Model discussion - hunt for cold Christmas period 2021

[Kasim Awan]

Euro 4 - follows wrf. 

[blizzard81]

Just now, Kasim Awan said:

Euro 4 - follows wrf. 

North Wales might do well

[Allseasons-Si]

6 minutes ago, Tamara said:

I do understand the feelings of UK members about the lapsed cold spell, but I am excited about the upcoming sub tropical ridge resident across my new homeland next week which looks set to produce afternoon values nudging towards and maybe even above the 21C mark and which seems surreal for the heart of winter..Its one thing having a winter break and some winter Mediterranean sun, but when its your new home it makes you stop and try to remember what month of the year it is because you are not getting on a plane back anytime.... Quite surreal for a first winter living out of the UK.

Feliz Natal x

Hi Tamara

just a quick question,do you think that this sub ridge will advance further into higher lat's with the MJO signal rebounding into higher amplitude phase 7?

PS looks to become warm down there,...enjoy and i hope that you have a great Xmas 

[blizzard81]

Some straddlers appearing on the approach to New Year. Oooooh! Meto forecast. Just need the sun to go to sleep for a while . 

[Allseasons-Si]

That is one hell of a -AO if ever you saw one

Perb 17.

[syed2878]

14 minutes ago, Kasim Awan said:

Boxing day is still 48 hours away. 1.2% chance of a flip & full on easterly. 

  I can’t see the models flipping back to any cold for most of the UK yes some of you may get snow on boxing day but for likes of Birmingham southI think it’s curtains any snow and cold in the next 48 hours

[Laurence]

1 hour ago, Kasim Awan said:

Wrf also produces a spell of marginal snow far n mids / into Peaks into northern England boxing day. Few cms over 150m here.

Come on Kasim. Roll your sleeves up and un board those windows . I had a theory came to me in the early hours of yesterday morning. It was that all the models are government run and they are cheesed of at all the independent wanna be top forecasters  who have access to them  . So over the years they have knobbled the outputs to lead these people up the proverbial garden path and humiliate them.

[Kasim Awan]

3 minutes ago, syed2878 said:

  I can’t see the models flipping back to any cold for most of the UK yes some of you may get snow on boxing day but for likes of Birmingham southI think it’s curtains any snow and cold in the next 48 hours

Do you understand what 1% means bud?

[Kasim Awan]

2 minutes ago, Laurence said:

Come on Kasim. Roll your sleeves up and un board those windows . I had a theory came to me in the early hours of yesterday morning. It was that all the models are government run and they are cheesed of at all the independent wanna be top forecasters  who have access to them  . So over the years they have knobbled the outputs to lead these people up the proverbial garden path and humiliate them.

The biggest failure would be an individual who refuses to learn from the run of events last 48h

[Cold Winter Night]

4 hours ago, MildCarlilse said:

As much as I like looking at these charts from years before computer models were invented,I ask how does anyone know what the pressure,synoptics and depths were in 1901? Are they crude extrapolation?

Just like today, the starting data come from observation and measurements and are used to calculate the state of the atmosphere at T+0h.

At many locations around the world, from fixed weather stations to moving ones like ships and airplanes, weather readings have been taken for a long time (min/max temperature, wet bulb temp, pressure, wind speed and direction). They can serve as input for modern day computer models. 20th century measurements are generally decent and reasonably spread.

Obviously there are no satellite data before the 70's and the further back you go (esp. early 20th century and into 19th century) the quality diminishes and number and density of stations as well.

[Laurence]

1 minute ago, Kasim Awan said:

The biggest failure would be an individual who refuses to learn from the run of events last 48h

I wasn't having a go Kasim as I think you are very, very good, but these models are not worth the time of day

[syed2878]

1 minute ago, Kasim Awan said:

Do you understand what 1% means bud?

