to receive our goods here in time for a good Christmas present for our coldies. Your base will be secure and we would like this to be a long term setup as we have only started our sales season which we hope this will be good for the coming next 3 months. 
 

I very much hope you will look into my request with great consideration and fulfill my desire. I look forward to continuation of our relationship in the coming days. My staff GFS, ECM, CFS, UKMO and the Pub run will all be updating me daily on your movement.

Thank you again

Kind regards

Coldie market
 

 

Dear E17 Boy

With regards to the above  i can assure you i am doing my upmost to ensure that everything runs as smoothly as possible and the end results you are looking for will be met. I understand your concern after the problems that were encountered last year, but please be assured that things have changed, lessons were learned and the mistakes will not reoccur.  We have a wonderful new addition to the team this year,  EQBO,  who has already proved to be a valuable asset since taking over from the recently  departed WQBO. Also new to our team this year is El Nino. Brought in to replace La Nina  he is another valuable  asset.  Our long term team , the MJO, Downwelling and Wind Reversal among others,  now combined with our new members have changed the dynamics  completely, thus ensuring your deliveries will be with you by 21st December,  giving you plenty of time to distribute  across the WHOLE of the uk, especially  SOUTH OF THE M4! 

[Notty]

To my untrained eye the I think the AI model is on board

 

ECMWF | Charts

CHARTS.ECMWF.INT

 

Edited December 7, 2023 by Notty
Added link

[MattStoke]

18 minutes ago, Neilsouth said:

If I remember correctly, back in the 90's before the great Easterly, there was a lot of high pressure and dense FOG. Something most winters have been lacking. So just maybe a settled high would be a good thing?

I think there have been a few incidents of severe cold spells following high pressure centre over or close to the UK. Could be wrong.

[IW Met]

14 minutes ago, Scandinavian High. said:

If we do get a greeny high at some point this winter is it possible it could transfer to Scandinavia later on.

The problem with a Scandinavian high is that in a sense it isn't always a true block. What I mean is that a Greenland high is quite often an extension or part of an Arctic high, and whilst a Scandi high can also work the same way (be part of an Arctic high like Feb 2018), more often than not a Scandi high is just a mid latitude block that is propped up by low pressure over Eastern Europe or the Med, and without the "prop" it often just sinks. So a Greenland high shifting to Scandi CAN happen, it just isn't a scenario that we usually see. We do occasionally see a Westward extension of the annual Siberian high but this is usually its own unique pattern and unrelated to Northern blocking. 
So to answer the question, yes it is possible but unlikely.

 

[Met4Cast]

11 minutes ago, alexisj9 said:

Could be well wrong here, but perhaps BOM mjo is the southern hemisphere pattern?

The BOM model is still modelling the entire MJO cycle. The MJO has a more direct impact on Australian weather so in theory you’d expect them to be quite good at modelling it.

I suspect we’ll see the BOM reduce the amplification but likely we’ll see the GFS & ECM increase it. Somewhere of a middle ground perhaps. 

[damianslaw]

12 hours ago, MJB said:

Depths of FI has potential

 

JFF of course 

Do I sit up when the GFS picks up a retrogressive high and shows an incoming northerly, yes... do I sit up when the ECM shows an easterly outbreak, yes... do I sit up when they show the reverse, no..

What I'm saying is GFS is the master in picking up changing dynamics to our NW long term, it is often the trend setter in such scenarios, ECM when it comes to continental influences.

Not saying it is right, but I am not discounting it either.

[Methuselah]

34 minutes ago, Methuselah said:

A pretty dire GFS 06Z IMO. . . Dull, coldish and incredibly boring: 

    

But it is, of course, only one run!

I gather from the negative responses, that some folks find the prospect of anticyclonic gloom exciting! 

[rwtwm]

13 minutes ago, alexisj9 said:

Could be well wrong here, but perhaps BOM mjo is the southern hemisphere pattern?

The MJO is an equatorial phenomenon. The maps at the bottom of this page suggest that the range is 20°N to 20°S. I can't see anything that suggests the projection is limited in someway.

http://www.bom.gov.au/climate/enso/#tabs=Tropics

 

[Nick2373]

2 minutes ago, Methuselah said:

I gather from the negative responses, that some folks find the prospect of anticyclonic gloom exciting! 

