Model output discussion - cold spell approaching?

[legritter]

Gfs is having snow chains fitted, plus a few more gaskets  ,as its going to go boom at 192 hrs ,get the sausage baps out ,and stock up ,cheers STellas on me .

[Scott Ingham]

I think people should give @Kasim Awan a break hes new to the forum and just bringing enthusiasm to party. A lot yesterday were also proclaiming a mild period was nailed on. 

Weve all done it. I think deep down we all know the models dont have a scooby doo theres been more flips than an olympic gymnast but i feel this time its someone learning excited to see an idea im his head have a chance.

Any way back to the models.

Anyone not calling a cut off Greenie high like me and Kasim should go use theweatheroutlook forum hahaha

[Kasim Awan]

12 minutes ago, Osbourne One-Nil said:

Just because a run is brilliant doesn't make it less volatile though. 

Don't fall into the trap of trying to call something early for credit later if it comes off!

I know, people are holding me to that comment, fair enough. Just happened to be one EC run which threw me off.

We all make mistakes, I'm an objective scientist aware of the logical tree of possibilities involved in this situation. Applying this logic to the model output there is a split between a 1) highly amplified, meridional pattern with clean, strong amplification to Greenland with 

2) & a semi-clean amplification to Greenland / Iceland producing less favourable synoptics for sustained cold, however keeping a southerly tracking jet & bouts of cold

3) A more stark failure of the amplification & weak cut off Greenland high unable to sustain the meridional pattern. This leading to increased Azores heights & a lack of cold air. 

Ultimately a middle ground (2) is favoured using the ensemble, median forecasting logic. However this approach is flawed statistically because probabilities say there is a chance of either (1) or (3) materializing too, so these must be considered as viable. Now, sometimes in forecasting human interpretation of model output is required to resolve model biases. In this instance, the GFS has been demonstrated to have a stronger grasp of Greenland heights. So it's support for a strong amplification here adds support but does not guarantee this outcome. To conclude, another episode of increased amplification towards Greenland with a strong potential for colder conditions as an outcome, however stark uncertainty with regards to the dynamics of the amplification and as a result > surface conditions in the UK. Until more robust model data is made available, nothing more can be argued imo unless someone has a credible model bias argument.

Edited January 11, 2021 by Kasim Awan

[Djdazzle]

Just now, Met4Cast said:

Cross model agreement at T48? That's optimistic!

The 15th seems to be the "tipping point", once that low phasing is resolved we'll either be heading into the freezer with a good Greenland block, or the pattern will collapse and the cold wont be able to get into the UK, there isn't really a middleground scenario for this one. 

The fun will probably continue for a couple more days yet..

If that's the choice, It's usually pretty clear what the outcome will be!

Let's see what the UKMO shows, as it's getting within its range now.

[nick sussex]

Whilst we’re waiting for the GFS 12hrs run the Arpege  might raise some eyebrows for northern parts, the East Midlands and inland parts of East Anglia fringing into the ne of London .

[Frostbite1980]

8 minutes ago, Scott Ingham said:

I think people should give @Kasim Awan a break hes new to the forum and just bringing enthusiasm to party. A lot yesterday were also proclaiming a mild period was nailed on. 

Weve all done it. I think deep down we all know the models dont have a scooby doo theres been more flips than an olympic gymnast but i feel this time its someone learning excited to see an idea im his head have a chance.

Any way back to the models.

Anyone not calling a cut off Greenie high like me and Kasim should go use theweatheroutlook forum hahaha

To be fair I am new to posting and when I call things are not necessarily going the cold way I got questioned on it because it wasn't what people wanted to hear. 

Again the 12z's will be interesting and think they could go either way but its the means we need to look at and I would want to see a decent improvement from earlier as IMO they are going the wrong way if you want cold at present.

Edited January 11, 2021 by Frostbite1980

[georgiedre]

7 minutes ago, legritter said:

Gfs is having snow chains fitted, plus a few more gaskets  ,as its going to go boom at 192 hrs ,get the sausage baps out ,and stock up ,cheers STellas on me .

Are we already up 2 192hrs?

[Nick F]

Even if we get a Greenland block, one thing I'm keeping an eye on that could be a spoiler to get the deep cold down from the N or NE, which had been hinted in the GFS PARA, is a strong jet stream cranking up across N America early next week - which then extends east over the Atlantic. A strong jet could undercut the Greenland block, but if the block is too far north, it allows the jet to move a little too far north over NW Europe to allow the deep cold to flood the UK from the N and NE. The deepening lows on a strengthening jet may bring the risk of a snowstorm wherever the low tracks, but if the low tracks too far north, the south is bathed in rain and milder air.