  Yes I do thank you just a quick question what happened to this col spell we were supposed to be in this weekend onward where did it all go wrong The reason I ask many members on here did say don’t get taken in by those outputs yet they were shot down for their opinions

[Kasim Awan]

8 minutes ago, Laurence said:

I wasn't having a go Kasim as I think you are very, very good, but these models are not worth the time of day

Yeah pal I know you wern't, difficult to portray tone in text

The failure has given us an improved understanding of reaction to cme events etc. Hopefully this can be somehow integrated into a probabilistic forecast next time, this may be difficult as the presumstions seem mostly lacking in concrete evidence. Also that the ecm / icon better resolve uncertainties in the strength of the hadley cell and / or rapid breakdown of blocking.

That is my take away from all this.

Merry Christmas all

Edited December 24, 2021 by Kasim Awan

[Kasim Awan]

4 minutes ago, syed2878 said:

  Yes I do thank you just a quick question what happened to this col spell we were supposed to be in this weekend onward where did it all go wrong The reason I ask many members on here did say don’t get taken in by those outputs yet they were shot down for their opinions

Seen as I was one of the members who was originally more bullish about the potential, I think it's fair I provided an explanation as to why it went pete tong.

There was a last minute downgrade of trough disruption from the Atlantic low to the Scandi low due to an overactive Azores / Iberian high. Trough disruption was an important mechanism required to ensure enough linkage between the Atlantic low & Scandi trough thereby ensuring effective sliding. The resultant lack of linkage reduced cold air advection westwards out of Scandi which allowed the low to push further north east. Simply put the lack of TD ->  less easterly influence -> Atlantic low has more space to develop.

Unfortunately it was also a negative reinforcement of blocking as the strengthening of the Atlantic low helped repell any further westwards advances from Scandi. This diverted CAA advection towards Greenland.. which has the opposite effect of WAA thereby working to breakdown the Greenland high. This deteriorated the negative NAO further.

The failed trough disruption is the main cause, underlying likely to be caused by strengthening of the Azores high.

Only a 5% downgrade in the trough disruption was enough to cause complete failure. The models never failed as a collective, given some output was showing a failure. This means modelling of the result of a less optimal TD & Azores profile was correct. The problem was that models failed to detect any strengthening of the Azores / jet. This lack of detection & last minute downgrade in TD & upgrade in Azores supports the idea that a sudden solar / telleconnection event may have been responsible. 

 

[CoxR]

anyone know when AAM is forecast to rise again?

[booferking]

1 hour ago, Kasim Awan said:

Seen as I was one of the members who was originally more bullish about the potential, I think it's fair I provided an explanation as to why it went pete tong.

There was a last minute downgrade of trough disruption from the Atlantic low to the Scandi low due to an overactive Azores / Iberian high. Trough disruption was an important mechanism required to ensure enough linkage between the Atlantic low & Scandi trough thereby ensuring effective sliding. The resultant lack of linkage reduced cold air advection westwards out of Scandi which allowed the low to push further north east. Simply put the lack of TD ->  less easterly influence -> Atlantic low has more space to develop.

Unfortunately it was also a negative reinforcement of blocking as the strengthening of the Atlantic low helped repell any further westwards advances from Scandi. This diverted CAA advection towards Greenland.. which has the opposite effect of WAA thereby working to breakdown the Greenland high. This deteriorated the negative NAO further.

The failed trough disruption is the main cause, underlying likely to be caused by strengthening of the Azores high.

Only a 5% downgrade in the trough disruption was enough to cause complete failure. The models never failed as a collective, given some output was showing a failure. This means modelling of the result of a less optimal TD & Azores profile was correct. The problem was that models failed to detect any strengthening of the Azores / jet. This lack of detection & last minute downgrade in TD &im upgrade in Azores supports the idea that a sudden solar / telleconnection event may have been responsible. 

 

I'm not going to buttercup buddy it's alot more than 5% it's a complete hiding 70% or more the trough diisturbance was in question from day dot ecm and icon nailed it simples.

[Laurence]

1 hour ago, Kasim Awan said:

Seen as I was one of the members who was originally more bullish about the potential, I think it's fair I provided an explanation as to why it went pete tong.