Better than constant days of rain and flooding i suppose.

[johncam]

13 minutes ago, Met4Cast said:

The BOM model is still modelling the entire MJO cycle. The MJO has a more direct impact on Australian weather so in theory you’d expect them to be quite good at modelling it.

I suspect we’ll see the BOM reduce the amplification but likely we’ll see the GFS & ECM increase it. Somewhere of a middle ground perhaps. 

So what does that mean for us ?

[TSNWK]

34 minutes ago, minus10 said:

There are no words...

Two words..

Sixteen days!

[Met4Cast]

1 minute ago, johncam said:

So what does that mean for us ?

Essentially steady as we go. MJO continues cycling in a reasonably amplified state, the AAM continues to rise helped by this secondary +EAMT event. This next event is of interest because it could be a fairly big one, this will extend the Pacific jet eastwards causing the pattern downstream to begin amplifying.

 1. Pacific jet extends east in response to the +EAMT event

2. Trough develops downstream

3. Pattern begins to amplify downstream

4. Atlantic wave break 1 leads to a UK high (well modelled now)

5. Atlantic wave break 2 retrogresses the high northwards towards Greenland, helped along by MJO cycling through phase 6-7 combined with +GLAAM. 

[PiscesStar]

34 minutes ago, minus10 said:

There are no words...

How about Gorg jus!!!! 

[Catacol]

It's going to be hard not to become obsessed with chances for cold/snow on Xmas Day.... it would be fantastic to see a proper nationwide snow event on the 25th but even with a favourable pattern such as we have seen evolve over the last few weeks (and is continuing to evolve positively) it is an outside bet.

Anyway. The value of reading drivers and then using a point in time to reference a potential development and benchmark against op runs has been shown to be positive. At a rough count over the last several days about 75% of op runs have had a UK high in place for next weekend as pacific impacts begin to work through, and we have an EPS now for Sat 16 that is about as close to nailed on medium range forecast as we can get.

Again - note the Russian High and Aleutian Low combo.

Note also a pattern that is quite meridional across the hemisphere. This is anything but a flat picture, and the trick in our sector is to get this strong azores ridge to kick higher.

That kick doesn't just "happen." It will be the product of drivers that have been well referenced over the last few weeks, drivers that we are confident are being under represented by NWP at the moment. @Met4Cast referenced torques earlier which is one...and the MJO is another. We continue to see BOM going high amplitude - and as one of the top 3 MJO models it has credence - but ECM not following suit. At least - not yet. Others have posted these charts this morning - I won't duplicate.

If we put some weight on composites then these are worth considering. Phase 7 Dec looks like this

= significant similarity for the end of next week when compared to ENS and direction of Op runs.

Phase 8 then goes here:

Even without a great degree of amplitude in the GFS/ECM MJO forecasts we are seeing a move in this direction in the GFS extended. See Sat 23rd:

The question would be - if GFS is picking up on this now with a low amplitude pacific forecast and when we actually hit phase 7/8 the amplitude is much higher, what occurs? In a nutshell greater meridionality. So - punch that high further north, drop that low further south. Both GFS and ECM bias corrected MJO models have phase 8 being each around 19/20 December. To me the lag of this impact will be longer - so the models are over accelerating the changes that are coming. Deep cold by Xmas? Might be more a case of deep cold by New Year.

A little snip from the CPC assessment on Monday:

All good. White Xmas might be a stretch in terms of timing but not an outrageous possibility. But no bumps in the road for the overall progression - not yet anyway.

Edited December 7, 2023 by Catacol

[johncam]

2 minutes ago, Met4Cast said:

Essentially steady as we go. MJO continues cycling in a reasonably amplified state, the AAM continues to rise helped by this secondary +EAMT event. This next event is of interest because it could be a fairly big one, this will extend the Pacific jet eastwards causing the pattern downstream to begin amplifying.

 1. Pacific jet extends east in response to the +EAMT event

2. Trough develops downstream

3. Pattern begins to amplify downstream

4. Atlantic wave break 1 leads to a UK high (well modelled now)

5. Atlantic wave break 2 retrogresses the high northwards towards Greenland, helped along by MJO cycling through phase 6-7 combined with +GLAAM. 