Still, the jet may remain weak over the Atlantic, so the threat of deepening lows undercutting a Greenland black will be low, and this allows the deep cold to flood S or SW unimpeded - this seems the more likely option for now, but can't rule out the higher risk but perhaps high reward of a snowstorm for some northern areas,

Edited January 11, 2021 by Nick F

[Tim Bland]

3 minutes ago, nick sussex said:

Whilst we’re waiting for the GFS 12hrs run the Arpege  might raise some eyebrows for northern parts, the East Midlands and inland parts of East Anglia fringing into the ne of London .

Consider my eyebrows raised  

[Scott Ingham]

Just now, Frostbite1980 said:

To be fair I am new to posting and when I call things are not necessarily going the cold way I got questioned on it because it wasn't what people didn't want to hear. 

Again the 12z's will be interesting and think they could go either way but its the means we need to look at and I would want to see a decent improvement from earlier as IMO they are going the wrong way if you want cold at present.

And its wrong as well.

The only time its right is when you have 95% for an outcome n someone trolls a scenario with a 5% chance of happening. 

I respect him because like me hes made a call a forecast and left himself out to dry.

A lot will snipe but dont have the balls to puy their rep on the line!

Myself i dont care what people think.

I have seamless confidence in my methods and let the models prove it right or wrong but if ye feels that strongly it will be the final outcome thats his opinion whether you like it or not

[Methuselah]

7 minutes ago, Kasim Awan said:

I know, people are holding me to that comment, fair enough. Just happened to be one EC run which threw me off.

We all make mistakes, I'm an objective scientist aware of the logical tree of possibilities involved in this situation. Applying this logic to the model output there is a split between a 1) highly amplified, meridional pattern with clean, strong amplification to Greenland with 

2) & a semi-clean amplification to Greenland / Iceland producing less favourable synoptics for sustained cold, however keeping a southerly tracking jet & bouts of cold

3) A more stark failure of the amplification & weak cut off Greenland high unable to sustain the meridional pattern

Ultimately a middle ground (2) is favoured using the ensemble, median forecasting logic. However this approach is flawed statistically because probabilities say there is a chance of either (1) or (3) materializing too.

Said the dalek, as he forlornly climbed off the dustbin!

[Scott Ingham]

7 minutes ago, nick sussex said:

Whilst we’re waiting for the GFS 12hrs run the Arpege  might raise some eyebrows for northern parts, the East Midlands and inland parts of East Anglia fringing into the ne of London .

Chart??

Dm ive seen! Amazing!

Edited January 11, 2021 by Scott Ingham

[MKN]

Just now, Scott Ingham said:

Chart??

[Frostbite1980]

5 minutes ago, Scott Ingham said:

And its wrong as well.

The only time its right is when you have 95% for an outcome n someone trolls a scenario with a 5% chance of happening. 

I respect him because like me hes made a call a forecast and left himself out to dry.

A lot will snipe but dont have the balls to puy their rep on the line!

Myself i dont care what people think.

I have seamless confidence in my methods and let the models prove it right or wrong but if ye feels that strongly it will be the final outcome thats his opinion whether you like it or not

Totally agree with that, just wish ALL input was accepted and not just that in favour of what people want! Although I like the possibility of snow down hear in 3 days

[mountain shadow]

Met Office 120 hours. Could go either way here...

[Scott Ingham]

1 minute ago, MKN said:

Backs up met office with 15-30cm weather warning!!!

[sheikhy]

2 minutes ago, MKN said:

Gives leicester 8 to 10cms of snow!!!

[danm]

I agree with all the comments saying nothing is nailed on until it's within t48 etc, however I think the point has been made now and we should move on. 

[Battleground Snow]

Ukmo steadies the ship somewhat at 144 with the low cut off... I'll be glad to see the back of this little pain in the ass feature!

 

[Kasim Awan]

Just now, danm said:

I agree with all the comments saying nothing is nailed on until it's within t48 etc, however I think the point has been made now and we should move on. 

Yeah, depends on what you mean is "nailed on". Within 20 hours for a hi res trough / volatile front, within 100 hours for the macro placement of lows, within 140 hours for the overall synoptic pattern.

[Spah1]

UKMO 144. 
 

Heading to Greenland ?!?!

[Paul]

GFS still delayed, this the latest from NCEP

Quote

We are having a connection issue between our supercomputer and downstream NOMADS/FTPPRD dissemination services. Our teams are working to resolve and all data should be available the connection issue is fixed.

 

[mountain shadow]

T144 looks good to me..

[Daniel]

Very good ukmo it manages to cut the low off 

[phil nw.]

10 minutes ago, nick sussex said:

Whilst we’re waiting for the GFS 12hrs run the Arpege  might raise some eyebrows for northern parts, the East Midlands and inland parts of East Anglia fringing into the ne of London .

Could be something in that Nick.

Thursdays fax  

showing that wave development along the front.Coming back west with a cold undercut-something to watch for.