There was a last minute downgrade of trough disruption from the Atlantic low to the Scandi low due to an overactive Azores / Iberian high. Trough disruption was an important mechanism required to ensure enough linkage between the Atlantic low & Scandi trough thereby ensuring effective sliding. The resultant lack of linkage reduced cold air advection westwards out of Scandi which allowed the low to push further north east. Simply put the lack of TD ->  less easterly influence -> Atlantic low has more space to develop.

Unfortunately it was also a negative reinforcement of blocking as the strengthening of the Atlantic low helped repell any further westwards advances from Scandi. This diverted CAA advection towards Greenland.. which has the opposite effect of WAA thereby working to breakdown the Greenland high. This deteriorated the negative NAO further.

The failed trough disruption is the main cause, underlying likely to be caused by strengthening of the Azores high.

Only a 5% downgrade in the trough disruption was enough to cause complete failure. The models never failed as a collective, given some output was showing a failure. This means modelling of the result of a less optimal TD & Azores profile was correct. The problem was that models failed to detect any strengthening of the Azores / jet. This lack of detection & last minute downgrade in TD & upgrade in Azores supports the idea that a sudden solar / telleconnection event may have been responsible. 

 

kasim you seem like a man of integrity unlike the models that fed you bullshite. Here we are Christmas eve  in what the models four weeks ago were predicting to be at least seasonal under HP ridge which then the models said would be  move west allowing the chance of frigid air to move west across the UK. You worked with what the models gave you but they are total rubbish and not to be trusted

[weathermadbarnsleylad]

I'm going to keep an eye on developments later next week around the 135hr mark from the icon 00z that's running now(image below) . This is a time when the south westerly makes its way north towards us . At the same time we have deep cold pool of -14/16 850hpa trying to drop south from Iceland area. I reckon in the future runs the south westerlys may not be has strong has forecast by the models. One to watch coldies. See what gfs shows on the 00z

[PiscesStar]

11 hours ago, KTtom said:

Almost identical to the 168 chart i posted yesterday, and the gfs 144 today. Funny how the models can suddenly find consistancy with a blow torch south westerly! You have to laugh!

I woukd if I wasnt so frustrated by the sheer folly played out by the last chase 

[nick sussex]

The GFS tries to bring something colder back se after a shortwave cuts se from the upstream trough.

The colder air returns to the n and ne before the Azores high pushes ne.

The op though only has limited GEFS support for this .

The UKMO has a shortwave further north so no joy there .

Scratching around for some other interest , the Arpege looks like it would also try and cut a shortwave se looking at its T102 hrs chart .

We await the ECM for the Christmas miracle !

Edited December 24, 2021 by nick sussex

[KTtom]

2 hours ago, PiscesStar said:

I woukd if I wasnt so frustrated by the sheer folly played out by the last chase 

Yes, hopefully lessons learnt will be don't go over the top in future and respect views from others which don't necesserily mirror yours! Talking of digging in, surely with pretty much unanimous charts like this for the turn of the year the Met will have to adjust their longer term forecast, if they don't, then they must be seeing something we don't have access to?!

 

Edited December 24, 2021 by KTtom

[mulzy]

FWIW, the day 16 GEFS mean anomaly gives some hope - albeit weak signals this far out.

Edited December 24, 2021 by mulzy

[daz_4]

Happy new year from ECM

[PiscesStar]

58 minutes ago, KTtom said:

Yes, hopefully lessons learnt will be don't go over the top in future and respect views from others which don't necesserily mirror yours! Talking of digging in, surely with pretty much unanimous charts like this for the turn of the year the Met will have to adjust their longer term forecast, if they don't, then they must be seeing something we don't have access to?!

 

I'm. Hoping for God's sake they are seeing something then.. Cos its ridiculous just how much they changed within such a short time Frame. Makes the whole thing  ridiculous in essence!! 

[mulzy]

1 hour ago, mulzy said:

FWIW, the day 16 GEFS mean anomaly gives some hope - albeit weak signals this far out.

EPS says no!  A +NAO pattern setting up according to the day 12-15 EPS mean.