Thank you 

[minus10]

Thats a pretty good mean signal in the extended..

[ITSY]

2 minutes ago, minus10 said:

Thats a pretty good mean signal in the extended..

Exactly. A clear northward push for HP towards Greenland and a clear southward push for part of the PV to relocate towards Scandi. 

It's basically a continued acceleration of the trend outlined earlier. 

[damianslaw]

22 minutes ago, Catacol said:

It's going to be hard not to become obsessed with chances for cold/snow on Xmas Day.... it would be fantastic to see a proper nationwide snow event on the 25th but even with a favourable pattern such as we have seen evolve over the last few weeks (and is continuing to evolve positively) it is an outside bet.

Anyway. The value of reading drivers and then using a point in time to reference a potential development and benchmark against op runs has been shown to be positive. At a rough count over the last several days about 75% of op runs have had a UK high in place for next weekend as pacific impacts begin to work through, and we have an EPS now for Sat 16 that is about as close to nailed on medium range forecast as we can get.

Again - note the Russian High and Aleutian Low combo.

Note also a pattern that is quite meridional across the hemisphere. This is anything but a flat picture, and the trick in our sector is to get this strong azores ridge to kick higher.

That kick doesn't just "happen." It will be the product of drivers that have been well referenced over the last few weeks, drivers that we are confident are being under represented by NWP at the moment. @Met4Cast referenced torques earlier which is one...and the MJO is another. We continue to see BOM going high amplitude - and as one of the top 3 MJO models it has credence - but ECM not following suit. At least - not yet. Others have posted these charts this morning - I won't duplicate.

If we put some weight on composites then these are worth considering. Phase 7 Dec looks like this

= significant similarity for the end of next week when compared to ENS and direction of Op runs.

Phase 8 then goes here:

Even without a great degree of amplitude in the GFS/ECM MJO forecasts we are seeing a move in this direction in the GFS extended. See Sat 23rd:

The question would be - if GFS is picking up on this now with a low amplitude pacific forecast and when we actually hit phase 7/8 the amplitude is much higher, what occurs? In a nutshell greater meridionality. So - punch that high further north, drop that low further south. Both GFS and ECM bias corrected MJO models have phase 8 being each around 19/20 December. To me the lag of this impact will be longer - so the models are over accelerating the changes that are coming. Deep cold by Xmas? Might be more a case of deep cold by New Year.

A little snip from the CPC assessment on Monday:

All good. White Xmas might be a stretch in terms of timing but not an outrageous possibility. But no bumps in the road for the overall progression - not yet anyway.

An excellent prognosis as per usual. Sometimes GFS can be a bit quick in showing projected direction of travel.

 As you say lets not get too fixated on prospects of a white christmas - but for many that is hard to do at this time in the year!! From a travel perspective it may be better for deep cold to arrive after it and close to New Year, still an inconvenience but less impact, a cold frosty christmas with some passing dustings of snow would be a better option in this respect. I say this with the chaos of last Saturday fresh in my mind! I also remember the run in to christmas 09 being problematic for travel. 

Anyhow getting fixated on christmas myself!! Back to watching how the evolving high pressure set up develops..

[bluearmy]

3 hours ago, northwestsnow said:

One things for sure I'm struggling to see last nights EC 46 in anything I've seen on the 00z runs...

The ens only go to end week 2. If you look at the 7 day mean 11-18 dec then ec46 is bang in line with the 3 suites

thereafter the five days 10/15 on the ens suites are very much on the same page as the ec46 18/25 dec anoms 

 

3 hours ago, Bricriu said:

The EC46 seems to change alot, but hopefully  this time it's a case of the models will quickly  change  to a more favourable outlook  to reflect what the EC46 is showing.

There is the facility to see the past two weeks of output on the 46 now to see how the charts are evolving. They don’t seem to be changing a lot to me - more of a slow evolution as time ticks down within a broad consistent macro pattern. 

[That ECM]

16 minutes ago, minus10 said:

Thats a pretty good mean signal in the extended..

With that mean, there must be some good ones.